@inproceedings{RichterSchmeisser, author = {Richter, Matthias and Schmeißer, Dieter}, title = {The Co2p oxidation state in Co-PI catalysts}, series = {Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012}, booktitle = {Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012}, publisher = {The Electrochemical Society}, pages = {1803}, language = {en} } @inproceedings{RichterFriedrichSchmeisser, author = {Richter, Matthias and Friedrich, Daniel and Schmeißer, Dieter}, title = {Multiple Auger decay at resonant photo-excitation in carbon thin films}, series = {Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012}, booktitle = {Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012}, publisher = {The Electrochemical Society}, pages = {3509}, language = {en} } @inproceedings{SchmeisserRichterTallarida, author = {Schmeißer, Dieter and Richter, Matthias and Tallarida, Massimo}, title = {Intrinsic defects in TiO2 to explain resistive switching devices}, series = {Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany}, booktitle = {Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany}, editor = {Heber, J{\"o}rg and Schlom, Darrell and Tokura, Yoshinori and Waser, Rainer and Wuttig, Matthias}, publisher = {Wiley-VCH}, address = {Weinheim}, isbn = {978-3-527-41191-7}, doi = {10.1002/9783527667703.ch45}, pages = {255 -- 256}, language = {en} } @inproceedings{MandalHenkelDasetal., author = {Mandal, Dipankar and Henkel, Karsten and Das, Suken and Schmeißer, Dieter}, title = {Control of β- and γ-Phase formation in electroactive P(VDF-HFP) films by silver nano-particle doping}, series = {Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany}, booktitle = {Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany}, editor = {Heber, J{\"o}rg and Schlom, Darrell and Tokura, Yoshinori and Waser, Rainer and Wuttig, Matthias}, publisher = {Wiley-VCH}, address = {Weinheim}, isbn = {978-3-527-41191-7}, doi = {10.1002/9783527667703.ch69}, pages = {640 -- 641}, language = {en} } @misc{TallaridaAdelmannDelabieetal., author = {Tallarida, Massimo and Adelmann, Christoph and Delabie, Annelies and Elshocht, Sven van and Caymax, Matty and Schmeißer, Dieter}, title = {III-V/Oxide Interfaces Investigated with Synchrotron Radiation Photoemission Spectroscopy}, series = {ECS Transactions}, volume = {50}, journal = {ECS Transactions}, number = {4}, issn = {1938-6737}, doi = {10.1149/05004.0123ecst}, pages = {123 -- 128}, abstract = {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.}, language = {en} } @misc{MuellerFleigeRachowetal., author = {M{\"u}ller, Klaus and Fleige, Michael and Rachow, Fabian and Schmeißer, Dieter}, title = {Sabatier based CO2-methanation of flue gas emitted by conventional power plants}, series = {Energy Procedia}, volume = {40}, journal = {Energy Procedia}, issn = {1876-6102}, doi = {10.1016/j.egypro.2013.08.028}, pages = {240 -- 248}, abstract = {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.}, language = {en} } @inproceedings{MaiDauderstaedtPahneretal., author = {Mai, Andreas and Dauderst{\"a}dt, Ulrike and Pahner, D. and Krellmann, M. and Schmeißer, Dieter and Wagner, M.}, title = {In situ determination of laser induced degradation of micro-mirror arrays}, series = {International Students and Young Scientists Workshop Photonics and Microsystems, Cottbus, Germany, 8 - 10 June 2011}, booktitle = {International Students and Young Scientists Workshop Photonics and Microsystems, Cottbus, Germany, 8 - 10 June 2011}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4577-1651-5}, doi = {10.1109/STYSW.2011.6155850}, pages = {84 -- 88}, abstract = {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.}, language = {en} } @misc{BarrecaCarraroGasparottoetal., author = {Barreca, Davide and Carraro, Giorgio and Gasparotto, Alberto and Maccato, Chiara and Rossi, Francesca and Salviati, Giancarlo and Tallarida, Massimo and Das, Chittaranjan and Fresno, Fernando and Korte, Dorota and Štangar, Urška Lavrenčič and Franko, Mladen and Schmeißer, Dieter}, title = {Surface Functionalization of Nanostructured Fe2O3 Polymorphs: From Design to Light-Activated Applications}, series = {ACS Applied Materials \& Interfaces}, volume = {5}, journal = {ACS Applied Materials \& Interfaces}, number = {15}, issn = {1944-8252}, doi = {10.1021/am401475g}, pages = {7130 -- 7138}, abstract = {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.}, language = {en} } @misc{AdelmannCuypersTallaridaetal., author = {Adelmann, Christoph and Cuypers, Daniel and Tallarida, Massimo and Rodriguez, Leonard and De Clercq, Astrid and Friedrich, Daniel and Conard, Thierry and Delabie, Annelies and Seo, Jin Won and Locquet, Jean-Pierre and De Gendt, Stefan and Schmeißer, Dieter and Elshocht, Sven van and Caymax, Matty}, title = {Surface Chemistry and Interface Formation during the Atomic Layer Deposition of Alumina from Trimethylaluminum and Water on Indium Phosphide}, series = {Chemistry of Materials}, volume = {25}, journal = {Chemistry of Materials}, number = {7}, issn = {1520-5002}, doi = {10.1021/cm304070h}, pages = {1078 -- 1091}, abstract = {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.}, language = {en} } @misc{RossiFabbriTallaridaetal., author = {Rossi, Francesca and Fabbri, Filippo and Tallarida, Massimo and Schmeißer, Dieter and Modreanu, Mircea and Attolini, Giovanni and Salviati, Giancarlo}, title = {Structural and luminescence properties of HfO2 nanocrystals grown by atomic layer deposition on SiC/SiO2 core/shell nanowires}, series = {Scripta Materialia}, volume = {69}, journal = {Scripta Materialia}, number = {10}, issn = {1359-6462}, doi = {10.1016/j.scriptamat.2013.08.017}, pages = {744 -- 747}, abstract = {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.}, language = {en} } @misc{HaeberleHenkelGargourietal., author = {Haeberle, J{\"o}rg and Henkel, Karsten and Gargouri, Hassan and Naumann, Franziska and Gruska, Bernd and Arens, Michael and Tallarida, Massimo and Schmeißer, Dieter}, title = {Ellipsometry and XPS comparative studies of thermal and plasma enhanced atomic layer deposited Al2O3-films}, series = {Beilstein Journal of Nanotechnology}, volume = {2013}, journal = {Beilstein Journal of Nanotechnology}, number = {4}, issn = {2190-4286}, doi = {10.3762/bjnano.4.83}, pages = {732 -- 742}, abstract = {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.}, language = {en} } @inproceedings{CuypersDorpTallaridaetal., author = {Cuypers, Daniel and Dorp, Dennis H. von and Tallarida, Massimo and Brizzi, Simone and Rodriguez, Leonard and Conard, Thierry and Arnauts, Sophia and Schmeißer, Dieter and Adelmann, Christoph and De Gendt, Stefan}, title = {Study of InP Surfaces After Wet Chemical Treatments}, series = {Meeting Abstracts-Electrochemical Society, San Francisco, 2013}, booktitle = {Meeting Abstracts-Electrochemical Society, San Francisco, 2013}, publisher = {The Electrochemical Society}, pages = {S. 2132}, language = {en} } @misc{CuypersDorpTallaridaetal., author = {Cuypers, Daniel and Dorp, Dennis H. von and Tallarida, Massimo and Brizzi, Simone and Rodriguez, Leonard and Conard, Thierry and Arnauts, Sophia and Schmeißer, Dieter and Adelmann, Christoph and De Gendt, Stefan}, title = {Study of InP Surfaces after Wet Chemical Treatments}, series = {ECS Transactions}, volume = {58}, journal = {ECS Transactions}, number = {6}, issn = {1938-6737}, doi = {10.1149/05806.0297ecst}, pages = {297 -- 303}, abstract = {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.}, language = {en} } @misc{CuypersDorpTallaridaetal., author = {Cuypers, Daniel and Dorp, Dennis H. von and Tallarida, Massimo and Brizzi, Simone and Conard, Thierry and Rodriguez, Leonard and Mees, M. and Arnauts, Sophia and Schmeißer, Dieter and Adelmann, Christoph and De Gendt, Stefan}, title = {Study of InP Surfaces after Wet Chemical Treatments}, series = {ECS Journal of Solid State Science and Technology}, volume = {3}, journal = {ECS Journal of Solid State Science and Technology}, number = {1}, issn = {2162-8777}, doi = {10.1149/2.005401jss}, pages = {N3016 -- N3022}, abstract = {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.}, language = {en} } @misc{MuellerStaedterRachowetal., author = {M{\"u}ller, Klaus and St{\"a}dter, Matthias and Rachow, Fabian and Hoffmannbeck, David and Schmeißer, Dieter}, title = {Sabatier-based CO2-methanation by catalytic conversion}, series = {Environmental Earth Sciences}, volume = {70}, journal = {Environmental Earth Sciences}, number = {8}, issn = {1866-6280}, doi = {10.1007/s12665-013-2609-3}, pages = {3771 -- 3778}, abstract = {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.}, language = {en} } @misc{DasTallaridaSchmeisser, author = {Das, Chittaranjan and Tallarida, Massimo and Schmeißer, Dieter}, title = {Linear dichroism in ALD layers of TiO₂}, series = {Environmental Earth Sciences}, volume = {70}, journal = {Environmental Earth Sciences}, number = {8}, issn = {1866-6280}, doi = {10.1007/s12665-013-2836-7}, pages = {3785 -- 3795}, abstract = {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.}, language = {en} } @misc{StaedterMuellerRachowetal., author = {St{\"a}dter, Matthias and M{\"u}ller, Klaus and Rachow, Fabian and Richter, Matthias and Schmeißer, Dieter}, title = {Ambient pressure thermal desorption spectroscopy (AP-TDS) of NiO/SiO2 catalysts}, series = {Environmental Earth Sciences}, volume = {70}, journal = {Environmental Earth Sciences}, number = {8}, issn = {1866-6280}, doi = {10.1007/s12665-013-2835-8}, pages = {3779 -- 3784}, abstract = {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.}, language = {en} } @misc{ScheckWenderothSchmeisserMuttietal., author = {Scheck-Wenderoth, Magdalena and Schmeißer, Dieter and Mutti, Maria and Kolditz, Olaf and Huenges, Ernst and Schultz, Hans-Martin and Liebscher, Axel and Bock, Michaela}, title = {Geoenergy: new concepts for utilization of geo-reservoirs as potential energy sources}, series = {Environmental Earth Sciences}, volume = {70}, journal = {Environmental Earth Sciences}, number = {8}, issn = {1866-6280}, doi = {10.1007/s12665-013-2877-y}, pages = {3427 -- 3431}, language = {en} } @misc{GerlichOhsiekKleinetal., author = {Gerlich, Lukas and Ohsiek, Susanne and Klein, Christoph and Geiß, Mario and Friedemann, Michael and K{\"u}cher, Peter and Schmeißer, Dieter}, title = {Interface engineering for the TaN/Ta barrier film deposition process to control Ta-crystal growth}, series = {Microelectronic Engineering}, volume = {Vol. 106}, journal = {Microelectronic Engineering}, doi = {10.1016/j.mee.2013.01.017}, pages = {63 -- 68}, abstract = {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.}, language = {en} } @misc{HenkelGargouriGruskaetal., author = {Henkel, Karsten and Gargouri, Hassan and Gruska, Bernd and Arens, Michael and Tallarida, Massimo and Schmeißer, Dieter}, title = {Capacitance and conductance versus voltage characterization of Al2O3 layers prepared by PE-ALD at 25°C ≤ T ≤ 200°C}, series = {Journal of Vacuum Science and Technology A}, volume = {1}, journal = {Journal of Vacuum Science and Technology A}, number = {32}, doi = {10.1116/1.4831897}, pages = {01A107-1 -- 01A107-10}, abstract = {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.}, language = {en} } @misc{RichterStarkeSchmeisser, author = {Richter, Matthias and Starke, Ulrich and Schmeißer, Dieter}, title = {Multiple Auger processes in Graphene}, series = {Journal of Electron Spectroscopy and Related Phenomena}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, number = {Vol. 192}, issn = {0368-2048}, doi = {10.1016/j.elspec.2013.12.009}, pages = {1 -- 6}, abstract = {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.}, language = {en} } @misc{TallaridaDasSchmeisser, author = {Tallarida, Massimo and Das, Chittaranjan and Schmeißer, Dieter}, title = {Quantum size effects in TiO2 thin films grown by atomic layer deposition}, series = {Beilstein Journal of Nanotechnology}, journal = {Beilstein Journal of Nanotechnology}, number = {5}, issn = {2190-4286}, doi = {10.3762/bjnano.5.7}, pages = {77 -- 82}, abstract = {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 {\AA}/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.}, language = {en} } @misc{RichterFriedrichSchmeisser, author = {Richter, Matthias and Friedrich, Daniel and Schmeißer, Dieter}, title = {Interlayer-exciton mediated three-hole-Auger-decay in the pi-band of highly oriented pyrolytic graphite}, series = {Physica E}, volume = {Vol. 56}, journal = {Physica E}, issn = {1386-9477}, doi = {10.1016/j.physe.2013.01.015}, pages = {441 -- 446}, abstract = {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.}, language = {en} }