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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 -