TY - GEN A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Yfantis, Alexandros D. A1 - Batchelor, David R. A1 - Appel, Günter A1 - Schmeißer, Dieter T1 - A Spectro-Microscopic Approach for Thin Film Analysis Grain Boundaries in mc-Si and Sn/SnO2 Nano Particles T2 - Microchimica Acta Y1 - 2001 SN - 1436-5073 SN - 0026-3672 VL - 136 IS - 3-4 SP - 109 EP - 113 ER - TY - GEN A1 - Müller, Klaus A1 - Paloumpa, Ioanna A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - A polymer high-k dielectric insulator for organic field effect Transistors T2 - Journal of Applied Physics Y1 - 2005 SN - 0021-8979 VL - 98 IS - 5 SP - S. 056104 ER - TY - JOUR A1 - Schmitt, Andrew L. A1 - Zhu, Lei A1 - Schmeißer, Dieter A1 - Himpsel, Franz J. A1 - Jin, Song T1 - Metallic Single-Crystal CoSi Nanowires via Chemical Vapor Deposition of Single-Source Precursor Y1 - 2006 ER - TY - JOUR A1 - Schmitt, Andrew L. A1 - Bierman, Matthew J. A1 - Schmeißer, Dieter A1 - Himpsel, Franz J. A1 - Jin, Song T1 - Synthesis and Properties of Single-Crystal FeSi Nanowires Y1 - 2006 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Henkel, Karsten A1 - Müller, Klaus A1 - Tallarida, Massimo T1 - Interface Reactions in Ultrathin Functional Dielectric Films KW - ultrathin KW - dielectric Y1 - 2009 ER - TY - GEN A1 - Lazareva, I. A1 - Koval, Yuri A1 - Müller, P. A1 - Müller, Klaus A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Interface screening and imprint in pol(vinylidene fluoride/trifluoroethylene) ferroelectric field effect transistors KW - interface KW - screening KW - transistors Y1 - 2009 ER - TY - CHAP A1 - Müller, Klaus A1 - Burkov, Yevgen A1 - Mandal, Dipankar A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Goryachko, Andriy A1 - Schmeißer, Dieter ED - Wöll, Christof T1 - Microscopic and spectroscopic characterization of interfaces and dielectric layers for OFET devices T2 - Organic Electronics : structural and Electronic Properties of OFETs KW - microscopic KW - spectrocsopic KW - dielectric Y1 - 2009 SN - 978-3-527-40810-8 SP - 445 EP - 468 PB - Wiley-VCH CY - Weinheim ER - TY - GEN A1 - Tallarida, Massimo A1 - Karavaev, Konstantin A1 - Schmeißer, Dieter T1 - HfO2/Si interface formation in atomic layer deposition films: an in situ investigation KW - atomic layer deposition Y1 - 2009 ER - TY - JOUR A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Schmeißer, Dieter T1 - Si(001) surface oxidation by N2O N2 - Ultra-thin homogeneous oxynitride films are prepared on Si(001). The Si surface is cleaned in UHV by heating (flashing) and is exposed to different pressures of N2Oat altered temperatures. Thus oxynitride layers of different thickness and different properties are grown depending on the N2O pressure and the Si temperature. This isillustrated by a schematic diagram. The properties of the different oxynitride layers were studied by a combined photoemission electron microscopy (PEEM) andphotoelectron spectroscopy (PES) investigation using highly monochromatic synchrotron radiation. The amount of oxygen and nitrogen incorporated in the oxynitridelayers is determined from the PES measurements. The typical surface morphology for different preparation conditions is shown in PEEM images. KW - SI(100) KW - dielectric KW - Oxynitride KW - Interface KW - SI KW - NO Y1 - 2002 ER - TY - JOUR A1 - Schmeißer, Dieter A1 - Hoffmann, Patrick T1 - Characterisation of the PrOx/Si(001) Interface by Photoelectron Spectroscopy Y1 - 2002 ER - TY - GEN A1 - Henkel, Karsten A1 - Sohal, Rakesh A1 - Torche, Mohamed A1 - Paloumpa, Ioanna A1 - Müller, Klaus A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Grenzflächenoptimierung für funktionale Dünnschichtsysteme: Oxide und Polymere T2 - Forum der Forschung Y1 - 2005 SN - 0947-6989 VL - 9 IS - 18 SP - 49 EP - 56 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Himpsel, Franz J. A1 - Denlinger, Jonathan D. A1 - Ederer, David L. T1 - Resonante Photoemission an der Cu2p Kante von Cu und CuO T2 - Forum der Forschung Y1 - 2005 SN - 0947-6989 VL - 9 IS - 18 SP - 57 EP - 62 ER - TY - JOUR A1 - Müller, Klaus A1 - Burkov, Yevgen A1 - Schmeißer, Dieter T1 - Photo-Emission-Electron-Microscopy for Characterization of an Operating Organic Electronic Device KW - photo-emission-electron-microscopy Y1 - 2006 ER - TY - JOUR A1 - Schmeißer, Dieter T1 - The Consequences of anisotropic Diffusion and Noise: PEEM at the CO Oxidation Reaction on Stepped Ir(111) Surfaces KW - Ir(111) Surfaces Y1 - 2006 ER - TY - GEN A1 - Müller, Klaus A1 - Henkel, Karsten A1 - Mandal, Dipankar A1 - Seime, Bernd A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Spin coated organic ferroelectric films for non volatile memories KW - organic KW - ferroelectric Y1 - 2011 ER - TY - GEN A1 - Seifarth, Olaf A1 - Schubert, Markus Andreas A1 - Giussani, A. A1 - Klenov, D. O. A1 - Schmeißer, Dieter A1 - Schroeder, Thomas T1 - Single crystalline Pr2-xYxO3 (x=0-2)dielectrics on Si with tailored electronic and crystallographic structure KW - crystalline KW - dielectric KW - structure Y1 - 2010 SN - 1089-7550 VL - 108 IS - 10 SP - 103709 ER - TY - GEN A1 - Mandal, Dipankar A1 - Henkel, Karsten A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Band gab determination of P(VDF-TrFE) copolymer film by electron energy loss spectroscopy Y1 - 2010 ER - TY - GEN A1 - Kolanek, Krzysztof A1 - Tallarida, Massimo A1 - Karavaev, Konstantin A1 - Schmeißer, Dieter T1 - In situ studies of the atomic layer deposition of thin HfO2 dielectrics by ultra high vacuum atomic force microscope KW - in situ KW - atomic layer deposition KW - dielectric KW - microscope Y1 - 2010 ER - TY - JOUR A1 - Schmeißer, Dieter A1 - Seibold, Götz A1 - Reif, Jürgen T1 - Nano-scaled Dielectric Barriers (NanoDieB) for CMOS compatible Si-technologies JF - Forum der Forschung KW - nano-scaled KW - dielectric KW - CMOS Y1 - 2006 SN - 0947-6989 IS - 19 SP - 131 EP - 136 ER - TY - CHAP A1 - Starzyk, Łukasz A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Band alignment of high-k/SiO2/Si stacks incorporating Zr and Al oxides prepared by atomic layer deposition Y1 - 2010 ER - TY - GEN A1 - Kolanek, Krzysztof A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Atomic layer deposition of HfO2 investigated in situ by means of a noncontact atomic force microscopy Y1 - 2010 ER - TY - CHAP A1 - Gehrlich, Lukas A1 - Ohsiek, Susanne A1 - Klein, M. A1 - Geiss, M. A1 - Friedemann, Michael A1 - Kücher, Peter A1 - Schmeißer, Dieter T1 - Ultrathin TaN/Ta barrier modifications to fullfill next technology node requirements T2 - 2011 IEEE International Interconnect Technology Conference and 2011 Materials for Advanced Metallization (IITC/MAM 2011), Dresden, Germany, 8 - 12 May 2011 Y1 - 2011 SN - 978-1-4577-0503-8 U6 - https://doi.org/10.1109/IITC.2011.5940322 SP - 82 EP - 84 PB - IEEE CY - Piscataway, NJ ER - TY - CHAP A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Philip, Shine A1 - Paloumpa, Ioanna A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Study of P3HT/PCBM based films by NEXAFS T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45 N2 - In this contribution we report on investigations of the electronic structure and composition of regioregular poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) based films by using Near Edge X-Ray Absorption Fine Structure (NEXAFS). The measurements were done at the U49/2-PGM2 beam line of BESSY II, Berlin using TEY (total electron yield) and TFY (total fluorescence yield) detection. The samples were produced by spin casting a mixture of P3HT (dissolved in chloroform) and PCBM (dissolved in chlorobenzene) on ITO (indium tin oxide) coated glass slides. Measurements of pure P3HT and PCBM show all typical excitations, whereas the blended system is a weighted superposition of the related peaks. Analyzing these weighted superposition, we observe in the surface sensitive TEY data an accumulation of P3HT, whereas in the bulk sensitive TFY signal an as expected mixture is found. We also show angular dependent NEXAFS measurements of the P3HT/PCBM blend in order to measure the orientation and distribution of the P3HT polymer. Additionally, we will show a new approach for organic solar cell application by introducing ferroelectric nanoparticles into the mixture. Y1 - 2010 UR - http://www.dpg-verhandlungen.de/year/2010/conference/regensburg/part/df/session/7/contribution/4 SN - 0420-0195 SP - S. 194 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Schmidt, Stephan A1 - Schmeißer, Dieter T1 - Cobalt/nickel mixed oxides - cathode materials for Li-Ion-Batteries T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45 N2 - Replacing Co by large amounts of Ni is considered to reduce costs in Li-Ion-Batteries while maintaining their performance. We are interested in whether this replacement causes changes in the valence band (VB) and conduction band (CB) states or not. Samples were prepared as thin films from nitrate solutions on metal substrates and annealed in air and UHV. The Co to Ni ratio was varied from 50/50 over 40/60 and 30/70 up to 20/80. The results are compared to the pure Co-oxide. Experiments were carried out at the U49/2 beamline at BESSYII, Berlin. XPS of the TM2p states reveals the existence of charge transfer ground states and different oxidation states. NEXAS at the Co2p, Ni2p and O1s edges projects the density of unoccupied states while resonant PES at these edges provides the related partial density of states (pDOS) and thus can be used to distinguish between the different contributions of TM3d and O2p states in the valence band region. We find systematic variation of the VB structure, the valence band maximum and a shift at the O1s absorption edge while the TM2p XPS and absorption spectra do not seem to be affected by the mixing. Y1 - 2010 UR - http://www.dpg-verhandlungen.de/year/2010/conference/regensburg/part/o/session/45/contribution/6 SN - 0420-0195 SP - S. 596 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, P. A1 - Chowdhury, F. A1 - Dremov, V. A1 - Koval, Yuri A1 - Lichtenberg, F. A1 - Müller, S. A1 - Schmeißer, Dieter A1 - Pentcheva, R. T1 - Resistive memory switching in perovskite-derivative single crystals T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43 N2 - We investigated several layered perovskite derivatives of the family AnBnO3n+2, such as LaTiO3.41, CaNbO3.41 and SrNbO3.41, which can be considered as a stacking of blocks consisting of 5 perovskite layers. Electric transport across these layers takes place via intrinsic tunnelling. Mesa devices with a cross-sectional area of 50 to 200 µm2 and a height between 30 and 500 nm were fabricated by electron-beam lithography and ion-beam etching. Both dc I-V characteristics and pulsed current injection have shown switching between different resistive states in these materials. The resistive states have long-term stability, which makes them interesting for memory applications. The transport experiments suggest that switching and resistive memory are controlled by trapping and release of charge carriers. Furthermore, photoelectron and NEXAFS spectroscopy of cleaved LaTiO3.41 surfaces have been performed. The results are compared to recent correlated band theory (LDA+U) calculations. Y1 - 2008 UR - http://www.dpg-verhandlungen.de/year/2008/conference/berlin/part/synf/session/1/contribution/11 SN - 0420-0195 SP - S. 818 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Müller, K. A1 - Goryachko, Andriy A1 - Burkov, Yevgen A1 - Schwiertz, Carola A1 - Ratzke, Markus A1 - Köble, J. A1 - Reif, Jürgen A1 - Schmeißer, Dieter T1 - Scanning Kelvin probe and photoemission electron microscopy of organic source-drain structures T2 - Synthetic Metals Y1 - 2004 VL - 146 IS - 3 SP - 377 EP - 382 ER - TY - GEN A1 - Das, Chittaranjan A1 - Richter, Matthias A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Electronic properties of atomic layer deposited films, anatase and rutile TiO2 studied by resonant photoemission spectroscopy T2 - Journal of Physics D: Applied Physics N2 - The TiO2 films are prepared by atomic layer deposition (ALD) method using titanium isopropoxide precursors at 250 °C and analyzed using resonant photoemission spectroscopy (resPES). We report on the Ti2p and O1s core levels, on the valence band (VB) spectra and x-ray absorption spectroscopy (XAS) data, and on the resonant photoelectron spectroscopy (resPES) profiles at the O1s and the Ti3p absorption edges. We determine the elemental abundance, the position of the VB maxima, the partial density of states (PDOS) in the VB and in the conduction band (CB) and collect these data in a band scheme. In addition, we analyze the band-gap states as well as the intrinsic states due to polarons and charge-transfer excitations. These states are found to cause multiple Auger decay processes upon resonant excitation. We identify several of these processes and determine their relative contribution to the Auger signal quantitatively. As our resPES data allow a quantitative analysis of these defect states, we determine the relative abundance of the PDOS in the VB and in CB and also the charge neutrality level. The anatase and rutile polymorphs of TiO2 are analyzed in the same way as the TiO2 ALD layer. The electronic properties of the TiO2ALD layer are compared with the anatase and rutile polymorphs of TiO2. In our comparative study, we find that ALD has its own characteristic electronic structure that is distinct from that of anatase and rutile. However, many details of the electronic structure are comparable and we benefit from our spectroscopic data and our careful analysis to find these differences. These can be attributed to a stronger hybridization of the O2p and Ti3d4s states for the ALD films when compared to the anatase and rutile polymorphs. KW - titanium dioxide (TiO2) KW - resonant photoemission spectroscopy (resPES) KW - defect states KW - partial density of states (pDOS) KW - charge neutrality level (CNL) Y1 - 2016 U6 - https://doi.org/10.1088/0022-3727/49/27/275304 SN - 0022-3727 SN - 1361-6463 VL - 49 IS - 27 SP - 275304-1 EP - 275304-17 ER - TY - CHAP A1 - Müller, Klaus A1 - Milko, Sergey A1 - Burkov, Yevgen A1 - Schmeißer, Dieter T1 - Mischkristalle des Systems ZnS-CuInS2 für multispektrale Solarzellen T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Wir haben CuInS2 (CIS) unterschiedlicher Herstellung (Koverdampfung, Sputtern, Pulsed Laser Deposition, CIS auf Kupferband aufgebracht) untersucht. Neben Tiefenprofilen (durch Sputtern) der Elementverteilung dieser Proben wurden der Einfluss der Temperatur, von aufgedampftem Kupfer und Indium, ebenfalls bei verschiedenen Temperaturen, auf das Verhalten der Stöchiometrie mit spektroskopischen Methoden (XPS, UPS) studiert. Parallel dazu wurde das Verhalten von im Vakuum aufgedampften ZnS und die entsprechenden Oberflächenreaktionen in Abhängigkeit von der Temperatur untersucht und charakterisiert, so dass Aussagen über die Optimierung und Anpassung von Präparationsbedingungen und Parametern zur Herstellung von erstens reinem CIS und zweitens von Mischkristallen des Typs Zn2-xCuxInxS2 möglich werden. Zwischen den beiden Endgliedern ZnS und CuInS2 besteht bis auf einen Phasenübergang bei etwa 80% CIS lückenlose Mischbarkeit gemäss Zn2-xCuxInxS2 (Bente: Chem.Erde (1991)). Die elektronische Bandlücke dieser Mischkristalle lässt sich im Vergleich zu reinem CuInS2 in einem Bereich von 3,67 eV (ZnS) bis 1,55 eV (CuInS2) variieren. Damit besteht die Möglichkeit, durch kontrollierte Änderung der Zusammensetzung der Schichten die Effizienz von Solarzellen aus diesem Material zu optimieren. KW - CIS-Solarzellen KW - Röntgen-Photoelektronenspektroskopie KW - Tiefenprofilierung Y1 - 2002 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Heller, Thomas A1 - Lopez, Alberto A1 - Bitzer, Thomas A1 - Richardson, Neville V. A1 - Schmeißer, Dieter T1 - The Adsorption of Maleic Anhydride on Si(100)-2x1: A Combined HREELS and NEXAFS Study T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Due to the growing range of applications for organic materials considerable interest has been focused on the controlled growth of films on silicon substrates. Recently, it has been shown that ultra-thin oligimide films can be grown on Si(100)-2x1 with a direct Si-C linkage to the substrate. In this study, we have focused on the chemisorption of maleic anhydride (C4O3H2) on Si(100)-2x1. The combined HREELS data indicate that the adsorption of maleic anhydride on Si(100)-2x1 at low dosages occurs mainly through cycloaddition of the C=C bond to the dangling bonds of the Si-Si dimer analogous to the behaviour of ethene. The Si-Si dimer bonds are not involved in the chemisorption, as the continued observation of a 2x1 pattern in LEED shows. In the NEXAFS spectra, a π* resonance indicative of a C=C bond is absent upon exposure of the silicon substrate to maleic anhydride. At higher dosages, we observe chemisorbed maleic anhydride species, which are bonded to the Si surface atoms via a single Si-C linkage with preservation of the C=C double bond. In this case, the dissociated hydrogen bonds to one of the neighbouring Si atoms. Possible adsorption geometries will be discussed. KW - adsorption KW - maleic anhydride KW - High resolution electron energy loss spectroscopy (HREELS) KW - low-energy electron diffraction (LEED) KW - Near-edge X-Ray absorption spectroscopy (NEXAFS) Y1 - 2000 UR - http://www.dpg-verhandlungen.de/year/2000/conference/regensburg/part/o/session/11/contribution/56?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Schmeißer, Dieter A1 - Kittler, Martin T1 - Spektro-Mikroskopie auf multikristallinem Silizium T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Es werden spektro-mikroskopische Untersuchungen an multikristallinem Silizium (mc-Si) vorgestellt, einem aussichtsreichen Material für die Herstellung preiswerter Solarzellen. Dazu wird ein Photoemissions- Elektronenmikroskop (PEEM) ausgestattet mit einem zusätzlichen Energieanalysator für Elektronen (µESCA) genutzt. Bei Verwendung eines Synchrotrons als Anregungsquelle ist es so möglich, sowohl Absorbtions-Spektren (NEXAFS) als auch Photoelektronen-Spektren (PES) mit Ortsauflösung zu erhalten. Dabei wird gezeigt, dass das natürliche Oxid zur Untersuchung der morphologie-abhängigen Oberflächenpotentiale nicht entfernt werden muss. Des Weiteren wird die Verteilung von Ca- und Na-Ausscheidungen, die auf dem mc-Si gefunden wurden, durch ortsaufgelöstes NEXAFS bzw. PES dargestellt. Für den Photoemissions-Prozess des mc-Si im PEEM wird ein Modell aufgestellt, welches Photoemission mit einer Quecksilberdampflampe (hνmax = 4,9 eV) erklärt. KW - mc-Si KW - Solarzellen KW - Röntgen-Photoelektronenspektroskopie (XPS) KW - Röntgen-Absorptionsspektroskopie (XAS, NEXAFS) KW - Photoemissionselektronenspektroskopie (PEEM) Y1 - 2000 UR - http://www.dpg-verhandlungen.de/year/2000/conference/regensburg/part/hl/session/16/contribution/10?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Mikalo, Ricardo Pablo A1 - Appel, Günter A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Conducting Polypyrrole doped with Phthalocyaninesulfonates - new materials for chemical sensors T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Polypyrrole - a conducting polymer - is used as an active electrode of a quartz micro ballance and considered as a gate electrode in all-polymer field effect transistors used as chemical sensor. We use substituted phthalocyanines as dopants of polypyrrole as they offer the possibility to enhance the dopant concentration as well as to include functionalized groups. We studied these films by photoelectron spectroscopy, NEXAFS, PEEM, and TEM. These investigations revealed that the electronic structure as well as the morphology are highly dependent on the dopant’s structure. We suggest a new charge transport model for 5-ring heterocycle conductive polymers. Whereas in the standard model only the carbon backbone is considered for the charge transport, we found by NEXAFS investigations that the heteroatom has a considerable high participation in the gap states, which are responsible for the charge transport. The dopants π-interactions force the nitrogen lone pair wave functions to contribute to the conducting polymer π-system. This is a novel approach concerning the application as chemical sensors since the reversible interaction of the analyte modifies the dopant and not the matrix. KW - polypyrrole KW - conducting polymer KW - X-ray photoelectron spectroscopy (XPS) KW - X-Ray absorption spectroscopy (XAS) KW - photo emission electron spectroscopy (PEEM) KW - transmission electron microscopy (TEM) KW - quartz crystal micro ballance (QMB) KW - gas sensor Y1 - 2000 UR - http://www.dpg-verhandlungen.de/year/2000/conference/regensburg/part/o/session/15/contribution/1?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Hoffmann, Patrick A1 - Böhme, Oliver A1 - Schmeißer, Dieter A1 - Lloyd Spetz, Anita A1 - Mårtenson, Per T1 - Einfluß von Nanopartikeln auf die Funktion von Hochtemperatursensoren T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Es werden Untersuchungen an als Hochtemperatur-Sensoren arbeitenden Schottky-Dioden mit dem Aufbau Metall-Oxidschicht-Siliziumkarbid vorgestellt. Dazu wurden Tiefenprofile mit XPS durch abwechselndes Abtragen durch Sputtern und Messen erstellt. Die Messungen erfolgten an thermisch unterschiedlich vorbehandelten Proben. Dabei konnten dipol-bedingte Verschiebungen der Bindungsenergie von Rumpfniveaus beobachtet werden. Das dazu notwendige Dipol-Moment wird durch das Entstehen von mit einer Oxidschicht überzogenen Nanoteilchen erklärt. Die unterschiedlich ausgeprägten Dipol-Verschiebungen auf den einzelnen Proben erlaubten eine Erklärung der thermischen Vorbehandlung, die bei Weglassen zu „frischen“ und je nach Temperatur zu „aktivierten“ oder „toten“ Sensoren führte. KW - Hochtemperatursensoren KW - Röntgen-Photoelektronenspektroskopie (XPS) KW - Tiefenprofilierung Y1 - 1999 UR - http://www.dpg-verhandlungen.de/year/1999/conference/muenster/part/o/session/16/contribution/1?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Mikalo, Ricardo Pablo A1 - Appel, Günter A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Leitfähiges Polypyrrol als Elektrodenmaterial: Wechselwirkungen mit Silber T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Untersuchungen des metallischen Kontaktes von Silber auf tosylat- und phthalocyanindotiertem Polypyrrol wurden mittels XPS- und µ-NEXAFS vorgenommen. Es wurde festgestellt, daß Silber mit dem Polypyrrol keine Verbindung eingeht. Daraus kann geschlossen werden, daß sowohl das leitfähige Polymer, als auch das Silber ihren Leitfähigkeitsmechanismus beibehalten. Es konnte gezeigt werden, daß bei steigender Silberbelegung die Intensität der Polaronenzustände des Polypyrrol in stärkerem Maße abnimmt, als die Intensität der unbesetzten Zustände. Das läßt darauf schließen, daß Silber die Grenzfläche stabilisiert. KW - Polypyrrol KW - leifähiges Polymer KW - Röntgen-Photoelektronenspektroskopie (XPS) KW - Röntgen-Absoprtionsspektroskopie (XAS, NEXAFS) Y1 - 1999 UR - http://www.dpg-verhandlungen.de/year/1999/conference/muenster/part/o/session/11/contribution/57?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Heller, Thomas A1 - Böhme, Oliver A1 - Schmeißer, Dieter T1 - Gap - Zustände in Wolframoxid WO3 - relaxierten Oberflächen T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Vorgestellt werden Arbeiten an dünnen WO3-Schichten, die durch Verdampfen aus einer Knudsenzelle im UHV präpariert wurden. Diese Filme sind im Rahmen der XPS-Analysen stöchiometrisch, ohne Gap-Zustände. Definierte Gap-Zustände bilden sich durch Relaxierung der Oberfläche: nach einigen Stunden im UHV, nach Heizen in Argon-Atmosphäre und nach Belegung mit Natrium. Die Charakterisierung dieser definierten Wolframoxid-Schichten erfolgt durch: 1.)XPS-Intensitäten 2.)detailierte Analyse der W4f-Rumpfniveaus durch Synchrotronstrahlung (Bessy, TGM 7) 3.)die Variation der Austrittsarbeit beim Heizen und bei Natrium-Belegung 4.)das Auftreten von Gap-Zuständen in der Bandlücke KW - WO3 KW - Röntgen-Photoelektronenspektroskopie (XPS) KW - Gapzustände Y1 - 1998 UR - http://www.dpg-verhandlungen.de/year/1998/conference/regensburg/part/o/session/11/contribution/102?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Schmeißer, Dieter T1 - PEEM-Untersuchung an Spaltflächen von MoTe2-(0001) T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Molybdänditellurid (MoTe2) gehört zu den Schichtgitterverbindung und ist im allgemeinen durch den Herstellungsprozeß n-dotiert. Proben dieses MoTe2 wurden im Ultrahochvakuum gespalten und die so erhaltenen sauberen (0001)-Spaltflächen mit einem Photoemissions-Elektronenmikroskop (PEEM) untersucht. Diese Untersuchung erbrachte nebeneinander auf den Proben- oberflächen liegende stark kontrastierte helle und dunkle Bereiche. Da das PEEM Austrittsarbeitsunterschiede als Kontrast darstellt, können diese hellen und dunklen Bereiche auf lokale Unterschiede in der Austrittsarbeit zurückgeführt werden. Weiterhin wird über den Versuch berichtet, eine Zuordnung zwischen dem Kontrast und dem Unterschied in der Austrittsarbeit mit Hilfe eines Elektronenenergie-Analysators (micro-ESCA) zu treffen. KW - MoTe2 KW - Photoemissionselektronenspektroskopie (PEEM) KW - Austrittsarbeit Y1 - 1998 UR - http://www.dpg-verhandlungen.de/year/1998/conference/regensburg/part/o/session/5/contribution/5?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Łobaza, Justyna A1 - Kot, Małgorzata A1 - Schmeißer, Dieter T1 - Analysis of surface oxidation of TiON ALD films T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Titanium oxynitride (TiON) films are interesting due to their remarkable optical and electronic properties which strongly depend on the O/N ratio. However, it is known that films containing Ti are prone to oxidation in contact with the air [1]. In this work, we study the thickness of a surface oxidation layer which is inherently formed on the atomic layer deposition (ALD) grown TiON/TiN films on Si substrate. We use an Ar+ ion bombardment source and X-ray photoelectron spectroscopy (XPS) for this analysis. We calibrate the sputter rate by using substrate signal intensity decay (here Si 2p) in the XPS spectra of the 5 nm thick TiON sample accordingly. This rate is assumed to be constant when films with a larger thickness are analyzed. We find that the surface oxidation layer is about 1 nm thick, independent on the detailed ALD parameters of the films. The TiN films found underneath are close to the stoichiometric values and have a residual O content below 5%. Finally, we compare these data to our previous results collected with synchrotron-based radiation source [2,3]. References: [1] Sowinska et al., Applied Physics Letters 100, 233509 (2012). [2] M. Sowinska et al., Applied Surface Science 381, 42-47 (2016). [3] M. Sowińska et al., Journal of Vacuum Science and Tech- nology A, 01A12734 (2016). KW - titanium oxynitride KW - X-Rax photoelectron spectroscopy KW - depth profiling KW - sputtering Y1 - 2017 UR - http://www.dpg-verhandlungen.de/year/2017/conference/dresden/part/ds/session/21/contribution/7 SN - 0420-0195 SP - S. 202 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Schmeißer, Dieter A1 - Janowitz, Christoph T1 - Two polarization dependent Auger decays observed by resonant photoelectron spectroscopy at the Cu2p-edge of superconducting BiSrCu-oxides T2 - Nuclear Instruments and Methods in Physics Research B N2 - We report on a resonant photoemission (resPES) study of PbxBi2-xSr2-yLayCan-1CunO2n+4+d (BISCO) single crystals to unravel the resonant decay mechanisms at the Cu2p absorption edge. The resPES studies on superconducting BISCO are performed at Bessy U49/2. We investigated BISCO single crystals with different hole doping concentrations at temperatures between 300 K and 17 K. CuO films have been used as a reference. We focus on the resPES data recorded at the Cu2p absorption edge. We find a strong polarization dependence for in-plane and out-of-plane geometries (with respect to the Cu-O plane) in our data which are caused by two independent Auger processes. We also report on the influence of different doping concentrations. Our resPES data enable us to sort the individual resonant mechanisms at the Cu2p edge in more detail than recently anticipated (Brookes et al., 2015). We discuss our data in the context of the recent discussion about the applicability of the Zhang-Rice model (Chen et al., 2013). KW - Synchrotron radiation KW - Superconductor KW - Cuprates KW - Resonant photoemission Y1 - 2017 U6 - https://doi.org/10.1016/j.nimb.2017.01.084 SN - 0168-583X SN - 1872-9584 VL - 411 SP - 53 EP - 56 ER - TY - CHAP A1 - Garain, Samiran A1 - Henkel, Karsten A1 - Mandal, Dipankar A1 - Schmeißer, Dieter T1 - One-Pot Synthesis of Copper Oxide Nanowires and PVDF/CuO Composite Films for Piezoelectric Energy Harvesting Application T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Band 53,3 N2 - Copper oxide (CuO) is an attractive p-type oxide semiconductor with narrow band gap that has intriguing properties such as non-toxicity, chemical stability, electrocatalytic activity, abundant availability and low production cost. Polymeric materials have attracted great interest owing to their high flexibility, light weight, low cost production and high resistance against corrosion. Poly(vinylidene fluoride) (PVDF) is a commonly used piezoelectric polymer due to its excellent flexibility and piezoelectric properties. In this work, we adopted a one-pot synthesis of CuO nanowires by facile and selective chemical etching process of Cu substrate. XPS, XRD, SEM data ascribed the formation of polycrystalline CuO nanowires over the entire Cu surface. It has been observed that the uniformity, shape and size of the nanowires could be conveniently controlled by etching time and etchant concentration. We have also prepared piezoelectric nanogenerator based on the flexible PVDF/CuO composite film, where the traditional electrical poling treatment was avoided. In addition, dielectric properties have been studied to demonstrate the role of interfacial polarization. KW - PVDF KW - electroactive phase KW - nanogenerators KW - energy storage Y1 - 2018 UR - https://www.dpg-verhandlungen.de/year/2018/conference/berlin/part/cpp/session/20/contribution/21 SN - 0420-0195 SP - S. 135 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Kot, Małgorzata A1 - Naumann, Franziska A1 - Garain, Samiran A1 - Poźarowska, Emilia A1 - Gargouri, Hassan A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Aluminum nitride films prepared by plasma atomic layer deposition using different plasma sources T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Band 53,3 N2 - Aluminum nitride (AlN) thin films are promising for versatile applications in optoelectronics, electronics, piezoelectrics, and acoustics due to their remarkable properties such as wide band gap, high dielectric constant, low electrical conductivity, good piezoelectric coefficient and high ultrasonic velocity. We present a comparative study of AlN films grown by plasma-enhanced atomic layer deposition at 350°C silicon wafers in the SENTECH SI ALD LL system using TMA and NH3 where either a capacitively coupled plasma (CCP) or a direct PTSA (planar triple spiral antenna) source was applied. The films were characterized by ellipsometry, XPS and electrical measurements. The layer properties are discussed concerning the varied ALD process parameters. In general, the process using the direct PTSA source delivered films with higher refractive index and better homogeneity over the wafer achieving also higher growth rates per cycle (GPC) in reduced total cycle durations. Films with refractive index in the range of 2.05 and permittivity around 8 could be realized with a GPC of 1.54 Å/cycle. KW - Aluminium nitride KW - plasma-enhanced atomic layer deposition (PEALD) KW - ellispsometry KW - field emission scanning electron microscopy KW - atomic force microscopy KW - X-ray photoelectron spectroscopy KW - electrical characterization Y1 - 2018 SN - 0420-0195 SP - S. 170 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Kot, Małgorzata A1 - Kegelmann, Lukas A1 - Kus, Peter A1 - Tsud, Nataliya A1 - Matolínová, Iva A1 - Albrecht, Steve A1 - Matolin, Vladimir A1 - Schmeißer, Dieter T1 - Room temperature atomic layer deposition for perovskite solar cells T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Band 53,3 N2 - After few years of efficiency driven research on perovskite solar cells, the focus now is shifting to understand the underlying processes governing the high efficiency and also to obtain long-term stable devices. Among various deposition methods, atomic layer deposition (ALD) may represent one of the best options, being possible to coat substrates in a very efficient way and at very low temperatures. In our previous work [1] we reported that the efficiency of the solar cell containing aged perovskite film can be enhanced twice while covering the perovskite with a thin ALD alumina film at room temperature. In this work, the chemical, electronic and morphological properties of the fresh perovskite film treated by ALD pulses of the trimethylaluminium and water at room temperature investigated using X-ray Photoelectron Spectroscopy and Field Emission Scanning Electron Microscopy will be discused and correlated with the solar cells performance and stability. [1] M. Kot et al., ChemSusChem 2016, 9, 3401. KW - Perovskite solar cells KW - atomic layer deposition KW - X-Ray photoelectron spectroscopy (XPS) KW - atomic force microscopy KW - field emission scanning electron microscopy KW - photo-conversion efficiency Y1 - 2018 SN - 0420-0195 SP - S. 174 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Schmeißer, Dieter A1 - Kot, Małgorzata A1 - Corrêa, Silma Alberton A1 - Das, Chittaranjan A1 - Henkel, Karsten ED - Wandelt, Klaus T1 - Interface Potentials, Intrinsic Defects, and Passivation Mechanisms in Al₂O₃, HfO₂, and TiO₂ Ultrathin Films T2 - Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, vol. 3.1 N2 - We study the electronic structure of ultrathin Al₂O₃, HfO₂, and TiO₂ ALD films by resonant photoelectron spectroscopy. We identify intrinsic defects which are responsible for the active sites in interface reactions, for the incorporation of intrinsic charges, and for the formation of local dipole momenta. All of these features determine the surface potentials and the reactivity of the surface of the atomic layer deposition coated systems. We give examples of charges and dipoles in Al₂O₃, on a study of the surface potentials in HfO₂, and relate the intrinsic defects in TiO₂ to their electrochemical relevance. KW - Atomic layer deposition (ALD) KW - Resonant photoelectron spectroscopy (resPES) KW - Band scheme KW - Interface potential KW - Intrinsic charges KW - Intrinsic defects KW - Partial density of states (pDOS) KW - Exciton KW - Polaron KW - Ligand-to-metal charge transfer KW - Aluminium oxide (Al₂O₃) KW - Hafnium oxide (HfO₂) KW - Titanium Oxide (TiO₂) Y1 - 2018 SN - 978-0-12-809739-7 SN - 978-0-12-814984-3 U6 - https://doi.org/10.1016/B978-0-12-409547-2.14119-8 SP - 162 EP - 171 PB - Elsevier CY - Oxford ER - TY - GEN A1 - Biswas, Anirban A1 - Garain, Samiran A1 - Maity, Kuntal A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Mandal, Dipankar T1 - Influence of In situ Synthesized Bismuth Oxide Nanostructures in Self-poled PVDF-based Nanogenerator for Mechanical Energy Harvesting Application T2 - Polymer Composites N2 - A self-poled piezoelectric nanogenerator (NG) based on bismuth oxide (Bi2O3) nanostructures (BNS)-doped poly(vinylidene fluoride) (PVDF) is demonstrated. The in-situ formation of BNS incorporated in the PVDF matrix is realized through a simple solution casting technique that favors the nucleation and stabilization of 99.6% of the electroactive phase in PVDF (i.e., beta/gamma-phases). The enhancement of the output voltage (3.6 V) and current (2.4mA) of the NG based on a nonelectrically poled BNS containing PVDF composite film is achieved and demonstrated by simple repeated human finger imparting. The improvement of the output performance is influenced by the generation of the electroactive polar beta-phase in PVDF, due to the electrostatic interactions between the –CH2–/–CF2– dipoles of PVDF and the surface charge of the BNS. The NGs are able to charge up capacitors demonstrating that the power generation from such a hybrid device structure can be utilized for powering various portable devices. KW - Nanogenerators KW - energy harvesting KW - PVDF KW - bismuth oxide KW - Field-emission scanning electron microscopy (FESEM) KW - X-ray photoelectron spectroscopy (XPS) KW - X-ray diffraction (XRD) KW - Fourier Transform Infrared Spectroscopy (FTIR) Y1 - 2019 U6 - https://doi.org/10.1002/pc.24628 SN - 0272-8397 SN - 1548-0569 VL - 40 IS - S1 SP - E265 EP - E274 ER - TY - GEN A1 - Das, Chittaranjan A1 - Kot, Małgorzata A1 - Hellmann, Tim A1 - Wittich, Carolin A1 - Mankel, Eric A1 - Zimmermann, Iwan A1 - Schmeißer, Dieter A1 - Nazeeruddin, Mohammad Khaja A1 - Jaegermann, Wolfram T1 - Atomic Layer-Deposited Aluminum Oxide Hinders Iodide Migration and Stabilizes Perovskite Solar Cells T2 - Cell Reports Physical Science N2 - Iodide migration causes degradation of the perovskite solar cells. Here,we observe the direct migration of iodide into the hole-transport layer in a device. We demonstrate that ultrathin room temperature atomic layer-deposited Al2O3 on the perovskite surface very effectively hinders the migration. The perovskite-Al2O3 interface enables charge transfer across the Al2O3 layer in the solar cells, without causing any drastic changes in the properties of the perovskite absorber. Furthermore, it helps to preserve the initial properties of the perovskite film during exposure to light and air under real operating conditions, and thus, improves the stability of the solar cells. The ultrathin Al2O3 layer deposited at room temperature significantly increases the lifetime of the perovskite solar cells, and we hope this may be a step toward the mass production of stable devices. KW - perovskite solar cells KW - iodine migration KW - stability KW - X-ray photoelectron spectroscopy (XPS) KW - atomic layer deposition (ALD) KW - aluminum oxide (Al2O3) Y1 - 2020 U6 - https://doi.org/10.1016/j.xcrp.2020.100112 SN - 2666-3864 VL - 1 IS - 7 ER - TY - GEN A1 - Kot, Małgorzata A1 - Kegelmann, Lukas A1 - Köbler, Hans A1 - Vorokhta, Mykhailo A1 - Escudero, Carlos A1 - Kúš, Peter A1 - Šmíd, Břetislav A1 - Tallarida, Massimo A1 - Albrecht, Steve A1 - Abate, Antonio A1 - Matolínová, Iva A1 - Schmeißer, Dieter A1 - Flege, Jan Ingo T1 - In situ Near-Ambient Pressure X-ray Photoelectron Spectroscopy Reveals the Influence of Photon Flux and Water on the Stability of Halide Perovskite T2 - ChemSusChem N2 - For several years, scientists have been trying to understand the mechanisms that reduce the long‐term stability of perovskite solar cells. In this work, we examined the effect of water and photon flux on the stability of CH3NH3PbI3 perovskite films and solar cells using in situ near‐ambient pressure X‐ray photoelectron spectroscopy (NAP‐XPS), field emission scanning electron microscopy (FESEM), and current density–voltage (J–V) characterization. The used amount of water vapor (up to 1 mbar) had a negligible impact on the perovskite film. The higher the photon flux, the more prominent were the changes in the NAP‐XPS and FESEM data; also, a faster decline in power conversion efficiency (PCE) and a more substantial hysteresis in the J‐V characteristics were observed. Based on our results, it can be concluded that the PCE decrease originates from the creation of Frenkel pair defects in the perovskite film under illumination. The stronger the illumination, the higher the number of Frenkel defects, leading to a faster PCE decline and more substantial hysteresis in the J‐V sweeps. KW - field emission scanning electron microscopy (FESEM) KW - Frenkel defects KW - near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) KW - perovskite KW - photon-induced degradation Y1 - 2020 U6 - https://doi.org/10.1002/cssc.202001527 SN - 1864-5631 SN - 1864-564X VL - 13 IS - 21 SP - 5722 EP - 5730 ER - TY - GEN A1 - Ghosh, Sujoy Kumar A1 - Sinha, Tridib Kumar A1 - Xie, Mengying A1 - Bowen, Christopher Rhys A1 - Garain, Samiran A1 - Mahanty, Biswajit A1 - Roy, Krittish A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Kim, Jin Kuk A1 - Mandal, Dipankar T1 - Temperature–Pressure Hybrid Sensing All-Organic Stretchable Energy Harvester T2 - ACS Applied Electronic Materials N2 - The design and development of intrinsically stretchable all-organic self-powered sensors concurrently perceiving temperature and pressure remain a challenge but deliver an exciting platform to realize environmentally friendly wearable electronics. In this approach, a biomimetic all-organic stretchable energy harvester is designed by a xylitol-added poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS/Xyl) film as a compatible overlay electrode with polyaniline-reinforced one-dimensional aligned poly(vinylidene fluoride) hybrid electroactive soft nanowires. The gradient of elastic modulus between the electrode and the active nanowire component enables the all-organic device to manifest excellent power-generating performance under external temperature fluctuation (∼3 μW/m2 under ΔT ∼ 92 K) and mechanical force (∼31 μW/cm2 at 30 N). Importantly, the device renders simultaneous energy scavenging of temperature and pressure changes under pressing and stretching conditions (∼20%). The excellent mechanosensitivity (∼100 mV/N), fast response time (∼1 ms), outstanding mechanical and thermal stability, and good temperature resolution <10 K enable the harvester to act as an epidermal sensor, which simultaneously detects and discriminates both subtle pressure and thermal deviations exposed to an epidermis surface. The real-time recording and wireless transferring of physiological signals to a smartphone indicate an effective way to realize remote healthcare monitoring for early intervention. KW - all-organic KW - piezoelectric KW - pyroelectric KW - energy harvester KW - sensor KW - healthcare monitoring Y1 - 2021 U6 - https://doi.org/10.1021/acsaelm.0c00816 SN - 2637-6113 VL - 3 IS - 1 SP - 248 EP - 259 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Müller, Klaus A1 - Henkel, Karsten T1 - Photosensitive and Rectifying Properties of Ga2O3 Described by Polaronic Screened Electrons and Internal Potentials T2 - Journal of Physical Chemistry C N2 - The photosensitive and rectifying properties of Ga2O3 are described by (n-type) intrinsic (π-) electrons. These polaronic screened multiatomic carriers populate the intrinsic defect states within the ionic gap; their spectroscopic evidence is based on resonant photoemission spectroscopy data that also provide the ionicity factor of Ga2O3 and the size of the ionic gap. The π-electron density depends on the internal potential and its photo- and field-induced dipole contributions, and it describes the observed combined ohmic-exponential carrier densities and current–voltage dependences. The π-electron dynamics is caused by pairing and dissociation dipoles in the bulk of Ga2O3. The material properties of the electrode contribute via external chemical potentials and define the criteria for ohmic and rectifying contacts. This quantitative and predictive concept not only convinces by perfect agreement with published experimental data but also points toward the achievable performance limits of UV absorbers and rectifying devices. KW - Resonant photoelectron spectroscopy KW - quantitative π-electron densities KW - multi-atomic quasi-particles KW - photosensitivity and rectifier devices Y1 - 2023 U6 - https://doi.org/10.1021/acs.jpcc.3c05785 SN - 1932-7447 SN - 1932-7455 VL - 127 IS - 47 SP - 23077 EP - 23089 ER - TY - GEN A1 - Henkel, Karsten A1 - Oprea, A. A1 - Paloumpa, Ioanna A1 - Appel, Günter A1 - Schmeißer, Dieter A1 - Kamieth, P. T1 - Selective polypyrrole electrodes for quartz microbalances : NO2 and gas flux sensitivities T2 - Sensors and Actuators : B, Chemical 76(2001)1-3 Y1 - 2001 SN - 0925-4005 VL - 76 IS - 1-3 SP - 124 EP - 129 ER - TY - CHAP A1 - Batchelor, David R. A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter A1 - Hulea, Iulian A1 - Brinza, Monica T1 - The Al-Fe interface of friction-welded joints T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The interface region of friction-welded joints Al-Fe samples is investigated by scanning Auger Spectroscopy, Electron Probe Micro-analysis (EPMA), X-ray Photoelectron spectroscopy, and Photoemission Electron Microscopy, performed at the synchrotron light source (BESSY). We investigated polished samples cut to obtain a cross-section of the Al-Fe joints. At the Al-Fe interface there is a small number of Fe teeth protuding into the adjacent Al-matrix. Beside this mechanical interlock mechanism we identify an Fe-Al alloy which is formed in an almost homogeneous interface layer of approximately 80 micron thickness. We determine the valence band spectra within that layer and notice that the alloying formation is limited to the interface region. In addition, the profile of both, the Fe and O distribution within the Al next to that interface is determined. A model of the friction-welding mechanism is derived and discussed in terms of the ability of achieving low temperature Fe-Al joints. KW - Fe-Al interface KW - friction-welded KW - X-ray photoelectron spectroscopy (XPS) KW - photoemission electron microscopy (PPEM) KW - scanning Auger spectroscopy KW - electron probe micro-analysis (EPMA) Y1 - 2000 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Rachow, Fabian A1 - Hagendorf, Moritz A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Synthesis of Methanol from CO2 for Power-to-Liquid applications T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The direct synthesis of methanol [CO2+3H2->CH3OH+H2O] represent a possibility to reduce the global CO2-emission by recycling the CO2 and also to store excess energy from renewable energy sources into a common fuel or chemical feedstock (Power-to-Liquid). For an acceptable conversion rate of CO2 a catalyst is needed, together with high temperatures (>200°C) and high pressure (50-200bar). Methanol is normally produced form synthesis gas, a mixture of CO and H2. By directly using CO2 for the exothermic reaction, we avoid the conversion of CO2 to CO by the reversed water gas shift reaction. We also present new concepts for the conversion from CO2-rich flue gases, eliminating the need for a separation of the CO2. The concept is backed up by measurements in laboratory scale. Here we use a Cu−ZnO catalyst on a ZrO2 substrate prepared by impregnation and compare the results with commercially available catalysts. We achieved a conversion of around 7% and a selectivity of 60% at a temperature of 240°C and 45bar. The reaction is thermodynamically limited with a maximum conversion rate of 15% at 250°C and 50bar. The conversion and the selectivity towards methanol is highly influenced by the catalyst used, the temperature, the pressure as well as the flow rate of the reactants. KW - direct methanol synthesis KW - power to liquide KW - Cu-ZnO catalyst KW - CO2 utilization Y1 - 2017 UR - http://www.dpg-verhandlungen.de/year/2017/conference/muenster/part/ake/session/8/contribution/5 SP - S. 256 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Henkel, Karsten A1 - Kot, Małgorzata A1 - Schmeißer, Dieter T1 - Localized defect states and charge trapping in Al₂O₃ films prepared by atomic layer deposition T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The evaluation of the electronic structure and intrinsic defect mechanisms in Al₂O₃ thin films is essential for their effective use in applications with desired functionality such as surface passivation schemes for solar cells [1]. We present a comparative study of different Al₂O₃ films grown by atomic layer deposition (ALD) [2]. The layers were deposited on different substrates using the same aluminum precursor (TMA, trimethylalumium) and employing different process parameters (thermal-ALD, plasma-enhanced-ALD, substrate temperature). These films were characterized by resonant photoelectron spectroscopy and by electrical measurements (capacitance-voltage). For all films investigated intrinsic defect states within the electronic band gap were observed including excitonic, polaronic, and charge-transfer defect states, where their relative abundance is subject of the choice of ALD parameters and of the used substrate. The spectroscopic assigned in-gap defect states are related with electronic charges as determined in the electrical measurements. [1] G. Dingemans and W.M.M. Kessels, J. Vac. Sci. Technol. A 30, 040802 (2012). [2] K. Henkel, M. Kot, D. Schmeißer, J. Vac. Sci. Technol. A 35, (2017), accepted. KW - defect states KW - Al₂O₃ KW - resonant photoelectron spectroscopy KW - X-Ray absorption spectroscopy KW - capacitance-voltage measurements Y1 - 2017 UR - http://www.dpg-verhandlungen.de/year/2017/conference/dresden/part/ds/session/32/contribution/4 SN - 0420-0195 SP - S. 205 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Richter, Matthias R. A1 - Cheng, Wen-Hui A1 - Crumlin, Ethan J. A1 - Drisdell, Walter S. A1 - Atwater, Harry A. A1 - Schmeißer, Dieter A1 - Lewis, Nathan S. A1 - Brunschwig, Bruce S. T1 - X‑ray Photoelectron Spectroscopy and Resonant X‑ray Spectroscopy Investigations of Interactions between Thin Metal Catalyst Films and Amorphous Titanium Dioxide Photoelectrode Protection Layers T2 - Chemistry of Materials N2 - The use of electrochemistry, X-ray photoelectron spectroscopy, and resonant X-ray spectroscopy has unlocked the paradox of interfacial hole conduction through amorphous TiO2 (a-TiO2) to deposited Ni, Ir, and Au metal catalysts. Although electrocatalysts for the oxygen-evolution reaction derived from metallic Ir and Ni have mutually similar overpotentials in alkaline media, Si/a-TiO2/Ir interfaces exhibit higher overpotentials than Si/a-TiO2/Ni interfaces. The data allow formulation of full band energy diagrams for n-Si/a-TiO2/metal interfaces for M = Ni, Ir, or Au. Although both Ni and Ir produce band bending in a-TiO2 favoring hole conduction, only Ni creates multiple states within the a-TiO2 band gap at the a-TiO2/Ni interface, which produces a quasi-metallic interface at the a-TiO2/Ni junction. Au, however, produces a flat-band interface that limits hole conduction without any new band gap states. KW - X‑ray Photoelectron Spectroscopy KW - Resonant X‑ray Spectroscopy KW - titanium oxide KW - oxygen-evolution reaction KW - protection layer KW - interface interaction Y1 - 2021 U6 - https://doi.org/10.1021/acs.chemmater.0c04043 SN - 0897-4756 SN - 1520-5002 VL - 33 IS - 4 SP - 1265 EP - 1275 ER - TY - CHAP A1 - Kot, Małgorzata A1 - Wojciechowski, Konrad A1 - Snaith, Henry J. A1 - Schmeißer, Dieter T1 - Characterization of the perovskite solar cells containing atomic layer deposited Al2O3 buffer layer T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft e.V. N2 - Hybrid perovskites have potential to overcome performance limits of the current solar cell technologies and achieve low cost and high versatility. Nonetheless, they are prone to degradation in presence of moisture within a couple of hours or days. In this work, we use the atomic layer deposition (ALD) of Al2O3 on the CH3NH3PbI3 perovskite at room temperature in order to verify if this thin ALD layer may protect the perovskite film against moisture degradation and to check the impact of the Al2O3 on the solar to power conversion efficiency (PCE). Depth profiling X-ray photoelectron spectroscopy study shows that the ALD precursors are chemically active only at the perovskite surface and the film bulk is not affected. The perovskite film coated with Al2O3 layer has enhanced moisture stability. Solar cells with a fresh-made CH3NH3PbI3 perovskite film have shown PCE of 15.4%, while the one with 50 days aged perovskite only 6.1%. However, when the aged perovskite is covered with RT-ALD-Al2O3 the PCE value is clearly enhanced.[1] [1] M. Kot et al., Room temperature ALD impact on efficiency, stability and surface properties in perovskite solar cells, ChemSusChem,acctepted. KW - Perovskite solar cell KW - atomic layer deposition KW - Al2O3 KW - efficiency recovery Y1 - 2017 UR - http://www.dpg-verhandlungen.de/year/2017/conference/dresden/part/cpp/session/38/contribution/5 SN - 0420-0195 SP - S. 147 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Israel, Johannes A1 - Rachow, Fabian A1 - Schwiertz, Carola A1 - Charlafti, Evgenia A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Direct CO2-Methanation of flue gas emitted by conventional power plants T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The catalytic conversion of CO2 with H2 into CH4 is possible by the Sabatier reaction CO2+4H2→CH4+2H2O. Using excess energy from renewable electricity generation, this approach offers an opportunity for recycling of CO2 as synthetic natural gas. In a new concept, we investigate the performance of the Sabatier reaction as direct methanation of flue gas, emitted by conventional power plants. We investigate the Sabatier process in an upscaled system, with a maximum input flow rate of 45 Nm3/h Gas. The performance is investigated in a simulated composition of flue gas and under real conditions at a lignite power plant in Schwarze Pumpe, Brandenburg, Germany. We can achieve a CO2-conversion of up to 90%, with approx. 100% selectivity towards CH4. Under flue gas conditions and at a certain limit of gas flow the system is operated at an autothermal running modus, a steady state equilibrium of exothermic heat production and thermal flow that needs neither external annealing nor cooling. KW - CO2 KW - methanation KW - Sabatier reaction KW - power plant KW - Schwarze Pumpe KW - autothermal mode Y1 - 2017 UR - http://www.dpg-verhandlungen.de/year/2017/conference/muenster/part/ake/session/8/contribution/5 SP - S. 255 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Klaus A1 - Israel, Johannes A1 - Rachow, Fabian A1 - Schmeißer, Dieter ED - Ramirez Reina, Tomas ED - Odriozola, José Antonio ED - Arellano-Garcia, Harvey T1 - Sabatier-Based Direct Synthesis of Methane and Methanol Using CO2 from Industrial Gas Mixtures T2 - Engineering Solutions for CO2 Conversion KW - Sabatier reaction KW - CO2 emission reduction KW - industrial CO2 sources Y1 - 2021 SN - 978-3-527-34639-4 SP - 253 EP - 280 PB - Wiley-VCH CY - Weinheim ET - 1 ER - TY - GEN A1 - Mahmoodinezhad, Ali A1 - Janowitz, Christoph A1 - Naumann, Franziska A1 - Plate, Paul A1 - Gargouri, Hassan A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Flege, Jan Ingo T1 - Low-temperature growth of gallium oxide thin films by plasma-enhanced atomic layer deposition T2 - Journal of Vacuum Science and Technology A N2 - Gallium oxide (Ga2O3) thin films were deposited by plasma-enhanced atomic layer deposition (PEALD) applying a capacitively coupled plasma source where trimethylgallium (TMGa) as the gallium precursor and oxygen (O2) plasma were used in a substrate temperature (Ts)in the range of 80–200 °C. TMGa exhibits high vapor pressure and therefore facilitates deposition at lower substrate temperatures. The Ga2O3 films were characterized by spectroscopic ellipsometry (SE), x-ray photoelectron spectroscopy (XPS), and capacitance-voltage (C-V) measurements. The SE data show linear thickness evolution with a growth rate of ∼0.66 Å per cycle and inhomogeneity of ≤2% for all samples. The refractive index of the Ga2O3 thin films is 1.86 ± 0.01 (at 632.8 nm) and independent of temperature, whereas the bandgap slightly decreases from 4.68 eV at Ts of 80 °C to 4.57 eV at 200 °C. XPS analysis revealed ideal stoichiometric gallium to oxygen ratios of 2:3 for the Ga2O3 layers with the lowest carbon contribution of ∼10% for the sample prepared at 150 °C. The permittivity of the layers is 9.7 ± 0.2 (at 10 kHz). In addition, fixed and mobile oxide charge densities of 2–4E12 and 1–2E12 cm−2, respectively, were observed in the C-V characteristics. Moreover, the Ga2O3 films show breakdown fields in the range of 2.2–2.7 MV/cm. Excellent optical and electrical material properties are maintained even at low substrate temperatures as low as 80 °C. Hence, the TMGa/O2 PEALD process is suitable for electronic and optoelectronic applications where low-temperature growth is required. KW - Plamsa enhanced atomic layer deposition (PEALD) KW - low-temperature growth KW - gallium oxide (Ga2O3) KW - x-ray photoelectron spectroscopy KW - spectroscopic ellipsometry KW - capacitance voltage measurements Y1 - 2020 U6 - https://doi.org/10.1116/1.5134800 SN - 0734-2101 SN - 1520-8559 VL - 38 IS - 2 ER - TY - GEN A1 - Maity, Kuntal A1 - Garain, Samiran A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Mandal, Dipankar T1 - Self-Powered Human-Health Monitoring through Aligned PVDFNanofibers Interfaced Skin-Interactive Piezoelectric Sensor T2 - ACS Applied Polymer Materials N2 - Flexible and wearable e-skin sensors are attracting a great interest for their smart sensing applications in next-generation electronics. However, implant ability, sensitivity, and biosignal detection capability in a self-powered manner are the prime concerns in embedded devices. In particular, electrode compatibility and imperishability have become challenging issues in wearable sensors due to the poor compatibility and fragileness of metal electrodes. In this context, we report on a skin-interactive metal-free spongy electrode in a piezoelectric sensor where highly aligned poly(vinylidenefluoride) (PVDF) nanofibers (NFs) arrays are introduced as the piezoelectric active component and conducting polyaniline- (PANI-) coated PVDF (PANI−PVDF) NFs mats served as flexible electrodes. Notably, a 99% yield of piezoelectric phases of the aligned PVDF arrays is the key factor to exhibit promising mechano-sensitivity (0.8 V/kPa) performance that in turn helps in human-health monitoring. The sensor shows excellent mechanical to electrical energy conversion that enable to sense human finger touch (10 V under 10 kPa) with energy conversion efficiency of 53%. Most importantly, due to the compatible electrodes excellent mechanical stability has been found showing negligible degradation over 12,000 periodic cycles. Furthermore, under mechanical stimuli, it is also possible to charge up a capacitor (1μF) to 4 V within 60 s confirming the possibility to use the device as a self-powered piezo-organic-e-skin sensor (POESS). This type of structural design enables to trace elusive movement of muscles and the operation in several conditions such as bending, compression and stretching. We demonstrated various human gestures monitoring, such as wrist bending, neck stretching, and arm compressions, throat movements during drinking water, coughing actions, and swallowing. In addition, diverse specific phonation recognition, heart-pulse measurement and its respective short-time Fourier transform (STFT) analysis indicate an efficient and convenient way of monitoring human-health status particularly in hospital-free mode. KW - e-skin sensor KW - piezoelectric nanofibers KW - PVDF KW - flexible electrode KW - health-care monitoring KW - self-powered electronics Y1 - 2020 U6 - https://doi.org/10.1021/acsapm.9b00846 SN - 2637-6105 VL - 2 IS - 2 SP - 862 EP - 878 ER - TY - GEN A1 - Kot, Małgorzata A1 - Vorokhta, Mykhailo A1 - Wang, Zhiping A1 - Snaith, Henry J. A1 - Schmeißer, Dieter A1 - Flege, Jan Ingo T1 - Thermal stability of CH3NH3PbIxCl3-x versus [HC(NH2)2]0.83Cs0.17PbI2.7Br0.3 perovskite films by X-ray photoelectron spectroscopy T2 - Applied Surface Science N2 - The thermal stability of CH3NH3PbIxCl3-x and [HC(NH2)2]0.83Cs0.17PbI2.7Br0.3 perovskite films was studied in-situ by X-ray photoelectron spectroscopy. It was found that below 85 °C both of them are relatively stable. After annealing above 85 °C, we observe a clear perovskite surface decomposition, i.e., a release of organic cations and creation of “metallic lead”. The mixed cation lead mixed halide perovskite, however, decomposes at a much lower rate. For both perovskite films, the metallic to the total lead ratio changes with the same rate for the same annealing temperatures. The release of A-site cations from the ABX3 crystal structure of perovskite and/or creation of “metallic lead” causes also a small shift of the valence band maximum towards the Fermi level. The release of [HC(NH2)2]± or Cs± is not as significant as the release of CH3NH3±; therefore, it may explain why [HC(NH2)2]0.83Cs0.17PbI2.7Br0.3 solar cells are thermally more stable. Therefore, as the stability of CH3NH3PbIxCl3-x is same as the stability of [HC(NH2)2]0.83Cs0.17PbI2.7Br0.3 below 85 °C, there must be more severe degradation pathways that are currently underappreciated on the solar cell level. KW - Hybrid organic inorganic perovskite solar cells KW - X-ray photoelectron spectroscopy KW - Film degradation KW - Thermal stability Y1 - 2020 U6 - https://doi.org/10.1016/j.apsusc.2020.145596 SN - 0169-4332 SN - 1873-5584 VL - 513 ER - TY - GEN A1 - Kot, Małgorzata A1 - Henkel, Karsten A1 - Naumann, Franziska A1 - Gargouri, Hassan A1 - Tarnawska, Lidia Lupina A1 - Wilker, Viola A1 - Kus, Peter A1 - Pożarowska, Emilia A1 - Garain, Samiran A1 - Rouissi, Zied A1 - Schmeißer, Dieter T1 - Comparison of plasma-enhanced atomic layer deposition AlN films prepared with different plasma sources T2 - Journal of Vacuum Science and Technology A N2 - A comparative study of thin aluminum nitride (AlN) films deposited by plasma-enhanced atomic layer deposition in the SENTECH SI ALD LL system applying either a direct inductively coupled plasma (ICP) or an indirect capacitively coupled plasma (CCP) source is presented. The films prepared with the ICP source (based on a planar triple spiral antenna) exhibit improved properties concerning the growth rate per cycle, total cycle duration, homogeneity, refractive index, fixed and mobile electrical charges, and residual oxygen content compared to the CCP source, where the comparison is based on the applied plasma power of 200 W. The increase of the plasma power to 600 W in the ICP process significantly reduces the residual oxygen content and enhances the electrical breakdown field. The AlN layers grown under these conditions, with a growth rate per cycle of 1.54 Å/cycle, contain residual oxygen and carbon concentrations of about 10% and 4%, respectively, and possess a refractive index of 2.07 (at 632.8 nm). KW - Plamsa-enhanced atomic layer deposition (PEALD) KW - inductively coupled KW - capacitively coupled KW - plamsa source KW - ellipsometry KW - X-ray photoelectron spectroscopy (XPS) KW - X-ray diffraction (XRD) KW - Field emission scanning electron microscopy (FESEM) KW - capacitance-voltage (CV) KW - atomic force microscopy Y1 - 2019 U6 - https://doi.org/10.1116/1.5079628 SN - 0734-2101 SN - 1520-8559 VL - 37 IS - 2 ER - TY - GEN A1 - Kotwica, Tomasz A1 - Domaradzki, Jarosław A1 - Wojcieszak, Damian A1 - Sikora, Andrzej A1 - Kot, Małgorzata A1 - Schmeißer, Dieter T1 - Analysis of surface properties of Ti-Cu-Ox gradient thin films using AFM and XPS investigations T2 - Materials Science-Poland N2 - The paper presents results of investigations on surface properties of transparent semiconducting thin films based on (Ti-Cu)oxide system prepared using multi-magnetron sputtering system. The thin films were prepared using two programmed profiles of pulse widt hmodulation coefficient, so called V- and U-shape profiles. The applied powering profiles allowed fabrication of thin films with gradient distribution of Ti and Cu elements over the thickness of deposited layers. Optical investigations allowed determination of transparency of prepared films that reached up to 60 % in the visible part of optical radiation, which makes them attractive for the transparent electronics domain. Surface properties investigations showed that the surface of mixed (Ti-Cu)oxides was sensitive to adsorption, in particular to carbon dioxide and water vapor. Soft etching with argon ions resulted in surface cleaning from residuals, however, deoxidation of Cu-oxide components was also observed. KW - surface KW - gradient distribution KW - thin film oxide Y1 - 2019 U6 - https://doi.org/10.2478/msp-2018-0100 SN - 0137-1339 SN - 2083-1331 SN - 2083-134X VL - 36 IS - 4 SP - 761 EP - 768 ER - TY - GEN A1 - Janowitz, Christoph A1 - Schmeißer, Dieter T1 - Out-of-plane electronic contributions in Bi-cuprates studied by resonant photoelectron spectroscopy at the Cu 2p edge T2 - Verhandlungen der DPG N2 - In high-temperature superconductors with a layered crystal structure out-of-plane contributions are often neglected, while the copper-oxygen planes are commonly considered to dominate the electronic properties around the Fermi energy. Here we report on a resonant photoemission study of (Pb,Bi)2201 and (Pb,Bi)2212 single crystals to unravel the resonant decay mechanisms at the Cu 2p absorption edge. We demonstrate a pronounced polarization dependence caused by two different Auger processes for in-plane and out-of-plane orientations. We deduce that the lowest energy valence state being involved in the two Auger processes, consists of three-dimensional contributions by admixed out-of-plane Sr, Bi, and O 2p states. It also suggests that the doping-induced charge density is dynamic, fluctuating within the Cu-O plane, and spills out perpendicular to it. C. Janowitz and D. Schmeißer, Supercond. Sci. Technol. 31, 045006 (2018) KW - high-temperature superconductors KW - resonant photoemission spectroscopy KW - single crystal KW - doping-induced charge density Y1 - 2019 UR - https://www.dpg-verhandlungen.de/year/2019/conference/regensburg/part/tt/session/49/contribution/19 SN - 0420-0195 SP - 403 EP - 403 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Mahmoodinezhad, Ali A1 - Pożarowska, Emilia A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Flege, Jan Ingo T1 - Depth profiling of PEALD-AlN films based on Al2p XPS peak decomposition T2 - Verhandlungen der DPG N2 - AlN has remarkable properties (wide band gap, low electrical and thermal conductivity, high dielectric constant, piezoelectricity) and is attractive for (opto)electronic and sensor applications. However, high oxygen content within nitride films is always a critical issue due to the thermodynamically favorable oxidation against nitridation resulting in deteriorated materials properties. In order to clarify whether the oxidation is a surface-limited or a bulk process elemental depth profiling is essential. In this work XPS in combination with Ar+ sputtering is applied to carry out depth profiling of AlN films prepared by plasma-enhanced atomic layer deposition using different parameters (plasma source, power and pulse duration). Particularly, the Al2p core levels are analyzed where the signals are decomposed into four components, representing weaker contributions of pure AlN and aluminum oxide phases as well as stronger signals of mixed oxygen-rich and nitrogen-rich phases. After sputtering (providing access to the deeper part of the film) the pure AlN phase content increases while the pure aluminum oxide content stays relatively constant. These issues are discussed with regard to the preparation parameters employed and accompanying XRD and electrical measurements. KW - X-Ray photoelectron spectroscopy (XPS) KW - peak decomposition KW - plasma enhanced atomic layer deposition (PEALD) KW - aluminium nitride (AlN) Y1 - 2019 UR - https://www.dpg-verhandlungen.de/year/2019/conference/regensburg/part/ds/session/14/contribution/25 SN - 0420-0195 SP - 157 EP - 157 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Obstarczyk, Agata A1 - Kaczmarek, Danuta A1 - Wojcieszak, Damian A1 - Mazur, Michał A1 - Domaradzki, Jarosław A1 - Kotwica, Tomasz A1 - Pastuszek, Roman A1 - Schmeißer, Dieter A1 - Mazur, Piotr A1 - Kot, Małgorzata T1 - Tailoring optical and electrical properties of thin-film coatings based on mixed Hf and Ti oxides for optoelectronic application T2 - Materials and Design N2 - In this work multi-magnetron sputtering stand was used for the deposition of the mixed oxides thin films based on HfO2 and TiO2. In order to obtain various material composition the power released to each magnetron (containing metallic hafnium and titanium targets) was precisely selected. Structural, surface, optical, electrical and mechanical properties of as-deposited coatings were analyzed. Depending on the hafnium content in the deposited thin films various types of the microstructure was obtained, i.e. HfO2-monoclinic, amorphous and TiO2-rutile. Increase of Ti content above 28 at. % in the as-prepared mixed oxides coatings caused their amorphization. It was found that with an increase of Ti content in prepared coatings their surface roughness and simultaneously water contact angle decreased. Performed measurements of electrical properties revealed that the lowest leakage current density in the range of 10−7 – 10−8 A/cm2 was obtained for amorphous coatings. Moreover, the tailoring of the dielectric constant was possible by a proper selection of material composition and microstructure of the deposited thin films. Average transparency in the visible wavelength region was in the range of ca. 79–86%. The influence of material composition and structure on shifting of the fundamental absorption edge and optical bandgap energy was also observed. The refractive index increased with an increase of Ti content, while extinction coefficient was the lowest for amorphous coatings. Additionally, hardness values were dependent on the material composition and optical packing density and were in the range from 7.6 GPa to 10.1 GPa. KW - Magnetron sputtering KW - Optical coatings KW - Electrical properties KW - Mixed oxides KW - HfO2 KW - TiO2 KW - High-k oxides KW - Amorphous thin films Y1 - 2019 U6 - https://doi.org/10.1016/j.matdes.2019.107822 SN - 0264-1275 VL - 175 ER - TY - GEN A1 - Roy, Krittish A1 - Ghosh, Sujoy Kumar A1 - Sultana, Ayesha A1 - Garain, Samiran A1 - Xie, Mengying A1 - Bowen, Christopher Rhys A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Mandal, Dipankar T1 - A Self-Powered Wearable Pressure Sensor and Pyroelectric Breathing Sensor Based on GO Interfaced PVDF Nanofibers T2 - ACS Applied Nano Materials N2 - This paper reports a self-powered,flexible, piezo- and pyro-electric hybrid nanogenerator (NG) device that can be fixed on different locations of human skin for detecting static and dynamic pressure variations and can also monitor temperature fluctuations during the respiration process. An efficient and cost-effective fabrication strategy has been developed to create electrospun poly(vinylidene fluoride) (PVDF)/graphene oxide (GO) nanofibers, which are used to create a highly sensitive wearable pressure sensor and pyroelectric breathing sensor. The sensor can accurately and rapidly detect pressures as low as 10 Pa with a high sensitivity (4.3 V/kPa), a key performance indicator for wearable sensors. Importantly, the sensor exhibits a high sensitivity to bending and stretching by finger, wrist, and elbow. The pressure sensor is also highly sensitive to vocal vibrations when attached to the human throat. The device can generate a maximum output power density of∼6.2 mW/m2 when subjected to a compressive stress, which enhances its range of applications. Moreover, it is demonstrated that doping with GO improves the pyroelectric energy harvesting and sensing performance of the device under repeated temperature fluctuations. The PVDF/GO-based nanogenerator has a maximum pyroelectric output power density of∼1.2 nW/m2 and can sense temperature changes during respiration, which makes it promising as a pyroelectric breathing sensor. It is demonstrated that processing of the PVDF-GO self-powered multifunctional pressure and pyroelectric breathing sensor can be up-scaled for fabricating compact and high-performance electronic skins for application in health monitoring, motion detection, and portable electronics. KW - piezo- and pyro-electric hybrid nanogenerator KW - poly(vinylidenefluoride) (PVDF)/graphene oxide (GO) nanofibers KW - wearable pressure sensor KW - breathing sensor Y1 - 2019 U6 - https://doi.org/10.1021/acsanm.9b00033 SN - 2574-0970 VL - 2 IS - 4 SP - 2013 EP - 2025 ER - TY - GEN A1 - Müller, Klaus A1 - Rachow, Fabian A1 - Günther, Vivien A1 - Schmeißer, Dieter T1 - Methanation of Coke Oven Gas with Nickel-based catalysts T2 - International Journal of Environmental Science N2 - For a complete transition from fossil to CO₂ neutral energy supply new energy storage concepts are needed that allow energy supply in times of absence of regenerative power production as during dark doldrums. A promising renewable energy storage approach is the power to gas (to power) technique based on the production of synthetic natural gas (also called e-methane) by methanation of CO₂ with H₂. The latter is usually produced by electrolysis. In any power to gas concept, electrolysis is a very critical part, due to its high costs, stability issues, or limited power of required electrolysers. As an alternative source of hydrogen, we investigate the methanation of coke oven gas (COG). COG is a byproduct of the carbon rich coke production from coal for the steel industry, with a high amount of hydrogen (~60vol%). Coke oven gas furthermore contains CH₄(~25vol%), CO (5-8vol%), and CO₂(1-3vol%), making it an attractive feedstock for the production of synthetic energy carriers like methane. In the present study, the authors investigate the direct conversion of CO and CO₂ from COG into e-methane. Compared to stoichiometric conversion, the COG hydrogen content is too high for catalytic methanation of CO₂. In order to achieve a higher methane yield, the addition of CO₂ from air, flue gas, or coal gasification can compensate the surplus of hydrogen in the coke oven gas. The process is evaluated by the conversion of CO and CO₂, the catalyst selectivity towards higher hydrocarbons for varying temperatures, and the CH₄ yield. KW - Coke Oven Gas KW - CO₂ recycling KW - Power to Gas (PtG) KW - Synthetic Natural Gas (SNG) KW - e-methane KW - Sabatier-Reaction Y1 - 2019 UR - https://www.iaras.org/iaras/home/caijes/methanation-of-coke-oven-gas-with-nickel-based-catalysts UR - https://iaras.org/iaras/filedownloads/ijes/2019/008-0009(2019).pdf SN - 2367-8941 IS - 4 SP - 73 EP - 79 ER - TY - GEN A1 - Kot, Małgorzata A1 - Henkel, Karsten A1 - Müller, Klaus A1 - Kegelmann, Lukas A1 - Albrecht, Steve A1 - Tsud, Nataliya A1 - Kús, Peter A1 - Matolinová, Iva A1 - Schmeißer, Dieter T1 - Al2O3-Atomic Layer Deposited Films on CH3NH3PbI3 : Intrinsic Defects and Passivation Mechanisms T2 - Energy Technology , The Journal of Physical Chemistry C N2 - The initial interaction of atomic layer deposited films of Al2O3 at room temperature on CH3NH3PbI3 (MAPI) films is studied. Synchrotron radiation–based photoelectron spectroscopy is applied to analyze the initial changes in the Al-derived features by comparing samples with different Al2O3 film thicknesses. It is found that polarons and excitons, both intrinsic defects of Al2O3, play a key role in the interface formation. The polaronic states uptake a charge from the MAPI substrate. This charge is transferred to and stabilized in the excitonic state of Al2O3 which is assigned to predominately tetrahedral coordinated Al sites. This charge transfer is initiated by vacancies present in the MAPI substrate and stabilizes a covalent bonding at the Al2O3–MAPI interface but also causes a roughening of the interface which may lead to the formation of grain boundaries. On top of the rough interface, 2D Al2O3 clusters with an increasing number of octahedrally coordinated Al—O bonds grow, and with increasing Al2O3 coverage, they introduce self-healing of the structural defects. KW - charge donation and transfer cycles KW - covalent interfaces KW - defect monitoring KW - model of Al2O3–CH3NH3PbI3 interactions KW - resonant photoelectron spectroscopy Y1 - 2019 U6 - https://doi.org/10.1002/ente.201900975 SN - 2194-4288 SN - 2194-4296 VL - 7 IS - 11 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Henkel, Karsten A1 - Pożarowska, Emilia A1 - Kegelmann, Lukas A1 - Tsud, Nataliya A1 - Kot, Małgorzata T1 - Point Defect-Mediated Interface Formation and Appearance of a Cooper Minimum for AlOₓ Atomic-Layer-Deposited Films on CH₃NH₃PbI₃ T2 - The Journal of Physical Chemistry. C N2 - We report on the interaction of CH₃NH₃PbI₃ substrates with AlOx films prepared by atomic layer deposition at room temperature. We use synchrotron radiation-based photoemission spectroscopy and study the Pb 4f, I 3d, and Al 2p core levels as well as the corresponding valence band states (Pb 5d and O 2p). A Cooper minimum is observed for both the Pb 5d and O 2p states, and it indicates that the bonding at the interface must be covalent. We focus on the electronic properties of the substrate and its interface and identify a delicate charge balance between polaronic and excitonic states in MAPI and AlOₓ. The perovskite vacancy sites, identified by changes in the core-level intensities, mediate the charge balance and covalent interaction. KW - Resonant photoelectron spectroscopy KW - Al₂O₃-CH₃NH₃PbI₃ interaction KW - Cooper minimum KW - point defects in CH₃NH₃PbI₃ KW - electronic structure of CH₃NH₃PbI₃ Y1 - 2019 U6 - https://doi.org/10.1021/acs.jpcc.9b05282 SN - 1932-7447 SN - 1932-7455 VL - 123 IS - 38 SP - 23352 EP - 23360 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Henkel, Karsten T1 - Intrinsic defects and multiple-atom processes in the oxidic semiconductor Ga₂O₃ T2 - Journal of Applied Physics N2 - We report on the electronic structure of gallium oxide (Ga₂O₃) single crystals as studied by resonant photoelectron spectroscopy (resPES). We identify intrinsic electronic defects that are formed by mixed-atomic valence states. We differentiate three coexisting defect states that differ in their electronic correlation energy and their spatial localization lengths. Their relative abundance is described by a fractional ionicity with covalent and ionic bonding contributions. For Ga₂O₃, our analyses of the resPES data enable us to derive two main aspects: first, experimental access is given to determine the ionicity based on the original concepts of Pauling and Phillips. Second, we report on multi-atomic energy loss processes in the Ga2p core level and X-ray absorption data. The two experimental findings can be explained consistently in the same context of mixed-atomic valence states and intrinsic electronic defects. KW - resonat photoelectron spectroscopy (resPES) KW - X-Ray absorption KW - gallium oxide (Ga₂O₃) KW - intrinsic electronic defects KW - band scheme Y1 - 2018 U6 - https://doi.org/10.1063/1.5010740 SN - 0021-8979 SN - 1089-7550 VL - 123 IS - 16 SP - 161596-1 EP - 161596-9 ER - TY - GEN A1 - Dorp, Dennis H. von A1 - Nyns, Laura A1 - Cuypers, Daniel A1 - Ivanov, Tsvetan A1 - Brizzi, Simone A1 - Tallarida, Massimo A1 - Fleischmann, Claudia A1 - Hönicke, Philipp A1 - Müller, Matthias A1 - Richard, Olivier A1 - Schmeißer, Dieter A1 - De Gendt, Stefan A1 - Lin, Dennis H. C. A1 - Adelmann, Christoph T1 - Amorphous Gadolinium Aluminate as a Dielectric and Sulfur for Indium Phosphide Passivation T2 - ACS Applied Electronic Materials N2 - The passivation of n-type InP (100) using sulfur in combination with a gadolinium aluminate (GAO) dielectric layer has been studied. Photoluminescence, minority-carrier lifetime, and capacitance−voltage measurements indicate that a (NH4)2S vapor passivation step prior to atomic layer deposition of the oxide effectively lowers the interface state density. Surface and interface chemistry were studied by synchrotron radiation photoemission spectroscopy (SRPES). The effect of ex situ surface passivation after native oxide removal in HCl solution was examined. It was observed that surface reoxidation occurred during (NH4)2S vapor exposure, leading to the formation of Inx(HPO4)y. S was present on the surface as a sulfide in both surface and subsurface sites. After atomic layer deposition of GAO, sulfates were detected in addition to Inx(HPO4)y, which was confirmed by near-edge X-ray absorptionfine structure analysis. The S in the stack was quantified using reference-free grazing incidence X-rayfluorescence analysis. X-ray absorption spectroscopy showed that Gd was oxidized and present in the 3+ oxidation state, most likely as a phosphate close to the InP interface and possibly mixed with sulfates. Energy-dependent SRPES measurements of Al 2p and Gd 4d core levels, complemented by transmission electron microscopy, further suggest that the dielectric layer was segregated. Valence band measurements confirm the effective passivation of InP, indicating unpinning of the surface Fermi level. KW - III−V KW - InP KW - sulfur passivation KW - atomic layer deposition KW - gadolinium aluminate KW - rare earth oxide KW - dielectric Y1 - 2019 U6 - https://doi.org/10.1021/acsaelm.9b00388 SN - 2637-6113 VL - 1 IS - 11 SP - 2190 EP - 2201 ER - TY - GEN A1 - Janowitz, Christoph A1 - Schmeißer, Dieter T1 - Significance of out-of-plane electronic contributions in Bi-cuprates studied by resonant photoelectron spectroscopy at the Cu2p-edge T2 - Superconductor Science and Technology N2 - In high-temperature superconductors with a layered crystal structure, the copper–oxygen planes are commonly considered to dominate the electronic properties around the Fermi energy. As a consequence, out-of-plane contributions are often neglected in the description of these materials. Here we report on a resonant photoemission study of Pb₀,4Bi1,₆Sr₂,₀CaCu₂0₈ ((Pb, Bi)-2212) and Pb₀,₆Bi₁,₄Sr₁.5La₀.5Cu0₆ ((Pb, Bi)-2201)) single crystals to unravel the resonant decay mechanisms at the Cu2p absorption edge. We find evidence for a pronounced polarization dependence caused by two different Auger processes for in-plane and out-of-plane orientations. We deduce that the lowest energy valence state—which is involved in the two Auger processes—consists of three-dimensional contributions by admixed out-of-plane Sr, Bi, and 02p states. It also suggests that the doping-induced charge density is dynamic, fluctuating within the Cu–0 plane, and spills out perpendicular to it. This suggests that out-of-plane electronic degrees of freedom should be included in future consistent theoretical models of these materials. KW - synchrotron radiation KW - polarization dependence KW - 3D hole doping KW - superconductor Y1 - 2018 U6 - https://doi.org/10.1088/1361-6668/aaadf6 SN - 0953-2048 SN - 1361-6668 VL - 31 IS - 4 ER - TY - GEN A1 - Kot, Małgorzata A1 - Łobaza, Justyna A1 - Naumann, Franziska A1 - Gargouri, Hassan A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Long-term ambient surface oxidation of titanium oxynitride films prepared by plasma-enhanced atomic layer deposition: An XPS study T2 - Journal of Vacuum Science and Technology A N2 - The surface oxidation of a titanium oxynitride (TiOxNy) film after long-time storage of 25 month in ambient conditions is investigated. The TiOxNy film is prepared by plasma-enhanced atomic layer deposition using etrakis(dimethylamino)titanium and nitrogen plasma, and the film is characterized by Ar+ ion sputtering of the film surface in combination with x-ray photoelectron spectroscopy (XPS) as well as by angle-resolved XPS. The total thickness of an oxygen-enriched layer at the surface of the TiOxNy films is found to be about 0.7 nm and it consists of a sequence of a 0.4 nm thick TiON/TiO2 enriched layer followed by a 0.3 nm thick TiO2 enriched layer underneath compared to the bulk composition of the film which shows constant values of 29% TiN, 29% TiO2, and 42% TiON. The results suggest that the TiON enrichment takes place initially at the surface followed by a surface and subsurface oxidation. KW - atomic layer deposition (ALD) KW - surface oxidation KW - X-Ray photoelectron spectroscopy (XPS) KW - titanium oxynitride Y1 - 2018 U6 - https://doi.org/10.1116/1.5003356 SN - 0734-2101 SN - 1520-8559 VL - 36 IS - 1 ER - TY - GEN A1 - Garain, Samiran A1 - Sen, Shrabanee A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Mandal, Dipankar T1 - Enhancement of Electroactive β-phase and Superior Dielectric Properties in Cerium Based Poly(vinylidene fluoride) Composite Films T2 - Materials Today: proceedings N2 - In this work we report on the preparation of poly(vinylidene fluoride) (PVDF) films with various mass fractions (wt%) of hydrated rare earth metal salt [(NH4)4Ce(SO4)4.2H2O] (CAS) and its electroactive phase (β- and γ-phase) formation. It was found that CAS can yield high amount of electroactive phases in PVDF. Compared to the neat PVDF film, a significantly increment of dielectric constant (ε ∼ 41) and a low loss factor (tan δ ∼ 0.8) were observed in the PVDF-CAS composite films. Thus the PVDF-CAS composite films with high electroactive phase and superior dielectric properties may meet the requirements of next generation electronic components. KW - PVDF KW - High amount of electroactive phase KW - Superior dielectric properties Y1 - 2018 U6 - https://doi.org/10.1016/j.matpr.2017.11.003 SN - 2214-7853 VL - 5 IS - 3 part 3 SP - 10084 EP - 10090 ER - TY - GEN A1 - Kot, Małgorzata A1 - Wojciechowski, Konrad A1 - Snaith, Henry J. A1 - Schmeißer, Dieter T1 - Evidence of Nitrogen Contribution to the Electronic Structure of the CH₃NH₃PbI₃ Perovskite T2 - Chemistry - A European Journal N2 - Despite fast development of hybrid perovskite solar cells, there are many fundamental questions related to the perovskite film which remain open. For example, there are contradicting theoretical reports on the role of the or-ganic methylammonium cation (CH₃NH₃+)in the methylam-monium lead triiodide (CH₃NH₃PbI₃)perovskite film. From one side it is reported that the organic cation does not contribute to electronic structure of the CH₃NH₃PbI₃ film. From the other side, valence band maximum fluctuations, dependent on the CH₃NH₃+ rotation, have been theoretically predicted. The resonant X-ray photoelectron spectroscopy results reported here show experimental evidence of nitrogen contribution to the CH₃NH₃PbI₃ electronic structure. Moreover,the observed strong resonances of nitrogen with the I 5s and the Pb 5d-6s levels indicate that the CH₃NH₃PbI₃ valence band is extended up to ~18 eV below the Fermi energy, and therefore one should also consider these shallow core levels while modeling its electronic structure. KW - methylammonium lead triiodide (CH₃NH₃PbI₃) KW - electronic structure KW - perovskite solar cells KW - resonant X-ray photoelectron spectroscopy (resPES) Y1 - 2018 U6 - https://doi.org/10.1002/chem.201705144 SN - 0947-6539 SN - 1521-3765 VL - 24 IS - 14 SP - 3539 EP - 3544 ER - TY - CHAP A1 - Henkel, Karsten A1 - Kot, Małgorzata A1 - Richter, Matthias A1 - Tallarida, Massimo A1 - Schmeißer, Dieter ED - Wandelt, Klaus T1 - An (In Situ)² Approach: ALD and resPES Applied to Al₂O₃, HfO₂, and TiO₂ Ultrathin Films T2 - Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, Vol. 3.1 N2 - Oxide surface coatings are of importance in tailoring interface properties with respect to surface passivation, adjustment of surface potentials, or providing active centers for surface reactions. In this contribution, we report about surface coatings prepared by the atomic layer deposition (ALD) method. ALD is known for its conformal growth of ultrathin, dense films which exhibit a low concentration of pinholes. KW - Atomic layer deposition (ALD) KW - Resonant photoelectron spectroscopy (resPES) KW - Band scheme KW - Partial density of states (pDOS) KW - Intrinsic charges KW - Intrinsic defects KW - Aluminum oxide (Al₂O₃) KW - Hafnium oxide (HfO₂) KW - Titanium oxide(TiO₂) Y1 - 2018 SN - 978-0-12-809739-7 SN - 978-0-12-809894-3 U6 - https://doi.org/10.1016/B978-0-12-409547-2.13852-1 SP - 18 EP - 26 PB - Elsevier CY - Oxford ER - TY - GEN A1 - Maity, Kuntal A1 - Garain, Samiran A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Mandal, Dipankar T1 - Natural Sugar-Assisted, Chemically Reinforced, Highly Durable Piezoorganic Nanogenerator with Superior Power Density for Self-Powered Wearable Electronics T2 - ACS Applied Materials & Interfaces N2 - Natural piezoelectric materials are of increasing interest, particularly for applications in biocompatible, implantable, and flexible electronic devices. In this paper, we introduce a cost-effective, easily available natural piezoelectric material, that is, sugar in the field of wearable piezoelectric nanogenerators (PNGs) where low electrical output, biocompatibility, and performance durability are still critical issues. We report on a high-performance piezoorganic nanogenerator (PONG) based on the hybridization of sugar-encapsulated polyvinylidenefluoride (PVDF) nanofiber webs (SGNFW). We explore the crucial role of single-crystal sugar having a fascinating structure along with the synergistic enhancement of piezoelectricity during nanoconfinement of sugar-interfaced macromolecular PVDF chains. As a consequence, the SGNFW-based PONG exhibits outstanding electricity generation capability (e.g.,∼100 V under 10 kPa human finger impact and maximum power density of 33 mW/m2) in combination with sensitivity to abundantly available different mechanical sources (such as wind flow, vibration, personal electronics, and acoustic vibration). Consequently, it opens up suitability in multifunctional self-powered wearable sensor designs for realistic implementation. In addition, commercially available capacitors are charged up effectively by the PONG because of its rapid energy storage capability. The high performance of the PONG not only offers“battery-free”energy generation (several portable units of light-emitting diodes and a liquid crystal display screen are powered up without using external storage) but also promises its use in wireless signal transmitting systems, which widens the potential in personal health care monitoring. Furthermore, owing to the geometrical stress confinement effect, the PONG is proven to be a highly durable power-generating device validated by stability test over 10 weeks. Therefore, the organic nanogenerator would be a convenient solution for portable personal electronic devices that are expected to operate in a self-powered manner. KW - natural piezoelectric material KW - sugar KW - PVDF KW - organic piezoelectric nanogenerator KW - high performance and durability KW - self-powered electronics Y1 - 2018 U6 - https://doi.org/10.1021/acsami.8b15320 SN - 1944-8244 SN - 1944-8252 VL - 10 SP - 44018 EP - 44032 ER - TY - GEN A1 - Kot, Małgorzata A1 - Kegelmann, Lukas A1 - Das, Chittaranjan A1 - Kus, Peter A1 - Tsud, Nataliya A1 - Matolínová, Iva A1 - Albrecht, Steve A1 - Matolin, Vladimir A1 - Schmeißer, Dieter T1 - Room temperature atomic layer deposited Al₂O₃ improves perovskite solar cells efficiency over time T2 - ChemSusChem N2 - Electrical characterisation of perovskite solar cells consisting of room-temperature atomic-layer-deposited aluminium oxide (RT-ALD-Al₂O₃) film on top of a methyl ammonium lead triiodide (CH₃NH₃PbI₃) absorber showed excellent stability of the power conversion efficiency (PCE) over along time. Under the same environmental conditions (for 355 d), the average PCE of solar cells without the ALD layer decreased from 13.6 to 9.6 %, whereas that of solar cells containing 9 ALD cycles of depositing RT-ALD-Al₂O₃on top of CH₃NH₃PbI₃ increased from 9.4 to 10.8 %. Spectromicroscopic investigations of the ALD/perovskite interface revealed that the maximum PCE with the ALD layer is obtained when the so-called perovskite cleaning process induced by ALD precursors is complete. The PCE enhancement over time is probably related to a self-healing process induced by the RT-ALD-Al₂O₃ film. This work may provide a new direction for further improving the long-term stability and performance of perovskite solar cells. KW - Perovskite Solar Cells (PSCs) KW - Atomic layer deposition (ALD) KW - long time stabilty KW - X-Ray photoelectron spectroscopy (XPS) KW - Field-emission scanning electron microscopy (FESEM) Y1 - 2018 U6 - https://doi.org/10.1002/cssc.201801434 SN - 1864-5631 SN - 1864-564X VL - 11 IS - 20 SP - 3640 EP - 3648 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Henkel, Karsten A1 - Janowitz, Christoph T1 - Ionicity of ZnO - a key system for transparent conductive oxides T2 - epl : a letters journal exploring the frontiers of physics N2 - The electronic structure of ZnO is dominated by coexisting electron and ionic states/bonds caused by charge polarization and self-trapping phenomena of the valence charges. Their interplay manifests itself in intrinsic electronic defects which have different degree of spatial localization and electronic correlation. The relative abundance of intrinsic defects can be determined by the ionicity factor fi and its value can be derived from three independent experimental procedures in a consistent way. This approach also explains the complex satellite features in the XPS and XAS data. Ionicity and satellite formation are two experimental findings which can be explained consistently in the same context of mixed-atomic valence states and intrinsic electronic defects. KW - Ionicity KW - zinc oxide (ZnO) KW - resonant photoelectron spectroscopy KW - defect states KW - transparent conductive oxide (TCO) Y1 - 2018 U6 - https://doi.org/10.1209/0295-5075/123/27003 SN - 1286-4854 SN - 0295-5075 VL - 123 IS - 2 SP - 27003-p1 EP - 27003-p7 ER - TY - CHAP A1 - Henkel, Karsten A1 - Haeberle, Jörg A1 - Müller, Klaus A1 - Janowitz, Christoph A1 - Schmeißer, Dieter ED - Fornari, Robert T1 - Preparation, properties and electronic structure of SnO₂ T2 - Single Crystals of Electronic Materials N2 - This chapter reports about tin oxide (SnO₂), a material which belongs to the transparent conducting oxide family and is best characterized by its high conductivity, high carrier mobility, and the ability to form p-type conductivity. We correlate these properties in terms of localized intrinsic electronic defect states which are resolved by resonant photoelectron spectroscopy measurements. We describe SnO₂ in terms of an inhomogeneous, mixed-ionic-covalent semiconductor in which these intrinsic electronic defects state are stabilized. KW - electronic structure KW - tin oxide (SnO₂) KW - resonant photoelectron spectroscopy KW - intrinsic defect states Y1 - 2018 SN - 978-0-08-102096-8 SN - 978-0-08-102097-5 SP - 547 EP - 572 PB - Elsevier, Woodhead Publishing CY - Duxford ER - TY - GEN A1 - Henkel, Karsten A1 - Kot, Małgorzata A1 - Schmeißer, Dieter T1 - Localized defect states and charge trapping in atomic layer deposited-Al₂O₃ films T2 - Journal of Vacuum Science and Technology, A : Vacuum, Surfaces, and Films N2 - In this study, the authors compared different Al₂O₃ films grown by atomic layer deposition (ALD) with the same aluminum precursor but on different substrates. The authors employed different process parameters such as thermal-ALD and plasma-enhanced-ALD using different substrate temperatures ranging from 280 °C down to room temperature. They characterized these films by resonant photoelectron spectroscopy and by electrical measurements. They established that generally the ALD-Al₂O₃ films show characteristic features of bulk Al₂O₃. For all films investigated, the authors found intrinsic defect states within the electronic band gap and identified excitonic, polaronic, and charge-transfer defect states. The authors gave an atomistic model to explain these intrinsic defects and found that their relative abundance is subject of the choice of ALD parameters and of the substrate used. They were able to relate the spectroscopic assigned in-gap defect states with the electronic charges as determined in our electrical measurements. KW - defect states KW - resonant photoelectron spectroscopy (resPES) KW - Al₂O₃ KW - atomic layer deposition (ALD) KW - excitons KW - polarons Y1 - 2017 U6 - https://doi.org/10.1116/1.4971991 SN - 0734-2101 SN - 1520-8559 VL - 35 IS - 1 SP - 01B125-1 EP - 01B125-18 ER - TY - GEN A1 - Henkel, Karsten A1 - Das, Chittaranjan A1 - Kot, Małgorzata A1 - Schmeißer, Dieter A1 - Naumann, Franziska A1 - Kärkkänen, Irina A1 - Gargouri, Hassan T1 - In-gap states in titanium dioxide and oxynitride atomic layer deposited films T2 - Journal of Vacuum Science and Technology: A N2 - Valence band (VB) spectra of titanium dioxide (TiO2) and oxynitride (TiOxNy) films prepared by different atomic layer deposition (ALD) processes are compared and related to electrical characterization [current–voltage (JV) and capacitance–voltage (CV)] results. By increasing the nitrogen amount in the TiO2 film, band-gap narrowing is observed. The band-gap decrease is related to the contribution of the nitrogen density of states, which induces defects within the band-gap and thus reduces its optical band-gap. In-gap states are found in the VB spectra at 1 eV below the Fermi energy in all investigated ALD samples, i.e., in TiO2 as well as in TiOxNy films. An exponential correlation between leakage current density and in-gap state intensity is derived by the combination of JV measurements and VB spectra, whereas the in-gap states seem to have no influence on hysteresis and fixed oxide charges found in the CV data. It is argued that the in-gap states in TiO2 and TiOxNy have an excitonic or polaronic origin. Both, band-gap narrowing and in-gap state intensity can be tuned by the ALD process selection and the variation of its parameters. KW - Titanium dioxide (TiO2) KW - Titanium oxynitrdie (TiON) KW - valence band spectra KW - in-gap states KW - band-gap narrowing KW - electrical characterization Y1 - 2017 U6 - https://doi.org/10.1116/1.4972247 SN - 0734-2101 SN - 1520-8559 VL - 35 IS - 1 SP - 01B135-1 EP - 01B135-8 ER - TY - GEN A1 - Menezes, Prashanth W. A1 - Indra, Arindam A1 - Das, Chittaranjan A1 - Walter, Carsten A1 - Göbel, Caren A1 - Gutkin, Vitaly A1 - Schmeißer, Dieter A1 - Driess, Matthias T1 - Uncovering the Nature of Active Species of Nickel Phosphide Catalysts in High-Performance Electrochemical Overall Water Splitting T2 - ACS Catalysis N2 - A systematic structural elucidation of the near-surface active species of the two remarkably active nickel phosphides Ni12P5 and Ni2P on the basis of extensive analytical, microscopic, and spectroscopic investigations is reported. The latter can serve as complementary efficient electrocatalysts in the hydrogen (HER) versus oxygen evolution reaction (OER) in alkaline media. In the OER Ni12P5 shows enhanced performance over Ni2P due to the higher concentration of nickel in this phase, which enables the formation of an amorphous NiOOH/Ni(OH)2 shell on a modified multiphase with a disordered phosphide/phosphite core. The situation is completely reversed in the HER, where Ni2P displayed a significant improvement in electrocatalytic activity over Ni12P5 owing to a larger concentration of phosphide/phosphate species in the shell. Moreover, the efficiently combined use of the two nickel phosphide phases deposited on nickel foam in overall electrocatalytic water splitting is demonstrated by a strikingly low cell voltage and high stability with pronounced current density, and these catalysts could be an apt choice for applications in commercial alkaline water electrolysis. KW - overall water splitting KW - electrocatalysis KW - nickel phosphide KW - structural rearrangement KW - surface structure Y1 - 2017 U6 - https://doi.org/10.1021/acscatal.6b02666 SN - 2155-5435 VL - 7 IS - 1 SP - 103 EP - 109 ER - TY - GEN A1 - Müller, Klaus A1 - Rachow, Fabian A1 - Israel, Johannes A1 - Charlafti, Evgenia A1 - Schwiertz, Carola A1 - Schmeißer, Dieter T1 - Direct Methanation of Flue Gas at a Lignite Power Plant T2 - International Journal of Environmental Science N2 - The combustion of fossil fuels results in CO2 emission, which is one of the primary causes of global warming. An important approach for solving this problem is the fixation, the chemical utilization and the recycling of CO2. Therefore, we investigate the catalytic conversion of CO2 with H2 into methane (CH4) with an upscaled test station at a brown coal power plant. In a completely new strategy, we realize the direct conversion of the CO2 content of the flue gas, without a cleaning process like amine scrubbing or optimized combustion like oxyfuel. Our experiments are performed in matters of catalytic performance, heat production and stability of the catalytic Sabatier process, as a function of the gas flow rate. The catalytic performance is investigated with a simulated composition of flue gas and under real conditions directly at the power plant. The CH4 production by the Sabatier process is realized with a maximum input flow rate of near 50Nm3/h, with 30Nm3/h flue gas and 20Nm3/h hydrogen. For these values, the necessary power scale for hydrogen generation by electrolysis is around 100kW. With synthetic and real flue gas, a conversion up to 99% (for hydrogen surplus) with 100% selectivity is stabilized. The reaction operates in thermal steady state equilibrium without any external energy supply. In consequence, the process of CO2 recycling could be integrated directly as a post combustion process of conventional power plants, without an expensive capturing step, for example. KW - CO2 recycling KW - Power to Gas (PtG) KW - Synthetic Natural Gas (SNG) KW - Sabatier-Reaction KW - Flue Gas Y1 - 2017 UR - http://www.iaras.org/iaras/home/caijes/direct-methanation-of-flue-gas-at-a-lignite-power-plant SN - 2367-8941 IS - 2 SP - 425 EP - 437 ER - TY - GEN A1 - Indra, Arindam A1 - Menezes, Prashanth W. A1 - Das, Chittaranjan A1 - Göbel, Caren A1 - Tallarida, Massimo A1 - Schmeißer, Dieter A1 - Driess, Matthias T1 - A facile corrosion approach to the synthesis of highly active CoOxwater oxidation catalysts T2 - Journal of Materials Chemistry A N2 - Ultra-small rock salt cobalt monoxide (CoO) nanoparticles were synthesized and subjected to partial oxidation (‘corrosion’) with ceric ammonium nitrate (CAN) to form mixed-valence CoOx(1 < x< 2) water oxidation catalysts. Spectroscopic, microscopic and analytical methods evidenced a structural reformation of cubic CoO to active CoOx with a spinel structure. The superior water oxidation activity of CoOx has been established in electrochemical water oxidation under alkaline conditions. Electrochemical water oxidation with CoOx was recorded at a considerably low overpotential of merely 325 mV at a current density of 10 mA cm-2 in comparison to 370 mV for CoO. Transformation of both octahedral CoII and CoIII sites into amorphous Co(OH)2–CoOOH is the key to high electrochemical activity while the presence of a higher amount of octahedral CoIII sites in CoOx is imperative for an efficient oxygen evolution process. KW - water splitting KW - water oxidation KW - cobalt oxide catalyst KW - transmission electron microscopy (TEM) KW - X-ray photoelectron spectroscopy (XPS) KW - X-ray absorption spectroscopy (XAS) KW - Cyclic voltammetry (CV) Y1 - 2017 U6 - https://doi.org/10.1039/c6ta10650a SN - 2050-7488 SN - 2050-7496 IS - 5 SP - 5171 EP - 5177 ER - TY - GEN A1 - Kot, Małgorzata A1 - Henkel, Karsten A1 - Das, Chittaranjan A1 - Brizzi, Simone A1 - Kärkkänen, Irina A1 - Schneidewind, Jessica A1 - Naumann, Franziska A1 - Gargouri, Hassan A1 - Schmeißer, Dieter T1 - Analysis of titanium species in titanium oxynitride films prepared by plasma enhanced atomic layer deposition T2 - Surface and Coatings Technology N2 - A comparative study of thin titanium oxynitride (TiOxNy) films prepared by plasma enhanced atomic layer deposition using tetrakis(dimethylamino)titanium (TDMAT) and N2 plasma as well as titanium(IV)isopropoxide and NH3 plasma is reported. The comparison is based on the combination of Ti2p core level and valence band spectroscopy and current-voltage measurements. The TDMAT/N2 process delivers generally higher fractions of TiN and TiON within the Ti2p spectra of the films and stronger photoemissions within the bandgap as resolved in detail by high energy resolution synchrotron-based spectroscopy. In particular, it is shown that higher TiN contributions and in-gap emission intensities correlate strongly with increased leakage currents within the films and might be modified by the process parameters and precursor selection. KW - Titanium oxynitride KW - Plasma enhanced atomic layer deposition (PEALD) KW - ALD process parameters KW - Ti-N contributions KW - In-gap defect states KW - Leakage current Y1 - 2017 U6 - https://doi.org/10.1016/j.surfcoat.2016.11.094 SN - 0257-8972 SN - 1879-3347 VL - 324 SP - 586 EP - 593 ER - TY - GEN A1 - Das, Chittaranjan A1 - Kot, Małgorzata A1 - Rouissi, Zied A1 - Kędzierski, Kamil A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Selective Deposition of an ultrathin Pt Layer on a Au-Nanoisland-Modified Si Photocathode for Hydrogen Generation T2 - ACS Omega N2 - Platinum, being the most efficient and stable catalyst, is used in photoelectrochemical (PEC) devices. However, a minimal amount of Pt with maximum catalytic activity is required to be used to minimize the cost of production. In this work, we use an environmentally friendly, ost-effective, and less Pt-consuming method to prepare PEC devices for the hydrogen evolution reaction (HER). The Pt monolayer catalyst is selectively deposited on a Au-nanoisland-supported boron-doped p-type Si (100) photocathode. The PEC device based on the Si photocathode with an ultralow loading of the Pt catalyst exhibits a comparable performance for the HER to that of devices with a thick Pt layer. In addition, we demonstrate that by using a thin TiO2 layer deposited by atomic layer deposition photo-oxidation of the Si photocathode can be blocked resulting in a stable PEC performance. KW - water splitting KW - hydrogen evolution reaction (HER) KW - Si photocathode KW - gold nanoislands KW - nanostructured platinum Y1 - 2017 U6 - https://doi.org/10.1021/acsomega.6b00374 SN - 2470-1343 VL - 2 IS - 4 SP - 1360 EP - 1366 ER - TY - GEN A1 - Kot, Małgorzata A1 - Das, Chittaranjan A1 - Henkel, Karsten A1 - Wojciechowski, Konrad A1 - Snaith, Henry J. A1 - Schmeißer, Dieter T1 - Room temperature atomic layer deposited Al₂O₃ on CH₃NH₃PbI₃ characterized by synchrotron-based X-ray photoelectron spectroscopy T2 - Nuclear Instruments and Methods in Physics Research B N2 - An ultrathin Al₂O₃ film deposited on methylammonium lead triiodide (CH₃NH₃PbI₃) perovskite has the capability to suppress the carrier recombination process and improve the perovskite solar cells efficiency and stability. However, annealing at temperatures higher than 85°C degrades the CH₃NH₃PbI₃ perovskite film. The X-ray photoelectron spectroscopy study performed in this work indicates that it is possible to grow Al₂O₃ by atomic layer deposition on the perovskite at room temperature, however, besides pure Al₂O₃ some OH groups are found and the creation of lead and iodine oxides at the Al₂O₃/CH₃NH₃PbI₃ interface takes place. KW - Synchrotron-based X-ray photoelectron spectroscopy KW - Perovskite solar cells KW - Atomic layer deposition KW - Al₂O₃ Y1 - 2017 U6 - https://doi.org/10.1016/j.nimb.2017.01.082 SN - 0168-583X SN - 1872-9584 VL - 411 SP - 49 EP - 52 ER - TY - GEN A1 - Cibrev, Dejan A1 - Tallarida, Massimo A1 - Das, Chittaranjan A1 - Lana-Villarreal, Teresa A1 - Schmeißer, Dieter A1 - Gómez, Roberto T1 - New insights into water photooxidation on reductively pretreated hematite photoanodes T2 - Physical Chemistry Chemical Physics N2 - It has been recently demonstrated that the photoactivity toward oxygen evolution of a number of n-type metal oxides can be substantially improved by a reductive electrochemical pretreatment. Such an enhancement has been primarily linked to the formation of low valent metal species that increase electrode conductivity. In this work, we report new insights into the electrochemical doping using highly ordered (110)-oriented hematite nanorods directly grown on FTO. The reductive pretreatment consists in applying negative potentials for a controlled period of time. Such a pretreatment was optimized in both potentiostatic and potentiodynamic regimes. We show that the optimized pretreatment enhances electrode conductivity due to an increase in charge carrier density. However, it additionally triggers changes in the morphologic, catalytic and electronic properties that facilitate the separation and collection of the photogenerated charge carriers causing an up to 8-fold enhancement in the photocurrent for water oxidation. The reductive pretreatment can be considered as a highly controllable electrochemical n-type doping with the amount of generated Fe2+/polaron species and the change in film morphology as the main factors determining the final efficiency for water photooxidation of the resulting electrodes. KW - hematite KW - photoanode KW - water oxidation KW - water splitting Y1 - 2017 U6 - https://doi.org/10.1039/C7CP03958A SN - 1463-9076 SN - 1463-9084 VL - 19 IS - 32 SP - 21807 EP - 21817 ER - TY - GEN A1 - Biswas, Anirban A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Mandal, Dipankar T1 - Comparison of the thermal stability of the α, β and γ phases in poly(vinylidene fluoride) based on in situ thermal Fourier transform infrared spectroscopy T2 - Phase Transitions N2 - The electroactive β phase of poly(vinylidenefluoride) (PVDF) is induced due to the aging time of PVDF solutions. The feasibility of the combination of the three crystalline polymorphs (α, β and γ) is demonstrated where their relative proportion within the PVDF film can be tailored by the simple monitoring of the preparation conditions. To identify all these phases, Fourier transform infrared (FT-IR) spectroscopy is carried out and it is spotlighted that the vibrational bands at 510 and 841 cm-1 are not sufficient to state the formation of the β phase. The main aim of this work is devoted to develop a better understanding on the thermal stability of these several phases of PVDF, which has a longstanding ambiguity persisting in this area. It has been found that the in situ thermal FT-IR spectroscopy is one of the best alternatives to understand this important issue. It is ascertained that the β phase is the least thermally stable phase among α, β and γ phases, whereas the γ phase is the most thermally stable phase. KW - PVDF KW - thermal stability KW - β-phase KW - infrared spectroscopy KW - in situ thermal FT-IR study Y1 - 2017 U6 - https://doi.org/10.1080/01411594.2017.1337902 SN - 0141-1594 SN - 1029-0338 VL - 90 IS - 12 SP - 1205 EP - 1213 ER - TY - GEN A1 - Indra, Arindam A1 - Menezes, Prashanth W. A1 - Das, Chittaranjan A1 - Schmeißer, Dieter A1 - Driess, Matthias T1 - Alkaline electrochemical water oxidation with multi-shelled cobalt manganese oxide hollow spheres T2 - Chemical Communications N2 - Multi-shelled hollow spheres of cobalt manganese oxides (CMOs) deposited on Ni foam exhibited superior alkaline electrochemical water oxidation activity and surpassed those of bulk CMO and commercial noble metal-based catalysts. A higher amount of cobalt in the spinel structure resulted in the transformation of the tetragonal to the cubic phase with a decrease in the overpotential of oxygen evolution. KW - Water oxidation KW - Cobalt manganese oxides (CMOs) KW - Multi-shelled hollow spheres KW - Near-edge X-ray absorption fine structure (NEXAFS) KW - Cyclic voltammetry KW - Scanning electron microscopy Y1 - 2017 U6 - https://doi.org/10.1039/C7CC03566G SN - 1359-7345 SN - 1364-548X VL - 53 IS - 62 SP - 8641 EP - 8644 ER - TY - GEN A1 - Alberton Corrêa, Silma A1 - Brizzi, Simone A1 - Schmeißer, Dieter T1 - Spectroscopic investigation of the electronic structure of thin atomic layer deposition HfO2 films T2 - Journal of Vacuum Science & Technology A N2 - The electronic structure of HfO2 thin films is investigated employing resonant photoelectron spectroscopy (resPES). The detailed analysis of the O1s resonance profile enables the determination of the partial density of states for the valence and the conduction bands as well as the electronic band gap to be 6.2 eV. The position of the charge neutrality level is evaluated. Thereby, it is demonstrated that the resPES data are able to combine information both for the valence as well as for the conduction band states. In addition, evidences for intrinsic in-gap states attributed to polaronic and charge transfer states are given. Electronic charges within the atomic layer deposition-HfO2films are identified, pointing out that the amount of charges is essential to determine the accurate position of the surface potentials. KW - resonant photoelectron spectroscopy KW - hafnium oxide KW - atomic layer deposition KW - partial density of states KW - electronic band gap Y1 - 2016 U6 - https://doi.org/10.1116/1.4935338 SN - 0734-2101 SN - 1520-8559 VL - 34 IS - 1 SP - 01A117-1 EP - 01A117-8 ER - TY - GEN A1 - Pitthan, E. A1 - dos Reis, R. A1 - Alberton Corrêa, Silma A1 - Schmeißer, Dieter A1 - Boudinov, H. I. A1 - Stedile, F. C. T1 - Influence of CO annealing in metal-oxide-semiconductor capacitors with SiO2 films thermally grown on Si and on SiC T2 - Journal of Applied Physics N2 - Understanding the influence of SiC reaction with CO, a by-product of SiC thermal oxidation, is a key point to elucidate the origin of electrical defects in SiC metal-oxide-semiconductor (MOS) devices. In this work, the effects on electrical, structural, and chemical properties of SiO2/Si and SiO2/SiC structures submitted to CO annealing were investigated. It was observed that long annealing times resulted in the incorporation of carbon from CO in the Si substrate, followed by deterioration of the SiO2/Si interface, and its crystallization as SiC. Besides, this incorporated carbon remained in the Si surface (previous SiO2/Si region) after removal of the silicon dioxide film by HF etching. In the SiC case, an even more defective surface region was observed due to the CO interaction. All MOS capacitors formed using both semiconductor materials presented higher leakage current and generation of positive effective charge after CO annealings. Such results suggest that the negative fixed charge, typically observed in SiO2/SiC structures, is not originated from the interaction of the CO by-product, formed during SiC oxidation, with the SiO2/SiC interfacial region. KW - metal-oxide-semiconductor KW - silicon KW - silicon carbide KW - CO annealing Y1 - 2016 U6 - https://doi.org/10.1063/1.4939836 SN - 0021-8979 SN - 1089-7550 IS - 119 SP - 025307-1 EP - 025307-6 ER - TY - GEN A1 - Sowińska, Małgorzata A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Kärkkänen, Irina A1 - Schneidewind, Jessica A1 - Naumann, Franziska A1 - Gruska, Bernd A1 - Gargouri, Hassan T1 - Plasma-enhanced atomic layer deposition of titanium oxynitrides films: A comparative spectroscopic and electrical study T2 - Journal of Vacuum Science and Technology A N2 - The process parameters’ impact of the plasma-enhanced atomic layer deposition (PE-ALD) method on the oxygen to nitrogen (O/N) ratio in titanium oxynitride (TiOxNy) films was studied. Titanium(IV)isopropoxide in combination with NH3 plasma and tetrakis(dimethylamino) titanium by applying N2 plasma processes were investigated. Samples were characterized by the in situ spectroscopic ellipsometry, x-ray photoelectron spectroscopy, and electrical characterization (current–voltage: I-V and capacitance–voltage: C-V) methods. The O/N ratio in the TiOxNy films is found to be very sensitive for their electric properties such as conductivity, dielectric breakdown, and permittivity. Our results indicate that these PE-ALD film properties can be tuned, via the O/N ratio, by the selection of the process parameters and precursor/coreactant combination. KW - plasma enhanced atomic layer deposition KW - titanium oxynitride KW - X-ray photoelectron spectroscopy KW - ellipsometry KW - current-voltage KW - capacitance-voltage Y1 - 2016 U6 - https://doi.org/10.1116/1.4936227 SN - 0734-2101 SN - 1520-8559 IS - 34 SP - 01A127-1 EP - 01A127-9 ER - TY - GEN A1 - Garain, Samiran A1 - Barman, Koushik A1 - Sinha, Tridib Kumar A1 - Jasimuddin, Sk A1 - Haeberle, Jörg A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Mandal, Dipankar T1 - Cerium(III) Complex Modified Gold Electrode: An Efficient Electrocatalyst for the Oxygen Evolution Reaction T2 - ACS Applied Materials and Interfaces N2 - Exploring efficient and inexpensive electrocatalysts for the oxidation of water is of great importance for various electrochemical energy storage and conversion technologies. In the present study, a new water-soluble [Ce III(DMF) (HSO4)3] complex was synthesized and characterized by UV−vis, photoluminescence, and high-resolution X-ray photoelectron spectroscopy techniques. Owing to classic 5d →4f transitions, an intense photoluminescence in the UV region was observed from the water-soluble [CeIII(DMF)(HSO4)3] complex. A stacking electrode was designed where self-assembled L-cysteine monolayer modified gold was immobilized with the synthesized cerium complex and was characterized by scanning electron microscopy, electrochemical impedance spectroscopy, and cyclic voltam-metry. The resulting electrode, i.e., [CeIII(DMF)(HSO4)3]−L-cysteine-Au stacks shows high electrocatalytic water oxidation behavior at an overpotential of η ≈0.34 V under neutral pH conditions. We also demonstrated a way where the overpotential is possible to decrease upon irradiation of UV light. KW - water oxidation KW - electrocatalyst KW - photoelectrocatalyst KW - photoluminescence KW - Ce(III)-complex KW - L-cysteine KW - gold electrode Y1 - 2016 U6 - https://doi.org/10.1021/acsami.6b05236 SN - 1944-8244 SN - 1944-8252 VL - 8 IS - 33 SP - 21294 EP - 21301 ER - TY - GEN A1 - Sowinska, Małgorzata A1 - Brizzi, Simone A1 - Das, Chittaranjan A1 - Kärkkänen, Irina A1 - Schneidewind, Jessica A1 - Naumann, Franziska A1 - Gargouri, Hassan A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Analysis of nitrogen species in titanium oxynitride ALD films T2 - Applied Surface Science N2 - Titanium oxynitride films are prepared by plasma enhanced atomic layer deposition method using two different precursors and nitrogen sources. Synchrotron radiation-based X-ray photoelectron spectroscopy and X-ray absorption spectroscopy are used to characterize the nitrogen species incorporated within these films depending on the deposition parameters. It is found that nitrogen atoms in these films are differently bonded. In particular, it can be distinguished between Ti-ON and Ti-N bonding configurations and molecular nitrogen species caused by precursor fragments. KW - titanium oxynitride KW - X-ray photoelectron spectroscopy KW - X-ray absorption spectroscopy KW - ALD process parameters Y1 - 2016 U6 - https://doi.org/10.1016/j.apsusc.2016.02.096 SN - 0169-4332 SN - 1873-5584 VL - 381 SP - 42 EP - 47 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Haeberle, Jörg T1 - Intrinsic localized gap states in IGZO and its parent single crystalline TCOs T2 - Thin Solid Films N2 - We report on the X-ray absorption data for Indium–Gallium–Zink–Oxide thin films, amorphous ZnO films, amorphous SnOx films, and single crystalline In2O3, Ga2O3, ZnO, and SnO2 data. These absorption data probe the empty conduction band states explicitly. Also they allow for an elemental assignment using resonant excitation to derive the contributions of each metal ion. We find that the lowest states appear right at the Fermi energy and result from configuration interaction induced charge transfer states which we consider as intrinsic gap states. KW - Transparent conducting oxide KW - X-ray photoelectron spectroscopy KW - Resonant photoemission spectroscopy KW - X-ray absorption spectroscopy KW - Electronic band structure KW - Intrinsic localized gap states Y1 - 2016 U6 - https://doi.org/10.1016/j.tsf.2016.02.010 SN - 0040-6090 SN - 1879-2731 IS - 603 SP - 206 EP - 211 ER - TY - GEN A1 - Kramm, Ulrike Ingrid A1 - Zana, Alessandro A1 - Vosch, Tom A1 - Fiechter, Sebastian A1 - Arenz, Matthias A1 - Schmeißer, Dieter T1 - On the structural composition and stability of Fe–N–C catalysts prepared by an intermediate acid leaching T2 - Journal of Solid State Electrochemistry N2 - The development of highly active and stable non-noble metal catalysts (NNMC) for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEM-FC) becomes of importance in order to enable cost reduction. In this work, we discuss the structural composition as derived from Fe-57Mößbauer spectroscopy and X-ray diffraction, catalytic performance determined by a rotating (ring)disk electrode (RRDE) technique and stability evaluation of our Fe–N–C catalysts prepared by an intermediate acid leaching (IAL). The advantage of this IAL is given by a high density of active sites within the catalyst, as even without sulphur addition, an iron carbide formation and related disintegration of active sites are inhibited. In addition, our accelerated stress tests illustrate better stability of the sulphur-free IAL catalyst in comparison to the sulphur-added one. KW - Non-noblemetal catalysts (NNMC) KW - Fe–N–C KW - oxygen reduction reaction (ORR) KW - PEM fuel cell (PEM-FC) KW - Accelerated stress tests (ASTs) KW - Mößbauer spectroscopy Y1 - 2016 U6 - https://doi.org/10.1007/s10008-015-3060-z SN - 1432-8488 SN - 1433-0768 N1 - 1. ISSN: P 2. ISSN: E VL - 20 IS - 4 SP - 969 EP - 981 ER - TY - CHAP A1 - Sowinska, Małgorzata A1 - Das, Chittaranjan A1 - Wojciechowski, Konrad A1 - Snaith, Henry J. A1 - Schmeißer, Dieter T1 - XPS study of the ALD growth of Al₂O₃ on the CH₃NH₃PbI₃ T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Organic-inorganic lead halide perovskites have emerged as very attractive absorber materials for the fabrication of low cost and high efficiency solar cells, but a delicate nature of these films is one of the main challenges for a successful commercialization. Typically, when exposed to air or moisture, perovskite films degrade within a couple of hours or days. Moreover, the methylammonium lead triiodide (CH₃NH₃PbI₃) perovskite cannot sustain a prolonged annealing at temperatures around 85∘C. In this work, we are investigating stability (upon air and thermal exposure) of a CH₃NH₃PbI₃ perovskite film coated with a thin layer of Al₂O₃ deposited by atomic layer deposition (ALD). In particular, the chemical and electronic changes occurred at the Al₂O₃/CH₃NH₃PbI₃ interface during the first 50 ALD cycles were monitored ex-situ by high-resolution and surface-sensitive synchrotron-based X-ray photoelectron spectroscopy (SR-XPS). The advantage of the ALD as a deposition method is that it can produce extremely dense layers with a very precise thickness control at room temperature. Detailed SR-XPS data analysis and a stability test of the perovskite film with alumina will be presented. KW - atomic layer deposition KW - perovskite solar cells KW - Al₂O₃ KW - X-Ray photoelectron spectroscopy KW - synchrotron Y1 - 2016 UR - http://www.dpg-verhandlungen.de/year/2016/conference/regensburg/part/cpp/session/31/contribution/6?lang=en SP - S. 206 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Das, Chittaranjan A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - TiO2 laminated Silicon microstructures based stable photocathode for water splitting T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The photoelectrochemical (PEC) water splitting is one of the most efficient ways to obtain hydrogen from water using solar power which can be used as carbon free fuel. The PEC device can bedesigned using semiconducting material that will convert solar radiation to H2. Silicon can be one of the best choices for PEC due to its success in solar cells technology. There are certain issues with Si such as stability in electrochemical medium [1] and higher surface reflectance (25%) which limits the Si as an ideal candidate for PEC technique [2]. In the present work we addressed these issues by surface structuring and laminating the surface with metal oxide. The microstructuring of Si was done by electrochemical method. The Si microstructure photocathode was stabilized by thin layer of ALD grown TiO2 film. The microstructuring and lamination of Si photocathode by ALD layer of TiO2 decreased the reflectance ofthe surface and shift the onset potential towards anodic direction by 350 mV with a prolonged stability over 60 hours[3]. [1] C. Levy-Clement, J. Electrochem. Soc 1991, 12, 69 [2] J. Oh, et al. Energy Environ. Sci., 2011, 4, 1690 [3] C. Das, et al. Nanoscale 2015,7, 7726 KW - water splitting KW - TiO2 KW - atomic layer deposition (ALD) KW - Si photoelectrodes Y1 - 2016 UR - http://www.dpg-verhandlungen.de/year/2016/conference/regensburg/part/ds/session/48/contribution/4?lang=en SP - S. 213 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Haeberle, Jörg A1 - Machulik, Stephan A1 - Janowitz, Christoph A1 - Manzke, Recardo A1 - Gaspar, Diana A1 - Barquinha, Pedro A1 - Schmeißer, Dieter T1 - Gap states in the electronic structure of SnO2 single crystals and amorphous SnOxthin films T2 - Journal of Applied Physics N2 - The electronic structure of a SnO2 single crystal is determined by employing resonant photoelectron spectroscopy. We determine the core level, valence band, and X-ray absorption (XAS) data and compare these with those of amorphous SnOx thin films. We find similar properties concerning the data of the core levels, the valence band features, and the absorption data at the O1s edge. We find strong signals arising from intrinsic in-gap states and discuss their origin in terms of polaronic and charge-transfer defects. We deduce from the XAS data recorded at the Sn3d edge that the Sn4d10 ground state has contributions of 4d9 and 4d8 states due to configuration interaction. We identify localized electronic states depending on the strength of the 4d-5s5p interaction and of the O2p-to-Sn4d charge-transfer processes, both appear separated from the extended band-like states of the conduction band. For the amorphous SnOx thin films, significant differences are found only in the absorption data at the Sn3d-edge due to a stronger localization of the in-gap states. KW - SnO2 KW - electronic structure KW - gap states KW - resonant photoelectron spectroscopy (resPES) Y1 - 2016 U6 - https://doi.org/10.1063/1.4962313 SN - 0021-8979 SN - 1089-7550 VL - 120 IS - 10 SP - 105101-1 EP - 105101-13 ER - TY - GEN A1 - Sowinska, Małgorzata A1 - Das, Chittaranjan A1 - Wojciechowski, Konrad A1 - Rouissi, Zied A1 - Snaith, Henry J. A1 - Schmeißer, Dieter T1 - Atomic layer deposition of Al2O3 on CH3NH3PbI3 for enhancement of perovskite solar cells stability T2 - Synchrotron Radiation in Natural Science : Bulletin of the Polish Synchrotron Radiation Society KW - atomic layer deposition KW - perovskite soloar cells KW - X-ray photoelectron spectroscopy (XPS) KW - Atomic foce microscopy (AFM) Y1 - 2016 SN - 1644-7190 VL - 15 IS - 1-2 SP - S. 33 ER - TY - CHAP A1 - Rouissi, Zied A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - HfO2 grow by ALD on Si(111)-H terminated stepped surface T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - We studied by STM the growth of HfO2 on Si (111)-H stepped surface (miscut by 0.5∘). The steps are aligned in the [11-2] direction. In order to obtain well defined steps and terraces we prepare the sample by chemical etching in 40% Nh4F. In our in-situ study we investigate the ALD growth of HfO2 by TDMAH and H2O [1-2]. We follow for the first four ALD cycles the distribution of the nucleation sites. We also study the influence of the substrate temperature by comparing the growth within the ALD window at 300K and 580K. We observed that at RT the as-grown HfO2 forms stripes which are oriented normal to the step orientations. Further growth starts from the step edges and proceeds towards the terraces. Defects created by the etching processes act as nucleation sites for 3D islands. Based on our STM data we are able to correlate the structural changes on that inert and stepped Si(111)-H surface during ALD with experimental [3] and theoretical [4] results obtained for planar Si(100) surfaces. [1] M. Tallarida et al., Semicond. Sci. Technol. 27, 074010 (2012) [2] K. Kolanek et al., Thin Solid Films 518, 4688 (2010) [3] K. Kolanek et al., J. Vac. Sci. Technol. A 31, 01A104 (2013) [4]L. Riikka et al., J. Appl. Phys.96, 7686 (2004) KW - atomic layer deposition KW - stepped surfaces KW - scanning tunneling micrsocopy KW - HfO2 KW - Si(111) Y1 - 2016 UR - http://www.dpg-verhandlungen.de/year/2016/conference/regensburg/part/o/session/89/contribution/13?lang=en SP - S. 419 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Rouissi, Zied A1 - Henkel, Karsten A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - ALD growth of Al2O3 on Stepped Surface of HOPG and Ag-HOPG T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Atomic Layer Deposition (ALD) is an excellent deposition technique to grow thin film with high homogeneity coverage on ideal surfaces. Here we are interested in the growth properties on non-ideal (stepped, inert) surfaces. Using STM we studied the growth of Al2O3 by ALD on stepped surface of HOPG and silver covered HOPG (Ag-HOPG). The HOPG sample was cleaved to and then cleaned by N2 in vacuum. We obtain regular steps with terrace widths of 50nm - 500nm. Ag was deposited by thermal deposition on the HOPG. The Al2O3 growth at RT was studies after the first, third, and fifth cycle. Silver evaporation leads to step decoration with island of 1nm-7nm. On the terraces we find the formation of 2D domain of Ag chains. The features caused by the individual ALD cycles of Al2O3 depend on the terrace widths of the HOPG substrate. For small terraces (<100nm) we obtain a growth of 2D domains ( 20nm-25nm) on the edge steps and in the middle of the terrace. For large terraces (>100nm) we find agglomeration of the precursors on individual nucleation sites. Here 3D islands are formed with a height of up to 5nm in the fifth ALD cycle. KW - atomic layer deposition KW - Scanning tunneling microscopy (STM) KW - Al2O3 KW - HOPG Y1 - 2016 UR - http://www.dpg-verhandlungen.de/year/2016/conference/regensburg/part/o/session/89/contribution/12?lang=en SP - S. 419 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Das, Chittaranjan A1 - Kot, Małgorzata A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Engineering of Sub-Nanometer SiOₓ Thickness in Si Photocathodes for Optimized Open Circuit Potential T2 - ChemSusChem N2 - Silicon is one of the most promising materials to be used for tandem-cell water-splitting devices. However, the electrochemical instability of bare Si makes it difficult to be used for stable devices. Besides that, the photovoltage loss in Si, caused by several factors (e.g., metal oxide protection layer and/or SiO₂/Si or catalyst/Si interface), limits its use in these devices. In this work, we present that an optimized open circuit potential (OCP) of Si can be obtained by controlling the SiOₓ thickness in sub-nanometer range. It can be done by means of a simple and cost-effective way using the combination of a wet chemical etching and the low temperature atomic layer deposition (ALD) of TiO₂. We have found that a certain thickness of the native SiOₓ is necessary to prevent further oxidation of the Si photocathode during the ALD growth of TiO₂. Moreover, covering the Si photocathode with an ALD TiO₂ layer enhances its stability. KW - atomic layer deposition KW - open circuit potential KW - Si photocathodes KW - silica KW - stability Y1 - 2016 U6 - https://doi.org/10.1002/cssc.201600777 SN - 1864-5631 SN - 1864-564X VL - 9 IS - 17 SP - 2332 EP - 2336 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Janowitz, Christoph T1 - The Cu2p-edge of superconducting BiSrCu-Oxides studed by resonant Photoelectron Spectroscopy T2 - Synchrotron Radiation in Natural Science : Bulletin of the Polish Synchrotron Radiation Society KW - synchrotron raidation KW - superconductor Y1 - 2016 SN - 1644-7190 VL - 15 IS - 1-2 SP - S. 35 ER - TY - CHAP A1 - Sowinska, Małgorzata A1 - Das, Chittaranjan A1 - Wojciechowski, Konrad A1 - Snaith, Henry J. A1 - Schmeißer, Dieter T1 - Spectroscopic investigation of the nitrogen role in organic-inorganic perovskite films T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Over the past few years, a wide range of device architectures employing organic-inorganic metal halide perovskite absorbers has been reported, with efficiencies exceeding 20%. Despite the tremendous progress, a number of key issues must be resolved before the wide-spread com- mercialization will be possible. Some of the primary challenges include lead toxicity, long-term stability, and fast degradation upon exposure to humid atmosphere. Recent computational and experimental studies suggest that hybrid metal-halide perovskites act as an ionic-electronic conductor. The study of vacancy-mediated migration of I−, Pb2+ and CH3NH3− ions and their relative activation energies suggests that migration of halide vacancies, to and from the interfaces in the solar cell during its operation, is the main conduction mechanism. In this work, we are presenting high resolution synchrotron-based spectroscopic study, which indicates that the contribution of nitrogen into the conduction mechanism of methyl ammonium lead iodide-based (CH3NH3PbI3) perovskite films should not be neglected. The N1s core level and resonant X-ray photoelectron spectroscopy at the N1s-egde of the CH3NH3PbI3 films are discussed in detail. KW - perovskite solar cells KW - X-ray photoelectron spectroscopy KW - nitrogen Y1 - 2016 UR - http://www.dpg-verhandlungen.de/year/2016/conference/regensburg/part/cpp/session/11/contribution/7?lang=en SP - S. 150 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Ghosh, Sujoy Kumar A1 - Biswas, Anirban A1 - Sen, Shrabanee A1 - Das, Chittaranjan A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Mandal, Dipankar T1 - Yb3+ Assisted Self-Polarized PVDF Based Ferroelectretic Nanogenerator: A Facile Strategy of Highly Efficient Mechanical Energy Harvester Fabrication T2 - Nano Energy N2 - Ytterbium (Yb3+) assisted porous poly(vinylidene fluoride) (PVDF) composite film comprising flexible ferroelectretic nanogenerator (FTNG) is highlighted where traditional poling treatment is completely avoided. The piezoelectric output of FTNG is realized by the co-operative activity of self-polarized -CH2/-CF2 dipoles with porous electret-like structure in the composite film. Owing to extraordinary ferroelectric and dielectric properties, FTNG is acting as a highly efficient mechanical energy harvester. It is capable to capture several forms of abundant mechanical energy arising from humanfinger movements, machine vibrations and sound waves. As a proof of concept, under compressive deformation, FTNG is enable to instantly powers up several consumer electronics and thus provides a promising strategy for achieving self-powered electronic devices. KW - PVDF KW - Yb 3+ KW - Porous ferroelectret material KW - Self-polarization KW - Ferroelectretic nanogenerator KW - Mechanical energy harvester KW - Self-powered electronics Y1 - 2016 U6 - https://doi.org/10.1016/j.nanoen.2016.10.042 SN - 2211-2855 VL - 2016 IS - 30 SP - 621 EP - 629 ER - TY - GEN A1 - Cuypers, Daniel A1 - Fleischmann, Claudia A1 - Dorp, Dennis H. von A1 - Brizzi, Simone A1 - Tallarida, Massimo A1 - Müller, Matthias A1 - Hönicke, Philipp A1 - Billen, Arne A1 - Chintala, Ravi A1 - Conard, Thierry A1 - Schmeißer, Dieter A1 - Vandervorst, Wilfried A1 - Elshocht, Sven van A1 - Armini, Silvia A1 - De Gendt, Stefan A1 - Adelmann, Christoph T1 - Sacrificial Self-Assembled Monolayers for the Passivation of GaAs(100) Surfaces and Interfaces T2 - Chemistry of Materials N2 - The use of sacrificial self-assembled monolayers (SAMs) to prepare clean n-type GaAs (100) surfaces without band bending in vacuo is demonstrated. GaAs surface passivation using octadecanethiol SAMs after HCl cleaning is shown to lead to an enhancement of the room-temperature photoluminescence intensity. Synchrotron-radiation photoelectron spectroscopy (SRPES) finds that the interfacial oxide between GaAs and the SAM remains below the detection limit. Evidence for both Ga–S and As–S bonds at the GaAs–thiolate interface is found. The limited thermal stability of the SAM allows the desorption of the alkyl chains by in situ thermal annealing at temperatures above 180 °C, leaving S bonded to Ga behind. The resulting surface contains only a very small amount of O (0.05 ML coverage) and C (about 3% of the SAM remaining) and shows no band bending with the surface Fermi level close to the conduction band. Atomic layer deposition of Al₂O₃ on this surface occurs via the formation of Al–S bonds without introducing any additional band bending. This indicates that the surface preparation of n-type GaAs (100) using sacrificial octadecanethiol SAMs followed by in situ thermal removal provides a route toward GaAs/oxide interfaces without interfacial oxides and without band bending. KW - GaAs KW - passivation KW - Al₂O₃ KW - atomic layer deposition (ALD) KW - Synchrotron-radiation photoelectron spectroscopy (SRPES) KW - self assembled monolayers (SAM) KW - interface engineering Y1 - 2016 U6 - https://doi.org/10.1021/acs.chemmater.6b01732 SN - 0897-4756 SN - 1520-5002 VL - 28 IS - 16 SP - 5689 EP - 5701 ER - TY - GEN A1 - Kot, Małgorzata A1 - Das, Chittaranjan A1 - Wang, Zhiping A1 - Henkel, Karsten A1 - Rouissi, Zied A1 - Wojciechowski, Konrad A1 - Snaith, Henry J. A1 - Schmeißer, Dieter T1 - Room-Temperature Atomic Layer Deposition of Al₂O₃: Impact on Efficiency, Stability and Surface Properties in Perovskite Solar Cells T2 - ChemSusChem N2 - In this work, solar cells with a freshly made CH₃NH₃PbI₃ perovskite film showed a power conversion efficiency (PCE) of 15.4 % whereas the one with 50 days aged perovskite film only 6.1 %. However, when the aged perovskite was covered with a layer of Al₂O₃ deposited by atomic layer deposition (ALD) at room temperature (RT), the PCE value was clearly enhanced. X-ray photoelectron spectroscopy study showed that the ALD precursors are chemically active only at the perovskite surface and passivate it. Moreover, the RT-ALD-Al2O3-covered perovskite films showed enhanced ambient air stability. KW - Al₂O₃ KW - atomic layer deposition (ALD) KW - perovskite KW - solar cells KW - X-ray photoelectron spectroscopy (XPS) Y1 - 2016 U6 - https://doi.org/10.1002/cssc.201601186 SN - 1864-5631 SN - 1864-564X VL - 9 IS - 24 SP - 3401 EP - 3406 ER - TY - GEN A1 - Garain, Samiran A1 - Sinha, Tridib Kumar A1 - Adhikary, Prakriti A1 - Henkel, Karsten A1 - Sen, Shrabanee A1 - Ram, Shanker A1 - Sinha, Chittaranjan A1 - Schmeißer, Dieter A1 - Mandal, Dipankar T1 - Self-Poled Transparent and Flexible UV Light-Emitting Cerium Complex–PVDF Composite: A High-Performance Nanogenerator T2 - ACS Applied Materials & Interfaces N2 - Cerium(III)-,N-dimethylformamide-bisulfate [Ce(DMF)(HSO4)3] complex is doped into poly(vinylidene fluoride) (PVDF) to induce a higher yield (99%) of the electroactive phases (β- and γ-phases) of PVDF. A remarkable enhancement of the output voltage (∼32 V) of a nano-generator (NG) based on a nonelectrically poled cerium(III) complex containing PVDF composite film is achieved by simple repeated human finger imparting, whereas neat PVDF does not show this kind of behavior. This high electrical output resembles the generation of self-poled electroactiveβ-phase in PVDF due to the electrostatic interactions between the fluoride of PVDF and the surface-active positive charge cloud of the cerium complex via H-bonding and/or bipolar interaction among the opposite poles of cerium complex and PVDF, respectively. The capacitor charging capability of the flexible NG promises its applicability as piezoelectric-based energy harvester. The cerium(III) complex doped PVDF composite film exhibit an intense photoluminescence in the UV region, which might be due to a participation of electron cloud from negative pole of bipolarized PVDF. This fact may open a new area for prospective development of high-performance energy-saving flexible solid-state UV light emitters. KW - PVDF KW - electroactive phase KW - nanogenerator KW - cerium charge transfer complex KW - piezoelectric energy harvester KW - UV-emitter Y1 - 2015 U6 - https://doi.org/10.1021/am507522r SN - 1944-8244 SN - 1944-8252 VL - 2015 IS - 7 SP - 1298 EP - 1307 ER - TY - GEN A1 - Das, Chittaranjan A1 - Henkel, Karsten A1 - Tallarida, Massimo A1 - Schmeißer, Dieter A1 - Gargouri, Hassan A1 - Kärkkänen, Irina A1 - Schneidewind, Jessica A1 - Gruska, Bernd A1 - Arens, Michael T1 - Thermal and plasma enhanced atomic layer deposition of TiO2: Comparison of spectroscopic and electric properties T2 - Journal of Vacuum Science and Technology A N2 - Titanium oxide (TiO2) deposited by atomic layer deposition (ALD) is used as a protective layer in photocatalytic water splitting system as well as a dielectric in resistive memory switching. The way ALD is performed (thermally or plasma-assisted) may change the growth rate as well as the electronic properties of the deposited films. In the present work, the authors verify the influence of the ALD mode on functional parameters, by comparing the growth rate and electronic properties of TiO2 films deposited by thermal (T-) and plasma-enhanced (PE-) ALD. The authors complete the study with the electrical characterization of selected samples by means of capacitance–voltage and current–voltage measurements. In all samples, the authors found a significant presence of Ti3+ states, with the lowest content in the PE-ALD grown TiO2 films. The observation of Ti3+ states was accompanied by the presence of in-gap states above the valence band maximum. For films thinner than 10 nm, the authors found also a strong leakage current. Also in this case, the PE-ALD films showed the weakest leakage currents, showing a correlation between the presence of Ti3+ states and leakage current density. KW - titanium oxide (TiO2) KW - atomic layer deposition KW - plasma enhanced atomic layer deposition KW - synchrotron radiation photoelectron spectroscopy (SR-PES) KW - x-ray absorption spectroscopy KW - capacitance-voltage (CV) KW - current-voltage (IV) KW - ellipsometry KW - in-gap states Y1 - 2015 U6 - https://doi.org/10.1116/1.4903938 SN - 1520-8559 SN - 0734-2101 VL - 2015 IS - 33 SP - 01A144-1 EP - 01A144-8 ER - TY - GEN A1 - Das, Chittaranjan A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Si microstructures laminated with a nanolayer of TiO2 as long-term stable and effective photocathodes in PEC devices T2 - Nanoscale N2 - Photoelectrochemical (PEC) water splitting is one of the most emerging fields for green energy generation and storage. Here we show a study of microstructured Si covered by a TiO2 nano-layer. The microstructures are prepared by galvanostatic selective etching of Si. The TiO2 nano-layer was deposited by atomic layer deposition (ALD) to protect the microstructured photocathode against corrosion. The obtained microstructured photocathode showed a shift in the onset potential of 400 mV towards the anodic direction compared to bare Si. The Si microstructures laminated with a nano-layer of TiO2 show stability over 60 hours of measurement. KW - water splitting KW - photocorrosion KW - protection layer KW - photoelectrochemical device (PEC device) KW - atomic layer deposition (ALD) KW - silicon (Si) KW - titanum oxide (TiO2) KW - microstructure Y1 - 2015 U6 - https://doi.org/10.1039/C5NR00764J SN - 2040-3364 SN - 2040-3372 IS - 7 SP - 7726 EP - 7733 ER - TY - GEN A1 - Corrêa, Silma Alberton A1 - Brizzi, Simone A1 - Schmeißer, Dieter T1 - Depicting the Electronic Structure of HfO₂ Films by Spectroscopic Techniques T2 - ECS Transactions N2 - The electronic structure of HfO₂ films was investigated. The partial density of states for the valence and the conduction bands was determined by the detailed analysis of the O1s resonance profile by resonant photoelectron spectroscopy. The positions of valence band maximum and conduction band minimum, the excitation range for the polaronic states and the range of charge transfer band were found to be not influenced by the preparation conditions. The band gap was determined to be 6.2 eV and the energy of the charge neutrality level (referred to vacuum level) was determined as 4.7 eV. The Fermi level position was observed to vary about 1.2 eV depending on the preparation conditions, which indicates the presence of charges within the films. KW - HfO₂ KW - resonant photoelectron spectroscopy (resPES) KW - electronic structure KW - partial density of states KW - charge neutrality level Y1 - 2016 U6 - https://doi.org/10.1149/07506.0145ecst SN - 1938-6737 SN - 1938-5862 VL - 75 IS - 6 SP - 145 EP - 153 ER - TY - GEN A1 - Nourbakhsh, Amirhasan A1 - Adelmann, Christoph A1 - Song, Yi A1 - Lee, Chang Seung A1 - Asselberghs, Inge A1 - Huyghebaert, Cedric A1 - Brizzi, Simone A1 - Tallarida, Massimo A1 - Schmeißer, Dieter A1 - Elshocht, Sven van A1 - Heyns, Marc A1 - Kong, Jing A1 - Palacios, Tomás A1 - De Gendt, Stefan T1 - Graphene oxide monolayers as atomically thin seeding layers for atomic layer deposition of metal oxides T2 - Nanoscale N2 - Graphene oxide (GO) was explored as an atomically-thin transferable seed layer for the atomic layer deposition (ALD) of dielectric materials on any substrate of choice. This approach does not require specific chemical groups on the target surface to initiate ALD. This establishes GO as a unique interface which enables the growth of dielectric materials on a wide range of substrate materials and opens up numerous prospects for applications. In this work, a mild oxygen plasma treatment was used to oxidize graphene monolayers with well-controlled and tunable density of epoxide functional groups. This was confirmed by synchrotron-radiation photoelectron spectroscopy. In addition, density functional theory calculations were carried out on representative epoxidized graphene monolayer models to correlate the capacitive properties of GO with its electronic structure. Capacitance–voltage measurements showed that the capacitive behavior of Al2O3/GO depends on the oxidation level of GO. Finally, GO was successfully used as an ALD seed layer for the deposition of Al2O3 on chemically inert single layer graphene, resulting in high performance top-gated field-effect transistors. KW - Graphene Oxide KW - seed layer KW - atomic layer deposition KW - oxygen plasma treatment KW - photoelectron spectroscopy KW - density functional theory KW - capacitance-voltage Y1 - 2015 U6 - https://doi.org/10.1039/C5NR01128K SN - 2040-3364 SN - 2040-3372 VL - 2015 IS - 7 SP - 10781 EP - 10789 ER - TY - GEN A1 - Tamang, Abiral A1 - Ghosh, Sujoy Kumar A1 - Garain, Samiran A1 - Alam, Md. Mehebub A1 - Haeberle, Jörg A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Mandal, Dipankar T1 - DNA-Assisted β‑phase Nucleation and Alignment of Molecular Dipoles in PVDF Film: A Realization of Self-Poled Bioinspired Flexible Polymer Nanogenerator for Portable Electronic Devices T2 - ACS Applied Materials & Interfaces N2 - A flexible nanogenerator (NG) is fabricated with a poly(vinylidene fluoride) (PVDF)film, where deoxyribonu-cleic acid (DNA) is the agent for the electroactive β-phase nucleation. Denatured DNA is co-operating to align the molecular−CH2/−CF2 dipoles of PVDF causing piezo- electricity without electrical poling. The NG is capable of harvesting energy from a variety of easily accessible mechanical stress such as human touch, machine vibration, football juggling, and walking. The NG exhibits high piezoelectric energy conversion efficiency facilitating the instant turn-on of several green or blue light-emitting diodes. The generated energy can be used to charge capacitors providing a wide scope for the design of self-powered portable devices. KW - PVDF KW - β-phase KW - DNA KW - self-poling KW - piezoelectric flexible nanogenerator Y1 - 2015 U6 - https://doi.org/10.1021/acsami.5b04161 SN - 1944-8244 SN - 1944-8252 IS - 7 SP - 16143 EP - 16147 ER - TY - CHAP A1 - Henkel, Karsten A1 - Das, Chittaranjan A1 - Sowinska, Małgorzata A1 - Tallarida, Massimo A1 - Schmeißer, Dieter A1 - Gargouri, Hassan A1 - Kärkkänen, Irina A1 - Schneidewind, Jessica A1 - Gruska, Bernd A1 - Arens, Michael ED - Glück, B. K. ED - Schmidt, S. ED - Stein, E. ED - Raschke, Jörg-Uwe ED - Richter, H. T1 - Charakterisierung von TiO2-ALD-Schichten und deren Nutzung für die Passivierung von Si-Photokathoden T2 - Tagungsband Photovoltaik-Meeting: Anwendungen-Qualität-Perspektiven, Senftenberg, 15.04.2015 N2 - Wir berichten zunächst über den Einfluss der Methode der Atomlagenabscheidung auf die TiO2-Schichteigenschaften. Insbesondere wird der Zusammenhang zwischen Ti3+- sowie Interbandzuständen mit elektrischen Kennlinien und deren Einfluss auf funktionale Schichteigenschaften diskutiert. Anschließend werden Mikrostrukturierung, Grenzflächen-Engineering und konforme Abscheidung einer TiO2-ALD-Schutzschicht effektiv zur Performance-Steigerung von p-Si-Photokathoden angewendet. KW - TiO2 KW - Korrosion KW - Atomlagenabscheidung KW - Silizium KW - Photokathoden KW - Linear Scan Voltametry KW - Photoelektronenspektroskopie Y1 - 2015 SP - 3 EP - 8 PB - BTU Cottbus-Senftenberg CY - Senftenberg ER - TY - GEN A1 - Schmeißer, Dieter A1 - Haeberle, Jörg A1 - Richter, Matthias A1 - Brazda, Petr T1 - Spin State and Satellite Structures of ε-Fe₂O₃ as determined by Resonant Photoelectron Spectroscopy T2 - Nuclear Instruments and Methods in Physics Research B N2 - We use resonant photoelectron spectroscopy at the Fe2p and the O1s absorption edges to report on spectroscopic investigation of Fe-oxides nanoparticles. We discuss the spectroscopic details like multiple Auger decays, satellite emission in the X-ray absorption process and the core level data. We explain these data by a novel mechanism in which the resonant excitation between Fe3d and Fe4s states are involved. This mechanism is observed when the photo-excited electron becomes polarized by the electron–hole pairs existing in the conduction and valence bands. KW - Resonant photoelectron spectroscopy KW - ε-Fe2O3nano particles KW - Satellite emission Y1 - 2015 U6 - https://doi.org/10.1016/j.nimb.2015.08.062 SN - 0168-583X VL - 2015 IS - 364 SP - 127 EP - 131 ER - TY - CHAP A1 - Das, Chittaranjan A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Determination of charge neutrality level in TiO2 films from res-PES measurements T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Titanium dioxide is one of the metal oxides which have versatile application in different fields. The applications of TiO2 are in the field of cosmetics, electronics (memory resistive switching), dye, photonics and photocatalysis. In the present paper we study the resPES data of TiO2 films prepared by atomic layer deposition. The measurements are done in in-situ system at beam line U49/2-PGM2 in BESSY-II. The density of state in valence band and conduction band is obtained from the resonance photo electron spectroscopy (res-PES) of the O1s and the Ti2p edge. The data allow to determine the position of the VBM and CBM with respect to the Fermi energy. Also the existence of localized O2p and Ti2p derived states is deduced which appear in the gap. In addition we determine the charge neutrality level (CNL).The CNL is the position where the weight of the density of state from valence band and conduction band are equal. This is an important quantity for the discussion of interface properties. KW - charge neutrality level KW - resonant photoelectron spectroscopy KW - TiO2 Y1 - 2015 UR - http://www.dpg-verhandlungen.de/year/2015/conference/berlin/part/o/session/58/contribution/12?lang=en SN - 0420-0195 SP - S. 415 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Alberton Corrêa, Silma A1 - Brizzi, Simone A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Spectroscopic investigation of the electronic structure of HfO2 thin films T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - HfO2 is of current interest as a material for memristive and ferroelectric devices. In this work, we used spectroscopic techniques to evaluate the electronic structure and defects mechanisms in thin HfO2 films deposited by atomic layer deposition and by metal-organic chemical vapour deposition. The partial density of states for the valence and the conduction bands was determined by the detailed analysis of the O1s resonance profile by resonant photoelectron spectroscopy. From the relative contributions we find a CNL 6.5 eV referred to Evac. We also find that the positions of valence band maximum and conduction band minimum, the excitation range for the polaronic states and the range of charge transfer band were not influenced by the preparation conditions. All films exhibit a band gap of 6.2 eV. However, the Fermi level position was found to vary within about 1.2 eV depending on the preparation conditions, which we argue that is due to the presence of charges within the films. This explains why the position of the Fermi level depends on the individual preparation parameters. KW - electronic structure KW - HfO2 Y1 - 2015 UR - http://www.dpg-verhandlungen.de/year/2015/conference/berlin/part/ds/session/36/contribution/106?lang=en SN - 0420-0195 SP - S. 211 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Henkel, Karsten A1 - Gargouri, Hassan A1 - Gruska, Bernd A1 - Arens, Michael A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Capacitance and conductance versus voltage characterization of Al2O3 layers prepared by PE-ALD at 25°C ≤ T ≤ 200°C T2 - Journal of Vacuum Science and Technology A N2 - In this work, plasma enhanced atomic layer deposited (PE-ALD) samples were prepared at substrate temperatures in the range between room temperature (RT) and 200 °C and investigated by capacitance–voltage and conductance–voltage recordings. The measurements are compared to standard thermal atomic layer deposition (T-ALD) at 200 °C. Very low interface state density (D it) ~1011 eV−1 cm−2 could be achieved for the PE-ALD process at 200 °C substrate temperature after postdeposition anneal (PDA) in forming gas at 450 °C. The PDA works very effectively for both the PE-ALD and T-ALD at 200 °C substrate temperature delivering also similar values of negative fixed charge density (N fix) around −2.5 × 1012 cm−2. At the substrate temperature of 150 °C, highest N fix (−2.9 × 1012 cm−2) and moderate D it (2.7 × 1011 eV−1 cm−2) values were observed. The as deposited PE-ALD layer at RT shows both low D it in the range of (1 to 3) × 1011 eV−1 cm−2 and low N fix (−4.4 × 1011 cm−2) at the same time. The dependencies of N fix, D it, and relative permittivity on the substrate temperatures and its adjustability are discussed. KW - Atomic layer deposition (ALD) KW - Al2O3 KW - dielectric properties KW - interface state density KW - fixed oxide charge KW - permittivity Y1 - 2014 UR - http://link.aip.org/link/?JVA/32/01A107&aemail=author U6 - https://doi.org/10.1116/1.4831897 VL - 1 IS - 32 SP - 01A107-1 EP - 01A107-10 ER - TY - CHAP A1 - Rouissi, Zied A1 - Brizzi, Simone A1 - Alberton Corrêa, Silma A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Comparison of charge neutrality level of Cu/CuO/HfO2 and Si/SiO2/HfO2 T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Copper Oxide (CuO) is a promising metal oxide semiconductor, which can be used in different applications, such as catalysis, solar energy conversion, and water splitting. In this work, we use resonance photoemission spectroscopy (ResPES) to analyse the electronics properties of HfO2 films deposited on Cu/CuO and Si/SiO2. For that, we deposited 10 cycles of HfO2 by atomic layer deposition (ALD) on Cu/CuO and Si/SiO2 samples and investigated the density states for the valence and conduction bands which were determined by the detailed analysis of the O1s resonance profile obtained by ResPES. We compared the positions of valence band maximum and conduction band minimum, the excitation range for the polaronic states and the range of charge transfer band in Cu/CuO/HfO2 and Si/SiO2/HfO2. Also, we determined the band gap and the charge neutrality level (CNL). KW - charge neutrality level (CNL) KW - resonant photoelectron spectroscopy KW - HfO2 Y1 - 2015 UR - http://www.dpg-verhandlungen.de/year/2015/conference/berlin/part/ds/session/36/contribution/47?lang=en SN - 0420-0195 SP - 208 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Cuypers, Daniel A1 - Dorp, Dennis H. von A1 - Tallarida, Massimo A1 - Brizzi, Simone A1 - Conard, Thierry A1 - Rodriguez, Leonard A1 - Mees, M. A1 - Arnauts, Sophia A1 - Schmeißer, Dieter A1 - Adelmann, Christoph A1 - De Gendt, Stefan T1 - Study of InP Surfaces after Wet Chemical Treatments T2 - ECS Journal of Solid State Science and Technology N2 - The influence of different wet chemical treatments (HCl, H₂SO₄, NH₄OH) on the composition of InP surfaces is studied by using synchrotron radiation photoemission spectroscopy (SRPES). It is shown that a significant amount of oxide remains present after immersion in a NH₄OH solution which is ascribed to the insolubility of In³⁺ at higher pH values. Acidic treatments efficiently remove the native oxide, although components like Pᴼ, Inᴼ and P(2±Δ)+ suboxides are observed. Alternatively, the influence of a passivation step in (NH₄)₂S solution on the surface composition was investigated. The InP surface after immersion into (NH₄)₂S results in fewer surface components, without detection of Pᴼ and P(2±Δ)+ suboxides. Finally, slight etching of InP surfaces in HCl/H₂O₂ solution followed by a native oxide removal step, showed no significant effect on the surface composition. KW - Synchrotron Radiation Photoelectron Spectroscopy KW - Scanning Tunneling Microscopy KW - InP KW - Wet chemical treatment Y1 - 2014 U6 - https://doi.org/10.1149/2.005401jss SN - 2162-8777 SN - 2162-8769 VL - 3 IS - 1 SP - N3016 EP - N3022 ER - TY - CHAP A1 - Mandal, Dipankar A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - A polymer nanogenerator based on silver nanoparticles doped electrospun P(VDF-HFP) nanofibers T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The rising energy demand within the increasing mobility of human society has driven the development of new alternative power sources for portable devices with ultra-low electric power consumption. Based on its piezoelectric properties poly-vinylidene fluoride (PVDF) is a good candidate for mechanical energy harvesting for such devices. Moreover the copolymer poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] offers better film flexibility and cost-effectiveness than pure PVDF. We report on a polymer nanogenerator (PNG) based on electrospun P(VDF-HFP) nanofibers doped with silver nanoparticles (Ag-NPs). The electrospun fibers were characterized by FTIR, XPS, SEM and pressure imparting probe. It has been found that the yield of the piezoelectric phase is increased by the addition of Ag-NPs due to an interaction between surface charges of Ag-NPs and the molecular dipoles. Furthermore, defects in the P(VDF-HFP) electrospun fibers are removed. Accordingly, a significant enhancement in the output power of the PNG was found. Similar trends were also observed with Pd-NPs. KW - nanogenerator KW - PVDF KW - nanoparticles Y1 - 2015 UR - http://www.dpg-verhandlungen.de/year/2015/conference/berlin/part/ds/session/36/contribution/34?lang=en SN - 0420-0195 SP - S. 208 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Haeberle, Jörg A1 - Gaspar, Diana A1 - Barquinha, Pedro A1 - Pereira, Luís A1 - Martins, Rodrigo A1 - Fortunato, Elvira A1 - Machulik, Stephan A1 - Janowitz, Christoph A1 - Manzke, Recardo A1 - Schmeißer, Dieter T1 - The Electronic Structure of amorphuos SnOx thin films and SnO2 single crystals T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - We compare the electronic properties of amorphous p-type SnOx thin film grown by rf magnetron sputtering with those of n-type SnO2 single crystals grown by cvt. We use resPES to study the electronic band structure. We measure the core levels, the VB PES data, partial Integrated Yield (pIY) and the XAS absorption data. From the resPES data recorded at the O1s and the Sn3d edges we derive the VB pDOS and the CB pDOS . The differences are most pronounced in the position of the VBM as for the a-SnOx films there appears a band closer to the Fermi energy. In addition for the SnOx we find in the XAS and pIY data a significant peak that appears right at the Fermi energy. This peak is absent in the single crystalline data. We attribute this to a change in the configuration of the Sn4d states to form a 4d8 configuration instead of 4d9 and 4d10 configurations which are identified in the single crystalline data. KW - electronic structure KW - SnO2 Y1 - 2015 UR - http://www.dpg-verhandlungen.de/year/2015/conference/berlin/part/hl/session/21/contribution/17?lang=en SN - 0420-0195 SP - S. 271 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Israel, Johannes A1 - Rachow, Fabian A1 - Schwiertz, Carola A1 - Charlafti, Evgenia A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Self restriction oft the Sabatier reaction in large scale T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - A main goal for a sustainable energy supply is a long term energy storage system. One opportunity in this research field is the power to gas concept, where the produced gas can be fed in the existing network of natural gas. Here we show in a technical scale how the direct CO2 conversion to methane according the Sabatier reaction, CO2 + 4 H2 → CH4 + 2H2O , is self organized. At a certain limit of gas flow, a steady state equilibrium of exothermic heat production and thermal flow is reached and the reaction needs no further external annealing. We find for the maximum volume rate at the steady state equilibirum a shift of around 250 ∘C above the optimized temperature of the catalytic supported chemical equilibrium. It is shown that also with this setup the used catalyst works with a stable conversion higher than 80 % under the reached temperature and given pressure conditions. KW - methanation KW - Sabatier reaction Y1 - 2015 UR - http://www.dpg-verhandlungen.de/year/2015/conference/berlin/part/ake/session/9/contribution/4?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Rachow, Fabian A1 - Israel, Johannes A1 - Schwiertz, Carola A1 - Charlafti, Evgenia A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - CO2 Methanation with different gas mixtures T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - A key issue in the Energiewende in Germany is the storage of excess energy, as it enables energy management systems to react to fluctuating sources and enhances the flexibility of an energy mix. Power to Gas may be the most reasonable approach to store the energy in the form of hydrogen or synthetic natural gas. We study the direct conversion of CO2 by the Sabatier reaction to gain a methane based mixture which can replace natural gas in CHP plants and gas motors and can help to partially reduce the CO2 emission. In laboratory scale we investigated the performance (with IR and QMS) of Ni-based catalyst for different sources of CO2 like clean CO2, CO2 emitted as flue gas from an Oxyfuel power plant or a synthetic mixture with O2, N2 and SO2 in concentration typical for conventional power plants. Measurements from an up-scaled system are also presented, showing data important for a technical application. Here, we are able to convert more than 200kg CO2/day with conversion rates up to 90%. KW - methanation KW - Sabatier reaction KW - contamination KW - catalyst Y1 - 2015 SN - 0420-0195 SP - S. 539 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Rouissi, Zied A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Study of atomic layer deposition with scanning tunneling microscopy T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - We present a work concerning the study of the initial steps of atomic layer deposition (ALD) with scanning tunneling microscopy (STM). We focus on the role of the substrates which has been often neglected.However, the detailed knowledge of precursor-substrate reactions is important for the understanding of how ALD proceeds. We report on the reaction of the Al-precursor, trimethyl-Al (TMA), on nanostructured surfaces such as Ag nanoclusters and nanostripes prepared by thermal evaporation on HOPG. We characterized the surface before and after one TMA adsorption pulse at room temperature, observing that the morphology of step edges changes after TMA creating a new terraces with a width of 7-10 nm, translated in the direction of the TMA deposition. This shows that, in case of a regular stepped surface, the substrate morphology would keep the same regularity with the translation in a direction privileged by the precursor absorption. KW - Atomic layer deposition (ALD) KW - Scanning tunneling microscopy (STM) KW - Al2O3 Y1 - 2015 SN - 0420-0195 SP - S. 401 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Tallarida, Massimo A1 - Das, Chittaranjan A1 - Schmeißer, Dieter T1 - Quantum size effects in TiO2 thin films grown by atomic layer deposition T2 - Beilstein Journal of Nanotechnology N2 - We study the atomic layer deposition of TiO2 by means of X-ray absorption spectroscopy. The Ti precursor, titanium isopropoxide, was used in combination with H2O on Si/SiO2 substrates that were heated at 200 °C. The low growth rate (0.15 Å/cycle) and the in situ characterization permitted to follow changes in the electronic structure of TiO2 in the sub-nanometer range, which are influenced by quantum size effects. The modified electronic properties may play an important role in charge carrier transport and separation, and increase the efficiency of energy conversion systems. KW - atomic layer deposition (ALD) KW - charge transfer multiplet KW - covalency KW - energy conversion KW - quantum size effects KW - titanium dioxide (TiO2) KW - water splitting KW - X-ray absorption spectroscopy (XAS) Y1 - 2014 U6 - https://doi.org/10.3762/bjnano.5.7 SN - 2190-4286 IS - 5 SP - 77 EP - 82 ER - TY - GEN A1 - Richter, Matthias A1 - Starke, Ulrich A1 - Schmeißer, Dieter T1 - Multiple Auger processes in Graphene T2 - Journal of Electron Spectroscopy and Related Phenomena N2 - Resonant Auger decay processes have been studied by resonant photoemission spectroscopy (resPES) and X-ray absorption spectroscopy (XAS) in Graphene systems. The pi*-resonance is used to identify the degree of localization of the lowest pi*-orbitals in the conduction band. Localization and lifetime of the photo-excited intermediate state cause the formation of multiple Auger processes. For the Graphene systems we identify two novel Auger decay combinations with a four hole final state: the (S+S) and the(S+S)* decay. We demonstrate that these processes are sensitive for interlayer coupling and interactions with the metallic free electrons of the substrate. KW - Graphene KW - X-Ray absorption spectroscopy KW - XAS KW - resonant photoemission spectroscopy KW - resPES KW - multiple hole Auger Y1 - 2014 U6 - https://doi.org/10.1016/j.elspec.2013.12.009 SN - 0368-2048 IS - Vol. 192 SP - 1 EP - 6 ER - TY - GEN A1 - Kramm, Ulrike Ingrid A1 - Lefèvre, Michel A1 - Larouche, Nicholas A1 - Schmeißer, Dieter A1 - Dodelet, Jean-Pol T1 - Correlations between Mass Activity and Physicochemical Properties of Fe/N/C Catalysts for the ORR in PEM Fuel Cell via 57 Fe Mössbauer Spectroscopy and Other Techniques T2 - Journal of the American Chemica Society N2 - The aim of this work is to clarify the origin of the enhanced PEM-FC performance of catalysts prepared by the procedures described in Science 2009, 324, 71 and Nat. Commun. 2011, 2, 416. Catalysts were characterized after a first heat treatment in argon at 1050 °C (Ar) and a second heat treatment in ammonia at 950 °C (Ar + NH3). For the NC catalysts a variation of the nitrogen precursor was also implemented. 57Fe Mössbauer spectroscopy, X-ray photoelectron spectroscopy, neutron activation analysis, and N2 sorption measurements were used to characterize all catalysts. The results were correlated to the mass activity of these catalysts measured at 0.8 V in H2/O2 PEM-FC. It was found that all catalysts contain the same FeN4-like species already found in INRS Standard (Phys. Chem. Chem. Phys. 2012, 14, 11673). Among all FeN4-like species, only D1 sites, assigned to FeN4/C, and D3, assigned to N-FeN2+2 /C sites, were active for the oxygen reduction reaction (ORR). The difference between INRS Standard and the new catalysts is simply that there are many more D1 and D3 sites available in the new catalysts. All (Ar + NH3)-type catalysts have a much larger porosity than Ar-type catalysts, while the maximum number of their active sites is only slightly larger after a second heat treatment in NH3. The large difference in activity between the Ar-type catalysts and the Ar + NH3 ones stems from the availability of the sites to perform ORR, as many sites of the Ar-type catalysts are secluded in the material, while they are available at the surface of the Ar + NH3-type catalysts. KW - Fe-N-C catalyst KW - 57 Fe Mössbauer Spectroscopy KW - X-ray photo-electron spectroscopy KW - neutron activation analysis KW - nitrogen sorption measurements KW - oxygen reduction reaction (ORR) KW - PEM Fuel Cell Y1 - 2014 U6 - https://doi.org/10.1021/ja410076f SN - 0002-7863 SN - 1520-5126 VL - 136 IS - 3 SP - 978 EP - 985 ER - TY - GEN A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Schmeißer, Dieter T1 - Interlayer-exciton mediated three-hole-Auger-decay in the pi-band of highly oriented pyrolytic graphite T2 - Physica E N2 - Resonant photoemission spectroscopy(resPES) is used to probe the occupied pi- and unoccupied pi*-bands of carbon thin films with particular focus on the Auger decay. Highly Oriented Pyrolytic Graphite (HOPG) is studied at the C1s edge. We find strong resonant features at 285.5 eV and 292 eV in the resPES diagram. The normal two-hole Auger decay proceeds under constant kinetic energy (451)only in the sigma*-region. In the pi*-region, however, it proceeds under 67.5° in terms of a Ebind(w) diagram. We attribute this to a multiple Auger decay with a net three hole final state. For this novel decay process we propose a model.We discuss the long lifetime of the first resonant excitation and conclude that it arises from the strong excitonic character of the first resonant state. We use HOPG as a reference system and suggest that this novel process is a tool to identify interlayer–substrate interaction of the carbon layers involved. KW - resonant excitation KW - three hole Auger decay KW - X-ray photoelectron spectroscopy KW - HOPG Y1 - 2014 U6 - https://doi.org/10.1016/j.physe.2013.01.015 SN - 1386-9477 VL - Vol. 56 SP - 441 EP - 446 ER - TY - CHAP A1 - Henkel, Karsten A1 - Tallarida, Massimo A1 - Haeberle, Jörg A1 - Gargouri, Hassan A1 - Naumann, Franziska A1 - Gruska, Bernd A1 - Arens, Michael A1 - Schmeißer, Dieter ED - Glück, Bernhard K. ED - Schmidt, Sindy ED - Stein, Erhard ED - Raschke, Jörg-Uwe ED - Richter, Hans T1 - PE-ALD-Al2O3-Schichten für die Passivierung von Solarzellen T2 - Tagungsband Photovoltaik-Meeting: Anwendungen-Qualität-Perspektiven, Senftenberg, 16.04.2014 N2 - Dünne Al2O3-Schichten wurden bei Substrattemperaturen zwischen Raumtemperatur und 200°C mittels PE-ALD auf Si-Substraten abgeschieden und ellipsometrisch, spektroskopisch und elektrisch charakterisiert. Ihr Potenzial für die chemische und Feldeffektpassivierung der Oberflächenrekombination wird bewertet. KW - Al2O3 KW - Atomlagenabscheidung (ALD) KW - Passivierung KW - PE-ALD KW - negative fixe Oxidladungen Y1 - 2014 SP - 7 EP - 14 PB - Cottbus-Senftenberg CY - BTU ER - TY - GEN A1 - Kramm, Ulrike Ingrid A1 - Herrmann-Geppert, Iris A1 - Fiechter, Sebastian A1 - Zehl, Gerald A1 - Zizak, Ivo A1 - Dorbandt, Iris A1 - Schmeißer, Dieter A1 - Bogdanoff, Peter T1 - Effect of iron carbide formation on the number of active sites in Fe-N-C catalysts for the oxygen reduction reaction in acidic media T2 - Journals of materials chemistry A KW - Oxygen reduction reaction (ORR) KW - Fe-N-C catalyst KW - acidic media KW - high-temperature X-ray diffraction (HT-XRD) KW - thermogravimetry coupled with mass-spectroscopy (TG-MS) Y1 - 2014 U6 - https://doi.org/10.1039/c3ta13821f SN - 2050-7488 SN - 2050-7496 IS - 8 SP - 2663 EP - 2670 ER - TY - GEN A1 - Tallarida, Massimo A1 - Das, Chittaranjan A1 - Cibrev, Dejan A1 - Kukli, Kaupo A1 - Tamm, Aile A1 - Ritala, Mikko A1 - Lana-Villarreal, Teresa A1 - Gómez, Roberto A1 - Leskelä, Markku A1 - Schmeißer, Dieter T1 - Modification of Hematite Electronic Properties with Trimethyl Aluminum to Enhance the Efficiency of Photoelectrodes T2 - The Journal of Physical Chemistry Letters N2 - The electronic properties of hematite were investigated by means of synchrotron radiation photoemission (SR-PES) and X-ray absorption spectroscopy (XAS). Hematite samples were exposed to trimethyl aluminum (TMA) pulses, a widely used Al-precursor for the atomic layer deposition (ALD) of Al2O3. SR-PES and XAS showed that the electronic properties of hematite were modified by the interaction with TMA. In particular, the hybridization of O 2p states with Fe 3d and Fe 4s4p changed upon TMA pulses due to electron inclusion as polarons. The change of hybridization correlates with an enhancement of the photocurrent density due to water oxidation for the hematite electrodes. Such an enhancement has been associated with an improvement in charge carrier transport. Our findings open new perspectives for the understanding and utilization of electrode modifications by very thin ALD films and show that the interactions between metal precursors and substrates seem to be important factors in defining their electronic and photoelectrocatalytic properties. KW - Hematite KW - Atomic Layer deposition KW - Photoelectrode KW - electro-catalysis KW - TMA KW - efficiency enhancement Y1 - 2014 U6 - https://doi.org/10.1021/jz501751w VL - 5 IS - 20 SP - 3582 EP - 3587 ER - TY - GEN A1 - Adelmann, Christoph A1 - Schram, Tom A1 - Chew, Soon Aik A1 - Woicik, J. C. A1 - Brizzi, Simone A1 - Tallarida, Massimo A1 - Schmeißer, Dieter A1 - Horiguchi, Naoto A1 - Elshocht, Sven van A1 - Ragnarsson, Lars-Åke T1 - On the scalability of doped hafnia thin films T2 - Applied Physics Letters N2 - The scaling behavior of Gd- and Al-doped HfO2 films as gate dielectrics in metal-oxide-semiconductor (MOS) capacitors was studied. For equivalent oxide thicknesses (EOTs) in the range of 10 Å, crystallized Gd:HfO2 showed higher leakage current densities than crystallized Al:HfO2, with undoped HfO2 in between. Ultimately, the scalability of Al:HfO2 was limited by the ability to crystallize the films at a given thermal budget. As a result, for post-deposition annealing at 800 °C, the EOT of Al:HfO2 based MOS capacitors was limited to ∼8 Å. However, for such an EOT, leakage current densities were reduced by about 100× with respect to HfO2. This demonstrates the high potential of Al:HfO2 for low-standby-power MOS devices. KW - scalability KW - hafnia thin films KW - Al:HfO2 KW - Gd:HfO2 KW - EXAFS KW - equivalent oxide thickness (EOT) KW - leakage current KW - X-ray absorption spectroscopy (XAS) Y1 - 2014 U6 - https://doi.org/10.1063/1.4870075 SN - 0003-6951 SN - 1077-3118 IS - 104 SP - 122906-1 EP - 122906-4 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Haeberle, Jörg A1 - Barquinha, Pedro A1 - Gaspar, Diana A1 - Pereira, Luís A1 - Martins, Rodrigo A1 - Fortunato, Elvira T1 - Electronic structure of amorphous ZnO films T2 - Physica Status Solidi C N2 - We use resonant photoemission spectroscopy (resPES) to study the electronic properties of amorphous ZnO (a-ZnO) layers. We report on the core levels, the valence band (VB) PES data, and the X-ray absorption (XAS) data which we use for the conduction band (CB) density of states. From these results we are able to derive the partial density of states (pDOS) of O2p and Zn4s4p states in the VB and CB, respectively as well as a band scheme. At the O1s resonance we observe a band of localized defect states which is located between the Fermi energy and the CBM. At the Zn2p edge the XAS data indicate that localized Zn4s4p states are involved in the DOS starting already at the Fermi energy. KW - a-ZnO thin films KW - intrinsic defects KW - resonant PES KW - amorphous oxide semiconductors (AOS) KW - transparent conducting oxides (TCO) KW - charge transfer Y1 - 2014 U6 - https://doi.org/10.1002/pssc.201400010 SN - 1610-1642 VL - 11 IS - 9-10 SP - 1476 EP - 1480 ER - TY - GEN A1 - Mandal, Dipankar A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Improved performance of a polymer nanogenerator based on silver nanoparticles doped electrospun P(VDF–HFP) nanofibers T2 - Physical Chemistry Chemical Physics N2 - We report on the electrospinning of poly(vinylidene fluoride–hexafluoropropylene) [P(VDF–HFP)] nanofibers doped with silver nanoparticles for the preparation of a polymer based nanogenerator (PNG). It has been found that the yield of the piezoelectric phase is increased by the addition of silver nanoparticles. Furthermore, defects in the P(VDF–HFP) electrospun fibers are removed resulting in a significant enhancement in the output power of the PNG. A maximum generated PNG output voltage of 3 V with a current density of 0.9 μA cm−2 is achieved. KW - piezoelectric thin polymer film KW - FTIR KW - nanogenerator KW - PVDF KW - P(VDF-HFP) KW - nanofibers Y1 - 2014 U6 - https://doi.org/10.1039/C3CP55238A SN - 1463-9084 SN - 1463-9076 VL - 2014 IS - 16 SP - 10403 EP - 10407 ER - TY - GEN A1 - Kramm, Ulrike Ingrid A1 - Lefèvre, Michel A1 - Bogdanoff, Peter A1 - Schmeißer, Dieter A1 - Dodelet, Jean-Pol T1 - Analyzing Structural Changes of Fe-N-C Cathode Catalysts in PEM Fuel Cell by Mößbauer Spectroscopy of Complete Membrane-Electrode-Assemblies T2 - The Journal of Physical Chemistry Letters N2 - The applicability of analyzing by Mößbauer spectroscopy the structural changes of Fe–N–C catalysts that have been tested at the cathode of membrane electrode assemblies in proton exchange membrane (PEM) fuel cells is demonstrated. The Mößbauer characterization of powders of the same catalysts was recently described in our previous publication. A possible change of the iron species upon testing in fuel cell was investigated here by Mößbauer spectroscopy, energy-dispersive X-ray cross-sectional imaging, and neutron activation analysis. Our results show that the absorption probability of γ rays by the iron nuclei in Fe–N–C is strongly affected by the presence of Nafion and water content. A detailed investigation of the effect of an oxidizing treatment (1.2 V) of the non-noble cathode in PEM fuel cell indicates that the observed activity decay is mainly attributable to carbon oxidation causing a leaching of active iron sites hosted in the carbon matrix. KW - iron-based catalyst KW - iron−nitrogen−carbon catalyst KW - non-noble metal catalyst KW - nonprecious metal catalyst KW - oxygen reduction reaction KW - ORR KW - polymer electrolyte membrane fuel cell KW - PEM-FC KW - degradation Y1 - 2014 U6 - https://doi.org/10.1021/jz501955g SN - 1948-7185 VL - 2014 IS - 5 SP - 3750 EP - 3756 ER - TY - GEN A1 - Indra, Arindam A1 - Menezes, Prashanth W. A1 - Sahraie, Nastaran Ranjbar A1 - Bergmann, Arno A1 - Das, Chittaranjan A1 - Tallarida, Massimo A1 - Schmeißer, Dieter A1 - Strasser, Peter A1 - Driess, Matthias T1 - Unification of Catalytic Water Oxidation and Oxygen Reduction Reactions: Amorphous Beat Crystalline Cobalt Iron Oxides T2 - Journal of the American Chemical Society N2 - Catalytic water splitting to hydrogen and oxygen is considered as one of the convenient routes for the sustainable energy conversion. Bifunctional catalysts for the electrocatalytic oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are pivotal for the energy conversion and storage, and alternatively, the photochemical water oxidation in biomimetic fashion is also considered as the most useful way to convert solar energy into chemical energy. Here we present a facile solvothermal route to control the synthesis of amorphous and crystalline cobalt iron oxides by controlling the crystallinity of the materials with changing solvent and reaction time and further utilize these materials as multifunctional catalysts for the unification of photochemical and electrochemical water oxidation as well as for the oxygen reduction reaction. Notably, the amorphous cobalt iron oxide produces superior catalytic activity over the crystalline one under photochemical and electrochemical water oxidation and oxygen reduction conditions. KW - photochemical KW - electrochemical KW - catalyst KW - water oxidation reaction KW - oxygen reduction reaction KW - cobalt iron oxides KW - control of crytallinity Y1 - 2014 U6 - https://doi.org/10.1021/ja509348t SN - 1520-5126 SN - 0002-7863 VL - 2014 IS - 136 SP - 17530 EP - 17536 ER - TY - CHAP A1 - Alberton Corrêa, Silma A1 - Brizzi, Simone A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Charging effect in HfO2 films deposited on SiO2/Si by atomic layer deposition T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Thin films of hafnium oxide (HfO2) deposited by atomic layer deposition (ALD) have been studied extensively as a high-k replacement for the SiO2 gate in field effect transistors. The use of ALD process allows one to grow homogeneous thin films at low temperatures with a precise control of thickness [1]. Some important electrical considerations for the application of a high-k dielectric include the presence of fixed charge (Qf) and charge trapping in the dielectric. For instance, in the case of Al2O3 thin films deposited on Si, the thickness of the interfacial SiO2 layer was identified as a key fundamental parameter determining Qf [2]. A similar trend can be also expected in HfO2/Si structures. Therefore, in this work, we proposed an in situ evaluation of photon induced charge trapping in HfO2 films deposited on SiO2/Si structures. For that, tetrakis-di-methyl-amino-hafnium (TDMAHf) and H2O were employed as precursors to deposit HfO2 films on SiO2/Si samples with variable thickness of the SiO2 interlayer. Measurements were performed by Synchrotron Radiation Photoemission Spectroscopy (SR-PES). Results indicated that the charging process is dependent on the thickness of the SiO2 interlayer and on the quality of the HfO2 film. [1] M. Leskelä and M. Ritala, Thin Solid Films 409, 138 (2002). [2] G. Dingemans et al., J. Appl. Phys. 110, 093715 (2011). KW - Charging KW - HfO2 KW - atomic layer deposition (ALD) Y1 - 2014 UR - http://www.dpg-verhandlungen.de/year/2014/conference/dresden/part/ds/session/49/contribution/10?lang=en SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Das, Chittaranjan A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - X-ray linear dichroism in atomic layer deposited Titanium dioxide layers T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Among the various metal oxides TiO2 has been investigated because of its wide range of applications in various fields such as self-cleaning, photocatalysis, solar cell, water splitting, bio-implants. In order to increase its efficiency in water splitting and solar cell energy conversion, it is necessary to understand the crystal structure and electronic properties of thin films. Generally the process of synthesis may modify the electronic properties of TiO2. In the present work we show X-ray linear dichroism (XLD) measurements of TiO2 thin films of different polymorphs. Titania thin films were produced by atomic layer deposition (ALD) and were characterized in-situ with X-ray photoelectron and absorption spectroscopy at synchrotron radiation center BESSY-II. We found that that all titania phases show XLD at Ti-L and O-K edges, but the intensity of XLD is different for different phases. We discuss our data in terms of the partial density of states. KW - X-ray linear dichroism KW - atomic layer deposition (ALD) KW - TiO2 KW - X-ray absorption spectroscopy KW - X-ray photoelectron spectroscopy Y1 - 2014 UR - http://www.dpg-verhandlungen.de/year/2014/conference/dresden/part/ds/session/49/contribution/4?lang=en SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Brizzi, Simone A1 - Tallarida, Massimo A1 - Adelmann, Christoph A1 - Ragnarsson, Lars-Åke A1 - Elshocht, Sven van A1 - Schmeißer, Dieter T1 - Structural changes in HfO2 thin films: thickness and doping dependence T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - In this work we show results regarding MOCVD and ALD HfO2 as well as Al-doped HfO2. We use Synchrotron Radiation Photoemission Spectroscopy (SRPES) to determine Hf/O atomic ratios and X-ray Absorption Spectroscopy (XAS) to investigate the electronic properties related to their crystallization. MOCVD films are synthesized at temperatures ranging from ambient to 400∘C and show structures from completely amorphous to monoclinic. ALD films are amorphous as deposited, and can crystallize after post-deposition anneal depending on the percentage of Al-doping. We discuss PES results in order to determine how close to stoichiometry the Hf/O atomic ratios of the films are, as well as the doping level. From XAS data, instead, we can point out how orbital hybridizations are related to structural and physical properties. KW - Structure KW - HfO2 thin films KW - thickness dependence KW - doping dependence KW - atomic layer deposition (ALD) Y1 - 2014 UR - http://www.dpg-verhandlungen.de/year/2014/conference/dresden/part/ds/session/49/contribution/9?lang=en SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Tallarida, Massimo A1 - Henkel, Karsten A1 - Gargouri, Hassan A1 - Haeberle, Jörg A1 - Gruska, Bernd A1 - Arens, Matthias A1 - Schmeißer, Dieter T1 - New opportunities with Plasma enhanced atomic layer deposition (PE-ALD) of oxides T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Thermal Atomic layer deposition (T-ALD) of oxides is obtained by the pulsed alternation of a metal precursor and an oxygen source, typically H2O or O3, and the reactions leading to ALD are thermally activated. With plasma enhanced ALD (PE-ALD), instead, the oxygen source is represented by an oxygen-containing plasma. The higher reactivity of the plasma-generated species extend the capabilities of ALD: improved film quality and increased flexibility in process conditions, such as growth at low temperature, are typical advantages of PE-ALD over T-ALD. We report on results on the preparation of thin (<100 nm) aluminum oxide (Al2O3) films on silicon substrates using T-ALD and PE-ALD in the SENTECH SI ALD LL system. Films were deposited in the temperature range between room temperature (RT) and 200∘C. We characterized the films with spectroscopic ellipsometry (thickness, refractive index, growth rate) over 4" wafers and with X-ray photoelectron spectroscopy. All films resulted in a high degree of homogeneity, independent of the deposition temperature. Investigations with capacitance-voltage and conductance-voltage measurements showed a very low interface states density for the PE-ALD films. KW - Atomic layer deposition KW - Plasma enhanced atomic layer deposition KW - X-ray photoelectron spectroscopy KW - spectroscopic ellipsometry KW - dielectric properties KW - Al2O3 Y1 - 2014 UR - http://www.dpg-verhandlungen.de/year/2014/conference/dresden/part/ds/session/49/contribution/3?lang=en SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Rösken, Liz M. A1 - Rohrbeck, Magdalena A1 - Catena, Alberto A1 - Wehner, Stefan A1 - Fischer, Christian B. A1 - Richter, Matthias A1 - Städter, Matthias A1 - Schmeißer, Dieter T1 - Characterization of diamond-like carbon (DLC) coatings on industrial polyethylene and polyoxymethylene by SEM, AFM and NEXAFS T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Diamond-like carbon (DLC) coatings are often utilized to change the base properties of raw materials, e. g. to gain robust or chemically inert surfaces. Here the deposition of hard DLC layers on soft polymers is tested. The common industrial polymers polyethylene (PE) and polyoxymethylene (POM) serve as model substrates in the present work. In order to examine the effect of the carbonaceous layers on PE and POM thin diamond-like carbon films were realized via PECVD. The topography of the different coatings was detected by AFM and SEM uncovering the different influence of the substrate material, e. g. interlayer formation for PE. The composition of the surface structures were analyzed in more detail by NEXAFS, showing the hybridization of carbon atoms in chemical different surroundings from the pure polymer to the carbon coating. The comparison of carbon coated PE- and POM-composites enables valuable insights into the interaction between soft substrates and hard coatings. For the chosen settings in PECVD, POM showed incomplete coating, while on PE a very stable and robust composite has formed. KW - Diamond-like carbon (DLC) KW - soft plolymers KW - Scanning electron microscopy (SEM) KW - Atomic foce microscopy (AFM) KW - Near-edge X-Ray absorption spectroscopy (NEXAFS) Y1 - 2014 UR - http://www.dpg-verhandlungen.de/year/2014/conference/dresden/part/ds/session/43/contribution/20?lang=en SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Das, Chittaranjan A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Control of thickness of SiO2 interfacial layer for photocatalytic water splitting on Si photocathodes T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Silicon with a band gap of 1.1eV is an excellent candidate for visible photocatalytic water splitting. But p-type Si has a low quantum yield and are less efficient for water splitting [1]. It has been shown that preventing oxidation of Si surface can shift the onset potential for water reduction by about 300mV towards more positive [2]. We investigated in detail the influence of the SiO2 layer thickness on the onset potential for water splitting on Si photocathodes: we used p-type Si substrates covered with SiO2 layers of varying thickness. Then, we deposited a thin TiO2 film on using atomic layer deposition (ALD) to inhibit Si oxidation during the electrochemical experiment. In this way we could shift the onset potential up to 200mV, depending on the SiO2 thickness. [1]E. L. Warren, S. W. Boettcher, M. G. Walter, H. A. Atwater, and N. S. Lewis: J. Phys. Chem. C 115 (2011) 594. [2]B. Seger, Anders B. Laursen, P. C. K. Vesborg, T. Pedersen, O. Hansen, S. Dahl, I. Chorkendorff, Angew. Chem. Int. Ed. 2012, 51, 9128 KW - photocatalysis KW - water splitting KW - Si photocathodes KW - atomic layer depsoition (ALD) KW - passivation layer KW - TiO2 Y1 - 2014 UR - http://www.dpg-verhandlungen.de/year/2014/conference/dresden/part/ds/session/49/contribution/5?lang=en SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Popovici, Mihaela A1 - Delabie, Annelies A1 - Adelmann, Christoph A1 - Meersschaut, Johan A1 - Franquet, Alexis A1 - Tallarida, Massimo A1 - Berg, Jaap van den A1 - Richard, Olivier A1 - Swerts, Johan A1 - Tomida, Kazuyuki A1 - Kim, Min-Soo A1 - Tielens, Hilde A1 - Bender, Hugo A1 - Conard, Thierry A1 - Jurczak, Malgorzata A1 - Elshocht, Sven van A1 - Schmeißer, Dieter T1 - Understanding the Interface Reactions of Rutile TiO2 Grown by Atomic Layer Deposition on Oxidized Ruthenium T2 - ECS Journal of Solid State Science and Technology N2 - The atomic layer deposition of titanium oxide TiO2 on ruthenium and oxidized ruthenium with titanium methoxide as metal precursor and H2O and O3 as oxidant was investigated by Rutherford backscattering (RBS) and time of flight secondary ion mass spectrometry (TOFSIMS). An ultra-thin layer of TiO2 deposited a priori with H2O plays the role of protection of Ru(Ox) substrates against etching by O3. Information about thin films (∼3 nm) interfacial reactions, thickness and structure was brought by Medium Energy Ion Scattering Spectroscopy (MEIS) and X-ray absorption spectroscopy (XAS) measurements. The growth enhancements observed in the first stages of the deposition depends on the pre-treatment (pre-oxidation, H2O based interlayer thickness) of the Ru substrate. Thick films (∼14 nm) were analyzed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The as deposited TiO2 films are crystalline with rutile structure, as resulted from structural analyzes. However, the presence of small amounts of anatase was detected by soft X-ray absorption spectroscopy (XAS) and is strongly influenced by the surface pre-treatment of the Ru substrate. The electrical properties (equivalent oxide thickness and leakage current density) correlate with a different rutile/anatase ratio present in the films. KW - TiO2 KW - atomic layer deposition KW - rutile KW - RuOx KW - Rutherford backscattering (RBS) KW - time of flight secondary ion mass spectrometry (TOFSIMS) KW - Medium Energy Ion Scattering Spectroscopy (MEIS) KW - X-Ray absorption spectroscopy KW - transmission electron microscopy (TEM) KW - X-ray diffraction (XRD) Y1 - 2013 U6 - https://doi.org/10.1149/2.035301jss SN - 2162-8769 VL - 2 IS - 1 SP - N23 EP - N27 ER - TY - GEN A1 - Fischer, Christian B. A1 - Rohrbeck, Magdalena A1 - Wehner, Stefan A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Interlayer formation of diamond-like carbon coatings on industrial polyethylene: Thickness dependent surface characterization by SEM, AFM and NEXAFS T2 - Applied Surface Science N2 - The coating of materials with diamond-like carbon (DLC) is a very common way to change and improve their basic characteristics. Although DLC is used on several substrates, the chemical and physical properties throughout the coating process on plastics are yet sparsely investigated. Two types of protective coatings one sp3-enriched (robust, r-type) and one with more sp2-centers (flexible, f-type) have been realized on polyethylene by PECVD deposition. SEM and AFM analysis of coated samples of DLC types revealed diverse surface topographies on different scales and images appeared even differently smoothed by the carbonaceous deposits. Grains of both DLC types are platelet-shaped and nearly double in size for the robust type indicating fundamental differences in the epitaxial DLC growth. NEXAFS spectroscopy showed significant details of carbon centers in chemically different neighborhood displaying a characteristic fingerprint behavior. Comparison of deposition models revealed a mechanism of interlayer formation which is discussed in detail. Interlayer formation is clearly the appropriate explanation of the process for the current carbon deposition between these two unequal materials. An improved understanding of hard DLC and soft polyethylene assembly is given in the presented work. KW - Diamond-like carbon KW - Interlayer formation KW - Polyethylene KW - Surface characterization KW - Coatings KW - Plastics Y1 - 2013 U6 - https://doi.org/10.1016/j.apsusc.2013.01.210 SN - 0169-4332 IS - 271 SP - 381 EP - 389 ER - TY - GEN A1 - Kolanek, Krzysztof A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Height distribution of atomic force microscopy images as a tool for atomic layer deposition characterization T2 - Journal of Vacuum Science and Technology : A N2 - The authors propose the analysis of surface height histograms as a tool for the atomic layer deposition (ALD) growth characterization in the initial stage of the process. ALD of HfO2 on a Si(100)/SiO2 substrate was investigated in situ by ultra high vacuum atomic force microscope working in noncontact mode. The ALD cycles, made by using tetrakis-di-methyl-amido-Hf and H2O as precursors, were performed at 230 C. After each ALD cycle, the relation between the film growth and the root mean square surface roughness was studied. Parameters equivalent to HfO2 layer thickness, coverage, and surface roughness of the substrate and deposited material can be calculated in the proposed routine. KW - Atomic layer deposition (ALD) KW - Atomic force microscopy KW - HfO2 KW - height distribution Y1 - 2013 U6 - https://doi.org/10.1116/1.4754557 VL - 31 IS - 1 SP - 01A104-1 EP - 01A104-9 ER - TY - GEN A1 - Kukli, Kaupo A1 - Dimri, Mukesh Chandra A1 - Tamm, Aile A1 - Kemell, Marianna A1 - Käämbre, Tanel A1 - Vehkamäki, Marko A1 - Puttaswamy, Manjunath A1 - Stern, Raivo A1 - Kuusik, Ivar A1 - Kikas, Arvo A1 - Tallarida, Massimo A1 - Schmeißer, Dieter A1 - Ritala, Mikko A1 - Leskelä, Markku T1 - Structural and Magnetic Studies on Iron Oxide and Iron-Magnesium Oxide Thin Films Deposited Using Ferrocene and (Dimethylaminomethyl)ferrocene Precursors T2 - ECS Journal of Solid State Science and Technology N2 - Iron oxide and magnesium-doped iron oxide films were grown by atomic layer deposition in the temperature range of 350–500 ◦C from ferrocene, (dimethylaminomethyl)ferrocene, magnesiumβ-diketonate, and ozone. Phase composition of the films depended on the deposition temperature, as magnetite and/or maghemite tended to form instead of hematite upon lowering the temperature. Iron oxide layers were also mixed with magnesium oxide by alternate deposition of MgO and Fe2O3 which also favored the formation of magnetite or maghemite structure prior to hematite. Scanning electron microscopy implied the smoothening of the films after doping with magnesium oxide. Magnetometry was used to study the effects of temperature and doping levels on the magnetic properties of the films. KW - iron oxide KW - iron magnesium oxide KW - GIXRD KW - Raman spectroscopy KW - X-Ray absorption spectroscopy (XAS) KW - scanning electron microscopy (SEM) KW - magnetization Y1 - 2013 U6 - https://doi.org/10.1149/2.004303jss SN - 2162-8769 VL - 2 IS - 3 SP - N45 EP - N54 ER - TY - GEN A1 - Richter, Matthias A1 - Paloumpa, Ioanna A1 - Friedrich, Daniel A1 - Schmeißer, Dieter T1 - Multiple Auger Decay At Resonant Photo-Excitation In Carbon Thin Films T2 - ECS Transactions N2 - We use resonant photoemission at the C1s edge to study the electronic structure of HOPG, graphene flakes and monolayer graphene. We find remarkable differences in the profile of the Auger decay channels, which we attribute to an additional multiple-Auger with a three-hole final state. A prerequisite for the appearance of this decay mechanism is the existence of localized excitonic states, which cause the appearance of the multiple Auger decay. We use those effects to identify the existence and the quantity of such defect states within the π*-band regime in carbon thin films, because the intensity of the three-hole Auger decay is varying with the defect density of the carbon films. We find that the appearance of the multiple Auger decay is different for multilayer and monolayer graphene. In particular the interaction of impurities leads to broadening of the C1s core levels. The three-hole Auger decay spectroscopy is a new method to detect such contaminations with a high sensitivity. KW - resonant photoelectron spectroscopy KW - graphene KW - HOPG KW - X-ray absorption spectroscopy (XAS) KW - X-ray photoelectron spectroscopy (XPS) Y1 - 2013 U6 - https://doi.org/10.1149/05020.0009ecst VL - 50 IS - 20 SP - 9 EP - 21 ER - TY - GEN A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - The Co2p Oxidation State In Co-PI Catalysts T2 - ECS Transactions N2 - The electronic structure of Cobalt based catalysts used for photocatalytic water splitting in solar cells is analyzed using synchrotron radiation photoelectron spectroscopy. The catalyst films are prepared by electrochemical deposition. We employ a X-ray photoelectron spectroscopy study to analyze the Co2p and O1s core levels,absorption edges and valence bands. We discuss our resonant data in terms of the partial density of states of the valence and conduction band. We find a difference in the Co oxidation state as a function of film thickness (deposited charge). From the relative amount of Co, O, K and P we favor the molecular cobaltate cluster-like structure as the structural motif of the Co-PI catalyst. KW - X-Ray photoelectron spectroscopy (XPS) KW - X-Ray absorption spectroscopy (XAS) KW - CoPI KW - oxygene evolution KW - water oxydation Y1 - 2013 U6 - https://doi.org/10.1149/05049.0113ecst VL - 50 IS - 49 SP - 113 EP - 126 ER - TY - GEN A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Spin states in Co-PI catalysts T2 - Applied Physics Letters N2 - Cobalt based oxygen evolution catalysts (Co-PI, PI=electrodeposited from pH 7 phosphate) are studied by resonant photoemission spectroscopy at the Co L3 and O1s edge. For the individual Co3d states, we determine their configuration, their spin, and their energy level relative to the Fermi energy. We identify the Co divalent high spin state and the trivalent low spin state. In addition, we also find the corresponding oxygen-to-metal charge transfer states. We attribute the trivalent charge transfer state to be the active state for the oxygen evolution reaction. KW - resonant photoelectron spectroscopy KW - CoPI KW - oxygen evolution reaction Y1 - 2013 U6 - https://doi.org/10.1063/1.4811748 SN - 1077-3118 IS - 102 SP - 253904-1 EP - 253904-4 ER - TY - GEN A1 - Barreca, Davide A1 - Carraro, Giorgio A1 - Gasparotto, Alberto A1 - Maccato, Chiara A1 - Rossi, Francesca A1 - Salviati, Giancarlo A1 - Tallarida, Massimo A1 - Das, Chittaranjan A1 - Fresno, Fernando A1 - Korte, Dorota A1 - Štangar, Urška Lavrenčič A1 - Franko, Mladen A1 - Schmeißer, Dieter T1 - Surface Functionalization of Nanostructured Fe2O3 Polymorphs: From Design to Light-Activated Applications T2 - ACS Applied Materials & Interfaces N2 - Nanostructured iron(III) oxide deposits are grown by chemical vapor deposition (CVD) at 400−500 °C on Si(100) substrates from Fe(hfa)2TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N′N′-tetramethylethylenediamine), yielding the selective formation of α-Fe2O3or the scarcely studiedε-Fe2O3 polymorphs under suitably optimized preparative conditions. By using Ti(OPr i)4(OPri= iso-propoxy) and water asatomic layer deposition (ALD) precursors, we subsequently functionalized the obtained materials at moderate temperatures (<300°C) by an ultrathin titanomagnetite (Fe3−xTixO4) overlayer. An extensive multitechnique character-ization, aimed at elucidating the system structure, morphology, composition and optical properties, evidenced that the photoactivated hydrophilic and photocatalytic behavior of the synthesized materials is dependent both on iron oxide phase composition and ALD surface modification. The proposed CVD/ALD hybrid synthetic approach candidates itself as a powerful tool for a variety of applications where semiconductor-based nanoarchitectures can benefit from the coupling with an ad hoc surface layer. KW - chemical vapor deposition KW - atomic layer deposition KW - iron oxide KW - titanomagnetite KW - photoactivated properties Y1 - 2013 U6 - https://doi.org/10.1021/am401475g SN - 1944-8252 VL - 5 IS - 15 SP - 7130 EP - 7138 ER - TY - GEN A1 - Adelmann, Christoph A1 - Cuypers, Daniel A1 - Tallarida, Massimo A1 - Rodriguez, Leonard A1 - De Clercq, Astrid A1 - Friedrich, Daniel A1 - Conard, Thierry A1 - Delabie, Annelies A1 - Seo, Jin Won A1 - Locquet, Jean-Pierre A1 - De Gendt, Stefan A1 - Schmeißer, Dieter A1 - Elshocht, Sven van A1 - Caymax, Matty T1 - Surface Chemistry and Interface Formation during the Atomic Layer Deposition of Alumina from Trimethylaluminum and Water on Indium Phosphide T2 - Chemistry of Materials N2 - The surface chemistry and the interface formation during the initial stages of the atomic layer deposition (ALD) of Al2O3 from trimethylaluminum (TMA) and H2O on InP(100)were studied by synchrotron radiation photoemission spectroscopy and scanning tunneling microscopy. The effect of the ex situ surface cleaning by either H2SO4 or (NH4)2S was examined. It is shown that the native oxide on the InP surface consisted mainly of indium hydrogen phosphates with a P enrichment at the interface with InP. After a (NH4)2S treatment, S was present on the surface as a sulfide in both surface and subsurface sites. Exposure to TMA led to the formation of a thin AlPO4 layer, irrespective of the surface cleaning. The surface Fermi level of p-type InP was found to be pinned close to midgap after H2SO4 cleaning and moved only slightly further toward the conduction band edge upon TMA exposure, indicating that the AlPO4/InP interface was rather defective. (NH4)2S passivation led to a Fermi level position of p-type InP close to the conduction band edge. Hence, the InP surface was weakly inverted, which can be attributed to surface doping by S donors. TMA exposure was found to remove surface S, which was accompanied by a shift of the Fermi level to midgap, consistent with the removal of (part of) the S donors in combination with a defective AlPO4/InP interface. Further TMA/H2O ALD did not lead to any detectable changes of the AlPO4/InP interface and suggested simple overgrowth with Al2O3. Y1 - 2013 U6 - https://doi.org/10.1021/cm304070h SN - 1520-5002 VL - 25 IS - 7 SP - 1078 EP - 1091 ER - TY - GEN A1 - Tallarida, Massimo A1 - Adelmann, Christoph A1 - Delabie, Annelies A1 - Elshocht, Sven van A1 - Caymax, Matty A1 - Schmeißer, Dieter T1 - III-V/Oxide Interfaces Investigated with Synchrotron Radiation Photoemission Spectroscopy T2 - ECS Transactions N2 - We used synchrotron radiation photoemission spectroscopy (SR-PES) to investigate the surface of GaAs and other III-V semiconductors after tri-methyl-aluminum (TMA) pulses performed at 250{degree sign}C. We observed the removal of native oxide and the growth of Al-oxide upon measuring the As3d, Ga3d, Al2p and VB spectra. After seven TMA pulses we performed one water pulse. As3d and Ga3d peaks showed almost no lineshape change, but a decrease of intensity due to the water adsorption. The valence band shows a change in the secondary electron cut-off and the decrease of work function. We conclude that water mostly adsorbs molecularly and induces the work function decrease. The molecular absorption of water indicates that the seven TMA pulses produce a passivated surface only partially terminated with OH groups. KW - Interfaces KW - III/V KW - Synchrotron Photoemission Spectroscopy Y1 - 2013 U6 - https://doi.org/10.1149/05004.0123ecst SN - 1938-6737 VL - 50 IS - 4 SP - 123 EP - 128 ER - TY - GEN A1 - Müller, Klaus A1 - Fleige, Michael A1 - Rachow, Fabian A1 - Schmeißer, Dieter T1 - Sabatier based CO2-methanation of flue gas emitted by conventional power plants T2 - Energy Procedia N2 - The hydrogenation CO2+ 4H2 ->CH4 + 2H2O discovered by Paul Sabatier nowadays is discussed as "Power-to-approach" to utilize excess energy from renewable electricity generation. In a laboratory scale, we investigate the Sabatier process in a simulated flue gas atmosphere of conventional base load power plants. The reaction is investigated with regard to conversion rates, yield, selectivity and long-term stability. Using a catalyst based on nickel,we extract selectivities near 100% with a conversion around 85%. Beside the influence of oxygen, we investigate further typical contaminations like NO2 and SO2. KW - Power to gas KW - CO2 -Methanation KW - Sabatier-reaction KW - flue gas Y1 - 2013 U6 - https://doi.org/10.1016/j.egypro.2013.08.028 SN - 1876-6102 VL - 40 SP - 240 EP - 248 ER - TY - GEN A1 - Haeberle, Jörg A1 - Henkel, Karsten A1 - Gargouri, Hassan A1 - Naumann, Franziska A1 - Gruska, Bernd A1 - Arens, Michael A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Ellipsometry and XPS comparative studies of thermal and plasma enhanced atomic layer deposited Al2O3-films T2 - Beilstein Journal of Nanotechnology N2 - We report on results on the preparation of thin (<100 nm) aluminum oxide (Al2O3) films on silicon substrates using thermal atomic layer deposition (T-ALD) and plasma enhanced atomic layer deposition (PE-ALD) in the SENTECH SI ALD LL system. The T-ALD Al2O3layers were deposited at 200 °C, for the PE-ALD films we varied the substrate temperature range between room temperature (rt) and 200 °C. We show data from spectroscopic ellipsometry (thickness, refractive index, growth rate) over 4” wafers and correlatethem to X-ray photoelectron spectroscopy (XPS) results. The 200°C T-ALD and PE-ALD processes yield films with similar refractive indices and with oxygen to aluminum elemental ratios very close to the stoichiometric value of 1.5. However, in both also fragments of the precursor are integrated into the film. The PE-ALD films show an increased growth rate and lower carbon contaminations. Reducing the deposition temperature down to rt leads to a higher content of carbon and CH-species. We also find a decrease of the refractive index and of the oxygen to aluminum elemental ratio as well as an increase of the growth rate whereas the homogeneity of the film growth is not influenced significantly. Initial state energy shifts in all PE-ALD samples are observed which we attribute to a net negative charge within the films. KW - Al2O3 KW - ALD KW - ellipsometry KW - PE-ALD KW - XPS Y1 - 2013 U6 - https://doi.org/10.3762/bjnano.4.83 SN - 2190-4286 VL - 2013 IS - 4 SP - 732 EP - 742 ER - TY - GEN A1 - Rossi, Francesca A1 - Fabbri, Filippo A1 - Tallarida, Massimo A1 - Schmeißer, Dieter A1 - Modreanu, Mircea A1 - Attolini, Giovanni A1 - Salviati, Giancarlo T1 - Structural and luminescence properties of HfO2 nanocrystals grown by atomic layer deposition on SiC/SiO2 core/shell nanowires T2 - Scripta Materialia N2 - In this work we report the morphological, structural and luminescence properties of HfO2 nanocrystals grown on the surface of SiC/SiO2 core/shell nanowires by atomic layer deposition. All the studies are carried out in comparison with HfO2 nanocrystal aggregates grown on planar oxidized silicon substrates. The structural analyses reveal that HfO2has monoclinic structure with dif-ferent orientations. The cathodoluminescence emission shows the main components at 2.7 and 2.3 eV, deeply influenced by the arrangement and aggregation of the nanocrystals. KW - Silicon carbide KW - Silicon dioxide KW - Nanowires KW - Hafnium oxide KW - Nanocrystals Y1 - 2013 U6 - https://doi.org/10.1016/j.scriptamat.2013.08.017 SN - 1359-6462 VL - 69 IS - 10 SP - 744 EP - 747 ER - TY - GEN A1 - Müller, Klaus A1 - Städter, Matthias A1 - Rachow, Fabian A1 - Hoffmannbeck, David A1 - Schmeißer, Dieter T1 - Sabatier-based CO2-methanation by catalytic conversion T2 - Environmental Earth Sciences N2 - The catalytic conversion of CO2is an important component for the reintegration of secondary products like CO2 or H2 into the energy supply. An example is the "power to gas’" concept with a conversion of CO2 into CH4. The CO2 is transferred into a carrier of chemical energy, with the possibility to feed the produced CH4 into the existing network of natural gas. At temperatures of around 350 °C, hydrogenation of CO2 to CH4 is possible by the Sabatier reaction CO2+4H2->CH4+H2O. One prerequisite for efficient kinetics of the Sabatier reaction is the application and optimization of catalysts. The focus of catalyst development is given to their performance under the conditions to be expected in the special application. As a part of the project Geoenergy-Research (GeoEn), we address questions related to the catalytic utilization of CO2 produced in the course of the oxyfuel combustion of lignite. In this contribution, we report on the experimental setup in laboratory scale, which enables an advanced characterization of the catalytic performance, including thermodesorption measurements at atmospheric pressure in order to determine the amount of adsorbed CO2 under real conditions. We also show data for activation energies, the catalytic performance as function of temperature and the long time stability of a commercial Ru-based catalyst. KW - CO2 KW - Sabatier reaction KW - Catalysis KW - RuO2 Y1 - 2013 U6 - https://doi.org/10.1007/s12665-013-2609-3 SN - 1866-6280 VL - 70 IS - 8 SP - 3771 EP - 3778 ER - TY - GEN A1 - Cuypers, Daniel A1 - Dorp, Dennis H. von A1 - Tallarida, Massimo A1 - Brizzi, Simone A1 - Rodriguez, Leonard A1 - Conard, Thierry A1 - Arnauts, Sophia A1 - Schmeißer, Dieter A1 - Adelmann, Christoph A1 - De Gendt, Stefan T1 - Study of InP Surfaces after Wet Chemical Treatments T2 - ECS Transactions N2 - In this work synchrotron radiation photoemission spectroscopy (SRPES) is used to study InP surfaces after different wet chemical treatments. All results are compared to a typical fingerprint of surface components present on an as received InP sample. It is shown that acidified (HCl and H₂SO₄) treatments efficiently remove the native phosphate, although components like Pᴼ, Inᴼ and P(2±∆)+ remain present. In alkaline solution (NH₄OH) oxide remains present at the surface. As an alternative treatment, the immersion into (NH₄)₂S was studied. This passivation treatment results in fewer surface components which suggests that a higher quality surface is obtained. KW - Synchrotron Radiation Photoelectron Spectroscopy KW - InP KW - Wet chemical treatment Y1 - 2013 U6 - https://doi.org/10.1149/05806.0297ecst SN - 1938-6737 SN - 1938-5862 VL - 58 IS - 6 SP - 297 EP - 303 ER - TY - CHAP A1 - Cuypers, Daniel A1 - Dorp, Dennis H. von A1 - Tallarida, Massimo A1 - Brizzi, Simone A1 - Rodriguez, Leonard A1 - Conard, Thierry A1 - Arnauts, Sophia A1 - Schmeißer, Dieter A1 - Adelmann, Christoph A1 - De Gendt, Stefan T1 - Study of InP Surfaces After Wet Chemical Treatments T2 - Meeting Abstracts-Electrochemical Society, San Francisco, 2013 KW - Synchrotron Radiation Photoelectron Spectroscopy KW - InP KW - Wet chemical treatment Y1 - 2013 UR - http://ma.ecsdl.org/content/MA2013-02/30/2132.full.pdf+html N1 - MA2013-02(30) SP - S. 2132 PB - The Electrochemical Society ER - TY - GEN A1 - Städter, Matthias A1 - Müller, Klaus A1 - Rachow, Fabian A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Ambient pressure thermal desorption spectroscopy (AP-TDS) of NiO/SiO2 catalysts T2 - Environmental Earth Sciences N2 - The Sabatier reaction is a key process in the "power-to-gas" application which is considered to con-tribute to future chemical energy storage systems. In this contribution we focus on the catalytic active sites of a NiO catalyst supported on SiO2(NiO/SiO2) which is commonly used in the Sabatier reaction. A novel technique for the characterization of the active sites is presented and dis-cussed using thermal desorption spectroscopy at ambient pressure. This analytical tool is operated under reaction conditions and allows element specific measurements during the catalytic process of CO2 reforming towards methane. Beside the desorption experiments, XPS and XAS measurements of pristine and catalytically used samples are performed to determine the influence of the Sabatier reaction conditions on the surface structure of the catalyst. KW - CO2 KW - NiO KW - TDS KW - XAS KW - XPS Y1 - 2013 U6 - https://doi.org/10.1007/s12665-013-2835-8 SN - 1866-6280 VL - 70 IS - 8 SP - 3779 EP - 3784 ER - TY - GEN A1 - Das, Chittaranjan A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Linear dichroism in ALD layers of TiO₂ T2 - Environmental Earth Sciences N2 - We prepare TiO₂film by ALD and study their electronic properties by soft X-ray absorption spectroscopy (XAS) and photoelectron spectroscopy. We focus on XAS and X-ray linear dichroism to indentify band onset and learn about local distortion of the Ti–O octahedral atomic and about defects which cause Ti-based electronic states within the band gap. KW - Anatase KW - Dichroism KW - Amorphous Y1 - 2013 U6 - https://doi.org/10.1007/s12665-013-2836-7 SN - 1866-6280 VL - 70 IS - 8 SP - 3785 EP - 3795 ER - TY - GEN A1 - Gerlich, Lukas A1 - Ohsiek, Susanne A1 - Klein, Christoph A1 - Geiß, Mario A1 - Friedemann, Michael A1 - Kücher, Peter A1 - Schmeißer, Dieter T1 - Interface engineering for the TaN/Ta barrier film deposition process to control Ta-crystal growth T2 - Microelectronic Engineering N2 - As a consequence of device shrinking the resistivity of the widely used TaN/Ta double barrier layer becomes an increasingly important parameter for device speed beyond the 32 nm technology node. In this study we describe the optimization of the deposition of TaN/Ta stacks in such a way that tantalum nitride layer thickness is minimized and tantalum grows in the favorable conducting alpha-phase. In the first part of the study we usedin situ ARXPS to investigate the growth of different tantalum nitride layers on SiO2 and SiOCH as a function of deposition time, nitrogen flow and deposition power. In the second part we analyzed the crystalline phase of a 20 nm thick tantalum layer deposited on top of the same series of tantalum nitride layers characterized in the growth study. The main findings are the appearance of tan-talum carbide and tantalum silicide as interface species for the deposition on SiOCH and only tantalum silicide for the deposition on SiO2. We found that alpha-tantalum grows preferably on tantalum carbide and nitrogen rich intermediate layers whereas silicide at the interface promotes the growth of beta-tantalum. To verify these findings we studied two additional modifications of the interface. A lower bias power for a deposition of tantalum nitride on SiO2 was used to confirm the role of tantalum silicide and a thermal treatment of a thin tantalum layer on SiOCH was applied to confirm the role of tantalum carbide. Finally, the contact resistance in via chains on patterned wafers for four selected processes showed the same trends as the sheet resistance of the corresponding barrier films on blanket wafer experiments. KW - Tantalum KW - in situ XPS KW - Ta-phase KW - TaNx KW - Barrier KW - Interface Y1 - 2013 U6 - https://doi.org/10.1016/j.mee.2013.01.017 VL - Vol. 106 SP - 63 EP - 68 ER - TY - GEN A1 - Scheck-Wenderoth, Magdalena A1 - Schmeißer, Dieter A1 - Mutti, Maria A1 - Kolditz, Olaf A1 - Huenges, Ernst A1 - Schultz, Hans-Martin A1 - Liebscher, Axel A1 - Bock, Michaela T1 - Geoenergy: new concepts for utilization of geo-reservoirs as potential energy sources T2 - Environmental Earth Sciences KW - Geothermal technologies KW - capturing and storing and utilizing CO2 KW - hydraulic fracturing Y1 - 2013 U6 - https://doi.org/10.1007/s12665-013-2877-y SN - 1866-6280 VL - 70 IS - 8 SP - 3427 EP - 3431 ER - TY - CHAP A1 - Choudhury, Sakeb Hasan A1 - Tallarida, Massimo A1 - Das, Chittaranjan A1 - Schmeißer, Dieter T1 - Atomic layer deposition of Ga2O3 using Tri-methyl-Gallium and H2O T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Considering numerous applications such as transparent conducting oxides, gas sensors, photovoltaic applications, deep UV photo detectors, field effect transistors and spintronics gallium oxide (Ga2O3) has earned quite a lot of focus recently. Various techniques have already been demonstrated to produce Ga2O3 naming evaporation, sputtering, pulsed laser deposition, chemical vapor deposition and atomic layer deposition (ALD). Among them, ALD gives the possibility of controlling the thickness at the atomic level, good step coverage and delivers dense and homogeneous films. In this contribution, we report on the growth of ALD Ga2O3 using trimethylgallium (TMG) and H2O as metal and oxygen precursors, respectively. We deposited thin Ga2O3 films on Si, TiO2, Al2O3 and RuO2 over a temperature range of 150-300°C and characterized them by X-ray photo emission spectroscopy and atomic force microscopy. From this study, we are able to discuss the influence of the temperature on the growth dynamics of Ga2O3 and its chemical composition. KW - atomic layer deposition KW - Ga2O3 KW - X-ray photoelectron spectroscopy (XPS) KW - Si, TiO2 , Al2O3 and RuO2 substrates Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/ds/session/4/contribution/2?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Brizzi, Simone A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - CVD and ALD deposited hafnia: an XPS study T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - In this work we report on Hafnium oxide deposited on silicon by means of chemical vapour deposition (CVD) and atomic layer deposition (ALD) using tetrakis-di-methyl-amino-Hf (TDMAHf) and water as precursors. We have studied the behavior of ALD and CVD at intermediate temperatures: ALD was performed outside the ALD window (T>300∘C), whereas CVD was performed at low temperatures, approaching the ALD window (T<400∘C). In this way we wanted to elucidate about the possibility of taking advantage of the conformality of ALD films and the high growth rate of CVD at the same time. Comparable sets of samples prepared with the two methods were measured by X-ray photoelectron spectroscopy and atomic force microscopy in order to determine differences between them: growth rate, Hf/O ratio, valence band positions and roughness are discussed and compared as a function of deposition temperature and process parameters. KW - HfO2 KW - chemical vapor deposition KW - atomic layer deposition (ALD) KW - X-Ray photoelectron spectroscopy Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/ds/session/30/contribution/1?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Das, Chittaranjan A1 - Tallarida, Massimo A1 - Skorupska, Katarzyna A1 - Lewerenz, Hans-Joachim A1 - Schmeißer, Dieter T1 - An efficient Si photo cathode for a wide range of electrolyte pH values T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Hydrogen fuel cells, being environmental friendly to produce energy, are a technology of future. One of the efficient ways to produce hydrogen is solar driven photocatalysis using semiconducting materials as photo electrodes. The choice of electrodes is a crucial factor and is done on the basis of photo corrosion stability, light absorption efficiency, and photocarrier lifetime. P-type Si can be used as photo cathode to produce H2 by direct photocatalysis. Si cathodes can be used in acidic electrolytes to have efficient photo catalytic activity but they are unstable in alkaline electrolytes. Therefore, to use both Si electrodes in the same electrolyte, their chemical stability should be extended over a wide range of pH. To this purpose we modified the surface of a p-type Si photocathode with very thin films of TiO2 grown by atomic layer deposition (ALD). We found that the modified Si cathode shows an increased photoresponse and a lower onset potential with respect to the pristine surface and an increased stability at various pH values. KW - Si photoelectrode KW - water splitting KW - atomic layer deposition (ALD) KW - TiO2 Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/ds/session/4/contribution/3?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Fleige, Michael A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Sabatier based CO2-Methanation of flue gas in conventional power plants T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Already discovered by Paul Sabatier in 1902 the Hydrogenation according to CO2 + 4H2 ->CH4 + 2H2O nowadays is discussed in the course of the ’Power-to-Gas’ approach to utilize excess energy from renewable electricity generation in times of oversupply of electricity. We investigate the behavior of this process in a simulated flue gas atmosphere of conventional base load power plants, which could be used as constant sources of the reactant CO2. Therefore the influence of different flue gas compositions such as varying contents of nitrogen and residual oxygen are tested in a laboratory scale. The heterogeneous catalysis process is investigated with regard to conversion rates, yield and selectivity and long-term stability of the Ni-catalyst. Earlier results of stable operating conditions in a 1:1 mixture of nitrogen and reactants, which is a typical ratio for flue gas in conventional power plants, could be confirmed in a first step. KW - methanation KW - flue gas KW - power plant KW - Sabatier reaction KW - power to gas Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/o/session/36/contribution/70?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Israel, Johannes A1 - Müller, Klaus A1 - Rachow, Fabian A1 - Beuckert, Guido A1 - Schmeißer, Dieter T1 - Reaction kinetics of the Sabatier Reaction in a demonstration plant T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - We currently build up a demonstration plant for the direct catalytic conversion of CO2 into methane according to the Sabatier reaction CO2+4H2→CH4+2H2O. We have already reached conversion rates higher than 90% and a selectivity close to unity in our laboratory experiments with NiO based catalysts. A good long term stability was obtained with a reactant gas flow density of 0.8 l/min cm2· at 350∘C. We will study the process now on a larger scale with a factor 10000. The process is controlled via mass flow controllers with a throughput of 20m3/h H2 and 5m3/h CO2 at an inlet gas pressure of up to 15 bar, the temperature is regulated by a PID multichannel controller. As water is a by-product we use an efficient cooling trap for its separation form the obtained methane. The reaction products are analyzed by a quadrupole mass spectrometer under reaction conditions. We start our experiments in using clean CO2 and H2. Later experiments will involve industrial quality (oxy-fuel) conditions also. Goal of this project is to determine the performance of the catalytic process under conditions which enable an industrial implementation in energy storage concepts. In this contribution we report of the design of a demonstration plant and on first experiments concerning the kinetics within the system. KW - methanation KW - Sabatier reaction KW - reaction kinetics Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/o/session/20/contribution/5?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Rachow, Fabian A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Sabatier based Methanation of carbon dioxide and Catalyst stability against contaminations T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The Sabatier-Reaction [CO2+4H2→CH4+2H2O] represents a possible way for the reduction and utilization of CO2 produced in the oxy-fuel combustion process. While using different ruthenium and nickel based catalysts we studied the catalytic performance with quadrupole mass spectroscopy and IR-spectroscopy in terms of conversion of CO2,yield of CH4, selectivity and stability. Conversions of up to 90% and a selectivity of well above 95% could be achieved. Further studies focus on the long term stability, especially with the influence of contaminations like SOx and NOx as they may occur in oxy-fuel or flue gas and could greatly reduce the life time of a catalyst. We investigate the limits of Ni based catalysts for those additives. However, technical oxy-fuel gas seems to have no particular effect on the activity of a commonly used NiO-catalyst when compared to quasi pure CO2 , showing only a small drop of performance after five days with a constant conversion rate of over 80% at the end. KW - methanation KW - Sabatier reaction KW - catalyst contaminations KW - NOx and SOx KW - long term stability Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/o/session/20/contribution/4?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - The Co2p spin and oxidation state in Co-PI catalysts T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The electronic structure of cobalt based catalysts used for photocatalytic water splitting in solar cells is analyzed using synchrotron radiation photoelectron spectroscopy. The catalyst films are prepared by electrochemical deposition. We employ a X-ray photoelectron spectroscopy study to analyze the Co2p and O1s core levels, absorption edges and valence bands. We discuss our resonant data in terms of the partial density of states of the valence and conduction band. We find a difference in the Co oxidation state as a function of film thickness (deposited charge). From the relative amount of Co, O, K and P we favor the molecular cobaltate cluster-like structure as the structural motif of the Co-PI catalyst. Further, at resonant PES at the Co2p edge we find the Co2p partial DOS to exhibit no sharp features next to the VBM, instead there is a broad emission at around 6eV below EFerrmi. The former are found in LiCoO2 and other Co-oxide systems with a Co3+ ground state. We attribute such sharp features to the low spin (LS) configuration of Co3+ and deduce that in the Co catalysts there is no evidence for the corresponding LS contributions. Our data prove the Co2+ ground state and demonstrate that it is exclusively in the Co3d7 high spin state in the pristine catalyst films. KW - X-Ray photoelectron spectroscopy KW - resonant photoemission spectroscopy KW - cobalt based catalyst KW - water splitting Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/ds/session/35/contribution/9?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Richter, Matthias A1 - Städter, Matthias A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Multiple Auger Decay at resonant photo-excitation in carbon thin films T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - We use resonant photoemission at the C1s edge to study the electronic structure of HOPG, graphene flakes and monolayer graphene. We find remarkable differences in the profile of the Auger decay channels, which we attribute to an additional multiple-Auger with a three-hole final state. A prerequisite for the appearance of this decay mechanism is the existence of localized excitonic states, which cause the appearance of the multiple Auger decay. Defects (pits, holes, steps and kinks) can act as localized excitonic states. We use those effects to identify the existence and the quantity of such defect states within the pi*-band regime in carbon thin films, because the intensity of the three-hole Auger decay is varying with the defect density of the carbon films. The defect-excitonic states can be either localized in the band-gap at the M-point or in case of surface defects like steps, kinks or pits even at the K-point by losing the pure sp2 character of the films. We find that the appearance of the multiple Auger decay is different for multilayer and monolayer graphene. In particular the interaction of impurities leads to broadening of the C1s core levels. The three-hole Auger decay spectroscopy is a new method to detect such contaminations with a high sensitivity. KW - resonant photoelectron spectroscopy KW - Auger decay KW - multiple decay KW - carbon thin films Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/hl/session/52/contribution/6?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Städter, Matthias A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Fano-Profiles in HOPG and graphene flakes T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - We investigated the electronic structure of the valence and conduction band of HOPG by 2D resonant photoemission spectroscopy. Our aim is to understand the electronic structure of defects and inhomogeneities in graphene and related materials in more detail. From our measurements we find that the transition from the sigma-band to the pi*-band at the M-point shows a characteristic Fano-Profile. A Fano-Profile occurs as the result of the interference of the band to band transition and a parallel transition to a discrete energy level within the band gap. The theory of Fano enables us to determine the energetic location of these discrete level. It is found to be several meV above the Fermi-Energy. Additional measurements on graphene flakes lead to similar results for the sigma- to pi*-band transition and the location of the discrete energy state. With this we not only can determine the energetic states of defects but also get a better understanding of the origin of the Fano profile which is a particular detail of the resonant absorption process. KW - resonant photoelectron spectroscopy KW - Fano profiles KW - Graphene KW - HOPG Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/hl/session/52/contribution/5?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Fischer, Christian B. A1 - Rohrbeck, Magdalena A1 - Wehner, Stefan A1 - Richter, Matthias A1 - Städter, Matthias A1 - Schmeißer, Dieter T1 - Interlayer formation of Diamond-Like Carbon Coatings on Polyethylene Plastic Material T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The coating of materials with diamond-like carbon (DLC) is a very common way to further improve and modify surface specific properties. Although DLC is frequently used as a protective coating on several substrates, the chemical and physical properties throughout the coating process on plastics are yet sparsely investigated. Different layer thicknesses of two types of protective coatings one sp3-enriched (robust, r-type) and one with more sp2-centers (flexible, f-type) have been realized on polyethylene by PECVD. Microscopic analysis showed diverse surface topographies for the two DLC-types. NEXAFS spectroscopy revealed significant details of carbon centers in chemically different neighborhood displaying a characteristic fingerprint behavior. The appropriate explanation for the current carbon deposition process is obviously the formation of an interlayer between these unequal materials. An improved understanding of hard DLC and soft polyethylene assembly is part of the present work. KW - Diamond-like carbon (DLC) KW - topography KW - X-ray absorption spectroscopy KW - plasma enhanced chemical vapor deposition Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/o/session/33/contribution/4?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Mandal, Dipankar A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Control of the Crystalline Polymorph, Molecular Dipole and Chain Orientations in P(VDF-HFP) for High Electrical Energy Storage Application T2 - International Conference on Nanoscience, Technology and Societal Implications (NSTSI), 2011 Y1 - 2012 SN - 978-1-4577-2035-2 U6 - https://doi.org/10.1109/NSTSI.2011.6111801 PB - IEEE ER - TY - GEN A1 - Mandal, Dipankar A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - The electroactive Beta-phase formation in Poly(vinylidene fluoride) by gold nanoparticles doping T2 - Materials Letters Y1 - 2012 SN - 0167-577X IS - 73 SP - 123 EP - 125 ER - TY - GEN A1 - Kolanek, Krzysztof A1 - Tallarida, Massimo A1 - Michling, Marcel A1 - Schmeißer, Dieter T1 - In situ study of the atomic layer deposition of HfO2 on Si T2 - Journal of Vacuum Science and Technology Y1 - 2012 SN - 0734-2101 IS - A 30 SP - 01A143-1 EP - 01A143-15 ER - TY - CHAP A1 - Garain, Samiran A1 - Adhikary, Prakriti A1 - Mandal, Dipankar A1 - Sen, Shrabanee A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Electro-active β-Phase Formation in Poly(vinylidene fluoride) Films by Hydrated Rare earth Metal Salt T2 - Proceeding of the International Conference on Nanotechnology 2013 (ICNT 2013) N2 - Polyvinylidene fluoride (PVDF) is a typical fluoro-polymer with complicated polymorphisms due to the semi-crystalline nature. Generally, four crystalline phases, α, β, γ and δ may exist in PVDF crystals. The nonpolar α- and δ-phase has a monoclinic lattice with trans-gauche conformation (TGTG⁄), which is thermodynamically most stable for PVDF. The polar β phase with all-trans (TTTT) planar zigzag conformation is attractive for its piezo-, pyro-, and ferroelectric properties. The polar β-Phase and also semi-polar γ-phase (TTTGTTTG⁄) have obtained wide device applications such as acoustic transducers, piezoelectric sensors, energy harvesting generators, pyroelectric sensors, non-volatile memories and energy storage capacitors. In this work, we explore the possibility to nucleate β-phase in PVDF hydrated salt composite films by addition of the hydrated Rare earth metal salt, (NH4)4 Ce (SO4)4, 2H2O) for the piezo- ferro and high dielectric based device applications. It has been found that the water molecules in (NH4)4 Ce (SO4)4, 2H2O could form hydrogen bonds with PVDF during the crystallization process and the hydrogen bonds promoted the electro-active crystalline β- phase in PVDF with all -trans conformations. In addition, the DMF (solvent used for films preparation) can also assist the rare-earth based nanoparticle preparation, as a result the electrostatic interaction of the surface charge of the nanoparticles and molecular dipoles in PVDF can resist the electroactive β- phase in PVDF. KW - PVDF KW - β-Phase KW - piezoelectric Y1 - 2013 SN - 978-81-927756-0-9 SP - S. 127 PB - Institute of Technology, Haldia, WB, India CY - Haldia ER - TY - GEN A1 - Müller, Klaus A1 - Richter, Matthias A1 - Philip, Shine A1 - Kunst, Manuel A1 - Schmeißer, Dieter T1 - Excited states in P3HT and P3HT/PCBM blends T2 - BioNanoScience Y1 - 2012 SN - 2191-1630 VL - 2 IS - 1 SP - 42 EP - 51 ER - TY - GEN A1 - Klocek, Jolanta A1 - Kolanek, Krzysztof A1 - Schmeißer, Dieter T1 - Spectroscopic and atomic force microscopy investigations of hybrid materials composed of fullerenes and 3-aminopropyltrimethoxysilane T2 - Journal of Physics and Chemistry of Solids Y1 - 2012 SN - 0022-3697 VL - 73 IS - 5 SP - 699 EP - 706 ER - TY - GEN A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Schmeißer, Dieter T1 - Valence and Conduction band states of PCBM as probed by photoelectron spectroscopy at resonant excitation T2 - BioNanoScience Y1 - 2012 SN - 2191-1630 VL - 2 IS - 1 SP - 59 EP - 65 ER - TY - GEN A1 - Mandal, Dipankar A1 - Müller, Klaus A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - The effect of X-ray photoelectron spectroscopy measurement on P(VDF-TrFE) copolymer thin films T2 - Applied Surface Science N2 - The impact of prolonged X-ray irradiation during X-ray photoelectron spectroscopy (XPS) measurement was investigated on poly(vinylidene-trifluoroethylene) (P(VDF-TrFE)) thin films. It was observed that prolonged X-ray irradiation can accelerate the crosslinking of P(VDF-TrFE) and diminish the ferroelectric phase. Fourier transform infrared spectroscopy (FT-IR) data indicate that the ferroelectric phase diminishes completely after 360 kJ of X-ray irradiation dose and it induces the paraelectric phase. In this work, the main emphasis was given to the optimization of the X-ray irradiation dose during XPS measurements to maintain the ferroelectric phase within the copolymer films. KW - P(VDF-TrFE) copolymer thin film KW - XPS measurement KW - X-ray irradiation KW - Ferroelectric to paraelectric phase transformation Y1 - 2012 U6 - https://doi.org/10.1016/j.apsusc.2012.07.144 SN - 0169-4332 SN - 1873-5584 IS - 261 SP - 209 EP - 213 ER - TY - GEN A1 - Schmidt, Stephan A1 - Schmeißer, Dieter T1 - Electronic structure of cobalt–nickel mixed oxides T2 - Solid State Ionics N2 - We investigate the electronic structure of cobalt–nickel mixed oxides by means of SR-based electron spectroscopy. We vary the Co–Ni content systematically and find that the most significant changes in the spectroscopic data occur at a mixing ratio of 30/70. We analyze the electronic structure of this material in detail and we are able to distinguish between pure covalent contributions, which cause a band gap of about 6 eV and empty defect states, whichfill the band gap almost completely. These defects are associated with the formation of 3d7L charge transfer states. These are correlated defect states and are identified by resonant photo-emission spectroscopy. KW - Transition metals KW - Oxides KW - Resonant photoemission KW - X-ray absorption spectroscopy Y1 - 2012 U6 - https://doi.org/10.1016/j.ssi.2012.06.009 SN - 1872-7689 IS - 225 SP - 737 EP - 741 ER - TY - GEN A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - In situALD experiments with synchrotron radiation photoelectron spectroscopy T2 - Semiconductor Science and Technology N2 - In this contribution, we describe some features of atomic layer deposition (ALD) investigated by means of synchrotron radiation photoelemission spectroscopy (SR-PES). In particular, we show how the surface sensitivity of SR-PES combined with the in situ nature of our investigations can point out interactions between the substrate and ALD precursors. We observed changes on all substrates investigated, included Si, GaAs, Ru and their surface oxides. These interactions are extremely important during the first ALD cycles and induce modifications in the substrate, which might lead to its functionality enhancement. KW - Atomic layer deposition (ALD) KW - in situ KW - photoelectron spectroscopy Y1 - 2012 U6 - https://doi.org/10.1088/0268-1242/27/7/074010 SN - 1361-6641 VL - 27 IS - 7 SP - 074010 ER - TY - GEN A1 - Michling, Marcel A1 - Schmeißer, Dieter T1 - Resonant Photoemission at the O1s threshold to characterize β-Ga2O 3 single crystals T2 - IOP Conference Series: Materials Science and Engineering N2 - We report on spectroscopic investigations on β-Ga2O3single crystals. We focus on the detailed analysis of the O1s resonance profile by resonant photoelectron spectroscopy. We analyze the electronic structure and assign the O2p to build the valence band and both, O2p and Ga4s4p states to contribute to the conduction band. We determine the partial density of states for the valence and conduction bands and find a strong hybridization of O2p and Ga4s states. This is deduced from constant final state spectra on the O-KLL-Auger over the O K-edge and Ga L2,3-edge and a comparison to the corresponding X-ray absorption spectroscopy data. We also identify several types of defects. A broad band of oxygen derived defects is identified that extends through-out the gap. Small polarons are attributed to cause an anti-resonance in the valence states around the O1s threshold. In addition, a separate Auger decay at resonance indicates the existence of localized charge transfer states which involves localized Ga4sp states. KW - resonant photoelectron spectroscopy KW - Ga2O3 Y1 - 2012 U6 - https://doi.org/10.1088/1757-899X/34/1/012002 SN - 1757-8981 IS - 34 SP - 012002 ER - TY - GEN A1 - Müller, Klaus A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Paloumpa, Ioanna A1 - Kramm, Ulrike Ingrid A1 - Schmeißer, Dieter T1 - Spectroscopic characterization of Cobalt–Phthalocyanine electrocatalysts for fuel cell applications T2 - Solid State Ionics N2 - For polymer–electrolyte–membrane fuel cells (PEM-FC), platinumcatalysts on carbon based substrates are state of the art, due to high electrochemical activity and chemical stability in acid electrolytes. High costs of platinum force investigations of alternative catalysts. With respect to the oxygen reduction reaction, possible candidates are transition metal (TM) complexes like TM-porphyrines or TM-phthalocyanines. Pyrolysis on carbon based substrates improves the catalytic activity. Highest activities were found for Fe or Co as transition metal centers. We present results of the pyrolysis of Co-phthalocyanine (CoPc) on carbon black. Besides an investigation of morphology by scanning electron microscopy (SEM) and chemical composition by energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) during pyrolysis, we present a near edge X-ray absorption fine structure (NEXAFS) study of the chemical composition for the related annealing steps. This investigation is accompanied by an electrochemical characterization of the catalytic activity and selectivity. The XPS and NEXAFS data indicate a decomposition of the CoN4(chelate-) complex during pyrolysis. The N1s data for 800 °C show graphite-like, formally pyrrolic and pyridinic like features, without any significant contri-bution of Co. The Co2p data for both, XPS and NEXAFS are dominated by CoO/Co2O3. It can be concluded that during the pyrolysis cobalt particles are formed by the disintegration of CoN4-centers, after pyrolysis these par-ticles become oxidized upon contact with air. KW - Co-phthalocyanine KW - Catalysis KW - Oxygen reduction reaction (ORR) KW - XPS KW - NEXAFS Y1 - 2012 U6 - https://doi.org/10.1016/j.ssi.2011.12.013 SN - 1872-7689 IS - 216 SP - 78 EP - 82 ER - TY - GEN A1 - Mandal, Dipankar A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Comment on "Preparation and Characterization of Silver-Poly(vinylidene fluoride) Nanocomposites:Formation of Piezoelectric Polymorph of Poly(vinylidene fluoride" Y1 - 2011 ER - TY - GEN A1 - Henkel, Karsten A1 - Torche, Mohamed A1 - Sohal, Rakesh A1 - Karavaev, Konstantin A1 - Burkov, Yevgen A1 - Schwiertz, Carola A1 - Schmeißer, Dieter T1 - Pr-O-Al-N dielectrics for metal insulator semiconductor stacks KW - semiconductor KW - dielectric Y1 - 2011 ER - TY - GEN A1 - Tallarida, Massimo A1 - Kukli, Kaupo A1 - Michling, Marcel A1 - Ritala, Mikko A1 - Leskelä, Markku A1 - Schmeißer, Dieter T1 - Substrate Reactivity Effects in the Atomic Layer Deposition of Aluminum Oxide from Trimethylaluminum on Ruthenium T2 - Chemistry of Materials Y1 - 2011 SN - 0897-4756 VL - 23 IS - 13 SP - 3159 EP - 3168 ER - TY - GEN A1 - Kolanek, Krzysztof A1 - Tallarida, Massimo A1 - Michling, Marcel A1 - Karavaev, Konstantin A1 - Schmeißer, Dieter T1 - Atomic layer deposition reactor for fabrication of metal oxides Y1 - 2011 ER - TY - GEN A1 - Tallarida, Massimo A1 - Friedrich, Daniel A1 - Städter, Matthias A1 - Michling, Marcel A1 - Schmeißer, Dieter T1 - Growth of TiO2 with Thermal and Plasma Enhanced Atomic Layer Deposition T2 - Journal of Nanoscience and Nanotechnology Y1 - 2011 SN - 1533-4880 VL - 11 IS - 9 SP - 8049 EP - 8053 ER - TY - CHAP A1 - Schmeißer, Dieter A1 - Müller, Sebastian A1 - Henkel, Karsten A1 - Müller, Klaus A1 - Wehner, Stefan T1 - In-situ analysis of moving reaction fronts for the bistable CO oxidation reaction on noble metal catalyst T2 - Extended Abstracts Book of First International Conference on Materials for Energy N2 - Experimental data on the reaction kinetics of catalytic processes are prerequisite for modeling of such reactions and their output. We investigate the CO oxidation on some noble metal catalysts, like Iridium(111) and Palladium(111) which is a bistable surface reaction. In a specific range of CO content in the feed gas islands of one or the other adsorbate nucleate and grow, which is recorded with photo electron emission microscopy (PEEM). During these transients the coverage on the surface changes from predominantly oxygen covered to predominantly CO covered resp. vice versa. But the resolution of PEEM and especially its unknown and nonlinear dependence of coverage of the two adsorbates (oxygen and CO) and image intensity make it impossible to extract the changes in coverage. On the other hand the reaction diffusion model based on the Langmuir-Hinshelwood-mechanism delivers the coverage of oxygen and carbon monoxide. The shapeand wall velocity of those islands has been connected perfectly to each other [CPL 423 (2006) 39], but not the absolute coverage and their variation during the reaction. Since the domain wall velocity is small on Iridium(111), this has opened the possibility for a detailed analysis of the changing coverage inside this domain wallutilizing synchrotron radiation and photo electron spectroscopy at BESSY II. The coverage profile of oxygen and CO inside a moving domain wall was measured for both cases using XPS spectra at O1s, C1s and the valence band during thereaction. Comparison with the reaction-diffusion-model and other catalytic surfaces, like Palladium(111) are done. KW - CO oxidation KW - Ir KW - Pd KW - photo electron emission microscopy (PEEM) Y1 - 2010 SN - 978-3-89746-117-8 SP - S. 932 PB - Dechema e.V. CY - Frankfurt ER - TY - CHAP A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Schmeißer, Dieter T1 - Multiple Auger decay at resonant photo-excitation in carbon thin films T2 - Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012 Y1 - 2012 UR - http://ma.ecsdl.org/content/MA2012-02/50/3509.full.pdf+html N1 - MA2012-02(50) SP - 3509 PB - The Electrochemical Society ER - TY - CHAP A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - The Co2p oxidation state in Co-PI catalysts T2 - Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012 Y1 - 2012 N1 - MA2012-02(14) SP - 1803 PB - The Electrochemical Society ER - TY - GEN A1 - Tallarida, Massimo A1 - Adelmann, Christoph A1 - Delabie, Annelies A1 - van Elshocht, Sven A1 - Caymax, Matty A1 - Schmeißer, Dieter T1 - GaAs clean up studied with synchrotron radiation photoemission T2 - IOP Conference Series : Materials Science and Engineering N2 - In this contribution we describe the chemical changes at the surface of GaAs upon adsorption of tri-methyl-aluminum (TMA). TMA is used to grow Al2O3 with atomic layer deposition (ALD) usually using H2O as oxygen source. Recently, it was pointed out that the adsorption of TMA on various III-V surfaces reduces the native oxide, allowing the growth of an abrupt III-V/High-K interface with reduced density of defects. Synchrotron radiation photoemission spectroscopy (SR-PES) is a powerful method to characterize surfaces and interfaces of many materials, as it is capable todetermine their chemical composition as well as the electronic properties. We performed in-situ SR-PES measurements after exposing a GaAs surface to TMA pulses at about 250°C. Upon using the possibility of tuning the incident photon energy we compared the Ga3d spectra at 41 eV, 71 eV, 91 eV and 121 eV, as well as the As3d at 71 eV and 91 eV. Finally, we show that using SR-PES allows a further understanding of the surface composition, which is usually not accessible with other techniques. KW - photoemission spectroscopy KW - atomic layer deposition KW - GaAs Y1 - 2012 U6 - https://doi.org/10.1088/1757-899X/41/1/012003 SN - 1757-899X IS - 41 SP - 012003 ER - TY - CHAP A1 - Mandal, Dipankar A1 - Henkel, Karsten A1 - Das, Suken A1 - Schmeißer, Dieter ED - Heber, Jörg ED - Schlom, Darrell ED - Tokura, Yoshinori ED - Waser, Rainer ED - Wuttig, Matthias T1 - Control of β- and γ-Phase formation in electroactive P(VDF-HFP) films by silver nano-particle doping T2 - Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany KW - P(VDF.HFP) KW - electroactive phase KW - nanoparticle doping KW - FTIR Y1 - 2012 SN - 978-3-527-41191-7 U6 - https://doi.org/10.1002/9783527667703.ch69 SP - 640 EP - 641 PB - Wiley-VCH CY - Weinheim ER - TY - CHAP A1 - Schmeißer, Dieter A1 - Richter, Matthias A1 - Tallarida, Massimo ED - Heber, Jörg ED - Schlom, Darrell ED - Tokura, Yoshinori ED - Waser, Rainer ED - Wuttig, Matthias T1 - Intrinsic defects in TiO2 to explain resistive switching devices T2 - Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany KW - resonant photoelectron spectroscopy KW - Auger processes KW - XPS KW - X-ray absorption spectroscopy Y1 - 2012 SN - 978-3-527-41191-7 U6 - https://doi.org/10.1002/9783527667703.ch45 SP - 255 EP - 256 PB - Wiley-VCH CY - Weinheim ER - TY - CHAP A1 - Müller, Klaus A1 - Hoffmannbeck, David A1 - Kirner, Georg A1 - Städter, Matthias A1 - Schmeißer, Dieter T1 - CO2-Methanation by Catalytic Conversion T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The utilization of CO2 as raw material is an important component of a program for CO2 reduction. A possibility is the production of methane. At a moderate temperature of around 350°C, hydrogenation of CO2 to methane is possible by the Sabatier reaction CO2 + 4H2 ->CH4 +2H2O. Prerequisite for an efficient kinetics of the Sabatier reaction is the application and optimization of catalysts. In this contribution, we present investigations of Ru and Ni catalysts on different substrates. For Ru/Al2O3 catalysts, we found stable operation without degradation within 500 hours with a conversion rate of 80% at 350°C. For NiO/SiO2 catalysts, a conversion rate of 90% was found for temperatures of 350-405°C. We also show the investigation of cross sensitivities against SOx and NOx, which are typical contaminations of CO2, generated by the industrial oxyfuel process. In our work the morphology (REM, AFM, specific surface), chemical composition (FTIR, XPS) and phase composition (XRD) of the catalysts are characterized. In addition, we report on thermodesorption (TDS) measurements at atmospheric pressure to determine the amount of adsorbed CO2 under real conditions. The project is funded by the German Ministry of Research and Education (BMBF-GeoEn). Y1 - 2012 UR - http://www.dpg-verhandlungen.de/year/2012/conference/berlin/part/ds/session/37/contribution/45 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Philip, Shine A1 - Müller, Klaus A1 - Richter, Matthias A1 - Kunst, Marinus A1 - Schmeißer, Dieter T1 - Study of excited states and a model for exciton-polaron interaction in P3HT T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47 N2 - Organic semiconductors efficiently harvest light in the region of the solar spectrum due to a high absorption/extinction coefficient.In our work we study the electronic structure and the charge carrier dynamics of polymeric organic semiconductor regioregular poly(3-hexylthiophen-2,5-diyl) (P3HT), an ideal p-type semiconductor and a widely used conjugated polymer, and blends with the fullerene derivative phenyl-C61-butyric acid methyl ester (PCBM), an electron acceptor material. The study was done with the help of time resolved microwave conductivity (TRMC) for contactless investigation of bulk carrier dynamics, optical spectroscopy, ultraviolet photoelectron spectroscopy(UPS) and high resolution X-ray absorption spectroscopy(XAS) which investigates excited states of rr-P3HT. From the data obtained we could infer the positions of the valence and conduction band, the existence of two excitons as well as the co-existence of one dimensional and two dimensional polarons. Based on our spectroscopic data we propose a model in which the scattering of virtual polarons and excitons are shown to create mobile polaronic charge carriers. Y1 - 2012 UR - http://www.dpg-verhandlungen.de/year/2012/conference/berlin/part/ds/session/44/contribution/31 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Das, Chittaranjan A1 - Städter, Matthias A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Investigation of Linear Dichroism in ALD layers of TiO2 T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47 N2 - Titanium dioxide is on the most studied material due to its wide range of applications in various fields such as self cleaning, photocatalysis, solar cell, water splitting, bio-implants, etc. In order to increase its efficiency in water splitting and solar cell, it is necessary to understand the crystal structure and electronic properties in thin films. In our approach we are investigating the X-ray linear dichroism (XLD) of thin layers of TiO2. XLD studies have been done in multiferroics, antiferromagnetic, and ferromagnetic materials, but a very less amount of work have been done in studying XLD effect of TiO2 thin films. These layers are grown by in-situ atomic layer deposition (ALD) system and are investigated with X-ray absorption spectroscopy (XAS) at BESSY II, Berlin. ALD is a promising technique to grow thin films on different substrates conveniently due to its uniform deposition property. XAS study will also help us to better understand the interfacial electronic properties of thin films of TiO2. Y1 - 2012 UR - http://www.dpg-verhandlungen.de/year/2012/conference/berlin/part/ds/session/44/contribution/59 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Städter, Matthias A1 - Schmeißer, Dieter T1 - AP-TDS characterization of CO2 methanation catalysts T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47 N2 - Development of new catalysts and their characterization by TDS (thermal desorption spectroscopy) is used in a wide field of applications. In our group we focus on catalysts usable to convert CO2 towards methane by the Sabatier reaction (CO2 + 4H2 → CH4 + 2H2O at 375∘C). For measuring large numbers of samples we designed an AP-TDS (ambient pressure TDS) chamber where various desorption experiments can be performed without bringing the catalyst into vacuum. The well-defined reaction chamber, in terms of temperature, pressure and gas composition (Ar atmosphere), is separated by a pin hole (∅ = 6 µ m) from an external UHV chamber. Evolving species and their composition are monitored by a mass spectrometer attached to the UHV chamber. Our first measurement results on commercially available NiO/SiO2 and Ru/Al2O3 based catalysts, with focus on the identification and enumeration of different adsorption sites for CO2, will be presented. CO2 saturated samples were heated from RT to 1100∘C (heating rate β = 0.3 K/s) while measuring the evolution of the CO2 content. Our measurements show large numbers of different adsorption sites for NiO (200-750∘C) whereas Ru shows only few different sites around 440∘C. For both catalysts, most of the formerly adsorbed CO2 remains at the surface (at 375∘C) available for methanation. Y1 - 2012 UR - http://www.dpg-verhandlungen.de/year/2012/conference/berlin/part/va/session/2/contribution/2 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Tallarida, Massimo A1 - Michling, Marcel A1 - Das, Chittaranjan A1 - Friedrich, Daniel A1 - Städter, Matthias A1 - Schmeißer, Dieter T1 - Role of substrate chemistry in ALD revealed by in-situ techniques T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47 N2 - We show recent results of our in-situ investigations where the role of substrate chemistry in ALD is outlined. While the usual strategy to develop new properties of ALD films is to find new precursors or new procedures, the influence of substrate chemistry on the growth properties of ALD films has been often underestimated. This has principally a technical reason, as the usual characterization methods (QMS, FTIR, ellipsometry) are only weakly sensitive to the substrate, and a characterization of substrates before ALD is often not possible. Thanks to the use of in-situ characterization methods, including photoemission and X-ray absorption spectroscopy with synchrotron radiation, we are able to determine chemical properties of substrates before ALD and after either half or complete ALD cycles. The substrate chemistry influences the standard Al2O3 ALD with TMA and water [1,2], as well as the TiO2 ALD with TTIP and either water, O2 or O2-plasma. [1] M. Tallarida, K. Kukli, M. Michling, M. Ritala, M. Leskelä and D. Schmeisser, Chem. Mater. 23, 3159 (2011); [2] M. Tallarida, C. Adelmann, A. Delabie, S. van Elshocht, M. Caymax, and D. Schmeisser, Appl. Phys. Lett. 92, 042906 (2011). Y1 - 2012 UR - http://www.dpg-verhandlungen.de/year/2012/conference/berlin/part/ds/session/22/contribution/3 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Rohrbeck, Magdalena A1 - Fischer, Christian B. A1 - Wehner, Stefan A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Diamond-Like Carbon Coatings on Industrial Polyethylene Surfaces T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47 N2 - Synthetic materials are used in a wide variety of fields. Depending on the intended application the plastic material must meet specific requirements. Since the material always interacts with its environment, particular attention is required regarding the surface. Possible damage of the plastic material and further risks could be caused by the adhesion of bacteria, biofilm formation and encrustations. Therefore, bacteria-repellent coatings and surface-modified materials that allow for an effective removal of adhered bacteria are of extremely high interest for many applications. In this study Polyethylene (PE) is chosen as simplest model for relevant plastic materials. Surface modification of PE samples is accomplished by plasma-deposited diamond-like carbon (DLC) coatings to achieve increased abrasion strength and bacterial resistance. Two types of nanometer-scaled DLC films with different layer thicknesses are compared by multiscale microscopic analysis. Further spectroscopic measurements with synchrotron radiation are performed. These results will provide an enhanced understanding of layer formation at the interface between the basic plastic material and the DLC coating and will possibly lead to optimal parameters for the surface coating to achieve improved product characteristics. Y1 - 2012 UR - http://www.dpg-verhandlungen.de/year/2012/conference/berlin/part/o/session/35/contribution/28 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Schmeißer, Dieter T1 - 3h-Auger decay in the π-band of HOPG T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47 N2 - In this contribution we report on the electronic structure of highly oriented pyrolitic graphite (HOPG). HOPG is a model system because of the clear separation between π- and σ-bands in the valence band regime. X-ray based measurements were done at the U49/2-PGM2 beam line at BESSYII in Berlin. The resonant photoemission spectra (resPES) at the carbon K-edge give a complete picture of the occupied and unoccupied states in these sp2 hybridized system. Above the K-edge the resPES data are dominated by the Auger process causing a C2p4 final state. The Auger lines appear at constant kinetic energy (spectator, 2h) or constant binding energy (participator, 1h). For the features right at the resonance we observe a different Auger decay mechanism. We attribute it to the decay out of an excitonic intermediate state with a long lifetime. It involves three valence hole states. The original primary core hole is filled by a normal KLL Auger decay. The excited electron rests in the excitonic intermediate state and decays later. We discuss the spectral features of such combined spectator-participator decays in detail which are found only close to resonance and only in the localized valence states of excitonic excitation i.e.C1s - 1π* transitions [1, 2, 3]. [1] Richter et al. (2011) BioNanoScience, submitted. [2] Michling et al. (2011) IOP C Ser Mater Sci Eng, submitted. [3] Schmidt et al. (2011) Solid State Ionics, submitted. Y1 - 2012 UR - http://www.dpg-verhandlungen.de/year/2012/conference/berlin/part/ds/session/35/contribution/4 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Fischer, Christian B. A1 - Rohrbeck, Magdalena A1 - Wehner, Stefan A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Diamond-Like Carbon Coatings on Selected Plastic Materials T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47 N2 - The manufacturing of synthetic materials and their wide range of use for daily life is accompanied by essential requirements. Besides the basic performance of materials such as flexibility, elasticity, fracture strength and chemical resistance, further determinants are long term stability or biocompatibility. To overcome mismatches in surface characteristics of optimal parent material they can be customized for their intended use resulting in suitable coatings for profitable applications. The determining factor for such modifications is the preservation of basic material performance in addition to the benefit of further advantages like changed adhesive, improved repellent or antibacterial behavior. Protective coatings of selected plastic materials have been realized by depositing a few layers of diamond-like carbon (DLC). The assembly of soft plastic material and robust DLC coating is important for the resulting material characteristics. The detailed understanding of materials interphasing between these unequal materials and the conjunction of carbon centers in chemically different neighborhood is part of the presented work. Results will be transferable to other plastic materials with diverse needs, e.g. energy storage devices, water treatments and coatings for everyday commodities or industrial parts. Y1 - 2012 UR - http://www.dpg-verhandlungen.de/year/2012/conference/berlin/part/o/session/66/contribution/9 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Tallarida, Massimo A1 - Adelmann, Christoph A1 - Delabie, Annelies A1 - Elshocht, Sven van A1 - Caymax, Matty A1 - Schmeißer, Dieter T1 - Surface chemistry and Fermi level movement during the self-cleaning of GaAs by trimethyl-aluminum T2 - Applied physics letters Y1 - 2011 U6 - https://doi.org/10.1063/1.3615784 SN - 1077-3118 VL - 99 IS - 4 SP - 042906-1 EP - 042906-3 ER - TY - GEN A1 - Tallarida, Massimo A1 - Weisheit, Martin A1 - Kolanek, Krzysztof A1 - Michling, Marcel A1 - Engelmann, Hans-Jürgen A1 - Schmeißer, Dieter T1 - Atomic layer deposition of nanolaminate oxide films on Si T2 - Journal of Nanoparticle Research Y1 - 2011 U6 - https://doi.org/10.1007/s11051-011-0319-x VL - 13 IS - 11 SP - 5975 EP - 5983 ER - TY - CHAP A1 - Mai, Andreas A1 - Dauderstädt, Ulrike A1 - Pahner, D. A1 - Krellmann, M. A1 - Schmeißer, Dieter A1 - Wagner, M. T1 - In situ determination of laser induced degradation of micro-mirror arrays T2 - International Students and Young Scientists Workshop Photonics and Microsystems, Cottbus, Germany, 8 - 10 June 2011 N2 - The Fraunhofer Institute for Photonic Microsystems (Fraunhofer IPMS) develops spatial light modulators (SLMs) based on arrays of tiltable micro mirrors on a semiconductor chip. Typical applications are pattern generation for deepUV-laser mask writing or structured illumination in microscopy. Development and optimization of such SLMs requires detailed knowledge of the device behaviour under operating conditions. Here, the flatness of each single mirror effects the image resolution and contrast of the generated pattern and is amongst others a characteristic property of SLMs. In this context a surface topography measurement under laser exposure (in situ) was designed. The interferometric setup uses the phase-shift principle and allows a resolution in z-direction in the single-digit nanometer range. During irradiation with UV-laser light at 248 nm (KrF) and energy densities of up to 20 mJ/cm2 the change in single micro-mirrors topography was detected in situ. Measurementswith varying pulse energies were carried out to identify an impacton the device performance. In general, the setup is neither limited to a specific illumination wavelength nor to micro-mirrors as structures under test. KW - micro-mirror arrays KW - laser induced degradation Y1 - 2011 SN - 978-1-4577-1651-5 U6 - https://doi.org/10.1109/STYSW.2011.6155850 SP - 84 EP - 88 PB - IEEE CY - Piscataway, NJ ER - TY - CHAP A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Electronic structure and optical properties of P3HT - Evidence of 2D-polarons in P3HT T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46 N2 - In this contribution we report on investigations of the electronic structure and optical characteristics of poly(3-hexylthiophene) (P3HT) based films. Various techniques like NEXAFS, SRXPS, UPS, UV-VIS and FTIR were used. X-Ray based measurements were done at the U49/2-PGM2 beam line at BESSYII. The samples were produced by spin casting P3HT dissolved in chloroform and other suitable solvents on ITO (indium tin oxide) coated glass slides and silicon substrates. Regioregular-P3HT is known to form thin films with nanocrystalline lamellae. This 2D structure give rise to additional electronic excitations in photoinduced absorption measurements, which are attributed to 2D-polarons [1]. In the Total Electron Yield (surface sensitive) and Total Fluorescence Yield (bulk sensitive) NEXAFS spectra of regioregular-P3HT three additional features can be found prior to the first typical π* excitation. The nature of these features was further investigated by means of SRXPS and UPS measurements. Energy differences relative to π*-peak maximum (0.54eV, 0.87eV and 2.24eV) suggest that these features are due to 2D-polarons. This presence of polarons is further confirmed by our FTIR and UV-VIS results. [1] Osterbacka et al., Synth. Met. 116 (2001) 317 Y1 - 2011 UR - http://www.dpg-verhandlungen.de/year/2011/conference/dresden/part/ds/session/64/contribution/3 SN - 0420-0195 SP - S. 311 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Schmidt, Stefan A1 - Schmeißer, Dieter T1 - Localized gap states in cobalt/nickel mixed oxides T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46 N2 - Replacing Co by large amounts of Ni is considered to reduce costs in Li-Ion-Batteries while maintaining their performance. We investigate the electronic structure of Co/Ni compounds because of their direct impact on battery operation. Thin Co/Ni oxide films on metal substrates were prepared by dropping/spin-coating from nitrate solutions followed by subsequent annealing in air and UHV. The following Co to Ni ratios have been investigated: 50/50, 40/60, 30/70, and 20/80. The results are compared with the pure Co-oxide and magnetron sputtered LiCoO2 reference samples. Spectroscopic measurements on these samples were carried out at the U49/2 beamline at BESSYII, Berlin. XPS of the transition metal (TM) 2p states reveals the existence of charge transfer ground states and different oxidation states. NEXAFS at the Co L3, Ni L3 and O K edges reflects the density of unoccupied states while resonant PES at these edges provides the related partial density of states (pDOS). Therefore, these techniques can be used in order to distinguish between the different contributions of TM3d and O2p states in the valence band region. We find sharp localized features at the valence band edge and at the O K and Co L3 absorption edges that are discussed to originate from the strong hybridization between metal and oxygen states in that region. Y1 - 2011 UR - http://www.dpg-verhandlungen.de/year/2011/conference/dresden/part/o/session/69/contribution/2 SN - 0420-0195 SP - S. 486 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Michling, Marcel A1 - Kolanek, Krzysztof A1 - Schmeißer, Dieter A1 - Tallarida, Massimo T1 - A growth model for the HfO2 ALD process T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46 N2 - In this contribution we report on our in-situ2 cycle-by-cycle (up to the 25 cycles) investigation of the HfO2 atomic layer deposition (ALD) process using the method of x-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS). We used Tetrakis-Dimethyl-Amino-Hafnium (TDMA-Hf) and H2O as precursors and p-type Si wafer with native oxide as a substrate. The XPS measurements were carried out at BESSY II in Berlin with primary energies of 150 eV and 640 eV and the EELS measurements were done with a primary energy of 50 eV. We measured the O1s, Si2p core level and the valence band including the Hf 4f core level. From the Hf4f to Si2p ratios taken at each energy we developed a growth model for the first monolayer and for the following layers too. From our data we conclude, that in the first monolayer up to the fourth ALD cycle an island growth occurs. The height of these islands is about 0,5nm. After the first monolayer is completed, a layer- by-layer growth can be expected. In order to proof this observation we have simulated the Hf/Si ratio for different excitation energies and found a very good agreement with our measurement data. The EELS data especially the evaluation of the loss function onset confirm our growth model. Y1 - 2011 UR - http://www.dpg-verhandlungen.de/year/2011/conference/dresden/part/ds/session/12/contribution/1 SN - 0420-0195 SP - S. 294 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Philip, Shine A1 - Martinez, Elias A1 - Müller, Klaus A1 - Kunst, Marinus A1 - Schmeißer, Dieter T1 - Time resolved microwave conductivity measurements of Bulk Heterojunction solar cells T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46 N2 - The time resolved microwave conductivity (TRMC) method was used in order to study the generation and decay kinetics of charge carriers in the Bulk Heterojunction (BHJ) solar cells. The charge carriers were generated with 532nm laser pulses of 10ns FWHM (Full Width at Half Maximum) induced in the cells. The BHJ solar cells used for the measurements had a photoactive layer consisting of a mixture of Poly (3-Hexylthiophene) P3HT and Phenyl-C61-butyric acid methyl ester (PCBM) which was spin coated onto Indium tin oxide (ITO)/glass substrates. In the field of Organic photovoltaic blends, TRMC method is introduced as a new method of direct investigation of the charge carrier lifetime as well as the charge carrier mobility and we were successful in studying the charge carrier lifetime of the reference BHJ solar cells. We also studied the influence of aligned ferroelectric fields on the charge separation in BHJ solar cells. As ferroelectric material, we used the copolymer Poly (vinylidene fluoride - trifluoroethylene) P(VDF-TrFE). Y1 - 2011 UR - http://www.dpg-verhandlungen.de/year/2011/conference/dresden/part/ds/session/42/contribution/31 SN - 0420-0195 SP - S. 301 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Mbua, Roy A1 - Müller, Klaus A1 - Richter, Matthias A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter A1 - Kramm, Ulricke T1 - Investigation of new Catalysts for PEM Fuel Cells T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46 N2 - Increasing green house emissions amplify global warming concerns worldwide. Fuel cells, based on polymer electrolyte membranes (PEM) are part of the solution to this issue. We aim at developing and testing new catalysts for fuel cells. Platinum catalysts perform best in PEM fuel cells to date but they are very expensive. For fuel cells to be perfectly applicable and economically affordable, an alternative catalyst with similar or even greater efficiency should be developed. Metal phthalocyanines are known to be good oxygen reduction catalysts and are associated with high electron transfer properties. We investigated Cobalt Phthalocyanine in its pure state mixed with Carbon Black (CoPc:Carbon Black=1:9) untreated and also after a treatment in N2 at several temperatures, up to 1000°C for 30 minutes. Results of XPS and EDX analyses reveal that the treatment at higher temperatures causes a rearrangement in the chemical states of Co, N and C atoms. Furthermore, results of cycling voltammetry (CV) analysis reveal that CoPc treated in N2 at 800°C exhibited a higher current density, in conclusion, a higher catalytic activity than the untreated CoPc. Y1 - 2011 UR - http://www.dpg-verhandlungen.de/year/2011/conference/dresden/part/o/session/60/contribution/119 SN - 0420-0195 SP - S. 483 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Hoffmannbeck, David A1 - Richter, Matthias A1 - Städter, Matthias A1 - Paloumpa, Ioanna A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Spectroscopic and microscopic characterization of potential catalysts for the hydrogenation of CO2 T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46 N2 - The reduction of CO2 emissions is a general demand of the society in order to avoid irreversible climate changes. We are investigating potential catalysts for the hydrogenation of CO2 in particular for its application in the so called oxyfuel combustion process. In order to understand the catalytic behavior of the investigated materials we use the techniques X-Ray Photoemission (XPS) and -absorption (XAS) Spectroscopy as well as X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The prospective of our work is to figure out the electronic and structural properties of the material and to optimize proper catalysts or design new ones for best catalytic activity. Beside the spectro-microscopic investigations the catalysts are tested under Sabatier reaction conditions in terms of activity, stability and sensitivity against poisoning. In our preliminary work we constructed a Sabatier reactor system with analytical parts based on infrared absorption and mass spectroscopy modules. First spectroscopic and catalytic results achieved on a commercially available Ru/Al2O3 catalyst will be presented. Y1 - 2011 UR - http://www.dpg-verhandlungen.de/year/2011/conference/dresden/part/o/session/60/contribution/123 SN - 0420-0195 SP - S. 483 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Friedrich, Daniel A1 - Koval, Yuri A1 - Müller, Paul A1 - Schmeißer, Dieter T1 - Electronic structure of thin spin-coated polyimide layers T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46 N2 - The conductivity of polyimide layers can be modified by several orders of magnitude by ion beam radiation. In order to understand the electronic structure of the pure polyimide before ion beam modification we focus in our preliminary experiments on spectroscopic investigations of thin as prepared polyimide films. The films were made by spin coating from a PMDA/ODA solution with subsequent vacuum annealing at 350°C. The layer thickness can be controlled by changing the concentration of PMDA/ODA in the solution realizing a thickness down to 3.5nm. For the characterization of the as prepared thin polyimide films the techniques NEXAFS, ResPES, XPS and CIS were applied at the U49/2-PGM2 beam line of Bessy II, Berlin. Our data including the valence band, core levels and absorption spectrum were compared with theoretical LCAO calculations. Based on these results we are able to attribute all spectral features to the specific atomic bonds in the molecule. Y1 - 2011 UR - http://www.dpg-verhandlungen.de/year/2011/conference/dresden/part/ds/session/63/contribution/3 SN - 0420-0195 SP - S. 311 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Tallarida, Massimo A1 - Deßmann, Nils A1 - Städter, Matthias A1 - Friedrich, Daniel A1 - Michling, Marcel A1 - Schmeißer, Dieter T1 - Atomic layer deposition of TiO T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46 N2 - We present a study of the initial growth of TiO2 on Si(111) by atomic layer deposition (ALD). The Si substrate was etched with NH4F before ALD to remove the native oxide film and to produce a Si-H termination. In−situ experiments by means of photoemission and X-ray absorption spectroscopy were conducted with synchrotron radiation on Ti-oxide films produced using Ti-tetra-iso-propoxide (TTIP) and water as precursors. O1s, Ti2p, C1s, and Si2p core level, and O1s and Ti2p absorption edges show the transition of the Ti-oxide properties during the first layers. The growth starts with a very small growth rate (0.03nm/cycle) due to the growth inhibition of the Si-H termination and proceeds with higher growth rate (0.1nm/cycle) after 1.5nm Ti-oxide has been deposited. Y1 - 2011 UR - http://www.dpg-verhandlungen.de/year/2011/conference/dresden/part/ds/session/12/contribution/2 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Friedrich, Daniel A1 - Henkel, Karsten A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Fullerenol as probed by Synchrotron X-Ray Photoemission and Absorption Spectroscopy Y1 - 2011 ER - TY - GEN A1 - Sioncke, Sonja A1 - Lin, Hang-Chu A1 - Brammertz, Guy A1 - Delabie, Annelies A1 - Conard, Thierry A1 - Franquet, Alexis A1 - Caymax, Matty A1 - Meuris, Marc A1 - Schmeißer, Dieter A1 - Tallarida, Massimo T1 - ALD on high mobility channels: engineering the proper gate stack passivation T2 - ECS Transactions KW - ALD KW - engineering KW - gate stack KW - passivation Y1 - 2010 SN - 1938-5862 VL - 33 IS - 2 SP - 9 EP - 23 ER - TY - CHAP A1 - Schwiertz, Carola A1 - Henkel, Karsten A1 - Blei, S. A1 - Heidenreich, R. A1 - Schmeißer, Dieter T1 - Nachweis von Aerosolen (<1µm) mit Schwingquarzimpedanzspektroskopie KW - Schwingquarzimpedanzspektroskopie Y1 - 2009 ER - TY - GEN A1 - Henkel, Karsten A1 - Seime, Bernd A1 - Paloumpa, Ioanna A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Optimization of MFIS structures containing poly(vinylidene-fluoride trifluoroethylene) for non-volatile memory applications Y1 - 2010 ER - TY - GEN A1 - Henkel, Karsten A1 - Seime, Bernd A1 - Paloumpa, Ioanna A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Buffer layer investigations on MFIS capacitors consisting of ferroelectric poly[vinylidene fluoride trifluoroethylene] Y1 - 2010 ER - TY - CHAP A1 - Dudek, Peter A1 - Lupina, Grzegorz A1 - Kozłowski, Grzegorz A1 - Dabrowski, Jarek Marek A1 - Lippert, Gunther A1 - Müssig, Hans-Joachim A1 - Schmeißer, Dieter A1 - Schroeder, Thomas T1 - Band structure and electrical properties of MBE grown HfO2 - based alkaline earth perovskites T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45 N2 - Ultra thin dielectric films (<20 nm) deposited on TiN electrodes are interesting for MIM capacitor application. High capacitance density and dielectric permittivity must be accompanied by extremely low leakage currents (10−8 A/cm2) at bias 0.5 V. To achieve such low leakage currents, high band gap and proper band alignment is required. Occupied electronic states can be probed with standard laboratory photoemission methods. Probing of unoccupied states is more challenging. Synchrotron based PES in combination with XAS forms a powerful method to study the band alignment. ASAM end station located at the U 49/2 PGM 2 beamline of BESSY II (Berlin) offers excellent conditions for performing such measurements. We investigated HfO2 - based alkaline earth perovskite - BaHfO3 with subsequent admixture of TiO2, resulting in formation of BaHf0.5Ti0.5O3 compound. The analysis of data indicates that band gap for HfO2 is similar to BaHfO3 and amounts 5.8 eV; for BaHf0.5Ti0.5O3 it decreases to 3.8 eV. We conclude that the addition of TiO2 to BaHfO3 increases significantly the dielectric permittivity but also impacts the band gap alignment. The conduction band offset shrinks, influencing the leakage current behavior. Y1 - 2010 UR - http://www.dpg-verhandlungen.de/year/2010/conference/regensburg/part/ds/session/24/contribution/4 SN - 0420-0195 SP - S. 232 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Philip, Shine A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Paloumpa, Ioanna A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Spectroscopic investigations of P3HT/PCBM films for organic BHJ solar cells T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45 N2 - Investigations of the electronic structure and composition of regioregular poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) based films using Near Edge X-Ray Absorption Fine Structure (NEXAFS) are presented. The measurements were performed at the U49/2-PGM2 beam line of BESSY II, Berlin recording TEY (total electron yield) and TFY (total fluorescence yield) data. Samples prepared by spin coating a mixture of P3HT dissolved in chloroform and PCBM dissolved in chlorobenzene onto ITO (indium tin oxide) coated glass slides were analyzed. Upon measuring the pure P3HT and PCBM, all reported excitations were observed, whereas the blended system is a weighted superposition of the related peaks. Analyzing the data we calculate the composition of the mixture. We also show angular dependent NEXAFS measurements of the P3HT/PCBM blend in order to measure the orientation and distribution of the P3HT polymer. Additionally, we show a new approach for organic solar cell application. BaTiO3 nanoparticles were incorporated as nanodispersion into the donor-acceptor blend or the ferroelectric copolymer poly(vinylidene fluoride trifluoroethylene) (P(VDF-TrFE)) was spincoated as an ultrathin film below the blend. Y1 - 2010 SN - 0420-0195 SP - S. 153 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Wyrodek, Jakub A1 - Tallarida, Massimo A1 - Weisheit, Martin A1 - Schmeißer, Dieter T1 - Determination of interfacial layers in high-k nanomaterials by ADXPS measurements Y1 - 2010 ER - TY - GEN A1 - Henkel, Karsten A1 - Seime, Bernd A1 - Paloumpa, Ioanna A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Buffer layer incestigaions on MFIS capacitors consisting of ferroelectric poly[vinylidene fluoride trifluoroethylene] T2 - IOP conference series : Materials Science and Engineering KW - MFIS capacitors KW - ferroelectric Y1 - 2010 SN - 1757-899X VL - 8 IS - 1 SP - 012036 ER - TY - GEN A1 - Wehner, Stefan A1 - Karpitschka, Stefan A1 - Burkov, Yevgen A1 - Schmeißer, Dieter A1 - Küppers, Jürgen A1 - Brand, Helmut R. T1 - Stochastic aspects of pattern formation during the catalytic oxidation of CO on Pd(111) KW - stochastic KW - pattern KW - catalytic oxidation Y1 - 2010 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Henkel, Karsten A1 - Bergholz, Matthias A1 - Tallarida, Massimo T1 - The band gab and band offset in ultrathin oxide-semiconductor heterostructures KW - band gab KW - offset KW - ultrathin KW - heterostructures Y1 - 2010 ER - TY - CHAP A1 - Wyrodek, Jakub A1 - Tallarida, Massimo A1 - Schmeißer, Dieter A1 - Weisheit, Martin T1 - Determination of interfacial layers in high - k ALD nanolaminate materials by ARXPS and SRXPS measurements T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45 N2 - The interfacial layers of high dielectric constant (high - k) nanolaminate films are here explored. Problems concerning ALD nanolaminate layers deals mainly with lack of accurate methods to determine in depth profile of few nm thick stacks. Modified angle resolved XPS(ARXPS) and synchrotron radiation XPS(SRXPS) are proposed as methods suitable in layer profiling. Studied stacks containing ZrO/HfO or AlO/ZrO, were prepared on Si substrates by atomic layer deposition (ALD). Two sets of experiments were covered. First dealt with initial growth (up to 20 cycles, with thickness d < 2nm) of AlO/ZrO and included layer by layer insitu investigation by SRXPS. Second experiment refer to industrial grown ZrO/HfO films ( d ∼ 3nm ) processed with various parameters resulting in both, layer by layer and homogenous depositions. For those samples exsitu XPS, with angle dependent variation of probing depth, measurements were covered. By comparing obtained intensity ratios for different angles with computational developed stack model it was found that no simple layer by layer but some intermixing growth occurred including interaction with silicon substrate. Y1 - 2010 UR - http://www.dpg-verhandlungen.de/year/2010/conference/regensburg/part/ds/session/24/contribution/6 SN - 0420-0195 SP - S. 232 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Kachel, Krzysztof A1 - Richter, Matthias A1 - Philip, Shine A1 - Paloumpa, Ioanna A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Performance of organic solar cells with a ferroelectric component T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45 N2 - Charge dissociation and recombination are important factors for the efficiency of organic solar cells, even in blended systems of different polymers. As a new approach, the influence of additional blended ferroelectric nanoparticles on the solar cell performance is investigated. The ferroelectric dipole of the nanoparticle causes a local field, which could lead to a longer recombination time of the polaron pairs. As solar cell system we use bulk heterojunction cells or bilayer structures based on regioregular poly(3-hexylthiophene) (P3HT) as the donor and phenyl-C61-butyric acid methyl ester (PCBM) as the acceptor molecule. As ferroelectric additive we use the ferroelectric copolymer poly(vinylidene fluoride trifluoroethylene) (P(VDF-TrFE)) or BaTiO3. The copolymer is spincoated as ultrathin film of 20nm, whereas the BaTiO3 is incorporated as nanodispersion into the donor-acceptor blend. We present the solar cell parameters for the different geometries and ferroelectric materials as a function of ferroelectric content and of the alignment of the ferroelectric dipoles after application of an external electric field. Y1 - 2010 UR - http://www.dpg-verhandlungen.de/year/2010/conference/regensburg/part/cpp/session/27/contribution/6 SN - 0420-0195 SP - S. 153 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Friedrich, Daniel A1 - Michling, Marcel A1 - Schmeißer, Dieter A1 - Koval, Yuri A1 - Müller, Paul T1 - Characterization of ion beam modified polyimide layers T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45 N2 - Ion beam modified polyimide show high conductivity. In our investigation we focus on the electronic structure and the element composition, in order to understand the mechanism of conductivity. In our experiments we use the methods NEXAFS and PES. The measurements were done at the U49/2-PGM2 beam line of BESSY II, Berlin. We find an increase of the sp2 hybridized graphite contribution, after low Ar+ ion doses bombardment while the temperature of the samples is varied from 300 K to 650 K. In addition we follow the He+ bombardment induced changes by in-situ monitoring of the O1s, N1s content in the polyimide films. Y1 - 2010 UR - http://www.dpg-verhandlungen.de/year/2010/conference/regensburg/part/ds/session/38/contribution/10 SN - 0420-0195 SP - S. 247 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Starzyk, Łukasz A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Electrically optimized high-κ metal gate MOSFET by specific modification of the band alignment T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45 N2 - The electrical optimization of metal/oxide/semiconductor gate stacks by specific modification of the band alignment for advanced MOS technology incorporating high dielectric constant (κ) materials is explored. Because of requirements concerning continued scaling of MOSFET transistors, gate oxides and cobalt electrode have been grown successively on Si substrate respectively by means of atomic layer deposition (ALD) and evaporation. The thicknesses of high-κ films were around 2 nm. In case of work function engineering, interfaces’ chemistry plays a fundamental role. We applied synchrotron radiation based x-ray photoelectron spectroscopy (SR XPS) to characterize our samples, which allows step by step in situ investigations. Co 2p, Al 2p, Hf 4f, Si 2p and O 1s core levels spectra were measured and analyzed. From valence band (VB) spectra we determined Schottky barrier height and electronic bands offsets. Y1 - 2010 UR - http://www.dpg-verhandlungen.de/year/2010/conference/regensburg/part/ds/session/23/contribution/3 SN - 0420-0195 SP - S. 231 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Klocek, Jolanta A1 - Friedrich, Daniel A1 - Zagorodniy, Kostyantyn A1 - Schmeißer, Dieter T1 - Spectroscopic investigations of interaction between C60 fullerene and nitrogen atom from amine group T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45 N2 - We investigated interactions between fullerene molecule and amine group from 3-aminopropyl-trimethoxysilane (3AT). Theoretical calculations show that the material obtained as a result of interactions between 3AT and C60 fullerene may have extremely low dielectric constant around 1.6, so it could be considered as a candidate for ultra low-k (ULK) material applications. We prepared films composed of 3AT and fullerene by using two preparation techniques: spin-coating and evaporation. Interactions between these two components were investigated by using X- ray photoelectron spectroscopy (XPS) and Near Edge X-ray Absorption Fine Structure Spectroscopy (NEXAFS). We found that there are strong chemical reactions between the nucleophilic nitrogen atom from 3AT and electrophilic fullerene molecule. Results of NEXAFS measurements suggest that due to direct interactions between 3AT and C60 the shape of fullerene molecule is changed. Y1 - 2010 UR - http://www.dpg-verhandlungen.de/year/2010/conference/regensburg/part/ds/session/23/contribution/1 SN - 0420-0195 SP - S. 231 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Michling, Marcel A1 - Tallarida, Massimo A1 - Kolanek, Krzysztof A1 - Schmeißer, Dieter T1 - In-situ EELS and UPS measurements on HfO2 ALD layers T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45 N2 - In this contribution we report on our in-situ cycle-by-cycle (up to 10 cycles) investigations of the HfO2 ALD process using the methods of EELS and UPS. We used TDMA-Hf as a precursor and p-type Si wafer with natural oxide as the substrate. The EELS measurements were done with a primary energy of 52,5 eV and the UPS measurements with He I (21,218 eV). The change in the onset of the loss function is readily observed. Already after two cycles the value approach to the bulk value of HfO2. Upon ALD growth there is a remarkable decrease in the intensity of states within the gap. They are rather smooth and saturate after 10 cycles. With UPS we follow the variation of the VB onset and changes in the secondary electron onset. We summarize our data in a band diagram not based on bulk values but on cycle dependent quantities. With these cycle-by-cycle experiments we study the initial growth of HfO2 especially in the very first cycles. Y1 - 2010 UR - http://www.dpg-verhandlungen.de/year/2010/conference/regensburg/part/ds/session/24/contribution/5 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Kolanek, Krzysztof A1 - Karavaev, Konstantin A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Atomic layer deposition of HfO2 onto SiO2 substrates investigated in-situ by non-contact UHV/AFM T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45 N2 - We investigated in-situ the atomic layer deposition (ALD) of HfO2 onto SiO2 substrates with ultra high vacuum (UHV) non-contact atomic force microscope (NC-AFM). The ALD process was started after detailed analysis of the initial Si(001)/SiO2 substrate. The ALD cycles, made by using tetrakis-di-methyl-amido-Hf (TDMAHf) and water as precursors, were performed on the SiO2 substrate maintained at 230 ∘C. We studied the relation between the film growth and the root mean square surface roughness, surface skewness, kurtosis, fractal dimension and correlation length. In the initial stages of the ALD process with our analysis of the surface height histograms we were capable of determination: HfO2 layer thickness, surface coverage and surface roughness of a substrate and deposited material. Observation of the surface height histograms evolution during deposition allowed us to verify conformal and effective ALD growth on SiO2 substrate. With this detailed analysis of the surface topography we confirmed the completion of the first HfO2 layer after four ALD cycles. Y1 - 2010 SN - 0420-0195 SP - S. 248 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Sebastian A1 - Schmeißer, Dieter T1 - Synchrotron radiation spectroscopy studies of the initial interaction between cobalt and titanium dioxide T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45 N2 - Small metallic particles deposited on oxide surfaces can serve as heterogeneous catalysts, as for example TiO2 supported cobalt is a known Fischer-Tropsch-Catalyst. The goal of the presented studies is to investigate the interaction between cobalt and TiO2 in the initial step of growth by synchrotron radiation based spectroscopy. PES studies of TiO2 supported cobalt show a reduction of the oxide support, accompanied by an oxidation of the deposited material. The oxidation is not complete, but metallic cobalt is found already in the very first step of growth. Uniform decrease of both substrate PES lines indicate very weak interaction between overlayer and TiO2. An atomic multiplet calculation including charge transfer and crystal field effects is applied to simulate the experimental Co 2p XAS and XPS spectra of the oxidized component. The results allow the identification of the local coordination as well as the identification of the oxidation state of cobalt. Y1 - 2010 SN - 0420-0195 SP - S. 652 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Henkel, Karsten A1 - Lazareva, I. A1 - Mandal, Dipankar A1 - Paloumpa, Ioanna A1 - Müller, Klaus A1 - Koval, Yuri A1 - Müller, P. A1 - Schmeißer, Dieter T1 - Electrical investigations on metal/ferroelectric/insulator/semiconductor structures using Poly[vinylidene fluoride trifluoroethylene] as ferroelectric layer for organic nonvolatile memory applications KW - metal KW - frerroelectric KW - insulator KW - semiconductor Y1 - 2009 ER - TY - CHAP A1 - Kolanek, Krzysztof A1 - Tallarida, Massimo A1 - Karavaev, Konstantin A1 - Schmeißer, Dieter T1 - In situ measurements of the atomic layer deposition of high-k dielectrics by atomic force microscope for advanced microsystems T2 - International Students and Young Scientists Workshop "Photonics and Microsystems", 2009, 25 - 27 June 2009, Harz University, Wernigerode, Germany KW - atomic layer deposition KW - microsystems KW - high-k dielectrics Y1 - 2009 SN - 978-1-4244-4303-1 SP - 47 EP - 51 PB - IEEE CY - Piscataway, NJ ER - TY - GEN A1 - Schmeißer, Dieter A1 - Müller, S. A1 - Seifarth, Olaf A1 - Dabrowski, Jarek Marek A1 - Müssig, Hans-Joachim A1 - Schroeder, Thomas T1 - On the band gaps and electronic structure of thin single crystalline praseodymium oxide layers on Si(111) T2 - Journal of vacuum science & technology / B KW - band gabs KW - electronic structure KW - oxide layers Y1 - 2009 VL - 27 IS - 1 SP - 271 EP - 276 ER - TY - GEN A1 - Henkel, Karsten A1 - Burkov, Yevgen A1 - Karavaev, Konstantin A1 - Torche, Mohamed A1 - Schwiertz, Carola A1 - Schmeißer, Dieter T1 - Optimization of the AION buffer layer for PrxOy/Si stacks KW - AION buffer Y1 - 2009 ER - TY - CHAP A1 - Müller, Sebastian A1 - Schmeißer, Dieter T1 - Synchrotron radiation spectroscopy studies of ultrathin chromium films on titanium dioxide T2 - International Students and Young Scientists Workshop "Photonics and Microsystems", 2009, 25 - 27 June 2009, Harz University, Wernigerode, Germany KW - synchrotron KW - radiation KW - spectroscopy KW - ultrathin KW - titanium KW - chromium Y1 - 2009 SN - 978-1-4244-4303-1 SP - 64 EP - 68 PB - IEEE CY - Piscataway, NJ ER - TY - CHAP A1 - Tallarida, Massimo A1 - Karavaev, Konstantin A1 - Kolanek, Krzysztof A1 - Schmeißer, Dieter T1 - Nobel "in-situ2" Approach to Modified ALD Processes for Nano-functional Metals Oxide Films KW - in-situ2 KW - ALD KW - nano-functional Y1 - 2009 ER - TY - GEN A1 - Tallarida, Massimo A1 - Karavaev, Konstantin A1 - Schmeißer, Dieter T1 - Novel "In-situ2" Approach to Modified ALD Processes for Nano-functional Metal Oxide Films Y1 - 2009 ER - TY - CHAP A1 - Karavaev, Konstantin A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Evolution of the interfacial layer during the atomic layer deposition of HfO2 on Si/SiO2 substrates T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44 N2 - We studied the formation of the interfacial layer in the Si/SiO2/HfO2 system using the in-situ Atomic Layer Deposition (ALD) reactor developed in our group [1,2]. We measured the X-ray photoelectron and X-ray absorption spectra with synchrotron radiation at the beamline U49-2/PGM2-BESSY II. The ALD growth was obtained using different Hf-precursors (HfCl4,TEMAHf and TDMAHf) on various prepared substrates at different temperatures. The investigation was carried out in-situ giving the possibility to determine the properties of the grown film after every ALD cycle without breaking the vacuum. We observed the evolution of the Si/SiO2/HfO2 system during the formation of first three Hf-oxide layers, detecting the interfacial growth of SiO2 during the initial ALD cycles from the XPS spectra of Si2p. We discuss how the interfacial layer growth depends on the various ALD parameters. [1] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Appl. Phys. 104, 064116 (2008); [2] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Vac. Sci. Technol. B, accepted for publication. Y1 - 2009 SN - 0420-0195 SP - S. 160 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Karavaev, Konstantin A1 - Kolanek, Krzysztof A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - In-Situ Studies of ALD Growth of Hafnium Oxide Films Y1 - 2009 ER - TY - CHAP A1 - Kolanek, Krzysztof A1 - Karavaev, Konstantin A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - In-situ investigations of the atomic layer deposition of HfO2 with UHV/AFM T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44 N2 - We studied in-situ the atomic layer deposition (ALD) of HfO2 with ultra high vacuum (UHV) atomic force microscope (AFM), using the ALD reactor developed by our group [1, 2]. The reactor was attached to the Omicron Large Sample-UHV/AFM system in the AFM-Lab of the Angewandte Physik-Sensorik chair at the BTU-Cottbus. We investigated different Si(001)/SiO2 substrates and surface preparation techniques performed before the ALD process. After each ALD cycle (using TDMAHf and H2O as precursors), we studied the influence of the HfO2 growth on the root mean square (RMS) roughness; the surface fractal dimension and the height histogram: the surface skewness and kurtosis. We focused on the influence of the substrate temperature on the surface topography during the ALD. The in-situ studies of the ALD process with the UHV/AFM system correlated with the experiments performed with photoelectron spectroscopy can be used for understanding the fundamental properties of the ALD of HfO2 on Si(001). [1] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Appl. Phys. 104, 064116 (2008); [2] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Vac. Sci. Technol. B, accepted for publication. Y1 - 2009 UR - http://www.dpg-verhandlungen.de/year/2009/conference/dresden/part/ds/session/11/contribution/6 SN - 0420-0195 SP - S. 160 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Michling, Marcel A1 - Friedrich, Daniel A1 - Schmeißer, Dieter A1 - Koval, Yuri A1 - Müller, Paul T1 - Study of polyimide after graphitization with low-energy Ar+ Ion irradiation by NEXAFS T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44 N2 - In this contribution we report on investigations of the electronic structure of Ar+ irradiated polyimide samples by using NEXAFS. The NEXAFS measurements were done at the U49/2-PGM2 beam line of BESSY II, Berlin using TEY and TFY detection. Polyimide samples are prepared using low Ar+ dose while the temperature of the samples is varied between 300K and 700K. In the NEXAFS data at the Carbon K-edge we see substantial changes between different samples. The differences appear in particular in the more surface sensitive TEY-Signal. The NEXFS data are consistent with the graphitization of the surface upon Ar+ bombardment as we identify the characteristic absorption bands of graphitic carbon. Its relative content increases with increasing sample temperature. In contrast, in the more bulk sensitive TFY data, the emission characteristic of polyimide is maintained. The possibility to cover insulating polymers with a conducting layer is a great demand for many applications. Because of the relative low price of the basic materials, the irradiation with low-energy Ions will play an important roll in the microelectronic of the future. Y1 - 2009 UR - http://www.dpg-verhandlungen.de/year/2009/conference/dresden/part/df/session/15/contribution/5 SN - 0420-0195 SP - S. 147 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Richter, Matthias A1 - Müller, Klaus A1 - Philip, Shine A1 - Paloumpa, Ioanna A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Temperature dependence of organic solar cell parameters T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 44 N2 - The influence of an annealing step on the parameters of bulk heterojunction organic solar cells is investigated. In order to fabricate the solar cells we use glass coated with ITO (Indiumtinoxide) as a substrate on which the active layer consisting of P3HT and PCBM is spincoated. Al-electrodes are evaporated on top of the active layer. We use PEDOT:PSS as buffer layer. Each sample is annealed at different temperatures for a short time. Between every temperature step the I-V characteristic of the cell is measured. The following parameters are derived afterwards: FF, Isc (density), Voc. Also the efficiency is estimated. The results show a maximum cell efficiency for drying at 100°C for 20sec. A further important step for preparation is the drying procedure of the PEDOT:PSS layer. Here an improvement of about 50% in cell efficiency is measured after drying at 50°C for 5 days under inert gas atmosphere. Y1 - 2009 UR - http://www.dpg-verhandlungen.de/year/2009/conference/dresden/part/syop/session/4/contribution/2 SN - 0420-0195 SP - S. 671 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Sebastian A1 - Schmeißer, Dieter T1 - Investigation of ultra-thin Chromium layers on Titanium Dioxide by resonant photoemission T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44 N2 - Oxide supported metal films and clusters offer interesting properties with a wide range of possible applications. In this context, Titanium Dioxide is chosen as a model substrate due to its simple electronic structure with a d0 configuration. We study the interaction of ultrathin Chromium films deposited on TiO2 film with focus on the modifications of the valence band and band gap region. Normal photoemission in bulk and surface sensitive modes as well as resonant photoemission at the Cr 2p and Ti 2p edges are used to distinguish the different Cr 3d and Ti 3d contributions to the valence band. In the initial step we find to gap states of distinct character with a sharp resonance of the Cr 3d related state at the Cr 2p edge. With increasing layer thickness we observe that this resonance extends to about 20 eV below the Fermi-Energy. Datasets of valence band spectra measured around the Cr 2p edge show 2 resonant mechanisms in this case i.e. a participator channel for the 3d state accompanied by a spectator channel at fixed kinetic energy. Y1 - 2009 UR - http://www.dpg-verhandlungen.de/year/2009/conference/dresden/part/o/session/3/contribution/5 SN - 0420-0195 SP - S. 453 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Tallarida, Massimo A1 - Karavaev, Konstantin A1 - Kolanek, Krzysztof A1 - Schmeißer, Dieter T1 - Basics of the atomic layer deposition of HfO2 onto Si/SiO2 substrates: in-situ investigations with XPS, XAS and UHV-AFM T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 44 N2 - We developed a reactor for investigating in-situ the atomic layer deposition (ALD) of HfO2. X-ray photoelectron and X-ray absorption spectra were collected after each ALD cycle using synchrotron radiation at the beamline U49-2/PGM2 - BESSY II, Berlin. The morphology of the substrate and thin film surfaces was investigated after each ALD cycle with an UHV-AFM microscopy attached to the ALD reactor. We studied the ALD on differently prepared substrates, at different substrate temperatures, and using different Hf-precursors (HfCl4, TEMAHf, TDMAHf). We observed the evolution of the Si/SiO2/HfO2 system during the formation of the first three Hf-oxide layers [1]; we detected the incorporation of Cl into the Hf-oxide films and proposed a mechanism responsible for the Cl contamination [2]; we found evidence of the interfacial-SiO2 growth during the initial ALD cycles and of dipole formation at the HfO2/SiO2 interface. In this contribution we illustrate the basics of the technique used, and discuss the physical-chemical properties of ALD on the basis of the experimental results. [1] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Appl. Phys. 104, 064116 (2008); [2] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Vac. Sci. Technol. B, accepted for publication. Y1 - 2009 UR - http://www.dpg-verhandlungen.de/year/2009/conference/dresden/part/ds/session/11/contribution/4 SN - 0420-0195 SP - S. 159 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Tallarida, Massimo A1 - Karavaev, Konstantin A1 - Kolanek, Krzysztof A1 - Schmeißer, Dieter T1 - In-situ experimental approach to the study of atomic layer deposition with atomic force microscope, X-ray photoelectron and X-ray absorption spectroscopy T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 44 N2 - We describe our experimental approach to the investigation of atomic layer deposition (ALD). ALD is a powerful deposition technique for growing conformal thin films of composite materials with atomically accurate thickness on large area [1]. Despite the enormous industrial interest growing around ALD, its fundamental properties were not yet properly studied. We developed an ALD reactor for the in-situ investigations using XPS, XAS and AFM as experimental techniques. We studied the chemical-physical properties of the growing thin films after each deposition cycle. Here, we illustrate the recent results concerning the ALD of HfO2 obtained using different Hf-precursors on various substrates [2]. We show how the in-situ investigations could deliver an important insight into the fundamental characteristics of ALD and how these information could be used to modify and optimize the deposition parameters. [1] M. Leskelä, M. Ritala, Thin Solid Films, 409, 138, 2002; [2] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Appl. Phys. 104, 064116 (2008). Y1 - 2009 UR - http://www.dpg-verhandlungen.de/year/2009/conference/dresden/part/ds/session/26/contribution/15 SN - 0420-0195 SP - S.176 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Seifarth, Olaf A1 - Walczyk, Christian A1 - Lupina, Grzegorz A1 - Zaumseil, Peter A1 - Schmeißer, Dieter A1 - Müssig, Hans-Joachim A1 - Schroeder, Thomas T1 - The electronic band diagram of thin PrO2(111) / Pr-silicate buffers on Si(111) and its relevance to dielectric properties T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44 N2 - Thin dielectric buffers of cubic PrO2(111) on Si(111) are ideally suited to integrate Ge onto Si by moderating the lattice mismatch between the materials. The leakage current across this dielectric buffer is strongly influenced by the electronic band diagram and defects inside the band gap. Therefore, we measured the band offsets, band gaps and defect positions by means of synchrotron radiation based photoemission spectroscopy techniques (XPS and XAS) with special emphasis on the Pr-silicate interface. In a next step we compare the spectroscopic data with information from dielectric studies, based on temperature dependent leakage current studies. We observe a close relation between dielectric properties and the electronic structure. Y1 - 2009 UR - http://www.dpg-verhandlungen.de/year/2009/conference/dresden/part/df/session/6/contribution/5 SN - 0420-0195 SP - S. 136 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - JOUR A1 - Schmeißer, Dieter A1 - Domaradzki, Jarosław A1 - Kaczmarek, Danuta A1 - Borkowska, Angnieszka A1 - Müller, Sebastian T1 - Influence of Annealing on the Structure and Stoichiometry of Europium-Doped Titanium Dioxide Thin Films Y1 - 2008 ER - TY - JOUR A1 - Schmeißer, Dieter A1 - Burkov, Yevgen A1 - Paloumpa, Ioanna A1 - Mandal, Dipankar A1 - Henkel, Karsten T1 - Microscopic and Spectroscopic Characterization of Interfaces and Dielectric Layers for OFET Devices Y1 - 2008 ER - TY - JOUR A1 - Schmeißer, Dieter A1 - Henkel, Karsten A1 - Karavaev, Konstantin T1 - Al-Oxynitride Interfacial Layer Investigations for PrxOy on SiC and Si Y1 - 2008 ER - TY - JOUR A1 - Bieniek, Tomasz A1 - Beck, Romuald B. A1 - Jakubowski, Andrzej A1 - Konarski, Piotr A1 - Cwil, M. A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Application of r.f. plasma ultrashallow nitrogen ion implantation for pedestal oxynitride layer formation KW - ultrashallow KW - oxynitride Y1 - 2008 ER - TY - CHAP A1 - Heller, Thomas A1 - Schmeißer, Dieter T1 - Polaronen in SrTiO3(100) T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Vorgestellt werden Untersuchungen zur elektronischen Struktur von oxidischen Halbleitern wie SrTiO3(100)-Einkristallen und WO3-Filmen. Die Charakterisierung der Oberflächen erfolgt im Valenzbandbereich mittels Photoelektronenspektroskopie (TGM 7, Bessy I, hν=3D 15-100eV). Zustände entstehen in der Bandlücke dieser=20 Materialien durch Dotierung (Heizen oder Natrium-Belegung). Wir untersuchen den Wirkungsquerschnitt speziell für diese Gapzustände. Ohne Dotierung ist der Verlauf des Wirkungsquerschnittes unstrukturiert. Bei Dotierung bilden sich molekulare Resonanzen. Deren Auftreten zeigt, daß diese Gapzustände lokalisiert sind. Weiterhin beobachten wir ausgeprägte Feinstrukturen, die die charakteristische Anregung f=FCr Polaronen enthalten. KW - Polaron KW - Röntgen-Photoelektronenspektroskopie KW - Gapzustände Y1 - 1999 UR - http://www.dpg-verhandlungen.de/year/1999/conference/muenster/part/o/session/21/contribution/8?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - JOUR A1 - Sohal, Rakesh A1 - Lupina, Grzegorz A1 - Lippert, Gunther A1 - Wenger, Christian A1 - Seifarth, Olaf A1 - Schröder, Thomas A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Interface chemistry of high-k PrxAl2-xO3 (x=2-0) dielectrics on TiN for dynamic random access memory applications KW - high-k KW - dielectric KW - random Y1 - 2008 ER - TY - JOUR A1 - Zimina, A. A1 - Batchelor, David R. A1 - Eisebitt, S. A1 - Schmeißer, Dieter A1 - Shukalov, A. A1 - Eberhardt, W. T1 - Soft X-ray emission electron microscopy: chemical state microscopy from interface and bulk KW - x-ray KW - microscopy KW - interface KW - bulk Y1 - 2008 ER - TY - JOUR A1 - Müller, Sebastian A1 - Schmeißer, Dieter T1 - Properties of Cr deposited on TiO2 thin films KW - cr KW - TiO2 Y1 - 2008 ER - TY - CHAP A1 - Oprea, Alexandru A1 - Schmeißer, Dieter A1 - Goldenblum, A. T1 - On the charge transfer process in ZnS based ac powder electroluminescent devices T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The charge transfer process in ZnS based ac powder electroluminescent devices was experimentally and theoretically investigated. The time dependence of active currents and the voltage dependence of the brightness were measured in different operating conditions. This data allowed the hypothesis that each ZnS grain of the ac powder electroluminescent device (PWELD) behaves as a thin films electroluminescent device (TFELD) with metal-insulator-semiconductor-insulator-metal (MISIM) structure. The whole PWELD, itself, can be considered as a sum of many litle MISIM sandwiches electrically conected among them and having the quasi Fermi level of the semiconductor-insulator interface randomly distributed. On this basis, in the frame of a statistical Monte-Carlo like procedure, was developed a quantative semiclassical model, in good agreement with the experimental data. KW - ZnS KW - charge transfer process KW - ac powder electroluminescent device KW - time and brightness dependence KW - Monte Carlo simulation Y1 - 1999 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Seifarth, Olaf A1 - Wilke, A. A1 - Walczyk, Christian A1 - Dabrowski, Jarek Marek A1 - Zaumseil, Peter A1 - Schmeißer, Dieter A1 - Müssig, Hans-Joachim A1 - Schroeder, Thomas T1 - Band gap and electronic structure determination with XAS and UPS of thin Pr-oxide films on Si(111) T2 - Proceedings of 15th Workshop on Dielectrics in Microelectronics, Bad Saarow, 23 - 25 June 2008, Bad Saarow (Berlin) KW - band gab KW - XAS KW - UPS KW - Si(111) Y1 - 2008 SP - 285 EP - 286 ER - TY - CHAP A1 - Henkel, Karsten A1 - Mandal, Dipankar A1 - Seime, Bernd A1 - Paloumpa, Ioanna A1 - Lazareva, I. A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Electrical investigations on MFIS structures consisting P[VDF/TrFE] as ferro-electric layer for non-volatile memory applications T2 - Proceedings of 15th Workshop on Dielectrics in Microelectronics, Bad Saarow, 23 - 25 June 2008, Bad Saarow (Berlin) KW - MFIS, P[VDF/TrFE] KW - ferroelectric KW - non-volatile Y1 - 2008 SP - 159 EP - 160 ER - TY - CHAP A1 - Henkel, Karsten A1 - Burkov, Yevgen A1 - Bergholz, Matthias A1 - Karavaev, Konstantin A1 - Sohal, Rakesh A1 - Torche, Mohamed A1 - Schmeißer, Dieter T1 - Al-Oxynitride as a buffer layer for high-k dielectrics T2 - Proceedings of 15th Workshop on Dielectrics in Microelectronics, Bad Saarow, 23 - 25 June 2008, Bad Saarow (Berlin) KW - buffer layer KW - high-k KW - dielectric Y1 - 2008 SP - 161 EP - 162 ER - TY - JOUR A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Study of silicon/oxides interfaces by means of Si2p resonant photoemission KW - photoemission KW - Si2p Y1 - 2008 ER - TY - JOUR A1 - Tallarida, Massimo A1 - Karavaev, Konstantin A1 - Schmeißer, Dieter T1 - The initial atomic layer deposition of HfO2/Si(001) as followed in situ by synchrotron radiation photoelectron spectroscopy KW - synchrotron KW - photoelectron KW - HfO2 Y1 - 2008 ER - TY - JOUR A1 - Müller, Klaus A1 - Mandal, Dipankar A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Ferroelectric properties of spin-coated ultrathin (down to 10nm) copolymer films KW - ferroelectric KW - spin-coated KW - copolymer Y1 - 2008 ER - TY - CHAP A1 - Müssig, Hans-Joachim A1 - Dabrowski, Jarek Marek A1 - Schmeißer, Dieter T1 - Interface Characterization of the High-k Gate Dielectric Pr2O3 T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Pr2O3 is currently under consideration as a potential alternative gate dielectric candidate for sub-0.1 µm Complementary Metal Oxide Semiconductor (CMOS) technology. For all thin gate dielectrics, the interface with silicon plays a key role, and in most cases is a dominant factor in determining overall electrical properties. We studied the Pr2O3/Si(001) interface by a non-destructive depth profiling using synchrotron radiation photo-electron spectroscopy and ab initio calculations. Our results provide evidence that a chemical reactive interface exists consisting of a mixed Si-Pr oxide such as (Pr2O3)x(SiO2)1−x, typically in non-stoichiometric composition. There is no formation of neither an interfacial SiO2 nor interfacial silicide: all Si-Pr bonds are oxidized and all SiO4 units dissolve in the Pr oxide. Interfacial silicates like (Pr2O3)x(SiO2)1−x are promising high-k dielectric materials because they represent incremental modification of SiO2 films by Pr ions so that the interface characteristics can be similar to Si-SiO2 interface properties. Under ultrahigh vacuum conditions, silicide formation is observed when the silicate film is heated above 800∘C. The praseodymium silicate system observed at the interface between Si(001) and Pr2O3 offers greater flexibility towards integration of Pr2O3 into future CMOS technologies. KW - high-k KW - Pr2O3 KW - X-ray photoelectron spectroscopy (XPS) KW - ab inito calculations KW - depth profiling KW - silicate Y1 - 2003 UR - http://www.dpg-verhandlungen.de/year/2003/conference/dresden/part/hl/session/40/contribution/1?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Opel, Matthias A1 - Nielsen, Karl-Wilhelm A1 - Bauer, Sebastian A1 - Goennenwein, Sebastian T. B. A1 - Gross, Rudolf A1 - Cezar, Julio C. A1 - Schmeißer, Dieter A1 - Simon, Jürgen A1 - Mader, Werner T1 - Ferromagnetism and magnetic clusters in cobalt-doped ZnO T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43 N2 - Ferromagnetic semiconductors (FMS) - i.e. semiconductors exhibiting long-range magnetic ordering - are intriguing materials. However, in spite of intensive research in the last decade, the existence of homogeneous FMS with a Curie temperature around or above room temperature still is controversial. A particularly tedious issue are local sample inhomogeneities or magnetic clusters, which can yield strong magnetic signals resembling the behaviour expected for a homogeneous FMS. Using pulsed laser deposition, we have grown cobalt-doped ZnO films on single crystalline ZnO substrates. Combining x-ray magnetic circular dichroism, DC magnetometry, and AC susceptibility measurements with a detailed structural analysis by high resolution x-ray diffraction, transmission electron microscopy, and electron-spectroscopic imaging, we can unambigously trace the characteristic, ferromagnetic-like behaviour of our ZnO:Co samples at room-temperature to nanometer-sized superparamagnetic metallic cobalt precipitates. Y1 - 2008 UR - http://www.dpg-verhandlungen.de/year/2008/conference/berlin/part/ma/session/3/contribution/6 SN - 0420-0195 SP - S. 430 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Seifarth, Olaf A1 - Walczyk, Christian A1 - Lupina, Grzegorz A1 - Dabrowski, Jaroslaw A1 - Weidner, Günter A1 - Zaumseil, Peter A1 - Schmeißer, Dieter A1 - Storck, Peter A1 - Müssig, Hans-Joachim A1 - Schroeder, Thomas T1 - On the electronic and dielectric characterisation of thin cubic PrO2 layers on Silicon T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43 N2 - For the integration of 100 % Ge onto the Si platform, a buffer oxide approach has been developed recently, using rare earth oxides to tune the lattice constant between the Si and the Ge. Among these buffer oxides, PrO2 is a prospective candidate with high quality crystalline growth on Si, moderated by an interfacial Pr-silicate between. In order to specify electronic properties of thin PrO2 and its interface on Si(111), especially the width of the band gap, we performed synchrotron radiation based XPS, UPS and XAS measurements at the U49/2 PGM 2 beamline at BESSY II and correlate the results with our structural characterisation performed by TEM and XRD. In order to evaluate the dielectric properties of thin PrO2 layers on Si(111), we performed temperature-, time-, voltage-, and layer thickness-dependent leakage current measurements (J-V). Here, we identified relaxation behaviour in the leakage current, successfully addressed to defect like states inside the Pr-silicate interface layer, corroborated by frequency dependent capacitance versus voltage (C-V) measurements. Y1 - 2008 UR - http://www.dpg-verhandlungen.de/year/2008/conference/berlin/part/df/session/12/contribution/6 SN - 0420-0195 SP - S. 196 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Lazareva, I. A1 - Koval, Yuri A1 - Müller, P. A1 - Paloumpa, Ioanna A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Field effect transistor of graphitized polyimide with P(VDF-TrFE) as gate insulator T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43 N2 - Surfaces of polyimide films were graphitized by low-energy ion irradiation. The conductivity was between 10−5 to 200 S/cm [1]. We prepared field effect transistors using this material. Ferroelectric P(VDF-TrFE) was used as gate insulator. The thickness of P(VDF-TrFE) varied from 120 nm to 1200 nm. Properties of P(VDF-TrFE) were investigated by current-voltage measurements of metal/ P(VDF-TrFE)/metal capacitors. We have found that at room temperature, the coercive field of P(VDF-TrFE) does not depend on the film thickness. At lower temperatures the coercive field increases proportionally to the reciprocal temperature. Remnant polarization is 9.5 µC/cm2. It slightly rises with decreasing temperature. Our recent results of field effect mobility, carrier concentration and threshold voltage are presented. [1] I. Lazareva, Y. Koval, M. Alam, S. Strömsdörfer, P. Müller, Appl. Phys. Lett. 90, 262108 (2007) Y1 - 2008 UR - http://www.dpg-verhandlungen.de/year/2008/conference/berlin/part/df/session/11/contribution/6 SN - 0420-0195 SP - S. 195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Mikalo, Ricardo Pablo A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter A1 - Lloyd Spetz, Anita A1 - Lundström, Ingemar A1 - Wawra, Herbert A1 - Pressel, Klaus A1 - Ourmazd, Abbas T1 - Depth profiling using synchrotron radiation with high energetic resolution as demonstrated for Si-, SiC-, SiGe-, and SiGeC-samples T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Photoelectron spectroscopy utilizing synchrotron radiation of high energetic resolution (more than E/ΔE=3000) was used to record the Si2p emission signal of Si, SiC, SiGe, and SiGeC samples. The spectra exhibit signals of the elemental silicon as well as of fully oxidised silicon. Upon variing the photon energy, and therefore the escape depth of the photoelectrons, we find an oxidic silicon signal which is only half oxidized. This half oxidized silicon is located to be at the interface of the bulk material with the oxide. We determine the thickness of the surface oxide from the total ratio of oxidic and elemental silicon. We find differences between the interface and bulk oxides regarding their elemental composition. The line width of the elemental Si2p-signal exhibits a broadening of approximately 200meV while variing the photoelectron escape depth. This behaviour is interpreted as caused by surface stress. KW - X-Ray photoelectron spectroscopy (XPS) KW - synchrotron KW - depth profiling Y1 - 2001 UR - http://www.dpg-verhandlungen.de/year/2001/conference/hamburg/part/o/session/13/contribution/74?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Carbon-plot-microstructuring for all-polymer-transistors T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - This contribution describes the use of a low-cost technology to form organic microstructures for electronical applications. We demonstrate the principle ability of this method through the fabrication of organic field effect- transistors. With a computer driven plotter, substrates like printing foil and colloidal graphite (diluted in water) for the electrodes, we realized channel lengths of 20+10 micrometers. Compared with transistor devices, fabricated using conventional photolithographic methods and the same semiconducting material, this technique is a hopefull approach to produce microelectronic structures that are low-cost and all-organic. KW - organic field effect transistor KW - low cost printing KW - microstructuring Y1 - 2002 UR - http://www.dpg-verhandlungen.de/year/2002/conference/regensburg/part/syoh/session/7/contribution/34?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Batchelor, David R. A1 - Follath, Rolf A1 - Schmeißer, Dieter T1 - Design of a PGM for the U49/2 Undulator at BESSY II T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - This poster describes the beamline proposed for the BESSY II U49/2 Undulator by the Collaborating Research Group of BTU Cottbus, HMI Berlin and the TU Darmstadt. The beamline is designed with both high resolution electron spectroscopy, valence band measurements and PEEM in mind and utilises the wide energy range of the U49 Undulator 40−1500eV. The design chosen is based on a Petersen PGM [1] but with the grating illuminated with parallel light [2]. This modification allows variation of the monochromator higher order content or resolution, spot size without changing the focus. The performance of the beamline was investigated using various programs available at BESSY. The Undulator character- istics were evaluated using both SMUT and WAVE, and the optical performance of the monochromator was checked using REFLEC and RAY. The calculations show a resolving power of 2×104 with a flux of the order 1013 photons s−1 over the energy range covered by the mono- chromator. The maximum nominal second order contributions are ≈ 2% at 300 eV for the first Undulator harmonic and ≈ 9% for the third harmonic at 500 eV, both of which can be reduced by increasing the grating incidence angle and, or decreasing the Undulator Pinhole size. KW - Bessy II KW - undulator beamline U49/2 KW - design Y1 - 1999 UR - http://www.dpg-verhandlungen.de/year/1999/conference/muenster/part/o/session/36/contribution/81?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Heller, Thomas A1 - Lopez, Alberto A1 - Bitzer, Thomas A1 - Richardson, Neville V. A1 - Schmeißer, Dieter T1 - Isopropoxy induced stabilisation of the 2x1 reconstruction of Si(100) T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Alcohols are successfully employed as an additive in the anisotropic etching of silicon. In this HREELS study, we modelled the silicon/etching interface by the adsorption of alcohols (ethanol, isopropanol, n-propanol, tert-butyl alcohol) on Si(100)-2x1 and post-exposure to H2O under ultra high vacuum conditions. The vibrational data show that the adsorption of the alcohol molecules involves the cleavage of the O-H bond and the formation of a Si-O-C linkage to the alkoxy species. The dissociated hydrogen saturates one of the neighbouring dangling Si bonds. The Si-Si dimer bonds are not involved in the adsorption process. We observe a considerable chemisorption of water on the ethoxy and tert-butoxy passivated Si(100)-2x1 surface. From the disappearance of the 2x1 LEED pattern it can be concluded that the chemisorption of water occurs through a cleavage of the Si-Si dimer bond. In contrast, isopropoxy species on Si(100)-2x1 reduces dramatically the reactivity of Si(100)-2x1 towards water. Even following extreme exposures to water (1012 Torr s), a 2x1 LEED pattern was observed indicating the presence of intact Si-Si dimer bonds at the isopropoxy/Si(100)-2x1 surface. KW - alcohol adsorption KW - anisotropic etching KW - high resolution electron energy loss spectroscopy (HREELS) KW - low-energy electron diffraction (LEED) Y1 - 2000 UR - http://www.dpg-verhandlungen.de/year/2000/conference/regensburg/part/o/session/11/contribution/55?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Henkel, Karsten A1 - Seime, Bernd A1 - Paloumpa, Ioanna A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - C(V) and C(t) measurements on MFIS structures consisting P[VDF/TrFE] as ferroelectric layer T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43 N2 - Ferroelectric Field Effect Transistors (FeFETs) are considered as a candidate for future non volatile and non destructive readout memory cells. A possible low cost solution is the use of poly[vinylidene fluoride trifluoroethylene (P[VDF/TrFE]). Using P[VDF/TrFE] we focus on metal ferroelectric insulator semiconductor (MFIS) capacitor structures. In this contribution we will summarize our investigations related to capacitance measurements in dependence of applied bias (C(V)) and time (C(t)). The thickness of the ferroelectric layer as well as the thickness and the material of the buffer layer have been investigated for optimization of the write voltage. CV measurements at higher temperatures deliver decreased flatband voltage shifts within one CV loop resulting in lower memory windows. At temperatures around 100∘C the hysteresis totally vanished, pointing out the ferroelectric behavior of the system. C(t) measurements at a constant bias have been performed for retention analysis of the MFIS stack. After applying a writing pulse we could distinguish between a higher and a lower capacitance state for more than 5 days. This work is supported by Deutsche Forschungsgemeinschaft within priority program 1157 (SCHM 745/11-2). Y1 - 2008 UR - http://www.dpg-verhandlungen.de/year/2008/conference/berlin/part/sysa/session/4/contribution/7 SN - 0420-0195 SP - S. 828 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Burkov, Yevgen A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - X-ray photoemission spectroscopy of Aluminium Oxynitride on Si(001) and the rise as buffer layers T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43 N2 - Praseodymium oxide (PrxOy) is one of the candidate as high-k transistor gate dielectrics, but aluminium oxynitride (AlxONy) as buffer layer is needed to prevent diffusions from the silicon into PrxOy and to hinder charge injection from the semiconductor into the insulator. The thermal stability and thickness dependence of aluminum oxynitride (AlxONy) has been investigated by synchrotron radiation photoemission spectroscopy (SR-PES). AlxONy layers were prepared by low energy ion-beam assisted deposition (LE-IBAD) at room temperature on a silicon substrate cleaned with HF-acid. Aluminium oxynitride is stable till 800∘C. From photoemission spectra we can assess that silicon oxynitride is built as first and then the growth of AlxONy follows. Resonant inelastic X-ray scattering measurements with synchrotron radiation have been performed. The combination of X-ray absorption spectroscopy (XAS) and RIXS make possible to determinate the band gap of AlxONy. Y1 - 2008 UR - http://www.dpg-verhandlungen.de/year/2008/conference/berlin/part/ds/session/23/contribution/5 SN - 0420-0195 SP - S. 243 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Elektronenspektroskopie an Kupferindiumdisulfid Oberflächen T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - In diesem Beitrag wird eine Studie vorgestellt, welche die elektronenspektroskopische Untersuchung von CIS-Oberflächen für Solarzellen zum Thema hatte. XPS-UPS Analysen von Cu-reichen CuInS2-Dünnfilmen zeigten, daß die Variationen der Elementverhältnisse im Verlauf eines kontrollierten Heizprozesses entlang binärer Schnitte des ternären Phasendiagramms Cu-In-S verlaufen. Die Elementverhältnisse bei zusätzlich aufgedampftem Kupfer und erhöhter Temperatur föhrten in den Homgenitätsbereich von CuInS2. PEEM-Untersuchungen zur Probenmorphologie zeigten, daß ein Sinterprozess während der Temperung der Proben bis 550 C und einer Belegung mit Kupfer erfolgt. Mit Differenz-PEEM-Aufnahmen konnten kupferreiche Fremdphasen wie CuS an der Oberfläche sichtbar gemacht werden. Die in-situ Charakterisierung des Oberflächenchemismus im Verlauf der Temperung zeigte eine zunehmende Homgenität der Elementverteilung, was auf einen geringer werdenden Anteil von Fremdphasen hindeutet. NEXAFS-Aufnahmen ergaben erstmals Informationen über die Bandstruktur oberhalb der Fermienergie und ebenfalls Hinweise auf Fremdphasen sowie deren Reaktionen bei höheren Temperaturen. KW - CIS-Solarzellen KW - Röntgen-Absorptionsspektroskopie KW - Photoemissionselektronenmikroskopie Y1 - 2003 UR - http://www.dpg-verhandlungen.de/year/2003/conference/dresden/part/hl/session/14/contribution/98?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Torche, Mohamed A1 - Müller, Klaus A1 - Henkel, Karsten A1 - Lupina, Grzegorz A1 - Goryako, Andrey A1 - Wollweber, Jürgen A1 - Schmeißer, Dieter T1 - Investigations of 3C-SiC growth on Si (001) T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Carbide was grown on Si (001) - substrates with supply of C2H2. Investigation of the interface Si/SiC (buffer layer) is essential for optimized preparation conditions, leading to a high quality of the growing SiC crystal. In addition to the lattice mismatch of 20 per cent between Si and SiC, which causes defects like dislocations or stacking faults, the chemical homogeneity of this layer is important. XPS was used to characterize the first state of SiC crystal growth on the Si substrate. Carbonizing with C2H2 leads to surface reactions which build up the buffer layer. By using electron spectroscopy, it was possible to characterize the SiC/Si (001) buffer layer, depending on the following reaction parameters: Tsubstrate , PC2H2 , PH2 , the ratio of pressures and the reaction time. The measurements were performed in terms of the content of carbide, oxide and roughness/etching-efficiency (Profilometer) for the reaction parameters above. We found, that the most critical parameter is the temperature of the substrate (Tsubstrate). KW - 3C-SiC KW - chemical vapor deposition (CVD) KW - X-ray photoelectron spectroscopy (XPS) Y1 - 2004 UR - http://www.dpg-verhandlungen.de/year/2004/conference/regensburg/part/hl/session/44/contribution/42?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Depth Profiling of Ultrathin Oxynitride Layers Using Synchrotron Radiation T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - To determine the depth structure of samples various destructive (SIMS, depth profiling with sputtering and AES or XPS) and non-destructive techniques (RBS - Rutherford-Back-Scattering) are available. But all methods are less suitable for investigating especially ultrathin (<5nm) layers: While the destructive techniques suffer from Ion-mixing the RBS can not deliver chemical information. Due to the depth-dependent attenuation of photo-electrons XPS also contains depth information. As XPS gives only a sum signal across the layer one needs to modify the Inelastic Mean Free Path (IMFP) of the photo-electrons to vary the depth information in the photo-electron spectra. This can be done by changing the kinetic energy with the use of different excitation energies delivered from a Synchrotron. Using this method we were able to investigate the chemical depth structure of silicon oxynitride layers. The layers were grown on Si(111) by a N2O-treatment. The depth profile of that layer shows a silicon nitride layer forming the interface between the silicon substrate and the oxynitride. KW - oxynitride KW - X-ray photoelectron spectroscopy KW - depth profiling Y1 - 2003 UR - http://www.dpg-verhandlungen.de/year/2003/conference/dresden/part/o/session/12/contribution/36?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Schmeißer, Dieter A1 - Wehner, Stefan A1 - Hoffmann, Patrick A1 - Brand, Helmut R. A1 - Küppers, Jürgen ED - Descalzi, Orazio T1 - Influence of the Substrate on the Pattern Formation of a Surface Reaction T2 - Nonequilibrium statistical mechanics and nonlinear physics, XV Conference on Nonequilibrium Statistical Mechanics and Nonlinear Physics, Mar del Plata, Argentina, 4 - 8 December 2006 Y1 - 2007 SN - 978-0-7354-0421-2 SP - 121 EP - 126 PB - AIP Publishing CY - Melville, New York ER - TY - JOUR A1 - Schmeißer, Dieter A1 - Bierman, Matthew J. T1 - Ferromagnetic Semiconducting EuO Nanorods Y1 - 2007 ER - TY - CHAP A1 - Bergholz, Matthias A1 - Schmeißer, Dieter T1 - Band gap determination of thin Praseodymiumoxide layers on Aluminiumoxynitride films T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43 N2 - High-k dielectrics are important as never bevore in semiconductor industry. We investigate Pr2O3 as one representative of this group on Silicon and Silicon-Aluminium oxynitride substrates. In earlier work we observed the positive influence of this AlOxNy intermediate layer on the electrical properties of the Pr2O3 layer. Now we present in-situ EELS, XPS and UPS measurements of gradually grown thin Pr2O3 on AlOxNy. From these measurements we determine the band structure and find a very fast change of the band gap for the first few Ångström, coupled with n-type behaviour for the Pr2O3 film. These results are compared with RIXS measurements of a 5 nm Pr2O3 on a 1 nm thick AlOxNy layer. Y1 - 2008 UR - http://www.dpg-verhandlungen.de/year/2008/conference/berlin/part/ds/session/23/contribution/4 SN - 0420-0195 SP - S. 243 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Opel, Matthias A1 - Nielsen, Karl-Wilhelm A1 - Bauer, Sebastian A1 - Goennenwein, Sebastian T. B. A1 - Gross, Rudolf A1 - Cezar, Julio C. A1 - Schmeißer, Dieter A1 - Simon, Jürgen A1 - Mader, Werner T1 - Nanosized superparamagnetic precipitates in cobalt-doped ZnO T2 - The European Physical Journal : B KW - nanosized KW - superparamagnetic Y1 - 2008 SN - 1434-6036 VL - 63 IS - 4 SP - 437 EP - 444 ER - TY - JOUR A1 - Henkel, Karsten A1 - Karavaev, Konstantin A1 - Torche, Mohamed A1 - Schwiertz, Carola A1 - Burkov, Yevgen A1 - Schmeißer, Dieter T1 - Al-Oxyxynitride interfacial layer investigations for PrXOY on SiC and Si Y1 - 2008 ER - TY - CHAP A1 - Müller, S. A1 - Schmeißer, Dieter T1 - Deposition of reactive and non-reactive metals on titanium dioxide - chromium and cobalt Y1 - 2008 ER - TY - CHAP A1 - Mandal, Dipankar A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Dipole orientation of the P[VDF-TrFE] co-polymer films: A NEXAFS study T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43 N2 - Ferroelectric properties of copolymers of vinylidene fluoride with trifluoroethylene (P[VDF-TrFE]) has become great deal of interest due to potential use in non volatile memory technology. Permanent dipoles (formed between the alternating hydrogen and fluorine atom within the copolymer) ordering of orientation are crucial for device efficiency. Here we focus on thickness dependence dipole orientation in these co-polymer films. In our systematic studies, we found there is prominent dipole re-orientation effect also for the intrinsic films (~10 nm thickness) before applying the electric field. It is observed after the application of the field, the dipoles re-oriented in opposite direction. Therefore, we conclude that the lowest thickness of the film should have well grown crystalline lamellae structure. As a result, c-axis of crystallites acts as well define manner in plane of the surface and for that reason the b-axis is more free. Because the b-axis is parallel to the polarization direction, it is easy to get a preferred orientation of the dipoles. For thicker films (here up to 100 nm), the average orientation effect is hindered, so a very low re-orientation effect has been observed. For this investigation, we used Near Edge X-ray Absorption Spectroscopy, at the U 49/2-PGM beam line of BESSY-II, Berlin. This work is supported by DFG within SPP1157 (SCHM 745/11-2). Y1 - 2008 UR - http://www.dpg-verhandlungen.de/year/2008/conference/berlin/part/sysa/session/5/contribution/76 SN - 0420-0195 SP - S. 840 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Heller, Thomas A1 - Böhme, Oliver A1 - Schmeißer, Dieter T1 - Molecular Resonances in the Photoionization Cross Section (PIX) of Oxidic Semiconductors T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Despite their fascinating physical applications in sensoric there is no clear view of the electronic structure of these class of oxidic semiconductor materials. We studied the photo ionization cross sections (PIX) in a CIS like experiment of the valence states as well as the defect state and compare these to the CFS data obtained from X-ray absorption spectroscopy. While the first technique contains only transitions from a defined initial state the latter covers all the possible optical channels. We show for WO3-films that a structural reorganization of the surface is induced by doping (Na exposure) which increases the O2p/W5d orbital mixing. Pristine TiO2 (110) single crystals show basically the same behavior but have an initially stronger hybridization of Ti3d derived states with the O2p valence states. Upon doping the defect intensity is increased as well as the orbital hybridization. Our data give evidence that valence band derived states have almost the same orbital parentage like the defect state. They offer that the wave functions of these states are localized on a molecular scale. This is in contrast to the common treatment of resonances in the PIX which are usually discussed in terms of the resonant photoemission model, which does not include the possibility of mixed valence/defect states. KW - X-Ray photoelectron spectroscopy KW - X-Ray absorption spectroscopy KW - Photoionization Cross Section (PIX) KW - defect states Y1 - 2000 UR - http://www.dpg-verhandlungen.de/year/2000/conference/regensburg/part/o/session/15/contribution/3?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Klaus A1 - Mandal, Dipankar A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Interface reactions of ferroelectric copolymer layers with different electrode materials T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43 N2 - The ferroelectric copolymer poly(vinylidene fluoride trifluoroethylene) (P(VDF-TrFE)) is a possible material for low cost applications as organic nonvolatile memory element. We present an XPS interface investigation of the copolymer/electrode interface. Below 100nm film thickness, interface phenomena becomes important. Possible interface reactions could lead to a reduction of the ferroelectric functionality.We present a comparative study of the two interfaces Al/P(VDF-TrFE) and PEDOT:PSS/P(VDF-TrFE). The result is a clear indication of a surface reaction in between the Aluminum-electrodes. In contrast, for PEDOT:PSS the measurements shows a layer by layer formation of the interface PEDOT:PSS/PVDF without any reaction. Second, we present a study of remanent polarization of ultrathin spincoated films of the copolymer, in a thickness range from 5 to 100mn, with organic electrodes like PEDOT:PSS. The measurements are carried out by using the flatband shift of a capacitance-voltage (CV) characteristic. This shift of flatband voltage is used as value for the electric polarization of the polymer. Y1 - 2008 UR - http://www.dpg-verhandlungen.de/year/2008/conference/berlin/part/sysa/session/5/contribution/16 SN - 0420-0195 SP - S. 830 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Schmeißer, Dieter T1 - Si(001) surface oxidation T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - A Si(001) surface is cleaned in UHV by heating (flashing) and is exposed to different pressures of N2O at altered temperatures. Oxynitride layers of different thicknesses and different properties are grown depending on the N2O-pressure and the Si- temperature. This is illustrated by a schematic diagram. The properties of the different Oxynitride layers were studied by a combined PEEM- and PES-investigation using highly monochromatised synchrotron radiation. The amount of Oxygen and Nitrogen incorporated in the Oxynitride layers is determined from the PES measurements. The typical surface morphology for different preparation conditions is shown in PEEM images. A model based on differently established dipole layers in the Oxynitride layers is proposed. This model is capable of interpreting the features appearing in the PE-spectra. This model can also be applied to the interface of Si/SiO2. KW - oxynitride KW - X-ray photoelectron spectroscopy (XPS) KW - photoemssion electron spectroscopy (PEEM) Y1 - 2001 UR - http://www.dpg-verhandlungen.de/year/2001/conference/hamburg/part/o/session/13/contribution/75?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Sebastian A1 - Schmeißer, Dieter T1 - Direct Observation of d2L2 Charge Transfer States in TiO2 thin films by Resonant Photoelectron Spectroscopy T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43 N2 - We investigate the electronic structure of TiO2 thin films by SR-PES, NEXAFS and ResPES. The films are prepared in a combined in-situ/ex-situ process that leads to stoichiometric thin films (≈ 10 nm) in Rutile structure. We focus on ResPES at the Ti 2p edge. When the photon energy is close to the Ti 2p absorption edge we observe additional features about 13 eV below the valence band main features. These features show clear spectator auger decay at the resonance leading to d0 final state. From this, we deduce the existence of the d2L2 initial charge transfer state as this is the only possible channel that enables the corresponding spectator auger decay. These features have the same origin as the satellite structures observed in core level spectra, esp. 2p and 3p. Y1 - 2008 UR - http://www.dpg-verhandlungen.de/year/2008/conference/berlin/part/o/session/32/contribution/3 SN - 0420-0195 SP - S. 592 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Schmeißer, Dieter A1 - Müssig, Hans-Joachim T1 - Stability and electronic properties of silicates in the system SiO2 - Pr2O3 - Si(001) T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Hetero- oxides are the candidates to replace SiO2 as the gate dielectric material for sub-0.1µm CMOS technology. In particular, the basic interaction mechanisms at the interface are a key issue and a solid knowledge of these mechanisms is required to address reliability issues. The challenge in material science is to understand the chemical bonding of the hetero oxides and Si on a microscopic scale. This report focuses on the interaction of the high dielectric constant (DK) material Pr2O3 with SiO2 and the bare Si(001) surface. Photoelectron spectroscopy (PES) using tunable Synchrotron radiation (undulator U49/2 at BESSY II) is shown to provide spectroscopic information which is used for characterization of the electronic structure elements at the interface as well as for a non-destructive depth profiling. The chemical state of the Si atoms at the interface is identified and the chemical stability of the various oxide phases is discussed. We determine the variation of the elemental composition across the interface and follow the stability of the silicate phase. KW - Pr2O3 KW - high-k KW - X-ray photoelectron spectroscopy (XPS) KW - silicate Y1 - 2004 UR - http://www.dpg-verhandlungen.de/year/2004/conference/regensburg/part/hl/session/31/contribution/3?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Klaus A1 - Paloumpa, Ioanna A1 - Schwiertz, Carola A1 - Jahnke, Agnes A1 - Schmeißer, Dieter T1 - All Polymer Field-Effect-Transistors based on Low-Cost-Microstructuring T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Thin film transistors with P3HT as active layer have been prepared by spin coating. The electrodes for source and drain have been prepared by a low cost plotting method with colloidal graphite or carbon black as the conducting material. PEDOT or carbon black was used as gate electrode. The devices, prepared by different methods and materials have been characterized by electrical measurements, for example, their transfer and output characteristics. Furthermore, the influence of different materials on effects like hysteresis or reproducibility will be compared. In addition, we describe a project investigating new types of biosensors with functionalized gate electrodes. Exchanges of dipole moments or charges by immobilisation of biomolecules will change the electrical characteristic of the transistor, which leads to a sensing signal proportional to their amount. KW - organic field effect transistor KW - low cost printing KW - microstructuring Y1 - 2004 UR - http://www.dpg-verhandlungen.de/year/2004/conference/regensburg/part/syoh/session/5/contribution/75?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Klaus A1 - Burkov, Yevgen A1 - Schmeißer, Dieter T1 - Spectromicroscopic Characterisation of All Polymer Transistor Structures T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - In order to optimize organic field effect transistors, the characterization of surfaces in terms of their roughness or chemical composition is very important. We report on high resolution spectromicroscopic mapping of organic thin film transistors by photoemission electron microscopy (PEEM). It was shown that PEEM is a useful technique to characterize the surface morphology (roughness), the chemical homogeneity or the composition of structures in between the source and drain electrodes. Mapping of surface potentials, especially at the interface electrode/channel is possible. We compare different preparation methods and the characterization at applied voltages is also shown. The transistors itself were prepared by a new low cost method. The electrodes for source and drain have been prepared by a plotting method with colloidal graphite or carbon black as the conducting material. P3HT was used as active layer and has been prepared by spin coating. KW - organic field effect transistor KW - photoemission electron microscopy (PEEM) Y1 - 2004 UR - http://www.dpg-verhandlungen.de/year/2004/conference/regensburg/part/syoh/session/5/contribution/74?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - JOUR A1 - Beck, Romuald B. A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter A1 - Bieniek, Tomasz A1 - Jakubowski, Andrzej T1 - Composition and Electrical Properties of Ultra-Thin SiOxNy Layers Formed by rf Plasma Nitrogen Implantation/Plasma Oxidation Processes Y1 - 2007 ER - TY - GEN A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Study of Bulk and Interface Defects in Silicon Oxide with X-ray Absorption Spectroscopy T2 - Materials Science and Engineering : B Y1 - 2007 SN - 0921-5107 VL - 144 IS - 1-3 SP - 23 EP - 26 ER - TY - CHAP A1 - Goryachko, Andriy A1 - Beuckert, Guido A1 - Zaumseil, Peter A1 - Wagner, Guenter A1 - Schmeißer, Dieter T1 - Investigations of Pr2O3 growth modes on 4H-SiC(0001) Surfaces T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The SiC is suited especially well for high power and high voltage semiconductor devices. In order to increase the reliability against electrical breakdown of metal-insulator-semiconductor (MIS) structures, one needs to use the insulator with possibly higher dielectric constant. Pr2O3 is shown to posses a much higher dielectric constant (equals 30) than traditionally used SiO2. Therefore, Pr2O3/SiC is an excellent material combination for high voltage MIS devices. The 4H-SiC(0001) substrates are characterised with scanning tunneling microscopy, while the Pr2O3 surface - with atomic force microscopy technique. We show distinct growth modes of Pr2O3 film, such as 3D and layer by layer growth. The crystalline structure and film thickness are determined by X-ray diffraction and its chemical composition by X-ray photoelectron spectroscopy. The Pr2O3 film characteristics are optimised for high-quality MIS structures in terms of lateral uniformity, low interface states density and leakage current, as well as physical integrity. KW - SiC KW - Pr2O3 KW - X-ray photoelectron spectroscopy (XPS) KW - X-Ray diffraction Y1 - 2004 UR - http://www.dpg-verhandlungen.de/year/2004/conference/regensburg/part/ds/session/9/contribution/4?lang=de SN - ISSN 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Hoffmann, Patrick A1 - Goryachko, Andriy A1 - Schmeißer, Dieter T1 - Growth of oxynitrides on Si-rich 4H-SiC(0001) surfaces T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Oxynitride layers are grown on 4H-SiC(0001) by a thermal treatment in N2O. The nitrogen content is controlled by varying the growth conditions (N2O pressure and substrate temperature) and the nitrogen incorporation is found to be stronger for higher substrate temperatures and lower N2O pressures. Excess carbon is generated due to SiC decomposition under such growth conditions (high temperature and low N2O pressure) which leads to unwanted high interface state density and has to be avoided. Our approach is to prepare a Si-rich or even Si-covered SiC surface by Si evaporation. Upon oxidation in N2O the additional silicon is expected to compensate the loss of silicon from the SiC while preparation. The Si-rich SiC surface as well as the grown layers were investigated by photoelectron spectroscopy (XPS) for chemical analysis and by AFM/STM for analysis of the surface morphology. Concerning the chemical analysis we focus on the total nitrogen content, on the amount of silicon nitride Si3N4 and of silicon oxynitride SiOxNy, and on the existence of sub-oxides which build the interface between SiC and the oxynitride layers. KW - X-Ray photoelectron spectroscopy KW - scanning tunneling microscopy (STM) KW - atomic force microscopy (AFM) KW - silicon oxynitride KW - 4H-SiC(0001) Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/hl/session/26/contribution/1?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Growth of oxynitrides on Si-rich 4H-SiC(0001) surfaces T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - It will be reported on the growth of oxynitride thin layers (≤10nm) on (0001)-oriented 4H-SiC surfaces. The oxynitride layers were grown by a thermal treatment of the samples in low pressure N2O ambient. By varying the growth conditions (N2O pressure, sample temperature, growth time) different layers were made. The grown layers were investigated by photoelectron spectroscopy (XPS) for chemical analysis and by AFM/STM for analysis of the surface morphology. Concerning the chemical analysis it will be discussed the general nitrogen content of the samples, the composition of the films (e.g. content of silicon nitride Si3N4 and silicon oxynitride SiOxNy) and the sub-oxides which build the interface between SiC and the oxynitride layers. Concerning the surface morphology mainly the roughness will be discussed. The so obtained results for oxynitride thin films on 4H-SiC will be compared to similarly prepared oxynitride layers on Si(111) investigated in the past. KW - oxynitride KW - 4H-SiC KW - X-ray photoelectron spectroscopy (XPS) KW - Atomic foce microscopy (AFM) KW - scanning tunneling microscopy (STM) Y1 - 2004 UR - http://www.dpg-verhandlungen.de/year/2004/conference/regensburg/part/hl/session/40/contribution/4?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - JOUR A1 - Schmeißer, Dieter A1 - Mroczynski, Robert A1 - Bieniek, Tomasz T1 - Comparison of Composition of Ultra-Thin Silicon Oxynitride Layers´ fabricated by PECVD and Ultrashallow rf Plasma Ion Implantation Y1 - 2007 ER - TY - JOUR A1 - Mroczynski, Robert A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - The Influence of Annealing (900 Grad C) of Ultra-Thin PECVD Silicon Oxynitride Layers Y1 - 2007 ER - TY - CHAP A1 - Geuss, Markus A1 - Müller, Klaus A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Surface Potential profiling on operating full organic thin film transistors by Kelvin probe force microscopy T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Kelvin-AFM is employed to study all polymer organic thin film transistors which are promising candidates for low cost - low performance applications like active matrix displays, sensors or single-serving devices. We use bottom contact source-drain- electrode structures of different organic materials like carbon-black or graphite plotted on a printing foil. Semiconducting regioregular Poly(3-Hexylthiophene-2,5-diyl) (P3HT) was subsequently deposited by spin coating. Surface potential profiles across the transistor channel were measured by Kelvin-AFM for various source-drain potential differences and signs. We found that contact resistances cause characteristic steps in the surface potential near the channel edges which vary with the electrode material. Furthermore, nonlinearities appear in the potential gradient which possibly give evidence for lateral inhomogeneities of the carrier mobilities. In summary, surface potential imaging with high lateral resolution ( approx. 100 nm) is introduced as a powerful tool for the characterisation of the transistor performance and the selection of suitable low cost electrode materials. KW - organic field effect transistor KW - Kelvin probe force microscopy Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/syoo/session/6/contribution/36?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Seifarth, Olaf A1 - Burkov, Yevgen A1 - Schmeißer, Dieter A1 - Sydorenko, Alexander A1 - Krenek, Radim A1 - Stamm, Manfred T1 - Photoelectron spectroscopy and microscopy on magnetic nano particles embedded into block copolymers T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The formation of metallic nano particles stored in thin films of block copolymers has been investigated by means of synchrotron radiation based photoemission spectroscopy (PES) and microscopy (PEEM). Empty channels in poly(styrene-block-4-vinylpyridine) copolymer with diameters of tens of nanometers filled with CrO2, Cr2O3 and Ni provide ideal bases for performing electron spectroscopy with energy and lateral resolution on magnetic nano particles. We present UPS, XPS, NEXAFS spectra and PEEM images on and off the C 1s, Cr 2p, Ni 2p resonances and discuss the geometric and electronic structure of such compounds. The synchrotron radiation was delivered from the U49/2 beamline at BESSY II. KW - photoelectron emission microscopy (PEEM) KW - X-ray photoelectron spectroscopy KW - X-ray absorption spectroscopy KW - block copolymers KW - magnetic nano particles Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/cpp/session/29/contribution/27?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Sohal, Rakesh A1 - Henkel, Karsten A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Growth and Characterization of 3C-SiC thin films on Si substrates T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - This work reports on the growth and characterization of cubic silicon carbide thin films. A cold wall low pressure chemical vapour deposition (LPCVD) system has been used to grow the cubic silicon carbide. The two step method, carbonization and subsequent growth, has been used to grow good quality 3C-SiC thin films. The composition and structure of deposited thin films have been analysed by Fourier Transform Infrared Spectroscopy (FTIR), XPS and X-Ray Diffractometry (XRD). The structural quality of the films has been optimized as a function of substrate temperature during carbonization and growth. X-rays diffraction measurements shows that the grown layers are highly oriented crystalline cubic silicon carbide. KW - low pressure chemical vapor deposition (LPCVD) KW - 3C-SiC KW - X-ray photoelectron spectroscopy (XPS) KW - Fourier Transform Infrared Spectroscopy (FTIR) KW - X-Ray diffraction Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/hl/session/58/contribution/50?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Schroeder, Thomas A1 - Lupina, Grzegorz A1 - Seifarth, Olaf A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Synchrotron radiation x-ray photoelectron spectroscopy study on the interface chemistry of high-k PrxAl2-xO3 (x=0-2) dielectrics on TiN for dynamic random access memory applications T2 - Journal of Applied Physics Y1 - 2007 SN - 0021-8979 VL - 102 IS - 1 SP - 014103 ER - TY - JOUR A1 - Henkel, Karsten A1 - Sohal, Rakesh A1 - Schmeißer, Dieter A1 - Schwiertz, Carola A1 - Burkov, Yevgen A1 - Torche, Mohamed T1 - Al-oxynitride buffer layer facilities for PrOx/SiC interfaces Y1 - 2007 ER - TY - GEN A1 - Seifarth, Olaf A1 - Burkov, Yevgen A1 - Schmeißer, Dieter A1 - Stamm, Manfred T1 - Metallic nickel nanorod arrays embedded into ordered block copolymer templates T2 - Thin Solid Films Y1 - 2007 SN - 0040-6090 VL - 515 IS - 16 SP - 6552 EP - 6556 ER - TY - CHAP A1 - Müller, Klaus A1 - Burkov, Yevgen A1 - Schmeißer, Dieter T1 - Surface potential profiling on organic thin film transistors by photoemission-electron-microscopy (PEEM) T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Surface potential imaging with Photoemission-electron-microskopy (PEEM) in high lateral resolution is introduced as a new tool for the characterisation of organic transistor structures. We use source-drain- electrode structures of different organic materials like carbon-black or graphite plotted on a printing foil. Semiconducting regioregular Poly(3-Hexylthiophene-2,5-diyl) (P3HT) was deposited by spin coating. For our measurements we used radiation of a standard high pressure Hg-lamp (4,9 eV) and synchrotron radiation at the BESSYII-U49/2 beam line. In contrast to Kelvin-AFM measurements of the surface potential, PEEM enables a simultaneous analysis of chemical composition by photoelectron spectroscopy. UPS, for example, at zero potential gives information on chemical homogeneity of the organic semiconductor in lateral resolution. PEEM images at applied voltages, compared with UPS-spectra, gives informations on doping profiles in the semiconductor, for example. In conclusion, PEEM should be a complementary method for characterisation of the surface potential with Kelvin-AFM. In addition, PEEM gives opportunities for measurements of chemical composition in the working state of the transistor (applied voltages). KW - organic field effect transistor KW - Photoemission-electron-microscopy (PEEM) KW - Kelvin-AFM KW - X-Ray photoelectron spectroscopy Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/syoo/session/6/contribution/41?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - P(VDF/TrFE) as a ferroelectric dielectric for Organic Field effect Transistors in MFIS structure T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - MFIS structures consisting of metal, ferroelectric poly[vinylidene fluoride trifluoroethylene](P[VDF/TrFE]), insulator, semiconductor (Si) are fabricated and the influence of the polarization of the P(VDF/TrFE) on the CV characteristics of these structures is investigated. We find a characteristic ferroelectric hysteresis in the CV curves upon increasing the voltage scan window (e.g.-U...U,U=6...30V, |UP(VDF/TrFE)|≤15V, dP(VDF/TrFE)=300 nm). A writing process with adequate electric fields causes large shifts in the flatband voltage ( Δ UFB>4V for the quoted example before) which are stable over days. We report on our investigations which focus on the switching behavior by varying the parameters like polymer thickness, writing field strength and time, long time stability, reversing voltage and insulating material (SiO2, PMMA (Polymethylmetacrylate)). This material combination is favorable for transfer into our full organic concept of field effect transistors for application as a nondestructive readout memory (NDRO) cell. KW - P(VDF/TrFE) KW - Organic ferroelectric field effect transistor KW - capacitance voltage measurements Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/syoo/session/6/contribution/39?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Klaus A1 - Paloumpa, Ioanna A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Organic Field Effect Transistors with polymer high-k dielectric insulator T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Organic field effect transistors consisting of the copolymer poly(vinylidene fluoridetrifluoroethylene) (P(VDF-TrFE)) and P3HT (poly(3-hexlythiophene)) as active layer have been fabricated. The influence of P(VDF-TrFE) on the transconductance of organic field effect transistors was investigated and enhanced gate effects are observed compared to similar transistors with PMMA (Polymethylmetacrylate) as gate dielectric. Due to the high dielectric constant of P(VDF-TrFE) (DK=12) an operation voltage smaller than for a conventional organic dielectric like PMMA (DK=3.3) was observed. The thickness of the spincoated dielectric layers is in the range of 2microns and in consequence, no significant hysteresis was found, a prerequisite for transistor operation. KW - organic field effect transistor KW - P(VDF/TrFE) KW - high-k organic Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/syoo/session/6/contribution/30?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - JOUR A1 - Müller, Klaus A1 - Mandal, Dipankar A1 - Schmeißer, Dieter T1 - No interfacial layer for PEDOT electrodes on PVDF: Characterization of reactions at the interface P(VDF/TrFE)/Al and P(VDF/TrFE)/PEDOT:PSS Y1 - 2007 ER - TY - JOUR A1 - Müller, Klaus A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Organic field effect transistors with ferroelectric hysteresis Y1 - 2007 ER - TY - CHAP A1 - Lupina, Grzegorz A1 - Schroeder, Thomas A1 - Dabrowski, Jarek Marek A1 - Schmeißer, Dieter A1 - Müssig, Hans-Joachim T1 - Ti-doping of Pr silicate layers for high-k dielectrics applications T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Near-term downscaling of the metal-oxide-semiconductor field-effect transistors (MOSFETs) requires the replacement of the SiO2 gate oxide with a material having a higher dielectric constant. Recent studies indicate that silicate materials are the most promising candidates; among them are Pr silicates. Applying a combination of x-ray photoelectron spectroscopy (XPS), electrical measurements (C-V), and ab initio calculations, we investigated the effect of thin Ti doping on the structural and electrical properties of the gate stacks composed of a Pr silicate film and a SiO2-based interfacial buffer layer. Metallic Ti was deposited at room temperature after the formation of the Pr silicate dielectric. The resulting layered structures were annealed under ultra-high vacuum (UHV) at various temperatures between 70∘C and 880∘C. XPS indicates that the evaporated layer preserves its metallic character over the whole range of UHV annealing temperatures. Synchrotron radiation XPS at BESSY II shows that large amounts of Ti atoms incorporated into the Pr silicate remain metallic even after air exposure at room temperature. Annealing in nitrogen ambient at 300∘C leads to the oxidation of these atoms so that a mixed Pr:Ti silicate is formed. We show that the so formed dielectrics exhibit an improved equivalent oxide thickness and a reduced density of interface states. KW - high-k KW - X-ray photoelectron spectroscopy KW - ab inito calculations KW - Capacitance-voltage measurements KW - Pr silicate Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/df/session/6/contribution/5?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Seime, Bernd A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Buffer layer investigation of MFIS stacks with an organic ferroelectric layer T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 42 N2 - Ferroelectric field effect transistors are considered as future non volatile and non destructive readout memory cells. Conventional Perowskite-type ferroelectric materials are shown to work but they need expensive high temperature and high partial pressure processing steps inducing also unintentional and undefined interfacial layers.A possible low cost solution is the use of poly[vinylidene fluoride trifluoroethylene (P[VDF/TrFE]). This is a ferroelectric polymer which can be spin coated at room temperature onto silicon suited with well defined buffer layers. Using P[VDF/TrFE] we focus on metal ferroelectric insulator semi-conductor (MFIS) structures. In MFIS structure a part of the programming voltage drops over the buffering insulator. We report on attempts to minimize this fraction by optimizing the voltage divider over the buffer and the ferroelectric layers. CV measurements for different thickness of the buffer (10-235nm) and the ferroelectric layer(100nm-1μm) and for different permittivity values of the buffer layer(SiO2, Al2O3, HfO2) will be presented. This work is supported by Deutsche Forschungsgemeinschaft within priority program 1157 (DSCH 745/11-1). Y1 - 2007 UR - http://www.dpg-verhandlungen.de/year/2007/conference/regensburg/part/df/session/11/contribution/1 SN - 0420-0195 SP - S. 216 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Styervoyedov, Andriy A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Composition and thermal stability of thin functional oxidic (Pr, La, Y) and metallic (Ru, Ti) layers on Si and SiC substrates T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Thin Pr-, La- and Y- based oxide layers for applications as gate dielectric in metal-oxide-semiconductor (MOS) structures are investigated with x-ray photoelectron spectroscopy. The films with a thickness of around 2nm have been prepared on Si and SiC wafers by various chemical deposition methods based on nitrate solutions. In addition, we report on Ti- and Ru- based metal contacts prepared in the same way. The film composition is analysed and annealing steps in vacuum up to 900∘C have been applied to test their thermal stability. The interface characteristics, surface composition and thermal stability of MOS functional multilayers have been studied and will be presented. KW - Pr-, La- and Y- based oxides KW - MOS transistor KW - high-k KW - X-Ray photoelectron spectroscopy Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/ds/session/24/contribution/17?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Schmeißer, Dieter T1 - The initial interaction of Pr2O3 to (001) and (111) oriented Si substrates T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The high surface sensitivity of synchrotron based core level spectroscopy is employed to study the initial growth of Pr2O3 on Si(001) and Si(111) substrates. The Si2p core levels are different for the two substrates when the exposure is below 1nm. The core level shifts indicate a single bonding of the oxide on the terminal Si atom in Si(111) while on Si(001) the two dangling bonds are reactive. On both surfaces a significant broadening in the substrate emission is found and interpreted in terms of non bonding Si atoms located at the interface. Upon increasing the Pr2O3 exposure above 1nm the Si back bonds in the first Si layer are attacked to form Si - O - Pr bonds which cause a silicate like core level shift. KW - Pr2O3 KW - high-k KW - X-ray photoelectron spectroscopy (XPS) Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/ds/session/11/contribution/2?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Karavaev, Konstantin A1 - Tallarida, Massimo A1 - Schmeißer, Dieter ED - Vierhaus, Heinrich Theodor T1 - In-situ Atomic Layer Deposition growth of Hafnium oxide T2 - DEDIS-Nano-Days, October 11th and October 12th, 2007 Y1 - 2007 SP - 13 EP - 19 PB - BTU CY - Cottbus ER - TY - JOUR A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Study of bulk and interface defects in silicon oxide with X-ray absorption spectroscopy Y1 - 2007 ER - TY - CHAP A1 - Henkel, Karsten A1 - Sohal, Rakesh A1 - Torche, Mohamed A1 - Schwiertz, Carola A1 - Burkov, Yevgen A1 - Schmeißer, Dieter T1 - PrOx/AlON stacks as a high-k candidate on SiC T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 42 N2 - We study the chemical stability and electrical properties of Pr-oxides-SiC MIS stacks. In MISFET devices for high power applications the electric field scaling at the interface between semiconductor and insulator is determined by the ratio of their permittivity values. A high-k material can be used to optimize the performance of such devices. In previous studies we had to understand that the chemical reactivity of the PrOx/SiC interface causes a destructive interaction yielding silicate and graphite formation as well as poor electrical performance after direct deposition of PrOx onto SiC. Therefore we introduced an additional chemically inert layer and in this contribution we focus on PrOx/AlON as a suitable insulator stack. In our spectroscopic investigations we recognized a stable AlON/3C-SiC interface even for annealing steps up to 900∘C. First electrical characterizations are performed on Si substrates and we find a strong improvement in the leakage current by several orders of magnitude down to values of 10−7 A/cm2 at an EOT of 4nm and interface state densities of mean values of 5*1011/eVcm2. We also report on our ongoing electrical characterization of such stacks on SiC substrates. This work is supported by Deutsche Forschungsgemeinschaft within priority program 1157 (DSCH 745/9-2). Y1 - 2007 UR - http://www.dpg-verhandlungen.de/year/2007/conference/regensburg/part/df/session/10/contribution/8 SN - 0420-0195 SP - S. 215 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Mandal, Dipankar A1 - Müller, Klaus A1 - Seifarth, Olaf A1 - Hoffman, Patrick A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Study of reactions at the interface P(VDF/TrFE)/Al and P(VDF/TrFE)/PEDOT:PSS T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 42 N2 - Due to potential use in non volatile memory application, Poly(vinylidene fluoride/trifluoroethylene) (P(VDF-TrFE)) is a great deal of interest, especially to produce organic field effect transistors (OFET). Right now it was found that Aluminum is one of the cost-effective inorganic electrode candidate. On the other hand, poly(3,4 ethylenedioxythiophene):poly(4-styrenesulfonate)(PEDOT:PSS) shows promising behavior for the application as organic electrode. In part of our investigations we have systematically studied surface interactions of organic ferroelectric thin films (P(VDF-TrFE))with inorganic (Al) and organic layers (PEDOT:PSS). By X-ray photoelectron spectroscopy (XPS) is has been found that there is a interfacial reaction with Al and the copolymer. In contrast, for electrodes, made of PEDOT: PSS, we found not such kind of behavior. In this case, we found no evidence for any surface reaction. Furthermore, we present our results concerning the orientation of permanent dipoles in the co-polymer (formed between hydrogen and fluorine atom). Here, we use Near-edge X-ray absorption fine structure (NEXAFS) analysis at the U 49/2 - PGM2 beam line of the BESSY-II Synchrotron. This work is supported by Deutsche Forschungsgemeinschaft (DFG) within priority program 1157 (DSCH 745/11-1). Y1 - 2007 UR - http://www.dpg-verhandlungen.de/year/2007/conference/regensburg/part/syoe/session/8/contribution/18 SN - 0420-0195 SP - S. 797 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Goriachko, Andrii A1 - Müller, Klaus A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Scanning Kelvin Probe Microscopy Investigations of Au-P3HT-Au structures for Organic Field Effect Transistors T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - We report on the scanning Kelvin probe microscopy (SKPM) investigation of the source-channel-drain structures of organic field effect transistor (OFET). A poly-3-hexyl-thiophen (P3HT) organic semiconductor film, spin-coated on a glass-substrate and 65 nm thick, is used as a 2 mkm channel between Au source (drain) electrodes. Depending on the preparation conditions, the P3HT film consists of either amorphous nm-seized molecular clsuters or mkm-long chains. The SKPM allows mapping of electric potential along with the surface topography on the DC-biased structures (8V applied between source and drain). It reveals a linear potential fall in the channel region as well as the abscence of potential jumps (contact resistance) in the electrode/channel regions. This is a direct indication of the top-gate OFET type advantage, which the given structure is suited for. Due to the high spatial resolution of the UHV-based SKPM, doping inhomogenities of the p-type P3HT semiconductor as well as the space charge region on the electron injecting electrode are observed. In addition we present SKPM investigations of the structure with source and drain electrodes but without a semiconductor, showing electric field configuration for the given electrodes geometry. KW - scanning Kelvin probe microscopy (SKPM) KW - organic field effect transistor (OFET) Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/syoo/session/6/contribution/24?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Sebastian A1 - Schmeißer, Dieter T1 - The initial stages of Chromium growth on Titaniumdioxide-Investigations using synchrotron radiation T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 42 N2 - We investigate the interface of Cr-TiO2 during the initial stages of Cr deposition. Experiments are carried out at BESSY II (BL U49/2-PGM2). Using XPS, XAS and ResPES we obtain information about electronic structure at the interface. We confirm the results of growth studies by Christian Winde obtained by TEM-EELS. In addition, we find that Cr deposition induces two gap states which appear about 1 eV and 3 eV below EF. Using ResPES, these states can be identified as being Cr-like and Ti-like respectively. Core-level-XPS and CIS-spectra of the lower gap state indicate the existence of mainly Cr4+ at low coverage (< 1 ML). At higher coverage (≈ 2.5 ML) metallic Cr is observed as well as metallic Ti. Oxidized Cr occurs mainly as Cr3+. CIS-spectra of higher gap state show metallic behavior with both Cr- and Ti-like character. CIS-spectra of lower gap-state confirm the existence of Cr3+. Reference: Christian Winde, Herstellung und Charakterisierung von Cr Schichten auf TiO2 (110)Oberflächen, PhD Thesis, University of Stuttgart, 2002 Y1 - 2007 UR - http://www.dpg-verhandlungen.de/year/2007/conference/regensburg/part/o/session/33/contribution/8 SN - 0420-0195 SP - S. 598 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Torche, Mohamed A1 - Schmeißer, Dieter T1 - The interaction of Al, Au, Ag, and Ti metal contacts with Pr2O3 thin films T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Pr2O3 is one of the promising high-k oxides desirable to replace SiO2 for the sub-100nm field-effect transistors (FETs) and dynamic random access memory (DRAM) capacitors. Here we focus on the metallic contacts used for the MOS and MIM based structures. With the thickness of Pr2O3 being around 3nm the metal interaction is crucial to avoid a reduction of the dielectric properties by metal percolation, crack filling or diffusion processes. We use XPS and SRPS to study the initial interaction as well as the thermal stability of metals (Al, Ag, Au, and Ti) on Pr2O3 films. We show that Al, Ag, Au form initial metallic layer which react already at temperatures around 300∘C. In contrast, Ti is found to be more stable than the other metals. We determine the formation of Ti-oxides at the Ti / Pr2O3 interface and its thermal stability. Ti is found to build a good diffusion barrier between the oxide and the metal. KW - high-k KW - Pr2O3 KW - X-ray photoelectron spectroscopy (XPS) KW - Al, Ag, Au, and Ti electrodes KW - metal dielectric interaction Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/ds/session/11/contribution/4?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Nielsen, Karl-Wilhelm A1 - Bauer, Sebastian A1 - Senn, Konrad A1 - Goennenwein, Sebastian T. B. A1 - Opel, Matthias A1 - Cezar, Julio C. A1 - Schmeißer, Dieter A1 - Gross, Rudolf T1 - X-ray magnetic circulardichroism in cobalt-doped ZnO T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 42 N2 - Cobalt-doped ZnO is a diluted magnetic semiconductor with a reported Curie-temperature well above 300 K. Nevertheless, the origin of the ferromagnetic exchange still is under debate. To clearify this issue we have investigated cobalt-doped ZnO thin films with x-ray magnetic circular dichroism (XMCD). The (0001)-oriented Zn0.95Co0.05O thin films were grown on (0001) ZnO, (0001) Al2O3, and (0001) ScAlMgO4 substrates by pulsed laser deposition. The magnetic properties were measured by SQUID magnetometry and XMCD. Room temperature magnetization measurements by SQUID magnetometry and XMCD in the fluorescence yield mode reveal ferromagnetic behavior with similar shape of the magnetization curves, however, with different absolute values. XMCD magnetization in total electron yield, which is surface sensitive, show only small magnetic moments, most likely due to a magnetically dead surface layer. This work is supported by the DFG via SPP1157. Y1 - 2007 UR - http://www.dpg-verhandlungen.de/year/2007/conference/regensburg/part/ma/session/15/contribution/13 SN - 0420-0195 SP - S. 454 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - JOUR A1 - Lupina, Grzegorz A1 - Schroeder, Thomas A1 - Schmeißer, Dieter A1 - Dabrowski, Jarek Marek T1 - Praseodymium Silicate Films on Si(100) for Gate Dielectric Applications: Physical and Electrical Characterization Y1 - 2006 ER - TY - CHAP A1 - Tallarida, Massimo A1 - Schmeißer, Dieter A1 - Zheng, Fan T1 - X-ray Absorption and Photoemission Spectroscopy of 3C- and 4H-SiC Y1 - 2006 ER - TY - CHAP A1 - Tallarida, Massimo A1 - Sohal, Rakesh A1 - Schmeißer, Dieter T1 - Resonant photoemission at the oxygen K edge as a tool to study the electronic properties of defects at SiO2/Si and SiO2/SiC interfaces Y1 - 2006 ER - TY - CHAP A1 - Sohal, Rakesh A1 - Torche, Mohamed A1 - Schmeißer, Dieter T1 - Al-Oxynitrides as a Buffer Layer for Pr2O3/SiC Interfaces Y1 - 2006 ER - TY - JOUR A1 - Müller, Klaus A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter A1 - Henkel, Karsten T1 - Organic thin film transistors with polymer high-k dielectric insulator KW - high-k Y1 - 2006 ER - TY - CHAP A1 - Schmeißer, Dieter A1 - Zheng, Fan A1 - Perez-Dieste, Virginia T1 - Silicate Formation at the Interface of Pr-Oxide as a High-K Dielectric and Si(001) surfaces Y1 - 2006 ER - TY - GEN A1 - Seifarth, Olaf A1 - Schmeißer, Dieter A1 - Stamm, Manfred A1 - Krenek, Radim A1 - Sydorenko, Alexander T1 - Electron spectroscopy and microscopy on chromium oxide nanowires on templated block copolymers T2 - Progress in Solid State Chemistry KW - copolymers KW - nanowires Y1 - 2006 SN - 0079-6786 VL - 34 IS - 2-4 SP - 111 EP - 119 ER - TY - CHAP A1 - Domaradzki, Jarosław A1 - Schmeißer, Dieter A1 - Kaczmarek, Danuta A1 - Beuckert, Guido A1 - Prociow, E. L. A1 - Borkowska, Angnieszka A1 - Kudrawiec, Robert A1 - Misiewicz, J. T1 - Characterization of Nanocrystalline TiO2 - HfO2 Thin Films Prepared by Low Pressure Hot Target Reactive Magnetron Sputtering Y1 - 2006 ER - TY - JOUR A1 - Domaradzki, Jarosław A1 - Kaczmarek, Danuta A1 - Schmeißer, Dieter A1 - Beuckert, Guido T1 - Microstructure and Optical Properties of TiO2 Thin Films Prepared by Low Pressure Hot Target Reactive Magnetron Sputtering Y1 - 2006 ER - TY - JOUR A1 - Hoffmann, Patrick A1 - Wehner, Stefan A1 - Schmeißer, Dieter T1 - Noise-Induced Spatiotemporal Patterns in a Bistable Reaction-Diffusion System: Photoelectron Emission Microscopy experiments and Modeling of the CO Oxidation Reaction on Ir(111) Y1 - 2006 ER - TY - JOUR A1 - Torche, Mohamed A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - The interaction of Al, Ag, Au and Ti to Pr2O3 thin film dielectrics KW - thin films KW - Pr2O3 Y1 - 2006 ER - TY - CHAP A1 - Henkel, Karsten A1 - Torche, Mohamed A1 - Sohal, Rakesh A1 - Schwiertz, Carola A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter ED - Dudley, Michael T1 - Pr-O-N Dielectrics for MIS Stacks on Silicon and Silicon Carbide Surfaces T2 - Silicon carbide 2006 - materials, processing and devices, symposium held April 18 - 20, 2006, San Francisco, California, U.S.A. Y1 - 2006 SN - 978-1-55899-867-4 SP - 353 EP - 358 PB - Materials Research Society CY - Warrendale, Pa. ER - TY - GEN A1 - Hoffmann, Patrick A1 - Wehner, Stefan A1 - Schmeißer, Dieter A1 - Brand, Helmut R. A1 - Küppers, Jürgen T1 - Noise-induced spatiotemporal patterns in a bistable reaction-diffusion system: Photoelectron emission micrsoscopy experiments and modeling of the CO oxidation reaction on Ir(111) T2 - Physical Review : E Y1 - 2006 SN - 1550-2376 VL - 73 IS - 5 SP - 056123 ER - TY - CHAP A1 - Schmeißer, Dieter T1 - Chemical Bonding in Low-k Dielectric Materials for Interconnect Isolation: Characterization using XAS and EELS KW - XAS KW - EELS KW - low-k Materials Y1 - 2006 ER - TY - JOUR A1 - Tallarida, Massimo A1 - Sohal, Rakesh A1 - Schmeißer, Dieter T1 - Resonant photoemission at the Oxygen K edge as a tool to study the eletronic properties of defects at SiO2/Si and SiO2/SiC interfaces Y1 - 2006 ER - TY - CHAP A1 - Wehner, Stefan A1 - Hofmann, Patrick A1 - Schmeißer, Dieter A1 - Brand, Helmut R. A1 - Küppers, Jürgen T1 - Pattern formation in the CO + O reaction on Ir(111) surfaces under the influence of noise T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 41 N2 - The rate of CO oxidation on Ir(111) surfaces exhibits bistability at T = 500 K in a range of the CO fraction Y in the CO + O reactant gas flux. Quadrupol mass spectrometer measurements of the CO2 rates as a function of the noise strength imposed on Y are well reproduced by parameter-free modeling. We present Photoelectron emission microscopy (PEEM) measurements and 2D calculations of the spatio-temporal patterns of CO and O rich domains. The role of combined multiplicative and additive noise on Y for CO and O domain wall motion and island nucleation-growth-coalescence processes is analysed. For small noise amplitudes few islands nucleate and grow up to some 100 µ m in diameter, before they merge with another island. With increasing noise amplitudes more islands nucleate. With large noise amplitudes bursts to and switching between the branches is observed. The domain wall velocity is found to be independent of the noise strength and island size. Y1 - 2006 UR - http://www.dpg-verhandlungen.de/year/2006/conference/dresden/part/syss/session/1/contribution/9 SN - 0420-0195 SP - S. 708 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Krenek, Radim A1 - Cimrova, Vera A1 - Seifarth, Olaf A1 - Bocharova, Vera A1 - Gorodyska, Ganna A1 - Sidorenko, Alexander A1 - Schmeißer, Dieter A1 - Stamm, Manfred T1 - Electronic Properties of Metals Embedded into Porous Polymeric Nanotemplates T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 41 N2 - We report on electrical measurements (current-voltage characteristics (CVC)) of metals which are templated via porous polymeric nanotemplates. The nanotemplates are based on self-organization of poly(styrene-block 4-vinylpyridine) (PS-PVP). The cylindrical pores of 8 nm in the diameter are ordered in a hexagonal lattice (24 nm in the period). Chromium and gold were embedded in the nanotemplates by magnetron sputtering, nickel was electrodeposited. These thin films were characterized by AFM, ellipsometry, x-ray reflectivity, XAS, XPS and NEXAFS. CVC were acquired by a connection common for light emitting diodes discussing a further use of nanotemplated metals in these devices. To make the connection, the nanotemplate was deposited on glass with ITO electrodes, then metal was embedded into it and finally Al electrodes were evaporated on the device. Behaviour of space charge limited currents (SCLC) was observed. Also, we deal with the electrical mode of AFM as well. Finally electronic behaviour of the metallic nanorods embedded in polymeric nanotemplates is discussed in respective to the structure and chemical composition obtained by AFM and x-ray techniques. Y1 - 2006 UR - http://www.dpg-verhandlungen.de/year/2006/conference/dresden/part/cpp/session/25/contribution/2 SN - 0420-0195 SP - S. 108 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Tallarida, Massimo A1 - Sohal, Rakesh A1 - Schmeißer, Dieter T1 - Electronic properties of the 2x1 3C-SiC surface reconstruction studied with resonant photoemission T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 41 N2 - We have studied the 2x1 reconstructed surface of the 3C-SiC polytype by means of photoemission spectroscopy. The reconstruction was characterized through Si2p and C1s core level and angle-integrated valence band spectroscopy, and confirmed by the observation of a two-domain 2x1 LEED pattern. The electronic properties of this surface were investigated by collecting valence band spectra at photon energies near the Si2p and C1s absorption edges. The results show a strong dependence of the photoemission intensity on the excitation energy with characteristic resonances for certain valence band features. With a detailed study of the resonances we are able to assign the electronic origin of the resonating states and the nature of the electronic transition near the absorption edges. Y1 - 2006 UR - http://www.dpg-verhandlungen.de/year/2006/conference/dresden/part/hl/session/5/contribution/2 SN - 0420-0195 SP - S. 239 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - JOUR A1 - Schmeißer, Dieter T1 - Pr4f occupancy and origin of gap states at the Pr2O3 / Si (001) interface Y1 - 2005 ER - TY - JOUR A1 - Goryachko, Andriy A1 - Yeromenko, Y. A1 - Henkel, Karsten A1 - Wollweber, Jürgen A1 - Schmeißer, Dieter T1 - The Si(001)/C2H2 interaction to form a buffer layer for 3C-SiC growth JF - Physica status solidi / A N2 - The intial stages of Si(001) interaction with C2H2 were investigated with XPS and surface profilometry. The carbon enriched layer serves as a buffer between Si substrate and the 3C-SiC film aimed at growing on Si(001). Such parameters as substrate temperature and process duration come into a complicated interplay of C deposition, its reaction with Si and out-diffusion of the later from the substrate. Three distinct regimes, namely graphite dominated, carbide dominated and roughness dominated are found to result from this interplay. Y1 - 2004 SN - 0031-8965 VL - 201 IS - 2 SP - 245 EP - 248 ER - TY - CHAP A1 - Sidorenko, Alexander A1 - Tokarev, Igor A1 - Krenek, Radim A1 - Burkov, Yevgen A1 - Schmeißer, Dieter A1 - Minko, S. A1 - Stamm, Manfred ED - Champion, Yannick ED - Fecht, Hans-Jörg T1 - Generation of Nanostructured Materials from Thin Films of Block Copolymer Assembles T2 - Nano-architectured and manostructured materials, fabrication, control and properties, EUROMAT 2003 Y1 - 2004 SN - 3-527-31008-8 SP - 143 EP - 150 PB - Wiley-VCH CY - Weinheim ER - TY - GEN A1 - Schmeißer, Dieter A1 - Müssig, Hans-Joachim A1 - Dabrowski, Jarek Marek T1 - Silicate Layer Formation at the Pr2O3 / Si(001) Interfaces T2 - Applied Physics Letters N2 - We studied Pr2O3/Si(001) interfaces by synchrotron radiation photoelectron spectroscopy and by ab initio calculations. We show that the interface formed during molecular-beam epitaxy under the oxygen partial pressure above 1%D710-8 mbar consists of a mixed Si-Pr oxide, such as (Pr2O3)(SiO)x(SiO2)y. Neither an interfacial SiO2 nor an interfacial silicide is formed. The silicate formation is driven by a low energy of O in a PrOSi bond and by the strain in the subsurface SiOx layer. We expect that this natural interfacial Pr silicate will facilitate the integration of the high-k dielectric Pr2O3 into future complementary metal-oxide-semiconductor technologies. Y1 - 2004 SN - 1077-3118 VL - 85 IS - 1 SP - 88 EP - 90 ER - TY - GEN A1 - Lupina, Grzegorz A1 - Dabrowski, Jarek Marek A1 - Formanek, Peter A1 - Schmeißer, Dieter A1 - Sorge, Roland A1 - Wenger, Christian A1 - Zaumseil, Peter A1 - Müssig, Hans-Joachim T1 - Solid-state reaction between Pr and SiO2 studied by photoelectron spectroscopy and ab initio calculations T2 - Materials Science in Semiconductor Processing N2 - We report on the structural and electrical properties of Pr-based high-k dielectric films fabricated by solid-state reaction between metallic Pr and SiO2 underlayers. A non-destructive depth profiling using synchrotron radiation excited photoelectron spectroscopy (SR-PES), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) were employed to examine the chemical composition and microstructure. Ab initio calculations were done to gain insight into the physical processes involved. SR-PES results indicate that Pr deposition at room temperature (RT) leads to the formation of a Pr silicide and a Pr oxide, what is in good agreement with the scenario expected from ab initio calculations. As revealed by TEM and electrical measurements, oxidation of the reacted structures, followed by annealing, results in a stacked dielectric composed of a SiO2-based buffer with an enhanced permittivity and a Pr silicate film with a high dielectric constant. The leakage current density of 10-4 A/cm2 was measured for stacks with capacitance equivalent thickness (CET) of 1.5 nm prepared by evaporation of the Pr layer on a 1.8 nm SiO2 film, followed by oxidation in air ambient and annealing in N2 atmosphere. The capacitance-voltage (C-V) curves exhibit a large flatband voltage (VFB) shift indicating the presence of a positive charge in the stack. Switching away from the Al contacts to Au gate electrodes introduces a significant reduction of the VFB by 1.3 eV, what is much more than the change expected from the work function difference between Al and Au (not, vert, similar0.9 eV). This in turn implies that VFB is strongly affected by the gate interface electrode. KW - High-k dielectrics KW - Photoelectron spectroscopy KW - Interface reaction Y1 - 2004 SN - 1369-8001 VL - 7 IS - 4-6 SP - 215 EP - 220 ER - TY - JOUR A1 - Paloumpa, Ioanna A1 - Yfantis, Alexandros D. A1 - Hoffmann, Patrick A1 - Burkov, Yevgen A1 - Yfantis, Alexandros D. A1 - Schmeißer, Dieter T1 - Mechanisms to inhibit corrosion of Al alloys by polymeric conversion coatings N2 - We introduce a recently developed novel polypyrrole-based coating, which can be formed on the aluminium surface from an aqueous pyrrole solution of fluorozirconic and fluorotitanic acid neutralised with zinc oxide. The composite layer consists of polypyrrole (Ppy) chemisorbed on titanium and zinc oxides and exhibits advanced corrosion resistance. For the investigation of the structure and the corrosion mechanism of the composite corrosion resistant layer we use a photo-electron emission microscope (PEEM). PEEM is especially suitable because it can deliver topographic contrast as well as elemental contrast and chemical information in connection with a variable X-ray source. Additionally, in order to investigate further the corrosion mechanism, but also the role of the alloy in the corrosion process, we examine the aluminium samples with SEM/EDX. The structure of the corrosion resistant layer was investigated before and after accelerated corrosion tests. Our results pointed out the important role of titanium oxide and zinc in the corrosion resistance of our Ppy coating on aluminium. KW - Polypyrrole KW - Fluorozirconates KW - Fluorotitanates KW - Aluminium KW - Corrosion Y1 - 2004 ER - TY - JOUR A1 - Goryachko, Andriy A1 - Paloumpa, Ioanna A1 - Beuckert, Guido A1 - Burkov, Yevgen A1 - Schmeißer, Dieter T1 - The Interaction of Pr2O3 with 4H-SiC(0001)surface JF - Physica status solidi / C N2 - Praseodymium oxide (Pr2O3) as a hetero-oxide on SiC(0001) represents a promising semiconductor / high-K dielectric material combination. We prepared thin films (<3 nm) of Pr2O3 on 4H-SiC(0001) surfaces by a wet chemical process involving aqueous solutions of Pr(NO3)3. Synchrotron radiation photoelectron spectroscopy (SR-PES) is used to study the chemical composition of these films after deposition and annealing in 300-900 %B0C range. The Si2p and C1s core level emissions are analysed in detail and reveal that praseodymium-silicate is formed at the interface. Our data are compared to corresponding studies of the Pr2O3 interaction with Si(001) surfaces. Y1 - 2004 SN - 1610-1634 VL - 1 IS - 2 SP - 265 EP - 268 ER - TY - JOUR A1 - Schmeißer, Dieter T1 - Covalent and localized contributions of Pr4f states at the interface of Pr2O3 to Si(001) N2 - Resonant photoelectron spectroscopy (PES) at the Pr4d and O1 s absorption edges is used to study the electronic properties at the interface of epitaxially grown Pr2O3 on Si(001).In the electronic structure of bulk Pr2O3, the valence band (VB) states are predominant of Pr6s and O2p atomic parentage. The contribution of Pr4f states is identified from the strong increase of the VB features at the Pr4d resonances. The data at the O1s edge are caused by Raman scattering and resonant Auger decay and reflect the existence of charge transfer (CT) complexes. These complexes are the consequence of a mixed valency caused by ligand-to-Pr4f charge transfer states. The decrease of their intensity is attributed to an increase in covalent bandwidth between the ligand (O2p, Si3p) and Pr4f states. The CT complexes, originally localized now, become broadened and form gap states which fill the gap towards a metallic density of states. The metallic phase may be hindered upon alloying with SiO2 or other oxides. Y1 - 2004 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Müssig, Hans-Joachim T1 - Stability and electronic properties of silicates in the system SiO2 - Pr2O3 - Si(001) T2 - Journal of Physics: Condensed Matter N2 - Pr2O3 is one of the most promising hetero-oxides that are the candidates of choice to replace SiO2 as the gate dielectric material for sub-0.1 micrometer CMOS technology. In order to enable process integration, however, hetero-oxides require substantial characterization. In particular, the basic interaction mechanisms at the interface to the silicon substrate are the key issues. A solid knowledge of these mechanisms is required to address reliability arguments. The challenges in material science are to understand the chemical bonding of the hetero-oxides and Si on a microscopic scale. We report on the specific variations in the electronic structure which are evident in the valence band features around resonant excitation at the Pr 4d threshold. We also determine the valance band discontinuities at the Pr2O3/Si(001) interface and follow the changes in the surface potentials to develop a band scheme, a prerequisite to understanding the properties of charge transport across that interface. Y1 - 2004 SN - 1361-648X VL - 16 IS - 2 SP - 153 EP - 160 ER - TY - GEN A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter A1 - Roters, G. A1 - Nenyei, Z. T1 - Non-destructive probing of interfacial oxidation and nitridation states at RTA Si-oxides T2 - Thin Solid Films N2 - The quality of the SiO2/Si interface is of crucial importance in the development and performance of sub 0.1 small mu, Greekm technologies. The knowledge of the chemical composition of the interface is an important piece of information in the preparation of ultra-thin oxides and high-k dielectrics, in order to maintain a high-quality interface and channel mobility. Here we report on investigations of 2 nm oxide layers formed by a RTP process under various gas mixtures containing N2O and NH3 at different concentrations. We studied the SiO2/Si(001) interface by a non-destructive depth profiling using Synchrotron radiation photoelectron spectroscopy. We determine the thickness of the oxide layer, the relative content and chemical state of nitrogen within the oxide, the thickness of the interface layer, and the relative abundance of Si intermediate oxides within. In all systems we find the thickness of the intermediate layer to be approximately 0.17 nm. The intermediate layer contains Si atoms in the oxidation states +1, +2 and +3 with similar relative abundance. Nitrogen is found predominantly close to the intermediate layer forming Si---N as well as Si---N---O bonds. Within the oxide there are only spurious nitrogen content with predominately Si---N---O bonds. Our method is able to detect a nitrogen content within the intermediate layer as low as approximately 5%. KW - Silicon KW - Oxynitride KW - N20 KW - NH3 KW - Photoelectron spectroscopy KW - Ultrathin oxide Y1 - 2003 SN - 0040-6090 VL - 428 IS - 1-2 SP - 216 EP - 222 ER - TY - JOUR A1 - Müller, Klaus A1 - Scheer, R. A1 - Schmeißer, Dieter A1 - Burkov, Yevgen T1 - Preparation of stoichiometric CuInS2-Surfaces JF - Thin Solid Films KW - preparation Y1 - 2004 SN - 0040-6090 VL - 451–452 SP - 120 EP - 123 ER - TY - GEN A1 - Müller, Klaus A1 - Burkov, Yevgen A1 - Schmeißer, Dieter T1 - PEEM and my-NEXAFS of Cu-In-S2-surfaces T2 - Thin Solid Films N2 - Polycrystalline CuInS2 samples are an ideal system for photoemission electron microscope studies. The polycrystalline grains have a diameter of approximately 5 small mu, Greekm and the system is expected to be highly inhomogeneous because of the existence of many sub-phases. We used a recently established procedure to reproducibly obtain stoichiometric CuInS2-surfaces and follow the changes in the morphology, the elemental inhomogeneous distribution, and the development of the electronic structure upon its preparation. We find that the individual grains trend to coagulate, the surface composition becomes more homogeneous, and identify characteristic features of the unoccupied DOS. KW - CuInS2 films KW - Annealing-process KW - PEEM KW - small mu KW - NEXAFS Y1 - 2003 SN - 0040-6090 VL - 431-432 SP - 307 EP - 311 ER - TY - JOUR A1 - Schmeißer, Dieter A1 - Paloumpa, Ioanna A1 - Hoffmann, Patrick A1 - Burkov, Yevgen A1 - Yfantis, Alexandros D. A1 - Yfantis, Alexandros D. T1 - Preventing Corrosion of Aluminium Alloys by Polymeric Coatings N2 - Aluminium is a material of everyday use in many applications,like automobile,aero-space or cookware,due to its specialproperties (low density,low weight,strength,easy to form and cast,abundance etc).Although aluminium is a reactive metal,italso has a significant corrosion resistance because of a thin,protective oxide layer which is generally stable in air and aqueous solutions.However,pores within the oxide film and other defects caused from alloying elements can lead to local corrosion and the formation of pits. Y1 - 2003 ER - TY - JOUR A1 - Müller, Klaus A1 - Milko, S. A1 - Schmeißer, Dieter T1 - Preparation of stoichiometric CuInS2-surfaces - an XPS, UPS-study JF - Thin Solid Films N2 - CuInS2 films are investigated with photoelectron spectroscopy. We find significant deviation from the stoichiometric composition depending on the preparation on the films. For Cu-rich films (start composition) we show that by Ar sputtering and annealing the surface composition varies along a binary cut of the Cu-In-S ternary phase diagram. We also present a novel technique which brings the surface composition close to the stoichiometric stability range of the CuInS2 phase. The technique used the evaporation of Cu on the sputter cleaned surface. KW - Stoichiometric CuInS2-films KW - Annealing KW - XPS KW - UPS Y1 - 2003 SN - 0040-6090 VL - 431-432 SP - 312 EP - 316 ER - TY - GEN A1 - Lewerenz, Hans-Joachim A1 - Aggour, Mohammed A1 - Murrell, Chris A1 - Kanis, M. A1 - Jungblut, H. A1 - Jakubowicz, J. A1 - Cox, P. A. A1 - Campbell, S. A. A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Initial stages of structure formation on silicon electrodes investigated by photoelectron spectroscopy using synchrotron radiation and in-situ atomic force microscopy T2 - Journal of the Electrochemical Society N2 - The surface condition of electrochemically H-terminated Si is compared with the situation at the first photocurrent maximum in dilute acidic ammonium fluoride solution where the divalent dissolution converts into the four-valence process. The first high spectral-resolution photoelectron spectroscopy data using synchrotron radiation of electrochemically hydrogenated Si are presented. A combined electrochemistry/ultrahigh vacuum surface analysis system, attached to the U 49/2 beamline at the synchrotron Bessy II, is used for photoelectron spectroscopy (PES) of the electrochemically conditioned samples. We analyze the Si 2p, O 1s, and F 1s core levels. A comparison of a density functional theory calculation of the reaction sequence, proposed in the dissolution model of Gerischer and co-workers, with the PES results supports this model. The anodized sample is characterized by a residual H coverage of 0.35 monolayers evidenced by a surface core level shift, Si-OH and Si-Fx species, F-, and a higher oxidized Si species. SiO2 is not found. Even on very well H-terminated surfaces, we find residual Si-OH complexes, fluoride and water. In situ atomic force microscopy shows a roughening with a root mean square roughness parameter of 2.6 nm. %A92003 The Electrochemical Society. All rights reserved. Y1 - 2003 SN - 1945-7111 VL - 150 IS - 3 SP - E185 EP - E189 ER - TY - GEN A1 - Müller, Klaus A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Carbon-plot-microstructuring for all-polymer-transistors T2 - Synthetic Metals N2 - This contribution describes the use of a low-cost technology to produce organic microstructures for electronically applications. With a computer driven plotter, substrates like printing foil and colloidal graphite (diluted in water) for the electrodes, we realised channel lengths of 20±10 microm. Compared with transistor devices, fabricated using conventional photolithographic methods and the same semiconducting material, this technique is a hopeful approach to produce microelectronic structures that are low-cost and all-organic. KW - Ten micrometer carbon-plot KW - Organic field-effect-transistors KW - Low-cost-technique Y1 - 2003 SN - 0379-6779 VL - 138 IS - 1-2 SP - 271 EP - 273 ER - TY - GEN A1 - Schmeißer, Dieter T1 - Valence states of poly(3-hexyl-thiophene) as probed by photoelectron spectra at resonant excitation T2 - Synthetic Metals N2 - Photoelectron spectroscopy employing synchrotron radiation is applied to learn about the electronic structure of regio-regular poly(3-hexyl-thiophene) (P3hT). We study the valence band photoelectron spectra around the carbon 1s threshold. This technique is equivalent to resonant excitation of core electrons into empty valence states. We probe the properties of these carriers in the conduction band and also learn about valence band states involved in the carbon (K L L) Auger transitions. The data give evidence that monomeric orbital energies are dominating in such processes. We conclude that poly(3-hexyl-thiophene) is a polymer with a rather short conjugation length. KW - Resonant photoelectron spectroscopy KW - Semi-conducting polymers KW - Organic field effect Y1 - 2003 SN - 0379-6779 VL - 138 IS - 1-2 SP - 135 EP - 140 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Müssig, Hans-Joachim T1 - The Pr2O3 / Si (001) interface studied by synchrotron radiation photo-electron spectroscopy T2 - Solid State Electronics N2 - Pr2O3 is currently under consideration as a potential replacement for SiO2 as the gate-dielectric material for sub-0.1micro m complementary metal-oxide-semiconductor (CMOS) technology. We studied the Pr2O3/Si(0 0 1) interface by a non-destructive depth profiling using synchrotron radiation photoelectron spectroscopy. Our data suggests that there is no silicide formation at the interface. Based on reported results, a chemical reactive interface exists, consisting of a mixed Si-Pr oxide such as (Pr2O3)x(SiO2)1?x, i.e. as a silicate phase with variable silicon content. This pseudo-binary alloy at the interface offers large flexibility toward successful integration of Pr2O3 into future CMOS technologies. KW - High-k dielectric material KW - Pr2O3 KW - Interface KW - Silicate Y1 - 2003 SN - 0038-1101 VL - 47 IS - 10 SP - 1607 EP - 1611 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Irmscher, Klaus A1 - Wagner, Gerd T1 - Photoelectron spectra of Al dopants in 4H-SiC T2 - Materials Science & Engineering B N2 - Al-doped 4H-SiC epitaxial layers were grown in a hot-wall chemical vapor deposition (CVD) system on commercial 4H-SiC substrates (CREE). The incorporation of Aluminum has been studied in the concentration range from 2*1014cm-3 up to 3*1020cm-3. Epitaxial layers with doping concentration NA-ND> 1019cm-3 were studied by HV-TEM and synchrotron radiation investigations. In the concentration range from 1*1019cm-3 to 3*1020 cm-3, measured by SIMS and Hall investigations, no Aluminum precipitation were detected in the grown layers. For SiC samples with an Al concentration of 1020cm-3 we have been able to detect the Al2p photoemission signal. The Al2p signal is recorded through the oxide layer (thickness of about 0.4nm), it has a main contribution at a binding energy of 73eV which corresponds to the energy typical for elemental Al0. In spectra excited with higher photon energies the sampled photoelectrons originate from deeper layers. In these data we notice an additional shoulder in the Al2p signal at around 71eV. The evidence of two contributions is attributed to the fact that Al is incorporated at different lattice sites. As the latter data represent more bulk like properties we argue that Al in the bulk SiC occupies both, substitutional lattice sites and interstitial sites while in the surface near regions Al is found only at substitutional lattice sites. KW - Photoelectron KW - Spectra KW - 4H-SiC Y1 - 2003 SN - 0921-5107 SN - 1873-4944 VL - 102 IS - 1-3 SP - 284 EP - 288 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Pressel, Klaus A1 - Yamamoto, Yuji A1 - Tillack, Bernd A1 - Krüger, D. T1 - Ge instabilities near interfaces in Si-SiGe-Si heterostructures T2 - Materials Science & Engineering B N2 - Compositional characterization of interfaces in Si-cap/SixGe1-x/Si heterostructures is an important topic in SiGe based advanced microelectronics and in quantum wells. Extremely high depth resolution is required to detect and optimize near-interface compositional gradients which are crucial for high circuit performance. We report on non-destructive, high-resolution, near-interface depth profiling using SR photoelectron spectroscopy at an undulator beamline. We measured the Ge content at the SixGe1-x interface towards the native SiO2 layer and investigated the influence of additional (1nm and 2nm) Si capping layers (Si-cap). For the uncapped samples we found near the oxide/ SiGe interface region a strong mixing of Ge-oxides and SiOx. This indicates a high instability of the Ge atoms at those interfaces while silicon capped (1nm, 2nm) SixGe1-x films are more stable. We detect sharp Ge concentration gradients within the first 1nm at the Si/SixGe1-x interface. These results open new possibilities for Ge profile optimization in Si-cap/SixGe1-x/Si heterostructures. In the Ge3d spectra we differentiate the Ge atoms to occupy three different lattice sites and are able to follow their relative occupation within the Ge gradient. KW - SiGe KW - Depth profiling KW - Interfaces KW - XPS Y1 - 2003 SN - 0921-5107 SN - 1873-4944 VL - 101 IS - 1-3 SP - 208 EP - 211 ER - TY - GEN A1 - Riess, W. A1 - Schmeißer, Dieter T1 - Organic Materials for Device Applications - Preface T2 - Synthetic Metals Y1 - 2003 SN - 0379-6779 VL - 138 IS - 1–2 ER - TY - JOUR A1 - Schmeißer, Dieter T1 - Resonant photoemission at the Pr2O3 /Si(001) interface N2 - In resonant photoemission studies photoelectron spectroscopy (PES) is done at photon ener-giesthat enable the excitation from a deep core hole to the empty conduction band states. Atresonant condition only such states are selectively enhanced which allow an optical couplingof the core hole to the empty conduction band states. Information is to be gained from theshape of the particular resonance and by a comparison of the valence band data at excitationenergies off and on resonance. Such studies provide information on the electronic structure, inparticular how to separate individual contributions in the valence band and conduction bandregime. Y1 - 2003 ER - TY - CHAP A1 - Yfantis, Alexandros D. A1 - Tsiniarakis, G. A1 - Labrakopoulos, S. A1 - Yfantis, Alexandros D. A1 - Schmeißer, Dieter T1 - Conductive polymers of pyrrole as pigments in organic anticorrosive coatings-application for aluminium alloys Y1 - 2001 ER - TY - CHAP A1 - Henkel, Karsten A1 - Elling, B. A1 - Danz, R. A1 - Büchtemann, A. A1 - Straube, Oliver A1 - Paloumpa, Ioanna A1 - Yfantis, Alexandros D. A1 - Schmeißer, Dieter T1 - Piezoelectric polymer sensor for high pressures in forming machines Y1 - 2001 UR - http://www.materialsweek.org/proceedings/index.htm ER - TY - CHAP A1 - Jaegermann, Wolfram A1 - Schmeißer, Dieter T1 - Elementary Processes at Solid/Electrolyte Interfaces Y1 - 2001 ER - TY - CHAP A1 - Hulea, Iulian A1 - Hoffmann, Patrick A1 - Brinza, Monica A1 - Batchelor, David R. A1 - Schmeißer, Dieter T1 - The interface of friction-welded Al-Fe joints. ATB Metallurgy Y1 - 2001 ER - TY - JOUR A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Batchelor, David R. A1 - Schmeißer, Dieter A1 - Soinski, M. S. A1 - Follath, Rolf T1 - The chromatic aberration of PEEM - demonstration on graphite inclusions in cast iron, Kategrorie: Microscopy - Spectromicroscopy Y1 - 2001 ER - TY - GEN A1 - Beerbom, Martin A1 - Mayer, Thomas A1 - Jaegermann, Wolfram A1 - Batchelor, David R. A1 - Schmeißer, Dieter T1 - Electrochemically Induced Redox-Reactions on GaAs-Surfaces: High Resolution Photoemission Spectra Taken at the U49/2 Beamline Y1 - 2001 ER - TY - JOUR A1 - Mikalo, Ricardo Pablo A1 - Hoffmann, Patrick A1 - Batchelor, David R. A1 - Schmeißer, Dieter T1 - Valence band spectroscopy of semiconducting regioregular Poly(3-Hexylthiophene)-2,5-diyl Y1 - 2001 ER - TY - JOUR A1 - Sieber, N. A1 - Mantel, B. F. A1 - Seyller, Th. A1 - Ristein, J. A1 - Ley, L. A1 - Heller, Thomas A1 - Batchelor, David R. A1 - Schmeißer, Dieter T1 - Structural, electronic and chemical properties of hydrogen terminated 6H-SiC Y1 - 2001 ER - TY - JOUR A1 - Graupner, R. A1 - Seyller, Th. A1 - Ley, L. A1 - Mikalo, Ricardo Pablo A1 - Hoffmann, Patrick A1 - Batchelor, David R. A1 - Schmeißer, Dieter T1 - PEEM Investigation of CVD-Diamond grown on Si Y1 - 2001 ER - TY - JOUR A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Batchelor, David R. A1 - Schmeißer, Dieter A1 - Follath, Rolf T1 - N2O-Oxidation of Si(100) Y1 - 2001 ER - TY - CHAP A1 - Müller, Klaus A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Carbon-Plot-Micostructuring for All-Polymer-Transistors Y1 - 2001 ER - TY - JOUR A1 - Yfantis, Alexandros D. A1 - Schmeißer, Dieter A1 - Kompotiatis, L. T1 - Polypyrrole based conversion coatings for aluminium alloys Y1 - 2001 ER - TY - JOUR A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Schwiertz, B. A1 - Elling, B. A1 - Danz, R. A1 - Büchtemann, A. A1 - Straube, Oliver A1 - Schmeißer, Dieter T1 - Kraftsensoren aus Polymerfolien-Piezoelektrische Polymersensoren für Hochdruckanwendungen Y1 - 2001 ER - TY - RPRT A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Schwiertz, D. A1 - Schmeißer, Dieter A1 - Kamieth, P. A1 - Schengber, P. T1 - Gezielte Entwicklung von Sensormaterialien und Sensoren zur spezifischen Detektion von schwefel- und stickstoffhaltigen Stoffgruppen Y1 - 2001 ER - TY - JOUR A1 - Kraft, D. A1 - Thißen, A. A1 - Mayer, Thomas A1 - Klein, A. A1 - Jaegermann, Wolfram A1 - Hoffmann, Patrick A1 - Batchelor, David R. A1 - Schmeißer, Dieter T1 - Backcontact Formation on CdTe Thin Film Solar Cells Y1 - 2001 ER - TY - RPRT A1 - Schwiertz, Carola A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter A1 - Kamieth, P. A1 - Schnegber, P. T1 - Aufbau eines Sensorarrays zur Detektion von umwelt- und tierphysiologisch relevanten Komponenten Y1 - 2001 ER - TY - JOUR A1 - Sieber, N. A1 - Seyller, Th. A1 - Graupner, R. A1 - Ley, L. A1 - Mikalo, Ricardo Pablo A1 - Batchelor, David R. A1 - Schmeißer, Dieter T1 - PES and LEED study of hydrogen and oxygen terminated 6H-SiC(0001) and (000-1) surfaces Y1 - 2001 ER - TY - JOUR A1 - Batchelor, David R. A1 - Follath, Rolf A1 - Mikalo, Ricardo Pablo A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Commissioning Results of the BTUC-PGM beamline Y1 - 2001 ER - TY - RPRT A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Oprea, A. A1 - Appel, Günter A1 - Schmeißer, Dieter A1 - Frandsen, W. A1 - Schölzel, Mario T1 - Entwicklung von Sensoren mit Elektroden aus leitfähigen Polymeren Y1 - 2000 N1 - Teilbericht 16SV335/7 im Gemeinsamen Abschlussbericht zum Verbundprojekt "Sensoren mit mikrostrukturierten Elektroden aus leitfähigen Polymeren", März 2000, Kurzfassung ER - TY - JOUR A1 - Appel, Günter A1 - Schmeißer, Dieter A1 - Bauer, Jakob A1 - Bauer, Monika A1 - Egelhaaf, H. J. A1 - Oelkrug, D. T1 - The formation of oligomers in the electrolyte upon polymerization of pyrrole Y1 - 1999 ER - TY - JOUR A1 - Yfantis, Alexandros D. A1 - Appel, Günter A1 - Schmeißer, Dieter A1 - Yfantis, Alexandros D. T1 - Polypyrrole doped with fluoro-metal complexes: thermal stability and structural properties Y1 - 1999 ER - TY - JOUR A1 - Batchelor, David R. A1 - Follath, Rolf A1 - Schmeißer, Dieter T1 - The optical design of a PGM for the Undulator U49/2 at BESSY II Y1 - 1998 ER - TY - JOUR A1 - Heller, Thomas A1 - Böhme, O. A1 - Tonti, D. A1 - Klein, A. A1 - Jaegermann, Wolfram A1 - Schmeißer, Dieter T1 - Na interaction with relaxed WO3 thin films Y1 - 1998 ER - TY - JOUR A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Böhme, O. A1 - Schmeißer, Dieter T1 - PEEM-investigations on cleaved MoTe2-surfaces Y1 - 1998 ER - TY - JOUR A1 - Appel, Günter A1 - Böhme, O. A1 - Schmeißer, Dieter T1 - NEXAFS-Spectroscopy of Differently Doped Polypyrroles Y1 - 1998 ER - TY - JOUR A1 - Bieniek, Tomasz A1 - Beck, Romuald B. A1 - Jakubowski, Andrzej A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter A1 - Konarski, Piotr A1 - Cwil, M. T1 - Formation of Pedestal Oxynitride Layer by Extremely Shallow Nitrogen Implantation in Planar R.F. Plasma Reactor Y1 - 2006 ER - TY - CHAP A1 - Henkel, Karsten A1 - Torche, Mohamed A1 - Schwiertz, Carola A1 - Paloumpa, Ioanna A1 - Sohal, Rakesh A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Inorganic and organic layers for high-k and organic memory applications T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 41 N2 - We report about organic and inorganic MIS stacks for new possibilities for high frequency and high power applications as well as for non volatile memory cell. The organic stack contains a ferroelectric polymer as the functional layer. Poly[vinylidene fluoride trifluoroethylene] (P[VDF/TrFE]) is spin coated from a solution onto oxidised silicon substrates. We report on the polarisation induced flatband voltage shifts. For the inorganic stack our attempt is to combine higk-k dielectrics with high band gap semiconductors (SiC). Praseodymium oxide layers are prepared by electron beam evaporation from Pr6O11 powder and in situ controlling of interface and volume composition (XPS). Praseodymium silicate layers were prepared either by metal evaporation onto a thin ox- ide on top of the semiconductor and following annealing steps or by a wet chemical process out of aqueous Pr(NO3)3 solutions. Using spectro-scopic characterisation we investigate the stability of the various inter-faces within the stacks as well as the reactivity of the metal electrodes on thin Pr2O3. We report the results of electrical characterisation consisting of permittivity values, leakage current and density of interface states. Y1 - 2006 UR - http://www.dpg-verhandlungen.de/year/2006/conference/dresden/part/df/session/1/contribution/4 SN - 0420-0195 SP - S. 127 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Wehner, Stefan A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter A1 - Brand, Helmut R. A1 - Küppers, Jürgen T1 - CO oxidation on Ir(111) surfaces: consequences of anisotropic diffusion and noise T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 41 N2 - The CO oxidation reaction on Iridium(111) surfaces shows bistability in a limited range of the CO fraction of the reactant gas flux Y and a wide range of temperatures T. The two branches are characterized by their reactivity for CO2 formation. The upper rate (high CO2 formation) rate is related to high oxygen coverage on the surface, the lower rate (little CO2 formation) to high CO coverage. Quadrupol mass spectroscopy and PEEM (photoelectron emission microscopy) was employed to study the influence of a noisy reactant gas flux composition on the spatio-temporal pattern development in the CO oxidation reaction on flat Ir(111) and stepped Ir(977) surfaces. PEEM shows nucleation and growth of few oxygen resp. CO islands at small noise amplitudes. Anisotropic diffusion of CO parallel and normal to the steps causes elliptic shapes of large islands. The long axes of the ellipses are aligned along the steps. At increased noise amplitudes the density of islands becomes larger. 2D modeling of the phenomena based on reaction-diffusion differential equations reproduces the experimental findings quite nicely. Y1 - 2006 UR - http://www.dpg-verhandlungen.de/year/2006/conference/dresden/part/o/session/14/contribution/37 SN - 0420-0195 SP - S. 475 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Bergholz, Matthias A1 - Sohal, Rakesh A1 - Schmeißer, Dieter T1 - ELS to determine the band gap of thin dielectric layers T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 41 N2 - In ultra thin layers of high-K materials the value of the band gap can be derived not explicitly although it is a key quantity in the electric behavior. We use ELS with a monochromatized (50 meV - 150 meV) electron gun and primary energies between 20 eV and 30 eV. Starting with the native SiO2/Si(001) layers we find that loss function of the substrate dominates for using primary energies beyond 50 eV. In contrast at energies below 50 eV the loss intensity can be used to derived the band gap with an accuracy of ±200 meV. We compare thin (<3 nm) films of HfOx, Pr2O3,Al2O3 and Si-Oxynitrides and discuss the band gap values as well as the scattered intensity observed within the gap. Y1 - 2006 UR - http://www.dpg-verhandlungen.de/year/2006/conference/dresden/part/ds/session/8/contribution/2 SN - 0420-0195 SP - S. 156 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Klaus A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - P(VDF/TrFE) as ferroelectric insulation layer for organic field effect transistors T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 41 N2 - The ferroelectric polymer poly(vinylidene fluoride trifluoroethylene)(P(VDF-TrFE)) is used as insulating material for organic field effect tran-sistors (OFET) and metal-insulator-semiconductor (MIS)-structures. For the MIS-structures, we find the typical hysteresis in the CV charac-teristic upon increasing the voltage scan window. Based on these results, we fabricate OFET with regioregular poly(3-hexlythiophene)(P3HT) as organic semiconductor. The transistors are constructed in bottom gate architecture with thin layers of spincoated P(VDF-TrFE) as gate insulation (100nm). The drain-source current of the OFET is reversible affected by the polarized gate, which gives opportunities for organic nonvolatile memory elements. We present characteristic features like the hysteretic drain current response or the data retention. Furthermore, we present measurements with Kelvin probe force microscopy, a method which gives informations on the lateral distributions of the surface potential. Y1 - 2006 UR - http://www.dpg-verhandlungen.de/year/2006/conference/dresden/part/cpp/session/23/contribution/28 SN - 0420-0195 SP - S. 101 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Tokarev, Igor A1 - Krenek, Radim A1 - Burkov, Yevgen A1 - Schmeißer, Dieter A1 - Sidorenko, Alexander A1 - Minko, Sergiy A1 - Stamm, Manfred T1 - Microphase separation in thin films of poly(styrene-block-4-vinylpyridine) Copolymer-2-(4-Hydroxybenzeneazo) benzoic Acid Assembly T2 - Macromolecules N2 - The fine structure of thin films of poly(styrene-block-4-vinylpyridine) copolymer-2-(4'-hydroxybenzeneazo)benzoic acid (PS-PVP+HABA) assembly has been studied using the combination of atomic force microscopy, ellipsometry, X-ray reflectivity, GISAXS, XPS, and XPEEM. The films consist of cylindrical nanodomains formed by PVP+HABA associates surrounded by PS matrix. Alignment of the domains can be switched upon exposure to vapors of different solvents from the parallel to perpendicular orientation and vice versa with respect to the surface plane. Swelling in 1,4-dioxane leads the system from the cylindrical to the spherical morphology. Solvent evaporation results in a shrinkage of the matrix in the vertical direction and subsequent merging of the spheres into the perpendicularly aligned cylinders. The cylinders form a regular hexagonal lattice with a spatial period of 25.5 nm. On the other hand, vapors of chloroform induce in-plane alignment. The films consist of parallel layers of the cylinders separated by PS matrix and demonstrate the fingerprint-like structure. The nanocylinders of PVP+HABA are packed into a distorted hexagonal lattice exhibiting 31 nm in plane and 17 nm vertical periodicity. In both cases a thin wetting layer is found at the polymer-substrate interface. The free surface is enriched with PS. Y1 - 2005 SN - 1520-5835 VL - 38 IS - 2 SP - 507 EP - 516 ER - TY - JOUR A1 - Schmeißer, Dieter T1 - Interface reactivity of Pr and SiO2 at 4H-SiC(0001) N2 - We use photoelectron spectroscopy to characterize the reactivity of Pr evaporated on SiO2 covered 4H-SiC substrates. We analyze the Si2p, C1s, and O1s core levels and find that Pr reacts at RT with the SiO2 layer to form Pr-silicate. In addition also Pr-silizide is formed as well as Pr-carbides. While the latter are formed as reaction intermediates after Pr evaporation, the Pr-silicate layer is formed upon annealing to 300 °C and is stable up to 800 °C. KW - Photoelectron spectroscopy KW - 4H-SiC KW - Interface reactivity KW - High-k dielectric layer Y1 - 2005 ER - TY - GEN A1 - Müller, Klaus A1 - Goryachko, Andriy A1 - Burkov, Yevgen A1 - Schwiertz, Carola A1 - Ratzke, Markus A1 - Köble, J. A1 - Reif, Jürgen A1 - Schmeißer, Dieter T1 - Scanning Kelvin Probe Microscopy and Photoemission electron microscopy of organic source-drain structures T2 - Synthetic Metals N2 - n order to optimize organic field effect transistors (OFETs), the characterisation of active-layer surfaces in terms of their roughness, chemical composition and distribution of surface potentials is important. We report on high-resolution microscopic mapping of organic source-drain structures with P3HT as the semiconductor by scanning Kelvin probe microscopy (SKPM) and photoemission electron microscopy (PEEM). It was shown that PEEM is able to characterise the surface morphology (roughness), the chemical homogeneity and the composition of organic structures. The two-dimensional mapping of surface potentials by SKPM with applied source-drain voltages is shown to be an important ingredient of OFETs failure mode analysis. KW - Photoemission electron microscopy (PEEM) KW - Scanning Kelvin probe microscopy (SKPM) KW - OFET Y1 - 2004 SN - 0379-6779 VL - 146 IS - 3 SP - 377 EP - 382 ER - TY - GEN A1 - Müssig, Hans-Joachim A1 - Dabrowski, Jarek Marek A1 - Wenger, Christian A1 - Lupina, Grzegorz A1 - Sorge, Roland A1 - Formanek, Peter A1 - Zaumseil, Peter A1 - Schmeißer, Dieter T1 - Ultrathin Dielectric Films Grown by Solid Phase Reaction of Pr with SiO2 T2 - MRS Proceedings Y1 - 2004 SN - 1946-4274 VL - 811 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Müssig, Hans-Joachim T1 - Pr4f occupancy and VB/CB band offsets of Pr2O3 at the interface to Si(001) and SiC(0001) surfaces T2 - MRS Proceedings Y1 - 2004 SN - 1946-4274 VL - 811 ER - TY - GEN A1 - Lupina, Grzegorz A1 - Schroeder, Thomas A1 - Dabrowski, Jarek Marek A1 - Schmeißer, Dieter A1 - Hoffmann, Patrick T1 - Praseodymium silicate layers with atomically abrupt interface on Si(100) T2 - Applied Physics Letters Y1 - 2005 SN - 0003-6951 VL - 87 IS - 5 ER - TY - GEN A1 - Yfantis, Alexandros D. A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter ED - Kainer, Karl Ulrich T1 - Corrosion Protection by Conductive Polymers for Magnesium Alloys T2 - Magnesium, proceedings of the 6th International Conference on Magnesium Alloys and their Applications, November 2003 in Wolfsburg N2 - In this work, we present the experimental data related to the effect of the polypyrrole concentration and the film thickness on the corrosion inhibition properties of these novel polymer coatings. The relative corrosion resistance properties of the films formed from the matrix solutions, where polypyrrole was in situ polymerized and in cases where polypyrrole is dispersed in a form of powder (pigment) in the polyaclylic polymer, are further examined. The evaluation of the experimental data provides significant evidence regarding the mechanism of corrosion inhibition, as well as the optimization of the synthesis and application conditions. KW - corrosion protection KW - conductive polymers for magnesium alloys KW - polypyrrole Y1 - 2004 SN - 3-527-30975-6 SP - 605 EP - 610 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter A1 - Soinski, M. S. T1 - Promieniowanie synchrotronowe jako uniwersalne narzedzie badawcze - Proby jego wykorzystania w badaniach struktury zeliwa Y1 - 2004 ER - TY - GEN A1 - Beerbom, Martin A1 - Mayer, Thomas A1 - Jaegermann, Wolfram A1 - Batchelor, David R. A1 - Schmeißer, Dieter T1 - Synchrotron-induced photoemission of GaAs electrodes after electrochemical treatment in aqueous electrolytes N2 - Electrochemically-induced oxidation and reduction reactions of UHV-cleaved GaAs(110) surfaces have been studied after emersion under potential control using highresolution synchrotron-induced photoelectron spectroscopy. High quality spectra of the As and Ga core 3d lines and the valence band region have been obtained. Thespectra of the anodic oxide show strong emission of bulk-like Ga2O3 and some As2O3 with the admixture of suboxides and hydroxides. Ga2O3 and As2O3 arecathodically reduced leaving the GaAs surface covered mostly with elemental As, some As-H and remnants of Ga-suboxides and -hydroxides. KW - GAAS(110) KW - GaAs KW - Electrochemistry KW - Aqueous electrolytes KW - Surface engineering Y1 - 2002 ER - TY - JOUR A1 - Gracia, F. A1 - Martin-Concepcion, A. I. A1 - Barranco, A. A1 - Holgado, J. P. A1 - Espinos, J. P. A1 - Yubero, F. A1 - Batchelor, David R. A1 - Schmeißer, Dieter A1 - Gonzalez-Elipe, A. R. T1 - XAS investigation of texture in TiO2 thin films prepared by IBICVD Y1 - 2002 ER - TY - GEN A1 - Yfantis, Alexandros D. A1 - Tzalas, B. A1 - Lambrakopoulos, S. A1 - Anagnostaki, E. A1 - Schmeißer, Dieter T1 - New chrome free, environmentally friendly methods in chemical processes N2 - It gives an overview of the research work to develop chrom-free methods in different chemical processes. A new class of materials, the conductive polymers, have been studied extensively for their anticorrosion properties. KW - Alloys KW - Polypyrrole KW - Polymers Y1 - 2002 ER - TY - JOUR A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Back-propagation based neural network with a two sensor system for monitoring of carbon dioxide and relative humidity Y1 - 2002 ER - TY - PAT A1 - Yfantis, Alexandros D. A1 - Schmeißer, Dieter T1 - Method of chemical deposition of compose conductive polymer coatings on aluminium alloy surfaces Y1 - 2002 ER - TY - CHAP A1 - Yfantis, Alexandros D. A1 - Bourdas, N. A1 - Yfantis, N. A1 - Yfantis, Alexandros D. A1 - Lambrakopoulos, S. A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - A study of anticorrosive conversion coatings based on conductive polymers of pyrrole Y1 - 2002 ER - TY - GEN A1 - Böhme, O. A1 - Lloyd Spetz, Anita A1 - Lundström, Ingemar A1 - Schmeißer, Dieter T1 - Nanoparticles as the Active Element of High-Temperature Metal-Insulator-Silicon Carbide Gas Sensors T2 - Advanced Materials Y1 - 2001 SN - 1521-4095 SN - 0935-9648 VL - 13 IS - 8 SP - 597 EP - 601 ER - TY - GEN A1 - Gürek, A. G. A1 - Appel, Günter A1 - Mikalo, Ricardo Pablo A1 - Schmeißer, Dieter T1 - Synthesis of dihydroxy silicon phthalocyanine tetrasulfonic acid and poly-µ-oxo silicon phthalocyanine tetrasulfonic acid T2 - Journal of Porphyrins and Phthalocyanines Y1 - 2001 SN - 1099-1409 SN - 1088-4246 VL - 5 IS - 10 SP - 751 EP - 757 ER - TY - JOUR A1 - Mikalo, Ricardo Pablo A1 - Appel, Günter A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Band Bending in Doped Conducting Polypyrrole Interaction with Silver Y1 - 2001 ER - TY - JOUR A1 - Batchelor, David R. A1 - Follath, Rolf A1 - Schmeißer, Dieter T1 - Commissioning Results of the BTUC-PGM beamline Y1 - 2001 ER - TY - JOUR A1 - Schmeißer, Dieter A1 - Mikalo, Ricardo Pablo A1 - Hoffmann, Patrick A1 - Seyller, Th. A1 - Ley, L. A1 - Lloyd Spetz, Anita T1 - Oxide growth on SiC (0001) surfaces Y1 - 2001 ER - TY - JOUR A1 - Mikalo, Ricardo Pablo A1 - Hoffmann, Patrick A1 - Batchelor, David R. A1 - Schmeißer, Dieter A1 - Lloyd Spetz, Anita A1 - Lundström, Ingemar T1 - Comparison of HF and ozone treated SiC surfaces Y1 - 2001 ER - TY - JOUR A1 - Mikalo, Ricardo Pablo A1 - Appel, Günter A1 - Schmeißer, Dieter T1 - Conductivity of Silver exposed Polypyrrole Films Y1 - 2001 ER - TY - JOUR A1 - Sieber, N. A1 - Mantel, B. F. A1 - Seyller, Th. A1 - Ristein, J. A1 - Ley, L. A1 - Heller, Thomas A1 - Batchelor, David R. A1 - Schmeißer, Dieter T1 - Electronic and chemical passivation of hexagonal 6H-SiC surfaces by hydrogen termination Y1 - 2001 ER - TY - CHAP A1 - Batchelor, David R. A1 - Berg, A. A1 - Simon, Sylvio A1 - Wagner, Lothar A1 - Viehweger, Bernd A1 - Schmeißer, Dieter T1 - Development of Joining Techniques through Pressforming of Steel and Aluminium Y1 - 2001 UR - http://www.materialsweek.org/proceedings/index.htm ER - TY - CHAP A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Batchelor, David R. A1 - Beuckert, Guido A1 - Schmeißer, Dieter A1 - Kittler, Martin A1 - Ourmazd, A. A1 - Lewerenz, Hans-Joachim T1 - Solare Energieumwandlung in dünnen Schichten Y1 - 2000 ER - TY - JOUR A1 - Mikalo, Ricardo Pablo A1 - Appel, Günter A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter A1 - Mast, M. T1 - Multi-Atom Resonant Photoemission applied to study the silver to nitrogen interaction in polypyrrole films Y1 - 2000 ER - TY - JOUR A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter A1 - Klein, A. A1 - Jaegermann, Wolfram A1 - Pettenkofer, Christian A1 - Follath, Rolf T1 - Spectro-Microscopy with PEEM / µESCA Y1 - 2000 ER - TY - JOUR A1 - Batchelor, David R. A1 - Scheer, M. A1 - Schmeißer, Dieter T1 - WAVE Calculations of Off Axis Undulator Radiation for the BESSY II U49 Undulator Y1 - 2000 ER - TY - CHAP A1 - Hoffmann, Patrick A1 - Batchelor, David R. A1 - Schmeißer, Dieter T1 - Spectro-Microscopic analyses in metallurgical systems: spheroidic graphite in cast iron and the interface of friction-welded Al-Fe joints Y1 - 2000 ER - TY - JOUR A1 - Schmeißer, Dieter A1 - Appel, Günter A1 - Böhme, O. A1 - Heller, Thomas A1 - Mikalo, Ricardo Pablo A1 - Hoffmann, Patrick A1 - Batchelor, David R. T1 - Nanoparticles and polarons: active centers in thin film sensor devices Y1 - 2000 ER - TY - JOUR A1 - Mikalo, Ricardo Pablo A1 - Hoffmann, Patrick A1 - Heller, Thomas A1 - Batchelor, David R. A1 - Appel, Günter A1 - Schmeißer, Dieter T1 - Doping and defect inhomogeneities of polypyrrole tosylate films as revealed by ?-NEXAFS Y1 - 1999 ER - TY - JOUR A1 - Oprea, A. A1 - Henkel, Karsten A1 - Oehmgen, R. A1 - Appel, Günter A1 - Schmeißer, Dieter A1 - Lauer, H. A1 - Hausmann, P. T1 - Increased sensor sensitivities obtained by polymer coated quartz microbalances Y1 - 1999 ER - TY - JOUR A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Schmeißer, Dieter A1 - Kittler, Martin T1 - A spectro-microscopic approach to study the morphology and elemental distribution of mc-Si surfaces Y1 - 1999 ER - TY - JOUR A1 - Lloyd Spetz, Anita A1 - Schmeißer, Dieter A1 - Baranzahi, A. A1 - Wälivaare, B. A1 - Göpel, W. A1 - Lundström, Ingemar T1 - X-ray photoemission and Auger electron spectroscopy analysis of fast responding activated metal oxide silicon carbide gas sensors Y1 - 1997 ER - TY - JOUR A1 - Naarmann, H. A1 - Schmeißer, Dieter A1 - Bartl, A. A1 - Dunsch, L. A1 - Göpel, W. T1 - Electronic and magnetic properties of polypyrrole films depending on their 1-dimensional and 2-dimensional microstructures Y1 - 1998 ER - TY - JOUR A1 - Mikalo, Ricardo Pablo A1 - Hoffmann, Patrick A1 - Böhme, O. A1 - Schmeißer, Dieter T1 - Doping inhomogenities in Polypyrrole films: a Photoemission Electron Microscope (PEEM) and Spectro-Microscopic Study Y1 - 1998 ER - TY - JOUR A1 - Mikalo, Ricardo Pablo A1 - Hoffmann, Patrick A1 - Heller, Thomas A1 - Schmeißer, Dieter T1 - Lateral Doping Inhomogeneities as Revealed by ?-NEXAFS and ?-PES Y1 - 1998 ER - TY - JOUR A1 - Appel, Günter A1 - Yfantis, Alexandros D. A1 - Göpel, W. A1 - Schmeißer, Dieter T1 - Highly conductive polypyrrole films on nonconductive substrates Y1 - 1996 ER - TY - GEN A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Improvement of Nitrogen Incorporation into Oxynitrides on 4H-SiC(0001) T2 - Nuclear Instruments and Methods in Physics Research, Section B : Beam with Materials and Atoms Y1 - 2006 VL - 246 IS - 1 SP - 85 EP - 89 ER - TY - JOUR A1 - Seifarth, Olaf A1 - Burkov, Yevgen A1 - Goryachko, Andriy A1 - Schmeißer, Dieter A1 - Sydorenko, Alexander A1 - Krenek, Radim A1 - Stamm, Manfred T1 - Photoelectron spectroscopy and microscopy on Cr nano particels embedded into block copolymers Y1 - 2005 ER - TY - JOUR A1 - Wehner, Stefan A1 - Schmeißer, Dieter A1 - Hoffmann, Patrick T1 - Spatiotemporal patterns of external noise-induced transitions in a bistable reaction-diffusion system : Photoelectron Emission Microscopy experiments and modeling Y1 - 2005 ER - TY - CHAP A1 - Schmeißer, Dieter A1 - Müssig, Hans-Joachim T1 - Pr-silicate formation on SiO2 covered 3C-SiC(111) T2 - Physics of semiconductors, 27th International Conference on the Physics of Semiconductors Y1 - 2005 SN - 0-7354-0257-4 SP - 75 EP - 76 PB - AIP, American Inst. of Physics CY - New York, NY ER - TY - JOUR A1 - Schmeißer, Dieter T1 - Pr2O3/Si(001) interface reactions and stability N2 - We show that an interfacial silicate is formed in a natural way between Si(0 0 1) and the deposited Pr2O3 film if a sufficient amount of oxygen is provided during deposition, as during electron beam evaporation from Pr6O11 source. We provide arguments from results of ab initio calculations and we present a ternary phase diagram of the Pr-O-Si system obtained for epitaxial films from non-destructive depth profiling data acquired by synchrotron radiation and photoelectron spectroscopy (SR-PES) at the undulator beam line U49/2-PGM2. The composition of the interfacial layer is (Pr2O3)(SiO)x(SiO2)y, with x+y between 2 and 6 and depends on the growth condition and distance from the substrate. No interfacial SiO2 and no interfacial silicide is formed during growth. The ternary phase diagram indicates that this non-stoichiometric pseudobinary alloy is stable on Si up to high temperatures, without phase separation into Pr2O3 and SiO2. Therefore, a complete re-engineering of the CMOS process may be not necessary. KW - High-k-material KW - Pr2O3/Si(0 0 1) interface KW - Photoelectron spectroscopy KW - Ab initio calculations KW - CMOS Y1 - 2004 ER - TY - GEN A1 - Lamprakopoulos, Stelios A1 - Schmeißer, Dieter A1 - Anastassopoulou, Jane A1 - Theophanides, Theophile A1 - Yfantis, Alexandros D. T1 - An FTIR study of the role of H2O and D2O in the aging mechanism of conductive polypyrroles T2 - Synthetic Metals N2 - In the present work the role of H2O was studied by conductivity measurements and FTIR spectroscopy using the isotopic effect of deuterium in order to elucidate the aging mechanism of conductivity of polypyrroles. Polypyrrole was prepared with PTS as a dopant, by using deuterated water. Conductivity measurements showed changes due to structural water and atmospheric humidity. The FTIR absorption spectra indicated that the most probable structure of polypyrrole is the two-dimensional one. This finding could be attributed to the inhibition of polypyrrole's IR modes. The infrared spectrum analysis show that the gamma -NH bending mode of pyrrole has significantly changed after polymerization of pyrrole and this result is in accordance with XPS measurements. KW - Polypyrrole KW - Conductivity KW - FTIR KW - Isotopic effect Y1 - 2004 U6 - https://doi.org/10.1016/j.synthmet.2004.03.006 SN - 0379-6779 VL - 144 IS - 3 SP - 229 EP - 234 ER - TY - GEN A1 - Sidorenko, Alexander A1 - Tokarev, Igor A1 - Krenek, Radim A1 - Burkov, Yevgen A1 - Schmeißer, Dieter A1 - Stamm, Manfred T1 - XPEEM investigations of 2D hierachical array of Ni nanorods using block copolymer templates Y1 - 2004 ER - TY - JOUR A1 - Schmeißer, Dieter T1 - Cooper minimum observed for the Pr5s and Pr5p states in Pr2O3 Y1 - 2004 ER - TY - CHAP A1 - Schmeißer, Dieter A1 - Lupina, Grzegorz A1 - Müssig, Hans-Joachim T1 - High reactivity of Pr on oxide covered 4H-SiC T2 - Bessy annual report 2003 Y1 - 2004 SP - 408 EP - 409 PB - Bessy CY - Berlin ER - TY - CHAP A1 - Müller, Klaus A1 - Bär, Werner A1 - Henkel, Karsten A1 - Jahnke, Agnes A1 - Schwiertz, Carola A1 - Schmeißer, Dieter T1 - Organische Feldeffekttransistoren als Transducer in der Biosensorik Y1 - 2003 SN - 3-935712-92-8 SP - 119 EP - 223 PB - w.e.b.-Univ.-Verl. CY - Dresden ER - TY - CHAP A1 - Henkel, Karsten A1 - Schwiertz, Carola A1 - Wagner, S. A1 - Valdeig, A. A1 - List, M. A1 - Schmeißer, Dieter T1 - Partikel- und Tropfendetektion im Mikrometerbereich mittels Schwingquarzen Y1 - 2003 SN - 3-935712-92-8 SP - 291 EP - 294 PB - w.e.b.-Univ.-Verl. CY - Dresden ER - TY - GEN A1 - Appel, Günter A1 - Ade, H. A1 - Gürek, A. G. A1 - Stadler, S. A1 - Mikalo, Ricardo Pablo A1 - Schmeißer, Dieter T1 - Orientation studies of Si-Phthalocyanines sulfonic acids cast on SiOx substrates T2 - Applied Physics / A N2 - Layers of dihydroxy silicon phthalocyanine tetrasulfonic acid and oligo-7-oxo silicon phthalocyanine tetrasulfonic acid were prepared by solution-casting methods. The purity of the material was checked by X-ray photoemission spectroscopy. The orientation of the molecules in respect to the substrate plane was investigated by angle-dependent near-edge X-ray absorption fine-structure spectroscopy. The morphology was characterized by atomic force microscopy. Most samples exhibited a significant orientation that was accompanied by crystalline structures; others had no orientation at all with a dominant amorphous morphology. This behavior indicates that several preparation parameters affect the crystallinity and the orientation of the phthalocyanines. Y1 - 2003 U6 - https://doi.org/10.1007/s003390201320 SN - 1432-0630 VL - 76 IS - 2 SP - 177 EP - 182 ER - TY - GEN A1 - Lewerenz, Hans-Joachim A1 - Murrell, Chris A1 - Jakubowicz, J. A1 - Aggour, Mohammed A1 - Kanis, M. A1 - Campbell, S. A. A1 - Cox, P. A. A1 - Hoffmann, Patrick A1 - Jungblut, H. A1 - Schmeißer, Dieter T1 - High Resolution Surface analysis of Si Roughenning in Dilute Ammonium Fluoride Solution T2 - Journal of Electroanalytical Chemistry N2 - The initial stages of porous Si formation on Si(111) in dilute ammonium fluoride solution are analysed by photoelectron spectroscopy using synchrotron radiation (SRPES). The PES results in the por-Si formation regime partly support a recent dissolution model. The contribution from the Si 2p surface core level shift shows that 0.35 ML of the surface is still H-terminated after interruption of the conditioning process at the first photocurrent maximum. Two signals shifted in binding energy by 0.8 and 1 eV, respectively, are attributed to reaction intermediates expected from the proposed reaction mechanism and from theoretical calculations using density functional theory (DFT). A distinct roughening is found in in-situ AFM measurements, with a calculated RMS roughness parameter of 2.6 nm. KW - Porous Si KW - transistors KW - Electropolishing KW - Photoelectron spectroscopy KW - AFM KW - Synchrotron radiation Y1 - 2003 SN - 1873-2569 VL - 540 SP - 3 EP - 6 ER - TY - GEN A1 - Lewerenz, Hans-Joachim A1 - Aggour, Mohammed A1 - Murrell, Chris A1 - Kanis, M. A1 - Hoffmann, Patrick A1 - Jungblut, H. A1 - Schmeißer, Dieter T1 - Interface engineering of photoelectrochemically prepared Si surfaces N2 - The oxide of Si(111) formed by electropolishing in dilute ammonium fluoride solution is analysed by photoelectron spectroscopy using synchrotron radiation. The oxidiclayer is about 3.1 nm thick and contains Si-F-x species as well as oxyfluorides. The oxyfluorides are found preferentially at the electropolishing layer surface. SiOHspecies are concentrated at the oxidic film/substrate interface. The full width half maximum of the Si 2p line indicates that the Si/electropolishing oxide interface issmoother than the Si/natural oxide interface. KW - Mean Free Paths KW - Silicon KW - Range Y1 - 2002 ER - TY - GEN A1 - Müller, Klaus A1 - Bär, Werner A1 - Henkel, Karsten A1 - Jahnke, Agnes A1 - Schwiertz, Carola A1 - Schmeißer, Dieter T1 - Organische Feldeffekttransistoren als Transducer in der Biosensorik T1 - Organic Field Effect Transistors as Biosensors T2 - Technisches Messen N2 - In diesem Beitrag wird der Einsatz neuartiger Sensortypen für die medizinische Diagnostik beschrieben. Diese Sensoren sollen komplett organisch sein und auf dem Prinzip des Feldeffekttransistors basieren. Als Modellsystem für die Anwendung in der Biosensorik soll die Einsatzmöglichkeit dieser Sensoren in der nicht-invasiven Diagnostik der Helicobacter-pylori-Infektion überprüft werden. N2 - In this contribution we describe the investigation of new types of sensors in medical diagnosis. These sensors are completely organic and are based on the principle of organic field effect transistors. As model system for application in medical diagnosis we test the usability of this sensors for the diagnosis of helicobacter pylori. KW - Feldeffekttransistor KW - Biosensorik KW - Helicobacter pylori KW - Field effect transistors KW - biosensors KW - helicobacter pylori Y1 - 2003 U6 - https://doi.org/10.1524/teme.70.12.565.20261 SN - 0171-8096 VL - 70 IS - 12 SP - 565 EP - 568 ER - TY - JOUR A1 - Mikalo, Ricardo Pablo A1 - Schmeißer, Dieter T1 - Electric contacts on conductive polymers: sodium on poly(3-hexylthiophene-2,5-diyl) N2 - Sodium as a model contact with low work function on regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) films was investigated. The interface was studied by X-rayand ultraviolet photoelectron spectroscopy in the range of 0.13 up to 1.8 metal atoms per hexylthiophene unit. In the range of 0.13-0.26 sodium atoms per hexylthiophenering we find a change inthe surface potentials which is interpreted as a discharge of positive surface charges. Sodium exposures above 0.5 sodium atoms perhexylthiophene unit exhibit a reduction of the thiophene sulfur due to the formation of sodium sulfide and breaking of the thiophene ring. Y1 - 2002 ER - TY - JOUR A1 - Yfantis, Alexandros D. A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter A1 - Yfantis, Alexandros D. T1 - Novel corrosion-resistant films for Mg alloys N2 - A novel method for the corrosion inhibition of Mg, alloys, based on the formation of a thin polyacrylic-polypyrrole film, is presented. The film was created after simpleimmersion of the samples in a specially formulated emulsion of polyacrylic and polypyrrole polymers. The synthesis conditions were studied, as well as the resultingcorrosion resistance of coated magnesium foils (AZ31) in terms of corrosion rate in neutral aqueous NaCl solutions. The relative ratio of polyacrylic polymer topolypyrrole was found to be important for the film properties. Furthermore, only in situ polymerisation of pyrrole in the polyacrylic emulsion can provide advancedcorrosion proper-ties in relatively thin films (2-5 mum). Blending of polypyrrole powder with the polyacrylic emulsion gives rise to thick films (20 mum) with reducedcorrosion-inhibition properties. The corrosion rate was only weakly dependent on the film thickness of these novel coatings. We argue that the mechanism of corrosioninhibition is related to the formation of a thin passive layer of chemisorbed polypyrrole polymers or oligomers on the native magnesium oxide of the C surface. Thestructure is further stabilised by polyacrylic polymer chains interacting as dopants of polypyrrole. The method is environmentally friendly: non-toxic chemicals are used,no rinsing is required, etc. The advanced corrosion-inhibition properties of the films. as well as the simple application process on the metal surface, provide significantpotential for the industrial application of the method. KW - polypyrrole KW - polyacrylic KW - coating KW - magnesium KW - corrosion inhibition Y1 - 2002 ER - TY - JOUR A1 - Sieber, N. A1 - Seyller, Th. A1 - Graupner, R. A1 - Ley, L. A1 - Mikalo, Ricardo Pablo A1 - Hoffmann, Patrick A1 - Batchelor, David R. A1 - Schmeißer, Dieter T1 - Wet-chemical preparation of silicate adlayer reconstructed SiC(0001) surfaces as studied by PIES and LEED N2 - We have studied the surface chemistry of 6H-SiC(0001) and 6H-SiC (000 (1) over bar) after wet-chemical treatment using photoelectron spectroscopy (PES) andlow-energy electron diffraction (LEED). The origin of chemically shifted components in the Si2p and C1s spectra is discussed in the light of previous studies onwet-chemically prepared surfaces and on silicate adlayer reconstructed surfaces. On 6H-SiC(0001) an ordered silicate adlayer was prepared by etching the surface withsulfuric acid based agents. KW - Core level KW - Photoelectron spectroscopy KW - Synchrotron radiation KW - Wet-chemical preparation OXIDE Y1 - 2002 ER - TY - GEN A1 - Aggour, Mohammed A1 - Stoerkel, Ulrich A1 - Murrell, Chris A1 - Campbell, S. A. A1 - Jungblut, H. A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Schmeißer, Dieter A1 - Lewerenz, Hans-Joachim T1 - Electrochemical interface modification of CuInS2 thin films N2 - We studied two novel electrochemical treatments of CuInS2 solar-cell absorber films, introduced to remove the deleterious segregated CuS phase. Their influence onsurface topography, chemistry and electronic properties was investigated using in situ atomic force microscopy (AFM) and photoclectron spectroscopy, performed inpart at the U49/2 undulator beam line at BESSY II. The results are examined in order to develop an improved understanding of the chemical-electrochemical surfacetransformation processes. KW - thin-film solar cells KW - copper indium disulfide KW - atomic force microscopy (AFM) KW - photoelectron spectroscopy KW - synchrotron radiation KW - Solar-Cell Y1 - 2002 ER - TY - GEN A1 - Müller, Klaus A1 - Henkel, Karsten A1 - Mikalo, Ricardo Pablo A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Elektronik mit organischen Materialien N2 - Plastikelektronik, flexible Solarzellen, intelligente Kleidung, neuartige und maßgeschneiderte Transducer für die Gas-, Flüssigkeits- und Biosensorik, all dies sind Anwendungen, die ohne halbleitende Polymere nicht denkbar wären und die Bereiche erschließen, in denen zur Zeit eine regelrechte Goldgräberstimmung herrscht. Mit wichtigen Beiträgen im Grundlagen- und Anwendungsbereich nimmt die BTU Cottbus an dieser Entwicklung teil, u. a. auch durch eine Kooperation mit dem Institut für Mikrobiologie des Carl-Thiem-Klinikums Cottbus.In diesem Artikel werden die Voraussetzungen für die Konstruktion organischer Feldeffekt-Transistoren mit gassensitiver Gate-Elektrode vorgestellt. Untersuchungen zur elektronischen Struktur des organischen Halbleiters Poly(3-Hexylthiophen), die Anwendung dieses Materials als aktive Schicht in organischen Feldeffekt-Transitoren, die Gassensitivität von Polypyrrolelektroden auf Quarz-Mikrowaagen und die Mikrorstukturierung organischer Elektroden werden beschrieben. Y1 - 2002 PB - BTU Cottbus, Eigenverlag ER - TY - JOUR A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Schmeißer, Dieter T1 - PEEM - a spectromicroscopic tool for mc-Si surface evaluation N2 - The photo emission electron microscope (PEEM) with its direct imaging of the sample surface is a convenient tool for fast evaluation of large sample areas. It is possibleto handle samples with a size of 30 mm x 30 mm.With PEEM it is possible to visualise grain boundaries and crystal displacements without removing the native oxide. No special sample treatment is needed exceptchemical polishing of the sample surface and a HF-dip to obtain a thin (1 ... 2 nm) oxide layer.The quality of that oxide was proofed by high resolution photo electron spectroscopy (PES) at a synchrotron. The results were compared to native oxide onsingle-crystalline Si and no suboxides (e.g. SiO) were found. Our spectromicroscopic PEEM measurements show no difference in the oxide qualities of different grainsand on grain boundaries or crystal displacements. Furthermore no difference in the binding energy of Si2p core levels were found.In addition to grain boundaries other spot-like features were found on the sample surface. These could be identified in some cases as precipitation of Ca underneath thenative oxide. KW - multicrystalline silicon KW - photoelectron spectroscopy KW - PEEM Y1 - 2002 ER - TY - CHAP A1 - Schwiertz, Carola A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Sensorsystem zur Unterscheidung von Geruchsmustern in Tierställen N2 - Es wurde ein kontinuierlich arbeitendes, preiswertes Schwingquarz-Mess-System zur olfaktometrischen Überwachung von Tierställen aufgebaut, mit dessen Hilfe im Arbeitsbereich von 65%B0C spezifische Gerüche verschiedener Tierarten unterschieden werden können. Zur Geruchsmustererkennung wurde ein einfaches neuronales Netz verwendet. Olfaktometrische Verdünnungen auf 33% sowie Messwertschwankungen von 5-10% wurden simuliert, wobei die richtige Musterzuordnung durch das Netz nicht beeinflusst wurde. Y1 - 2002 ER - TY - CHAP A1 - Schmeißer, Dieter A1 - Hoffmann, Patrick A1 - Müssig, Hans-Joachim T1 - The Pr2O3/Si(001) interface: a mixed Si-Proxide T2 - BESSY annual report 2001 Y1 - 2002 SP - 171 EP - 173 PB - Bessy CY - Berlin ER - TY - CHAP A1 - Müller, Klaus A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Low-cost-Plot-Technologie fur die Mikrostrukturierung von Gassensoren T2 - Sensoren im Fokus neuer Anwendungen, 5. Dresdner Sensor-Symposium, 10. - 12. Dezember 2001, Dresden N2 - Bei der Herstellung von Mikrosensoren ist die Strukturierung von Elektroden oder elektrischen Zu-leitungen mit einem hohen Miniaturisierungsgrad ein entscheidender Punkt. Dazu müs-sen häufig teure Verfahren (Lithographie, Maskentechniken) herangezogen werden.Dieser Beitrag beschreibt eine low-cost-Technologie zur Herstellung organischer Mikrostrukturen für elektronische und messtechnische Anwendungen im Bereich der Sensorik. Geplottete Strukturen mit Polypyrrol und Poly(3,4-Ethylen-Dioxy-Thiophen), dotiert mit Polystyrolsulfonat (PEDOT/PSS) wurden als Widerstandssensoren für die Detektion von Luftfeuchte ein-gesetzt. Die prinzipielle Ein-satzmöglichkeit unserer Technik im Bereich der organischen Elektronik konnten wir mit dem Bau organischer Feldeffekttransistoren nachweisen. Mit einem computergesteu-erten Plotter des Typs Rol-land DXY-1150A, Plot-Kapillaren für das Tuschezeichnen, handelsüblichen Folien für wasserlösliche Tinten als Substrat und kolloidalen Graphit als leitendes Material konnten wir Auflösungen, das heißt insbesondere Kanalbreiten bzw. Elektrodenabstände im Bereich von 20+10%B5m (auf 2cm Länge) her-stellen. Y1 - 2002 SN - 3-935712-71-5 SP - 166 EP - 169 PB - w.e.b. Universitätsverlag CY - Dresden ER - TY - JOUR A1 - Müller, Klaus A1 - Hoffmann, Patrick A1 - Milko, S. A1 - Burkov, Yevgen A1 - Schmeißer, Dieter T1 - PEEM and µ-NEXAFS of Cu-In-S-Surfaces N2 - The composition of CuInS2-films tends to differ from the ideal ratio of 1:1:2. A molecularlyvariation of dm=[Cu]/[In]-1 not equal 0 occurs due to the formation of binary phases as segregation's at the surface, as crystallites in the bulk of the film or at the surface of grains [1]. Furthermore, the range of homogeneity of the phase CuInS2 is relatively large caused by a low enthalpy of formation of defects like Cu-vacancies [2]. Segregation's at surfaces can be removed by KCN etching or by an electrochemical process [3, 4] We investigated the effect of an in-situ-heat-treatment of samples, prepared in the Cu-rich regime with additional amounts of copper, deposited on the surface of the Cu-In-S-films.We used Cu-In-S-films on molybdenum, prepared from precursors of Cu/In and a following reactive annealing-process in a sulphur-atmosphere. The experiments were performed as follows: The surface of the films was cleaned in situ to remove CuS-Phases by Argon-bombardment. The thin layers of additional Copper were prepared by evaporation of copper metal in Knudsen-cells. The thickness of this copper-films is in the range of monolayers, revealed by a calibration with copper on iron-substrates. After this deposition the samples were heated up to several temperatures (up to 550 ºC) for ten minutes, respectively. Here the molybdenum back-contact was used as electrical heater. Y1 - 2002 ER - TY - CHAP A1 - Henkel, Karsten A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Backpropagation-Netzwerke für ein Zweisensorsystem zur Erfassung von Kohlendioxidkonzentrationen und relativer Luftfeuchte T2 - Sensoren im Fokus neuer Anwendungen : Verbraucherschutz und Lebensmittelkontrolle, Biosysteme und Nanobiotechnologie, Umweltmesstechnik, neue Sensormaterialien, Mess- und Eichwesen N2 - Zwei Schwingquarzsensoren mit gleicher sensitiver Beschichtung wurden zur Messung von CO2-Konzentrationen bei variierenden Luftfeuchten genutzt. Die Daten wurden neuronalen Netzen mit unterschiedlicher Architektur trainiert. Zwei Netze wurden auf ihre Generalisierungsfähigkeit getestet und miteinander verglichen. Für ein einstufiges Netz konnten Ergebnisse mit Fehlern kleiner 12% für die CO2-Konzentration und kleiner 5% für die Luftfeuchte erzielt werden. Ein zweistufiges Netz erkannte Kategorien der Luftfeuchte 100%-ig, für die CO2-Konzentration wurden Fehler kleiner 9% erreicht, wobei eine deutlich bessere Generalisierungsfähigkeit dieses Netzes im Vergleich zum einstufigen Netz zu verzeichnen ist. Y1 - 2002 SN - 3-935712-71-5 SN - 978-3-935712-71-2 SP - 104 EP - 107 PB - w.e.b. Universitätsverlag CY - Dresden ER - TY - JOUR A1 - Batchelor, David R. A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Photoemission study of Aluminium Steel cold welded joints N2 - Aluminium and Stainless Steel bi-metal material is extremely versatile and is used in a wide range of products; from cooking utensils to high technology applications such as automobile manufacture and Synchrotron radiation instrumentation. As a consequence of this wide range of applications the study of the formation of Aluminium Steel junctions and the bonding mechanism is of considerable industrialimportance [1-3].In a previous publication [4] evidence for a chemical bond, alloying at the interface was found. As the monochromator focus and welded region are similar in size about 200 µm (the actual interface from SEM is an order of magnitude smaller) a simple photoemission experiment of translating the sample perpendicular (vertically, weld horizontal) to the weld and measuring spectra was performed. Y1 - 2002 ER - TY - JOUR A1 - Jäckel, B. A1 - Thißen, A. A1 - Hunger, Ralf A1 - Klein, A. A1 - Jaegermann, Wolfram A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Focus IS-PEEM investigations at U49/II: experimental determination of a magnification function, the contrast mechanism and the spectral resolution Y1 - 2002 ER - TY - JOUR A1 - Pop, D. A1 - Winter, B. A1 - Batchelor, David R. A1 - Freyer, W. A1 - Weber, R. A1 - Bröcker, D. A1 - Hertel, I. V. A1 - Schmeißer, Dieter A1 - Widdra, Wolf T1 - Copper Satellite Structure in Porphyrazine Compounds Y1 - 2002 ER - TY - JOUR A1 - Seyller, Th. A1 - Sieber, N. A1 - Graupner, R. A1 - James, D. A1 - Riley, J. A1 - Leckey, R. A1 - Polcik, M. A1 - Schmeißer, Dieter T1 - High Resolution Photoelectron Spectroscopy on SiC Surfaces Y1 - 2002 ER - TY - JOUR A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Schmeißer, Dieter T1 - A spectro-microscopic approach for spatially resolved characterisation of semiconductor structures in PEEM Y1 - 2000 ER - TY - JOUR A1 - Appel, Günter A1 - Mikalo, Ricardo Pablo A1 - Henkel, Karsten A1 - Oprea, A. A1 - Yfantis, Alexandros D. A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Polymeric Electrodes Y1 - 2000 ER - TY - JOUR A1 - Schmeißer, Dieter A1 - Richter, H. A1 - Pfitzner, L. A1 - Prasad, S. T1 - E-MRS 1999 Spring Meeting, Strasbourg, June1-4,1999-Preface Y1 - 2000 ER - TY - JOUR A1 - Yfantis, Alexandros D. A1 - Yfantis, Alexandros D. A1 - Tzalas, B. A1 - Schmeißer, Dieter T1 - A new chrome - free passivation method of tinplate used in the canning industry Y1 - 2000 ER - TY - JOUR A1 - Mikalo, Ricardo Pablo A1 - Appel, Günter A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter T1 - Determination of the Vacuum Level in NEXAFS-spectra by Selected-Yield-NEXAFS Y1 - 1999 ER - TY - GEN A1 - Batchelor, David R. A1 - Schmeißer, Dieter A1 - Follath, Rolf T1 - The BTU Cottbus Beamline at BESSY II Y1 - 1999 ER - TY - JOUR A1 - Hoffmann, Patrick A1 - Mikalo, Ricardo Pablo A1 - Schmeißer, Dieter T1 - Photoemissionselektronenmikroskopie - ein Instrument für die Materialforschung Y1 - 1999 ER - TY - JOUR A1 - Heller, Thomas A1 - Böhme, O. A1 - Schmeißer, Dieter T1 - Polarons in oxidic semiconductors - the SrTiO3 case Y1 - 1999 ER - TY - JOUR A1 - Schmeißer, Dieter A1 - Böhme, O. A1 - Yfantis, Alexandros D. A1 - Heller, Thomas A1 - Batchelor, David R. A1 - Lundström, Ingemar A1 - Lloyd Spetz, Anita T1 - Dipole moment of nanoparticles at interfaces Y1 - 1999 ER - TY - JOUR A1 - Appel, Günter A1 - Böhme, O. A1 - Mikalo, Ricardo Pablo A1 - Schmeißer, Dieter T1 - The polaron and bipolaron contributions to the electronic structure of polypyrrole films Y1 - 1999 ER - TY - CHAP A1 - Karavaev, Konstantin A1 - Tallarida, Massimo A1 - Schmeißer, Dieter A1 - Zschech, Ehrenfried T1 - In-situ ALD growth of Hafnium oxide films T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43 N2 - We report on a novel system for in-situ atomic layer growth (ALD) of high-k dielectric films. First results were obtained for Hf-oxide samples by using Hf-tetrachloride as precursor and water as oxidizer. We compare the photoelectron spectra of Si2p, O1s and Hf4f of our in-situ prepared films with samples (ex-situ) prepared by industrial ALD reactors and discuss similarities and differences observed in the core level spectra of the various samples by considering the different growth conditions. Y1 - 2008 UR - http://www.dpg-verhandlungen.de/year/2008/conference/berlin/part/ds/session/23/contribution/12 SN - 0420-0195 SP - S. 244 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Dudek, Piotr T. A1 - Lupina, Grzegorz A1 - Kozłowski, Grzegorz A1 - Zaumseil, Peter A1 - Bauer, Jakob A1 - Fursenko, Oksana A1 - Dabrowski, Jarek Marek A1 - Schmidt, R. A1 - Lippert, Gunther A1 - Müssig, Hans-Joachim A1 - Schröder, Thomas A1 - Schmeißer, Dieter A1 - Zschech, Ehrenfried T1 - Atomic-scale engineering of future high-k dynamic random access memory dielectrics: The example of partial Hf substitution by Ti in BaHfO3 T2 - Journal of Vacuum Science and Technology / B Y1 - 2011 SN - 2166-2754 VL - 29 IS - 1 ER - TY - CHAP A1 - Heim, S. A1 - Friedrich, Daniel A1 - Guttmann, P. A1 - Rehbein, S. A1 - Chumakov, Dmytro A1 - Ritz, Y. A1 - Schneider, G. A1 - Schmeißer, Dieter A1 - Zschech, Ehrenfried T1 - Dynamical X-ray Microscopy Study of Stress-Induced Voiding in Cu Interconnects KW - x-ray KW - Microscopy KW - Interconnects Y1 - 2009 UR - http://link.aip.org/link/?APCPCS/1143/20/1 ER - TY - CHAP A1 - Tallarida, Massimo A1 - Karavaev, Konstantin A1 - Schmeißer, Dieter A1 - Zschech, Ehrenfried T1 - HfO2 ALD-growth studied by in situ photoemission T2 - Proceedings of 15th Workshop on Dielectrics in Micoelectronics, Bad Saarow, 23 - 25 June 2008 KW - ald KW - photoemission Y1 - 2008 SP - 289 EP - 290 ER - TY - GEN A1 - Zschech, Ehrenfried A1 - Ho, O. S. A1 - Schmeißer, Dieter A1 - Meyer, Moritz Andreas A1 - Vairagar, A. V. A1 - Schneider, G. A1 - Hauschildt, Meike A1 - Kraatz, Matthias A1 - Sukharev, V. T1 - Geometry and Microstructure Effect on EM-Induced Copper Interconnect Degradation T2 - IEEE Transactions on Device and Materials Reliability KW - Microstructure Y1 - 2009 UR - http://ieeexplore.ieee.org/xpls/icp.jsp?arnumber=4796372 SN - 1530-4388 VL - 9 IS - 1 SP - 20 EP - 30 ER - TY - GEN A1 - Klocek, Jolanta A1 - Kolanek, Krzysztof A1 - Henkel, Karsten A1 - Zschech, Ehrenfried A1 - Schmeißer, Dieter T1 - Influence of the fullerene derivatives and cage polyhedral oligomeric silsesquioxanes on 3-aminopropyltrimethoxysilane based hybrid nanocomposites chemical, morphological and electrical properties T2 - Journal of Physics and Chemistry of Solids N2 - In this study we produced 3-aminopropyltrimethoxysilane based hybrid nanocomposites using fullerene derivative [6,6]–phenyl–C61–butyric acid methyl ester (PCBM) as nanodopants. Additionally, we modified obtained material with incompletely condensed cage polyhedral oligomeric silsesqiuox-anes (POSS) in order to improve its properties. Thin films were deposited by means of the spin-coating method. The films were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and capacitance–voltage (CV) measurements. We observed that a properly chosen PCBM concentration may be a crucial factor to obtain high quality APTMS based films by the spin-coating technique. XPS revealed the presence of the C-NH-C species within POSS containing films indicating chemical interaction between the amino group of APTMS and the POSS molecules. AFM results suggest that at high POSS monomer concentration in the range of 1% the creation of fractal-shaped aggregates takes place. The CV characterization of the samples exhibits a decrease of the APTMS based films dielectric constant due to the POSS and PCBM contribution. The combination of the applied methods delivers complementary information concerning the properties of the analyzed films. KW - low-k KW - fullerene KW - aminopropyltrimethoxysilane KW - silsesqiuoxane KW - X-ray photoelectron spectroscopy (XPS) KW - Atomic force microscopy (AFM) KW - Capacitance voltage (CV) Y1 - 2013 U6 - https://doi.org/10.1016/j.jpcs.2012.08.013 SN - 0022-3697 VL - 74 IS - 1 SP - 135 EP - 145 ER - TY - CHAP A1 - Tallarida, Massimo A1 - Karavaev, Konstantin A1 - Schmeißer, Dieter A1 - Zschech, Ehrenfried T1 - Photoemission and absorption spectroscopy for in situ investigations of the ALD growth T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43 N2 - We have investigated the growth of Hf-oxide on Si by means of photoemission and X-ray absorption spectroscopy using synchrotron radiation at Bessy, Berlin. The Hf-oxide layers were grown via atomic layer deposition (ALD) using an in-situ ALD reactor attached to the investigation chamber. The XPS and XAS spectra were measured after every deposition cycle by transferring the sample into the investigation chamber without breaking the vacuum. From the experimental data we have obtained information about the early stages of the Hf-oxide growth, concerning in particular the reactivity of the interface with Si. Due to the possibility to study the layers after every cycle and with different oxidation parameters without exposing them to contaminants, the in situ investigation revealed to be a very important method to understand the growth properties of Hf-oxide. Y1 - 2008 UR - http://www.dpg-verhandlungen.de/year/2008/conference/berlin/part/ds/session/22/contribution/5 SN - 0420-0195 SP - S. 242 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter A1 - Engelmann, Hans-Jürgen A1 - Zschech, Ehrenfried A1 - Stegmann, Heiko A1 - Himpsel, Franz J. A1 - Denlinger, Jonathan D. ED - Tsui, Ting Y. T1 - Characterization of chemical bonding in low-k dielectric materials for interconnect isolation: A XAS and EELS Study T2 - Materials, technology and reliability of low-k dielectrics and copper interconnects, symposium held April 18 - 21, 2006, San Francisco, California Y1 - 2006 SN - 978-1-55899-870-5 SP - 55 EP - 62 PB - Materials Research Society CY - Warrendale, Pa. ER - TY - CHAP A1 - Friedrich, Daniel A1 - Michling, Marcel A1 - Klocek, Jolanta A1 - Schmeißer, Dieter A1 - Avdoshenko, Stas A1 - Chumakov, Dmytro A1 - Zschech, Ehrenfried T1 - Study of C60 based films formation by NEXAFS T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44 N2 - The C60 fullerenes and some of its -OH, -CF3 and -Cl derivates are candidates for application as ultra-low-k insulators in the semiconductor industry. Future preparation of thin films based on these materials requires the stability of the substituted fullerenes against chemical handling and processing steps. The latter issue was addressed by our NEXAFS studies that were done by synchrotron radiation at the beam line U49/2-PGM2 at BESSY II. Performed were the C K-edge NEXAFS studies in total fluorescence and total electron yield modes. The C60 based films were deposited on silicon by spraying from solutions. The influence of the different substitutional groups with C60 molecules was studied. The data were compared to the reference spectra of a pure C60 film. For C60(OH)24, C60-Cl2 and C60(CF3)12 a variance of the intensity of the π*-resonance as well as shift to higher energies of 0.5 eV (-OH), 0.6 eV (-F), 0.7 eV (-Cl) were observed. The results confirm the necessary stability of the used C60 derivatives and shall be used for optimization of the film deposition chemistry and conditions. Y1 - 2009 SN - 0420-0195 SP - S. 145 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Kraatz, Matthias A1 - Gall, Martin A1 - Zschech, Ehrenfried A1 - Schmeißer, Dieter A1 - Ho, Paul S. T1 - A model for statistical electromigration simulation with dependence on capping layer and Cu microstructure in two dimensions T2 - Computational Materials Science N2 - A model has been developed to simulate electromigration degradation in an interconnect segment in two dimensions using finite differences. The model was deployed on a parallel computer to statistically assess the lifetimes. The simulation takes into account the diffusion paths for electromigration mass transport along the grain boundaries and the capping layer. The microstructure is generated with a Monte Carlo algorithm, using a modified Potts model. Diffusivities along the grain boundaries and the capping layers were applied as multiples of a base diffusivity and were statistically scattered. The simulation results correlate well with electromigration tests. KW - Electromigration KW - Grain growth KW - Computer simulation KW - 2D KW - Copper Interconnects KW - On-chip KW - Statistics KW - Parallel computing Y1 - 2016 U6 - https://doi.org/10.1016/j.commatsci.2016.04.020 SN - 1879-0801 SN - 0927-0256 VL - 120 SP - 29 EP - 35 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Tallarida, Massimo A1 - Henkel, Karsten A1 - Müller, Klaus A1 - Mandal, Dipankar A1 - Chumakov, Dmytro A1 - Zschech, Ehrenfried T1 - Characterization of oxidic and organic materials with synchrotron radiation based XPS and XAS KW - oxidic KW - organic KW - materials KW - synchrotron radiation KW - XPS KW - XAS Y1 - 2009 ER - TY - CHAP A1 - Hoffmann, Patrick A1 - Schmeißer, Dieter A1 - Himpsel, Franz J. A1 - Engelmann, Hans-Jürgen A1 - Zschech, Ehrenfried A1 - Stegmann, Heiko A1 - Denlinger, Jonathan D. T1 - Characterization of Chemical Bonding in Low-K Dielectric Materials for Interconnect Isolation: XAS and EELS Study T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 41 N2 - The use of low dielectric constant materials in the on-chip interconnect process reduces interconnect delay, power dissipation and crosstalk noise. In CVD deposited organo-silicate glass (OSG) the substitution of oxygen in SiO2 by methyl groups (-CH3) reduces the permittivity significantly (from 4.0 in SiO2 to 2.6-3.3 in the OSG). However, plasma processing removes C and H containing molecular groups. Therefore, compositional analysis and chemical bonding characterization of structured films with nanometer resolution is necessary. OSG thin films as-deposited and after plasma treatment are studied using XAS and EELS. In both techniques, the fine structure near the C1s edge allows to identify C-H, C-C, and C-O bonds. XAS spectra have been recorded for non-patterned films and EELS spectra for patterned structures. The chemical bonding is compared for as-deposited and plasma-treated low-k materials. The flu-orescence and the electron yield recorded while XAS measurement are compared. Examination of the C 1s near-edge structures reveal a mod-ified bonding of the remaining C atoms in the plasma-treated sample regions. Y1 - 2006 SN - 0420-0195 SP - S. 156 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Kraatz, Matthias A1 - Zhang, Lijuan A1 - Schmeißer, Dieter A1 - Zschech, Ehrenfried A1 - Ho, Paul S. T1 - Statistical Analysis of Computer-simulated On-Chip Interconnect Electromigration Lifetimes under the Influence of Microstructure and Strengthened Top Interface T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46 N2 - We are investigating the statistics of computer-simulated interconnect electromigration (EM) lifetimes with regard to the effects of microstructure and a strengthened top interface. The degradation process of EM once threatened the entire existence of integrated circuit industry in the 1960s and has remained a major reliability concern. Ongoing miniaturization and the introduction of new materials further complicate the task of EM-resistant chip manufacturing. We have developed a simple two-dimensional finite difference simulation that models the mass transport by electromigration along the grain boundaries and the top interface of interconnect segments that allows us to do calculations of void nucleation and growth. A parallel computer simulates hundreds of interconnects simultaneously and statistical analysis becomes feasible. A Monte Carlo grain growth algorithm (a modified Potts version) is applied to model the grain structure of the interconnect segments. We will show that the simulation can be used to compare simulation and experiment qualitatively. Four cases have been studied: interconnect segments with small/large grains and weak/strong top interface. Y1 - 2011 UR - http://www.dpg-verhandlungen.de/year/2011/conference/dresden/part/ds/session/7/contribution/2 SN - 0420-0195 SP - S. 292 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Kraatz, Matthias A1 - Schmeißer, Dieter A1 - Zschech, Ehrenfried A1 - Ho, Paul S. T1 - Electromigration simulation for on-chip Cu interconnects T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44 N2 - We are investigating the influence of copper microstructure on electromigration degradation effects and interconnect lifetimes using computer simulation. The simulation is carried out in three dimensions. For the copper microstructure, a Monte Carlo technique was used to model the Cu grain growth. Different diffusivities where applied to grain boundaries and top interface of the interconnect model according to the qualitative crystallographic orientation of adjacent grains. The grain boundary network and the top interface form the diffusion paths for the electromigration mass transport. Along the diffusion paths, the fluxes of vacancies where calculated including mechanical stress and electromigration driving forces using a finite difference method. Positive flux divergent sites of the FDM lattice are treated as void nucleation sites after a critical vacancy concentration is reached. The resistance increase due to void growth was calculated using a cellular automaton, masking current free regions as quasi voids and adding the resistance of the slices of the lattice normal to the electron flow direction in series. A parallel computing environment was used to generate large numbers of interconnect models in order to obtain a pool of data for statistical analysis of interconnect lifetimes. The results of this analysis will be shown Y1 - 2009 UR - http://www.dpg-verhandlungen.de/year/2009/conference/dresden/part/ds/session/13/contribution/4 SN - 0420-0195 SP - S. 161 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Klocek, Jolanta A1 - Henkel, Karsten A1 - Kolanek, Krzysztof A1 - Zschech, Ehrenfried A1 - Schmeißer, Dieter T1 - Spectroscopic and capacitance-voltage characterization of thin aminopropylmethoxysilane films doped with copper phthalocyanine, tris(dimethylvinylsilyloxy)-POSS and fullerene cages T2 - Applied surface science Y1 - 2012 SN - 0169-4332 VL - 258 IS - 10 SP - 4213 EP - 4221 ER - TY - CHAP A1 - Broczkowska, K. A1 - Klocek, Jolanta A1 - Friedrich, Daniel A1 - Henkel, Karsten A1 - Kolanek, Krzysztof A1 - Urbanowicz, A. A1 - Schmeißer, Dieter A1 - Miller, M. A1 - Zschech, Ehrenfried T1 - Fullerene based materials for ultra-low-k application T2 - International Students and Young Scientists Workshop "Photonics and Microsystems", Szklarska, Poreba, Poland, 25 - 27 June 2010 Y1 - 2010 SN - 978-1-4244-8324-2 SP - 39 EP - 43 PB - IEEE CY - Piscataway, NJ ER - TY - GEN A1 - Klocek, Jolanta A1 - Henkel, Karsten A1 - Kolanek, Krzysztof A1 - Broczkowska, K. A1 - Schmeißer, Dieter A1 - Miller, M. A1 - Zschech, Ehrenfried T1 - Studies of the chemical and electrical properties of fullerene and 3-aminopropyltrimethoxysilane based low-k materials T2 - Thin Solid Films Y1 - 2012 SN - 0040-6090 VL - 520 IS - 7 SP - 2498 EP - 2504 ER - TY - GEN A1 - Klocek, Jolanta A1 - Henkel, Karsten A1 - Kolanek, Krzysztof A1 - Zschech, Ehrenfried A1 - Schmeißer, Dieter T1 - Annealing influence on siloxane based materials incorporated with fullerenes, phthalocyanines and silsesquioxanes T2 - BioNanoScience Y1 - 2012 SN - 2191-1630 VL - 2 IS - 1 SP - 52 EP - 58 ER - TY - GEN A1 - Zagorodniy, Kostyantyn A1 - Chumakov, Dmytro A1 - Täschner, Christine A1 - Lukowiak, Anna A1 - Stegmann, Heiko A1 - Schmeißer, Dieter A1 - Geisler, Holm A1 - Engelmann, Hans-Jürgen A1 - Hermann, Helmut A1 - Zschech, Ehrenfried T1 - Novel Carbon-cage based ultralow-k materials: Modelling and first experiments KW - carbon-cage KW - ultralow-k Y1 - 2008 U6 - https://doi.org/10.1109/TSM.2008.2005396 ER - TY - GEN A1 - Ho, Paul S. A1 - Zschech, Ehrenfried A1 - Schmeißer, Dieter A1 - Meyer, Moritz Andreas A1 - Huebner, Rene A1 - Hauschildt, Meike A1 - Zhang, Lijuan A1 - Gall, Martin A1 - Kraatz, Matthias T1 - Scaling effects on microstructure and reliability for cu interconnects KW - scaling KW - microstructure KW - interconnects Y1 - 2010 ER - TY - CHAP A1 - Klocek, Jolanta A1 - Friedrich, Daniel A1 - Schmeißer, Dieter A1 - Hecker, Michael A1 - Zschech, Ehrenfried T1 - The stability of C60 and its derivatives upon handling in microsystems technologies T2 - International Students and Young Scientists Workshop "Photonics and Microsystems", 2009, 25 - 27 June 2009, Harz University, Wernigerode, Germany KW - c60 KW - derivatices Y1 - 2009 SN - 978-1-4244-4303-1 SP - 43 EP - 46 PB - IEEE CY - Piscataway, NJ ER - TY - GEN A1 - Zschech, Ehrenfried A1 - Geisler, Holm A1 - Rinderknecht, Jochen A1 - Schneider, Gerd A1 - Spolenak, Ralph A1 - Schmeißer, Dieter T1 - Nano-scale analysis using synchrotron-radiation: Applications in the semiconductor industry T2 - Current nanoscience KW - synchrotron-radiation KW - semiconductor Y1 - 2008 SN - 1573-4137 VL - 4 IS - 3 SP - 256 EP - 266 ER - TY - CHAP A1 - Schmeißer, Dieter A1 - Zheng, Fan A1 - Himpsel, Franz J. A1 - Engelmann, Hans-Jürgen A1 - Zschech, Ehrenfried T1 - Silicate Formation at the Interface of High-k Dielectrics and Si(001) Surfaces Y1 - 2006 ER - TY - JOUR A1 - Schmeißer, Dieter A1 - Zschech, Ehrenfried T1 - Silicate Formation at the Interface of Hf-Oxide and Pr-Oxide as a High-k Dielectric and Si(001) surfaces Y1 - 2006 ER - TY - GEN A1 - Schwarzkopf, Jutta A1 - Dirsyte, R. A1 - Devi, A. A1 - Kwasniewski, A. A1 - Schmidbauer, M. A1 - Wagner, Gerd A1 - Michling, Marcel A1 - Schmeißer, Dieter A1 - Fornari, Robert T1 - Influence of Na on the structure of Bi4Ti3O12 films deposited by liquid-delivery spin MOCVD T2 - Thin solid films Y1 - 2011 SN - 0040-6090 VL - 519 IS - 17 SP - 5754 EP - 5759 ER - TY - CHAP A1 - Schmeißer, Dieter A1 - Hoffmann, Patrick A1 - Beuckert, Guido ED - Zschech, Ehrenfried ED - Whelan, Caroline T1 - Electronic Properties of the Interface Formed by Pr2o3 Growth on Si(001), Si(111)and SiC(0001) Surfaces Y1 - 2005 ER - TY - CHAP A1 - Zschech, Ehrenfried A1 - Stegmann, Heiko A1 - Schmeißer, Dieter A1 - Hoffmann, Patrick T1 - Chemical Bonding, Permittivity, and Elastic Properties in Locally Modified Organosilicate Glass Y1 - 2006 ER - TY - CHAP A1 - Haeberle, Jörg A1 - Gaspar, Diana A1 - Barquinha, Pedro A1 - Machulik, Stephan A1 - Janowitz, Christoph A1 - Galazka, Zbigniew A1 - Schmeißer, Dieter T1 - A spectroscopic comparison of AOS thin films and TCO single crystals T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Amorphous oxide semiconductors (AOS) and transparent conductive oxides (TCO) are today one of most attractive fields of research in many industrial products, like e.g. high definition, low cost, transparent, and flexible displays. We got the unique possibility to measure a-GIZO and a-SnOx thin films and compare their electronic properties with those of In2O3, Ga2O3, ZnO, and SnO2 single crystals. We use resPES to study the electronic properties. We report on the core levels, the VB PES data, partial Integrated Yield (pIY) and the XAS absorption data. From these we are able to derive the elemental ratio, the pDOS as well as the band scheme. At the O1s resonance we observe multiple Auger processes from which we deduce that a band of localized defect states is located between the Fermi energy and the CBM. The resonant profiles taken at the corresponding metal edges indicate that metal states are involved in the DOS. KW - Amorphous oxide semiconductors (AOS) KW - Transparent conductive oxides (TCO) KW - In2O3 KW - Ga2O3 KW - ZnO KW - SnO2 KW - GIZO KW - resonant photoelectron spectroscopy Y1 - 2014 UR - http://www.dpg-verhandlungen.de/year/2014/conference/dresden/part/hl/session/107/contribution/15?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Janowitz, Christoph A1 - Scherer, Valentina A1 - Mohamed, Mansour A1 - Krapf, Alica A1 - Dwelk, Helmut A1 - Manzke, Recardo A1 - Galazka, Zbigniew A1 - Uecker, Reinhard A1 - Irmscher, Klaus A1 - Fornari, Robert A1 - Michling, Marcel A1 - Schmeißer, Dieter T1 - Experimental electronic structure of In2O3 and Ga2O3 T2 - New Journal of Physics Y1 - 2011 SN - 1367-2630 VL - 13 IS - 8 SP - 085014 ER - TY - GEN A1 - Haeberle, Jörg A1 - Richter, Matthias A1 - Galazka, Zbigniew A1 - Janowitz, Christoph A1 - Schmeißer, Dieter T1 - Resonant Photoemission at the O1s threshold to characterize In2O3 single crystals T2 - Thin Solid Films N2 - We report on spectroscopic investigations on In2O3 single crystals. We focus on the detailed analysis of the O1s resonance profile by resonant photoelectron spectroscopy. We analyze the electronic structure and assign the O2p to build the valence band and both, O2p and In5s5p states to contribute to the conduction band (CB). We determine the partial density of states for the valence and CBs and find a strong hybridization of O2p and In5s states. This is deduced from constant final state spectra on the O-KLL-Auger over the O K-edge and In M4,5-edge and a comparison to the corresponding X-ray absorption spectroscopy data.We also identify several types of defects. A broad band of oxygen derived defects is identified that extends throughout the gap. These are attributed to small polarons which cause an anti-resonance in the valence states around the O1s threshold. In addition, a separate Auger decay at resonance indicates the existence of localized charge transfer states which involves localized In5s5p states. KW - In2O3 KW - TCO KW - X-ray spectroscopy KW - Small polaron KW - Charge transfer Y1 - 2014 U6 - https://doi.org/10.1016/j.tsf.2013.03.036 SN - 0040-6090 SN - 1879-2731 VL - 2014 IS - 555 SP - 53 EP - 56 ER - TY - GEN A1 - Haeberle, Jörg A1 - Brizzi, Simone A1 - Gaspar, Diana A1 - Barquinha, Pedro A1 - Galazka, Zbigniew A1 - Schulz, Detlev A1 - Schmeißer, Dieter T1 - A spectroscopic comparison of IGZO thin film and the parent In2O3, Ga2O3, and ZnO single crystals T2 - Materials Research Express N2 - We use resonant photoelectron spectroscopy at the Zn 2p, Ga 2p, In 3d, and O 1s absorption edges to report on the electronic properties of indium–gallium–zinc-oxide thin films. We also compare the data with the respective data of the corresponding single crystals In2O3, Ga2O3, and ZnO. We focus on the elemental composition and, in particular, find no evidence for oxygen deficiency. The In, Ga, and Zn absorption data at resonance can be used to analyze the conduction band states in detail. We deduce that a configuration interaction between d10s0 and d9s1states is of importance. We provided a novel mechanism in which configuration interaction induced gap states create both, extended unoccupied states around E F as well as localized occupied states within the gap. KW - transparent conducting oxides (TCO) KW - resonant photoelectron spectroscopy KW - in-gapdefect states Y1 - 2016 U6 - https://doi.org/10.1088/2053-1591/3/10/106302 SN - 2053-1591 VL - 3 IS - 10 SP - 106302-1 EP - 106302-17 ER - TY - JOUR A1 - Viehweger, Bernd A1 - Simon, Sylvio A1 - Wagner, Lothar A1 - Schmeißer, Dieter T1 - Entwicklung eines neuartigen Fügeverfahrens für die Herstellung von Aluminium-Stahl-Tailored Blanks N2 - Die Anwendung von Tailored Blanks im Karosseriebau trägt wesentlich zur Gewichtsreduzierung und damit zur Kraftstoffeinsparung an Fahrzeugen bei. Bisher bekannte Tailored Blanks aus Aluminium und Stahl werden mittels Laserschweißen überlappend gefügt. Für ein Aluminium-Stahl-Tailored Blank wurde ein Verfahren entwickelt, das die Herstellung desselben durch ein umformendes Fügeverfahren ermöglicht. Unter Berücksichtigung der Erkenntnisse des Kaltpressschweißens wird mittels eines Walzvorganges eine Fügung erreicht. Dadurch wird ein Aufschmelzen der Fügepartner und die damit eventuell verbundene Bildung interkristalliner Zonen verhindert. Der Walzvorgang verhindert gleichzeitig die bei Kaltpressschweißen sonst üblichen Kerben. Durch eine anschließende Wärmebehandlung lässt sich die Festigkeit der Verbindung steigern. Das Aluminium-Stahl-Tailored Blank kann in verschiedenen Abmessungen gefertigt werden und ist blecheben. KW - Fügen durch Umformen KW - Kaltpressschweißen KW - Stahl-Aluminium-Verbund Y1 - 2002 ER - TY - CHAP A1 - Haeberle, Jörg A1 - Richter, Matthias A1 - Schmeißer, Dieter A1 - Galazka, Zbigniew A1 - Janowitz, Christoph T1 - Resonant Photoemission at the O1s threshold to characterize In2O3 single crystals T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - We report on spectroscopic investigations on In2O3 single crystals. We focus on the detailed analysis of the O1s resonance profile by resonant photoelectron spectroscopy (resPES). From these we analyze the electronic structure and assign the O2p- and In5sp state to build the valence band and the conduction band in different contributions, respectively. This is deduced from constant final state spectra on the O-KLL-Auger along the O K-edge and In M4,5-edge and a comparison to the corresponding X-ray absorption spectroscopy data. We also identify several types of defects. A broad band of oxygen derived defects is identified in the valence band and extends throughout the gap. Small polarons are attributed to cause an anti-resonance in the constant initial states around the O1s threshold. In addition, an Auger decay separated by the O-KLL is present at O-K resonance and indicates the existence of localized charge transfer states which involves In5sp states. Finally, we are able to distinguish two different oxygen species from the resPES data. One corresponds to theintrinsic In2O3 structure and the other is a non-corresponding species. KW - resonant photoelectron spectroscopy KW - In2O3 Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/mm/session/15/contribution/57?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - JOUR A1 - Müller, Sebastian A1 - Seibold, Götz A1 - Schmeißer, Dieter ED - Vierhaus, Heinrich Theodor T1 - Preparation and Characterization of TiO2 Thin Films and Cr and Co Doped TiO2 Thin Films Y1 - 2007 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Schmidt, Stephan A1 - Seibold, Götz A1 - Cherkashinin, Gennady A1 - Jaegermann, Wolfram T1 - Localized Gap States in LiCoO2 and their Influence on the Transport Properties in Li-Ion Batteries T2 - ECS Transactions Y1 - 2010 SN - 1938-5862 VL - 25 IS - 35 SP - 37 EP - 45 ER -