TY - GEN A1 - Schmeißer, Dieter A1 - Janowitz, Christoph T1 - Two polarization dependent Auger decays observed by resonant photoelectron spectroscopy at the Cu2p-edge of superconducting BiSrCu-oxides T2 - Nuclear Instruments and Methods in Physics Research B N2 - We report on a resonant photoemission (resPES) study of PbxBi2-xSr2-yLayCan-1CunO2n+4+d (BISCO) single crystals to unravel the resonant decay mechanisms at the Cu2p absorption edge. The resPES studies on superconducting BISCO are performed at Bessy U49/2. We investigated BISCO single crystals with different hole doping concentrations at temperatures between 300 K and 17 K. CuO films have been used as a reference. We focus on the resPES data recorded at the Cu2p absorption edge. We find a strong polarization dependence for in-plane and out-of-plane geometries (with respect to the Cu-O plane) in our data which are caused by two independent Auger processes. We also report on the influence of different doping concentrations. Our resPES data enable us to sort the individual resonant mechanisms at the Cu2p edge in more detail than recently anticipated (Brookes et al., 2015). We discuss our data in the context of the recent discussion about the applicability of the Zhang-Rice model (Chen et al., 2013). KW - Synchrotron radiation KW - Superconductor KW - Cuprates KW - Resonant photoemission Y1 - 2017 U6 - https://doi.org/10.1016/j.nimb.2017.01.084 SN - 0168-583X SN - 1872-9584 VL - 411 SP - 53 EP - 56 ER - TY - GEN A1 - Naumann, Franziska A1 - Reck, Johanna A1 - Gargouri, Hassan A1 - Gruska, Bernd A1 - Blümich, Adrian A1 - Mahmoodinezhad, Ali A1 - Janowitz, Christoph A1 - Henkel, Karsten A1 - Flege, Jan Ingo T1 - In situ real-time and ex situ spectroscopic analysis of Al₂O₃ films prepared by plasma enhanced atomic layer deposition T2 - Journal of Vacuum Science and Technology B N2 - In situ real-time ellipsometry (irtE) with a very high time resolution of 24 ms was applied to monitor the inductively coupled plasma enhanced atomic layer deposition (ALD) process of Al₂O₃ thin films to precisely resolve each step of the ALD process and its complete cycle. The influence of plasma power, plasma pulse duration, and deposition temperature on the film growth characteristics was investigated. Ex situ ellipsometry [UV-VIS-NIR-SE (ultraviolet-visible-nearinfrared-spectroscopic ellipsometry) and IR-SE (infrared spectroscopic ellipsometry)] and x-ray photoelectron spectroscopy revealed the bulk properties (thickness, refractive index, chemical composition, and carbon incorporation) of the films, which together with the in situ results are compared to those of the films prepared by thermal ALD (T-ALD). The ICPEALD (inductively coupled plasma enhanced ALD) films were deposited at substrate temperatures between 80 and 250 °C and the role of plasma power (50–300 W) and its pulse duration (1–20 s) was investigated at 250 °C. The reference T-ALD layers were prepared at 200 °C. The ICPEALD process of Al₂O₃ shows an increased growth rate, and the produced films exhibit higher carbon contaminations than the T-ALD Al₂O₃ films. Plasma pulse times of up to 15 s further increase the content of carbon and CH species; at the same time, the refractive index decreases. The optical properties of ICPEALD deposited Al₂O₃ films are comparable with those of the T-ALD films for low plasma power and short plasma pulse durations. For the ICPEALD films, UV absorption is found and it is dependent on the deposition parameters. irtE resolves process effects that correlate with the bulk properties of Al₂O₃, such as impurities and oxygen deficiencies. KW - Plamsa enhanced atomic layer deposition (PEALD) KW - spectroscopic ellipsometry KW - X-ray photoelectron spectroscopy KW - real-time monitoring KW - aluminum oxide (Al₂O₃) Y1 - 2020 U6 - https://doi.org/10.1116/1.5122797 SN - 0734-211X SN - 1071-1023 SN - 2166-2746 SN - 2166-2754 VL - 38 IS - 1 ER - TY - GEN A1 - Janowitz, Christoph A1 - Mahmoodinezhad, Ali A1 - Naumann, Franziska A1 - Plate, Paul A1 - Henkel, Karsten A1 - Flege, Jan Ingo T1 - XPS and UPS investigation of an ALD prepared Al2O3/ZnO heterojunction T2 - Verhandlungen der DPG - SurfaceScience21 N2 - The band alignment of two large band gap oxides was studied by a combination of XPS and UPS using consecutive sputter steps to unravel the electronic structure and elemental composition of each layer and the interface region. An Al2O3/ZnO heterointerface (10 nm Al2O3 on 59 nm ZnO) was grown on top of a Si single crystal substrate by consecutive thermal and plasma-assisted atomic layer deposition (ALD) respectively. The valence band maximum of Al2O3 was found to be 1.1 eV below that of ZnO, the conduction band minimum 2.3 eV above, resulting in a type-I staggered heterojunction. A reduction of ZnO to elemental Zn in the interface region was detected by the apparent shoulder of the Zn 2p and 2s core levels and by the Zn LMM Auger. This suggests an ALD interface formation mechanism different from previous models identified for other heterointerfaces. KW - X-ray photoelectron spectroscopy KW - ultraviolet photoelectron spectroscopy KW - atomic layer deposition KW - large bandgap materials KW - band offsets Y1 - 2021 UR - https://www.dpg-verhandlungen.de/year/2021/conference/surfacescience/part/o/session/74/contribution/4 VL - 2021 PB - Deutsche Physikalische Gesellschaft e.V. CY - Bad Honnef ER - TY - GEN A1 - Mahmoodinezhad, Ali A1 - Morales, Carlos A1 - Naumann, Franziska A1 - Plate, Paul A1 - Meyer, Robert A1 - Janowitz, Christoph A1 - Henkel, Karsten A1 - Kot, Małgorzata A1 - Flege, Jan Ingo T1 - Low-temperature atomic layer deposition of indium oxide thin films using trimethylindium and oxygen plasma T2 - Verhandlungen der DPG - SurfaceScience21 N2 - Indium oxide thin films were deposited on Si (100) by plasma-enhanced atomic layer deposition (PEALD) using trimethylindium (TMIn) and oxygen plasma (O2) in a low-temperature range of 80 to 200 °C. The In2O3 layers were characterized by in-situ spectroscopic ellipsometry (SE), ex-situ X-ray photoelectron spectroscopy (XPS) and electrical measurements. The SE data show a growth rate of 0.56 Å/cycle within the ALD window (100 to 150 °C) with a thickness inhomogeneity of ≤1.2%. In addition, the highest refractive index is 2.07 (at 632.8 nm) for the layer grown at 150 °C, and the films exhibit indirect and direct band gaps of 2.8±0.1 eV and 3.3±0.2 eV, respectively. XPS characterization indicates no carbon incorporation and a temperature-dependent off-stoichiometry of the layers. The chemical analysis of the In 3d and O 1s core levels confirms the formation of In-O bonds and suggests the additional presence of hydroxyl groups and defects. With increasing temperature, the contribution of OH groups and defects decreases whereas that of In-O bonds increases. Notably, higher growth temperatures result in an indium rich phase within the layers. KW - Indium oxide KW - Plasma enhanced atomic layer deposition KW - Spectroscopic ellipsometry KW - X-ray photoelectron spectroscopy Y1 - 2021 UR - https://www.dpg-verhandlungen.de/year/2021/conference/surfacescience/part/o/session/74/contribution/8 VL - 2021 PB - Deutsche Physikalische Gesellschaft e.V. CY - Bad Honnef ER - TY - GEN A1 - Mahmoodinezhad, Ali A1 - Janowitz, Christoph A1 - Naumann, Franziska A1 - Plate, Paul A1 - Gargouri, Hassan A1 - Henkel, Karsten A1 - Schmeißer, Dieter A1 - Flege, Jan Ingo T1 - Low-temperature growth of gallium oxide thin films by plasma-enhanced atomic layer deposition T2 - Journal of Vacuum Science and Technology A N2 - Gallium oxide (Ga2O3) thin films were deposited by plasma-enhanced atomic layer deposition (PEALD) applying a capacitively coupled plasma source where trimethylgallium (TMGa) as the gallium precursor and oxygen (O2) plasma were used in a substrate temperature (Ts)in the range of 80–200 °C. TMGa exhibits high vapor pressure and therefore facilitates deposition at lower substrate temperatures. The Ga2O3 films were characterized by spectroscopic ellipsometry (SE), x-ray photoelectron spectroscopy (XPS), and capacitance-voltage (C-V) measurements. The SE data show linear thickness evolution with a growth rate of ∼0.66 Å per cycle and inhomogeneity of ≤2% for all samples. The refractive index of the Ga2O3 thin films is 1.86 ± 0.01 (at 632.8 nm) and independent of temperature, whereas the bandgap slightly decreases from 4.68 eV at Ts of 80 °C to 4.57 eV at 200 °C. XPS analysis revealed ideal stoichiometric gallium to oxygen ratios of 2:3 for the Ga2O3 layers with the lowest carbon contribution of ∼10% for the sample prepared at 150 °C. The permittivity of the layers is 9.7 ± 0.2 (at 10 kHz). In addition, fixed and mobile oxide charge densities of 2–4E12 and 1–2E12 cm−2, respectively, were observed in the C-V characteristics. Moreover, the Ga2O3 films show breakdown fields in the range of 2.2–2.7 MV/cm. Excellent optical and electrical material properties are maintained even at low substrate temperatures as low as 80 °C. Hence, the TMGa/O2 PEALD process is suitable for electronic and optoelectronic applications where low-temperature growth is required. KW - Plamsa enhanced atomic layer deposition (PEALD) KW - low-temperature growth KW - gallium oxide (Ga2O3) KW - x-ray photoelectron spectroscopy KW - spectroscopic ellipsometry KW - capacitance voltage measurements Y1 - 2020 U6 - https://doi.org/10.1116/1.5134800 SN - 0734-2101 SN - 1520-8559 VL - 38 IS - 2 ER - TY - GEN A1 - Janowitz, Christoph A1 - Schmeißer, Dieter T1 - Out-of-plane electronic contributions in Bi-cuprates studied by resonant photoelectron spectroscopy at the Cu 2p edge T2 - Verhandlungen der DPG N2 - In high-temperature superconductors with a layered crystal structure out-of-plane contributions are often neglected, while the copper-oxygen planes are commonly considered to dominate the electronic properties around the Fermi energy. Here we report on a resonant photoemission study of (Pb,Bi)2201 and (Pb,Bi)2212 single crystals to unravel the resonant decay mechanisms at the Cu 2p absorption edge. We demonstrate a pronounced polarization dependence caused by two different Auger processes for in-plane and out-of-plane orientations. We deduce that the lowest energy valence state being involved in the two Auger processes, consists of three-dimensional contributions by admixed out-of-plane Sr, Bi, and O 2p states. It also suggests that the doping-induced charge density is dynamic, fluctuating within the Cu-O plane, and spills out perpendicular to it. C. Janowitz and D. Schmeißer, Supercond. Sci. Technol. 31, 045006 (2018) KW - high-temperature superconductors KW - resonant photoemission spectroscopy KW - single crystal KW - doping-induced charge density Y1 - 2019 UR - https://www.dpg-verhandlungen.de/year/2019/conference/regensburg/part/tt/session/49/contribution/19 SN - 0420-0195 SP - 403 EP - 403 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Janowitz, Christoph A1 - Schmeißer, Dieter T1 - Significance of out-of-plane electronic contributions in Bi-cuprates studied by resonant photoelectron spectroscopy at the Cu2p-edge T2 - Superconductor Science and Technology N2 - In high-temperature superconductors with a layered crystal structure, the copper–oxygen planes are commonly considered to dominate the electronic properties around the Fermi energy. As a consequence, out-of-plane contributions are often neglected in the description of these materials. Here we report on a resonant photoemission study of Pb₀,4Bi1,₆Sr₂,₀CaCu₂0₈ ((Pb, Bi)-2212) and Pb₀,₆Bi₁,₄Sr₁.5La₀.5Cu0₆ ((Pb, Bi)-2201)) single crystals to unravel the resonant decay mechanisms at the Cu2p absorption edge. We find evidence for a pronounced polarization dependence caused by two different Auger processes for in-plane and out-of-plane orientations. We deduce that the lowest energy valence state—which is involved in the two Auger processes—consists of three-dimensional contributions by admixed out-of-plane Sr, Bi, and 02p states. It also suggests that the doping-induced charge density is dynamic, fluctuating within the Cu–0 plane, and spills out perpendicular to it. This suggests that out-of-plane electronic degrees of freedom should be included in future consistent theoretical models of these materials. KW - synchrotron radiation KW - polarization dependence KW - 3D hole doping KW - superconductor Y1 - 2018 U6 - https://doi.org/10.1088/1361-6668/aaadf6 SN - 0953-2048 SN - 1361-6668 VL - 31 IS - 4 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Henkel, Karsten A1 - Janowitz, Christoph T1 - Ionicity of ZnO - a key system for transparent conductive oxides T2 - epl : a letters journal exploring the frontiers of physics N2 - The electronic structure of ZnO is dominated by coexisting electron and ionic states/bonds caused by charge polarization and self-trapping phenomena of the valence charges. Their interplay manifests itself in intrinsic electronic defects which have different degree of spatial localization and electronic correlation. The relative abundance of intrinsic defects can be determined by the ionicity factor fi and its value can be derived from three independent experimental procedures in a consistent way. This approach also explains the complex satellite features in the XPS and XAS data. Ionicity and satellite formation are two experimental findings which can be explained consistently in the same context of mixed-atomic valence states and intrinsic electronic defects. KW - Ionicity KW - zinc oxide (ZnO) KW - resonant photoelectron spectroscopy KW - defect states KW - transparent conductive oxide (TCO) Y1 - 2018 U6 - https://doi.org/10.1209/0295-5075/123/27003 SN - 1286-4854 SN - 0295-5075 VL - 123 IS - 2 SP - 27003-p1 EP - 27003-p7 ER - TY - CHAP A1 - Henkel, Karsten A1 - Haeberle, Jörg A1 - Müller, Klaus A1 - Janowitz, Christoph A1 - Schmeißer, Dieter ED - Fornari, Robert T1 - Preparation, properties and electronic structure of SnO₂ T2 - Single Crystals of Electronic Materials N2 - This chapter reports about tin oxide (SnO₂), a material which belongs to the transparent conducting oxide family and is best characterized by its high conductivity, high carrier mobility, and the ability to form p-type conductivity. We correlate these properties in terms of localized intrinsic electronic defect states which are resolved by resonant photoelectron spectroscopy measurements. We describe SnO₂ in terms of an inhomogeneous, mixed-ionic-covalent semiconductor in which these intrinsic electronic defects state are stabilized. KW - electronic structure KW - tin oxide (SnO₂) KW - resonant photoelectron spectroscopy KW - intrinsic defect states Y1 - 2018 SN - 978-0-08-102096-8 SN - 978-0-08-102097-5 SP - 547 EP - 572 PB - Elsevier, Woodhead Publishing CY - Duxford ER - TY - GEN A1 - Haeberle, Jörg A1 - Machulik, Stephan A1 - Janowitz, Christoph A1 - Manzke, Recardo A1 - Gaspar, Diana A1 - Barquinha, Pedro A1 - Schmeißer, Dieter T1 - Gap states in the electronic structure of SnO2 single crystals and amorphous SnOxthin films T2 - Journal of Applied Physics N2 - The electronic structure of a SnO2 single crystal is determined by employing resonant photoelectron spectroscopy. We determine the core level, valence band, and X-ray absorption (XAS) data and compare these with those of amorphous SnOx thin films. We find similar properties concerning the data of the core levels, the valence band features, and the absorption data at the O1s edge. We find strong signals arising from intrinsic in-gap states and discuss their origin in terms of polaronic and charge-transfer defects. We deduce from the XAS data recorded at the Sn3d edge that the Sn4d10 ground state has contributions of 4d9 and 4d8 states due to configuration interaction. We identify localized electronic states depending on the strength of the 4d-5s5p interaction and of the O2p-to-Sn4d charge-transfer processes, both appear separated from the extended band-like states of the conduction band. For the amorphous SnOx thin films, significant differences are found only in the absorption data at the Sn3d-edge due to a stronger localization of the in-gap states. KW - SnO2 KW - electronic structure KW - gap states KW - resonant photoelectron spectroscopy (resPES) Y1 - 2016 U6 - https://doi.org/10.1063/1.4962313 SN - 0021-8979 SN - 1089-7550 VL - 120 IS - 10 SP - 105101-1 EP - 105101-13 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Janowitz, Christoph T1 - The Cu2p-edge of superconducting BiSrCu-Oxides studed by resonant Photoelectron Spectroscopy T2 - Synchrotron Radiation in Natural Science : Bulletin of the Polish Synchrotron Radiation Society KW - synchrotron raidation KW - superconductor Y1 - 2016 SN - 1644-7190 VL - 15 IS - 1-2 SP - S. 35 ER - TY - CHAP A1 - Haeberle, Jörg A1 - Gaspar, Diana A1 - Barquinha, Pedro A1 - Pereira, Luís A1 - Martins, Rodrigo A1 - Fortunato, Elvira A1 - Machulik, Stephan A1 - Janowitz, Christoph A1 - Manzke, Recardo A1 - Schmeißer, Dieter T1 - The Electronic Structure of amorphuos SnOx thin films and SnO2 single crystals T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - We compare the electronic properties of amorphous p-type SnOx thin film grown by rf magnetron sputtering with those of n-type SnO2 single crystals grown by cvt. We use resPES to study the electronic band structure. We measure the core levels, the VB PES data, partial Integrated Yield (pIY) and the XAS absorption data. From the resPES data recorded at the O1s and the Sn3d edges we derive the VB pDOS and the CB pDOS . The differences are most pronounced in the position of the VBM as for the a-SnOx films there appears a band closer to the Fermi energy. In addition for the SnOx we find in the XAS and pIY data a significant peak that appears right at the Fermi energy. This peak is absent in the single crystalline data. We attribute this to a change in the configuration of the Sn4d states to form a 4d8 configuration instead of 4d9 and 4d10 configurations which are identified in the single crystalline data. KW - electronic structure KW - SnO2 Y1 - 2015 UR - http://www.dpg-verhandlungen.de/year/2015/conference/berlin/part/hl/session/21/contribution/17?lang=en SN - 0420-0195 SP - S. 271 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Haeberle, Jörg A1 - Gaspar, Diana A1 - Barquinha, Pedro A1 - Machulik, Stephan A1 - Janowitz, Christoph A1 - Galazka, Zbigniew A1 - Schmeißer, Dieter T1 - A spectroscopic comparison of AOS thin films and TCO single crystals T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Amorphous oxide semiconductors (AOS) and transparent conductive oxides (TCO) are today one of most attractive fields of research in many industrial products, like e.g. high definition, low cost, transparent, and flexible displays. We got the unique possibility to measure a-GIZO and a-SnOx thin films and compare their electronic properties with those of In2O3, Ga2O3, ZnO, and SnO2 single crystals. We use resPES to study the electronic properties. We report on the core levels, the VB PES data, partial Integrated Yield (pIY) and the XAS absorption data. From these we are able to derive the elemental ratio, the pDOS as well as the band scheme. At the O1s resonance we observe multiple Auger processes from which we deduce that a band of localized defect states is located between the Fermi energy and the CBM. The resonant profiles taken at the corresponding metal edges indicate that metal states are involved in the DOS. KW - Amorphous oxide semiconductors (AOS) KW - Transparent conductive oxides (TCO) KW - In2O3 KW - Ga2O3 KW - ZnO KW - SnO2 KW - GIZO KW - resonant photoelectron spectroscopy Y1 - 2014 UR - http://www.dpg-verhandlungen.de/year/2014/conference/dresden/part/hl/session/107/contribution/15?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Janowitz, Christoph A1 - Scherer, Valentina A1 - Mohamed, Mansour A1 - Krapf, Alica A1 - Dwelk, Helmut A1 - Manzke, Recardo A1 - Galazka, Zbigniew A1 - Uecker, Reinhard A1 - Irmscher, Klaus A1 - Fornari, Robert A1 - Michling, Marcel A1 - Schmeißer, Dieter T1 - Experimental electronic structure of In2O3 and Ga2O3 T2 - New Journal of Physics Y1 - 2011 SN - 1367-2630 VL - 13 IS - 8 SP - 085014 ER - TY - GEN A1 - Haeberle, Jörg A1 - Richter, Matthias A1 - Galazka, Zbigniew A1 - Janowitz, Christoph A1 - Schmeißer, Dieter T1 - Resonant Photoemission at the O1s threshold to characterize In2O3 single crystals T2 - Thin Solid Films N2 - We report on spectroscopic investigations on In2O3 single crystals. We focus on the detailed analysis of the O1s resonance profile by resonant photoelectron spectroscopy. We analyze the electronic structure and assign the O2p to build the valence band and both, O2p and In5s5p states to contribute to the conduction band (CB). We determine the partial density of states for the valence and CBs and find a strong hybridization of O2p and In5s states. This is deduced from constant final state spectra on the O-KLL-Auger over the O K-edge and In M4,5-edge and a comparison to the corresponding X-ray absorption spectroscopy data.We also identify several types of defects. A broad band of oxygen derived defects is identified that extends throughout the gap. These are attributed to small polarons which cause an anti-resonance in the valence states around the O1s threshold. In addition, a separate Auger decay at resonance indicates the existence of localized charge transfer states which involves localized In5s5p states. KW - In2O3 KW - TCO KW - X-ray spectroscopy KW - Small polaron KW - Charge transfer Y1 - 2014 U6 - https://doi.org/10.1016/j.tsf.2013.03.036 SN - 0040-6090 SN - 1879-2731 VL - 2014 IS - 555 SP - 53 EP - 56 ER - TY - CHAP A1 - Haeberle, Jörg A1 - Richter, Matthias A1 - Schmeißer, Dieter A1 - Galazka, Zbigniew A1 - Janowitz, Christoph T1 - Resonant Photoemission at the O1s threshold to characterize In2O3 single crystals T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - We report on spectroscopic investigations on In2O3 single crystals. We focus on the detailed analysis of the O1s resonance profile by resonant photoelectron spectroscopy (resPES). From these we analyze the electronic structure and assign the O2p- and In5sp state to build the valence band and the conduction band in different contributions, respectively. This is deduced from constant final state spectra on the O-KLL-Auger along the O K-edge and In M4,5-edge and a comparison to the corresponding X-ray absorption spectroscopy data. We also identify several types of defects. A broad band of oxygen derived defects is identified in the valence band and extends throughout the gap. Small polarons are attributed to cause an anti-resonance in the constant initial states around the O1s threshold. In addition, an Auger decay separated by the O-KLL is present at O-K resonance and indicates the existence of localized charge transfer states which involves In5sp states. Finally, we are able to distinguish two different oxygen species from the resPES data. One corresponds to theintrinsic In2O3 structure and the other is a non-corresponding species. KW - resonant photoelectron spectroscopy KW - In2O3 Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/mm/session/15/contribution/57?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Mahmoodinezhad, Ali A1 - Morales, Carlos A1 - Naumann, Franziska A1 - Plate, Paul A1 - Meyer, Robert A1 - Janowitz, Christoph A1 - Henkel, Karsten A1 - Kot, Małgorzata A1 - Zöllner, Marvin Hartwig A1 - Wenger, Christian A1 - Flege, Jan Ingo T1 - Low-temperature atomic layer deposition of indium oxide thin films using trimethylindium and oxygen plasma T2 - Journal of Vacuum Science and Technology A N2 - Indium oxide (InxOy) thin films were deposited by plasma-enhanced atomic layer deposition (PEALD) using trimethylindium and oxygen plasma in a low-temperature range of 80–200 °C. The optical properties, chemical composition, crystallographic structure, and electrical characteristics of these layers were investigated by spectroscopic ellipsometry (SE), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), as well as current-voltage and capacitance-voltage measurements. The SE results yielded a nearly constant growth rate of 0.56 Å per cycle and a thickness inhomogeneity of ≤1.2% across 4-in. substrates in the temperature range of 100–150 °C. The refractive index (at 632.8 nm) was found to be 2.07 for the films deposited at 150 °C. The PEALD-InxOy layers exhibit a direct (3.3 ± 0.2 eV) and an indirect (2.8 ± 0.1 eV) bandgap with an uptrend for both with increasing substrate temperature. Based on XPS characterization, all InxOy samples are free of carbon impurities and show a temperature-dependent off-stoichiometry indicating oxygen vacancies. XRD diffraction patterns demonstrate an onset of crystallization at 150 °C. Consistent with the optical, XPS, and XRD data, the films deposited at ≥150 °C possess higher electrical conductivity. Our findings prove that a low-temperature PEALD process of InxOy is feasible and promising for a high-quality thin-film deposition without chemical impurities on thermally fragile substrates. KW - Indium oxide KW - Plasma-enhanced atomic layer deposition KW - X-ray photoelectron spectroscopy KW - Ellipsometry KW - X-ray diffraction KW - Electrical properties Y1 - 2021 U6 - https://doi.org/10.1116/6.0001375 SN - 0734-2101 SN - 1520-8559 VL - 39 IS - 6 ER - TY - GEN A1 - Janowitz, Christoph A1 - Mahmoodinezhad, Ali A1 - Kot, Małgorzata A1 - Morales, Carlos A1 - Naumann, Franziska A1 - Plate, Paul A1 - Zöllner, Marvin Hartwig A1 - Bärwolf, Florian A1 - Stolarek, David A1 - Wenger, Christian A1 - Henkel, Karsten A1 - Flege, Jan Ingo T1 - Toward controlling the Al2O3/ZnO interface properties by in situ ALD preparation T2 - Dalton Transactions N2 - An Al2O3/ZnO heterojunction was grown on a Si single crystal substrate by subsequent thermal and plasma-assisted atomic layer deposition (ALD) in situ. The band offsets of the heterointerface were then studied by consecutive removal of the layers by argon sputtering, followed by in situ X-ray photoelectron spectroscopy. The valence band maximum and conduction band minimum of Al2O3 are found to be 1.1 eV below and 2.3 eV above those of ZnO, resulting in a type-I staggered heterojunction. An apparent reduction of ZnO to elemental Zn in the interface region was detected in the Zn 2p core level and Zn L3MM Auger spectra. This suggests an interface formation different from previous models. The reduction of ZnO to Zn in the interface region accompanied by the creation of oxygen vacancies in ZnO results in an upward band bending at the interface. Therefore, this study suggests that interfacial properties such as the band bending as well as the valence and conduction band offsets should be in situ controllable to a certain extent by careful selection of the process parameters. KW - ALD heterojunction KW - band alignement KW - ZnO KW - Al2O3 KW - interface properties Y1 - 2022 U6 - https://doi.org/10.1039/D1DT04008A SN - 1477-9234 SN - 1477-9226 VL - 51 SP - 9291 EP - 9301 ER -