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 - JOUR A1 - Hoffmann, Patrick T1 - Photoemission studies of very thin (<10nm) silicon oxynitride (SiOxNy) layers formed by PECVD N2 - The "ITRS Roadmap" suggests the necessity of working out the processing methods allowing formation of ultrathin dielectric layers with higher values of the dielectric permittivity than for silicon dioxide. The silicon oxynitride layers (SiOxNy) seem to be the most natural compromise. But still none of high temperature methods used for its formation can be seriously considered as final solution for future ULSI-CMOS ICs production due to the inevitable formation of nitride monolayers just at the silicon-insulator interface. The main scope of this investigation is to check if this is true. KW - Semiconductors KW - Thin films KW - Vapour deposition KW - Photoelectron spectroscopies KW - Synchrotron radiation Y1 - 2004 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 -