@inproceedings{WyrodekTallaridaSchmeisseretal., author = {Wyrodek, Jakub and Tallarida, Massimo and Schmeißer, Dieter and Weisheit, Martin}, title = {Determination of interfacial layers in high - k ALD nanolaminate materials by ARXPS and SRXPS measurements}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 232}, abstract = {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.}, language = {en} } @inproceedings{BergholzSchmeisser, author = {Bergholz, Matthias and Schmeißer, Dieter}, title = {Band gap determination of thin Praseodymiumoxide layers on Aluminiumoxynitride films}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 243}, abstract = {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 {\AA}ngstr{\"o}m, 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.}, language = {en} } @inproceedings{BurkovHenkelSchmeisser, author = {Burkov, Yevgen and Henkel, Karsten and Schmeißer, Dieter}, title = {X-ray photoemission spectroscopy of Aluminium Oxynitride on Si(001) and the rise as buffer layers}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 243}, abstract = {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.}, language = {en} } @inproceedings{HenkelSeimePaloumpaetal., author = {Henkel, Karsten and Seime, Bernd and Paloumpa, Ioanna and M{\"u}ller, Klaus and Schmeißer, Dieter}, title = {C(V) and C(t) measurements on MFIS structures consisting P[VDF/TrFE] as ferroelectric layer}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 828}, abstract = {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).}, language = {en} } @inproceedings{KaravaevTallaridaSchmeisseretal., author = {Karavaev, Konstantin and Tallarida, Massimo and Schmeißer, Dieter and Zschech, Ehrenfried}, title = {In-situ ALD growth of Hafnium oxide films}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 244}, abstract = {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.}, language = {en} } @inproceedings{MandalMuellerSchmeisser, author = {Mandal, Dipankar and M{\"u}ller, Klaus and Schmeißer, Dieter}, title = {Dipole orientation of the P[VDF-TrFE] co-polymer films: A NEXAFS study}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 840}, abstract = {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).}, language = {en} } @inproceedings{MuellerMandalHenkeletal., author = {M{\"u}ller, Klaus and Mandal, Dipankar and Henkel, Karsten and Paloumpa, Ioanna and Schmeißer, Dieter}, title = {Interface reactions of ferroelectric copolymer layers with different electrode materials}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 830}, abstract = {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.}, language = {en} } @inproceedings{MuellerSchmeisser, author = {M{\"u}ller, Sebastian and Schmeißer, Dieter}, title = {Direct Observation of d2L2 Charge Transfer States in TiO2 thin films by Resonant Photoelectron Spectroscopy}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 592}, abstract = {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.}, language = {en} } @inproceedings{TallaridaKaravaevSchmeisseretal., author = {Tallarida, Massimo and Karavaev, Konstantin and Schmeißer, Dieter and Zschech, Ehrenfried}, title = {Photoemission and absorption spectroscopy for in situ investigations of the ALD growth}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 242}, abstract = {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.}, language = {en} } @inproceedings{OpelNielsenBaueretal., author = {Opel, Matthias and Nielsen, Karl-Wilhelm and Bauer, Sebastian and Goennenwein, Sebastian T. B. and Gross, Rudolf and Cezar, Julio C. and Schmeißer, Dieter and Simon, J{\"u}rgen and Mader, Werner}, title = {Ferromagnetism and magnetic clusters in cobalt-doped ZnO}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 430}, abstract = {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.}, language = {en} } @inproceedings{LazarevaKovalMuelleretal., author = {Lazareva, I. and Koval, Yuri and M{\"u}ller, P. and Paloumpa, Ioanna and M{\"u}ller, Klaus and Schmeißer, Dieter}, title = {Field effect transistor of graphitized polyimide with P(VDF-TrFE) as gate insulator}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 195}, abstract = {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. Str{\"o}msd{\"o}rfer, P. M{\"u}ller, Appl. Phys. Lett. 90, 262108 (2007)}, language = {en} } @inproceedings{BergholzSohalSchmeisser, author = {Bergholz, Matthias and Sohal, Rakesh and Schmeißer, Dieter}, title = {ELS to determine the band gap of thin dielectric layers}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 41}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 41}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 156}, abstract = {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.}, language = {en} } @inproceedings{HenkelTorcheSchwiertzetal., author = {Henkel, Karsten and Torche, Mohamed and Schwiertz, Carola and Paloumpa, Ioanna and Sohal, Rakesh and M{\"u}ller, Klaus and Schmeißer, Dieter}, title = {Inorganic and organic layers for high-k and organic memory applications}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 41}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 41}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 127}, abstract = {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.}, language = {en} } @inproceedings{MuellerHenkelPaloumpaetal., author = {M{\"u}ller, Klaus and Henkel, Karsten and Paloumpa, Ioanna and Schmeißer, Dieter}, title = {P(VDF/TrFE) as ferroelectric insulation layer for organic field effect transistors}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 41}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 41}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 101}, abstract = {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.}, language = {en} } @inproceedings{HoffmannSchmeisserHimpseletal., author = {Hoffmann, Patrick and Schmeißer, Dieter and Himpsel, Franz J. and Engelmann, Hans-J{\"u}rgen and Zschech, Ehrenfried and Stegmann, Heiko and Denlinger, Jonathan D.}, title = {Characterization of Chemical Bonding in Low-K Dielectric Materials for Interconnect Isolation: XAS and EELS Study}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 41}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 41}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 156}, abstract = {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.}, language = {en} } @inproceedings{MuellerChowdhuryDremovetal., author = {M{\"u}ller, P. and Chowdhury, F. and Dremov, V. and Koval, Yuri and Lichtenberg, F. and M{\"u}ller, S. and Schmeißer, Dieter and Pentcheva, R.}, title = {Resistive memory switching in perovskite-derivative single crystals}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 818}, abstract = {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.}, language = {en} } @inproceedings{SeifarthWalczykLupinaetal., author = {Seifarth, Olaf and Walczyk, Christian and Lupina, Grzegorz and Dabrowski, Jaroslaw and Weidner, G{\"u}nter and Zaumseil, Peter and Schmeißer, Dieter and Storck, Peter and M{\"u}ssig, Hans-Joachim and Schroeder, Thomas}, title = {On the electronic and dielectric characterisation of thin cubic PrO2 layers on Silicon}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 196}, abstract = {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.}, language = {en} } @inproceedings{FriedrichMichlingKloceketal., author = {Friedrich, Daniel and Michling, Marcel and Klocek, Jolanta and Schmeißer, Dieter and Avdoshenko, Stas and Chumakov, Dmytro and Zschech, Ehrenfried}, title = {Study of C60 based films formation by NEXAFS}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 145}, abstract = {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.}, language = {en} } @inproceedings{KaravaevTallaridaSchmeisser, author = {Karavaev, Konstantin and Tallarida, Massimo and Schmeißer, Dieter}, title = {Evolution of the interfacial layer during the atomic layer deposition of HfO2 on Si/SiO2 substrates}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 160}, abstract = {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.}, language = {en} } @inproceedings{KolanekKaravaevTallaridaetal., author = {Kolanek, Krzysztof and Karavaev, Konstantin and Tallarida, Massimo and Schmeißer, Dieter}, title = {In-situ investigations of the atomic layer deposition of HfO2 with UHV/AFM}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 160}, abstract = {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.}, language = {en} } @inproceedings{KraatzSchmeisserZschechetal., author = {Kraatz, Matthias and Schmeißer, Dieter and Zschech, Ehrenfried and Ho, Paul S.}, title = {Electromigration simulation for on-chip Cu interconnects}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 161}, abstract = {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}, language = {en} } @inproceedings{MichlingFriedrichSchmeisseretal., author = {Michling, Marcel and Friedrich, Daniel and Schmeißer, Dieter and Koval, Yuri and M{\"u}ller, Paul}, title = {Study of polyimide after graphitization with low-energy Ar+ Ion irradiation by NEXAFS}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 147}, abstract = {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.}, language = {en} } @inproceedings{MuellerSchmeisser, author = {M{\"u}ller, Sebastian and Schmeißer, Dieter}, title = {Investigation of ultra-thin Chromium layers on Titanium Dioxide by resonant photoemission}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 453}, abstract = {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.}, language = {en} } @inproceedings{RichterMuellerPhilipetal., author = {Richter, Matthias and M{\"u}ller, Klaus and Philip, Shine and Paloumpa, Ioanna and Henkel, Karsten and Schmeißer, Dieter}, title = {Temperature dependence of organic solar cell parameters}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 44}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 44}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 671}, abstract = {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.}, language = {en} } @inproceedings{TallaridaKaravaevKolaneketal., author = {Tallarida, Massimo and Karavaev, Konstantin and Kolanek, Krzysztof and Schmeißer, Dieter}, title = {Basics of the atomic layer deposition of HfO2 onto Si/SiO2 substrates: in-situ investigations with XPS, XAS and UHV-AFM}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 44}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 44}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 159}, abstract = {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.}, language = {en} }