TY - CHAP A1 - Tallarida, Massimo A1 - Henkel, Karsten A1 - Gargouri, Hassan A1 - Haeberle, Jörg A1 - Gruska, Bernd A1 - Arens, Matthias A1 - Schmeißer, Dieter T1 - New opportunities with Plasma enhanced atomic layer deposition (PE-ALD) of oxides T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Thermal Atomic layer deposition (T-ALD) of oxides is obtained by the pulsed alternation of a metal precursor and an oxygen source, typically H2O or O3, and the reactions leading to ALD are thermally activated. With plasma enhanced ALD (PE-ALD), instead, the oxygen source is represented by an oxygen-containing plasma. The higher reactivity of the plasma-generated species extend the capabilities of ALD: improved film quality and increased flexibility in process conditions, such as growth at low temperature, are typical advantages of PE-ALD over T-ALD. We report on results on the preparation of thin (<100 nm) aluminum oxide (Al2O3) films on silicon substrates using T-ALD and PE-ALD in the SENTECH SI ALD LL system. Films were deposited in the temperature range between room temperature (RT) and 200∘C. We characterized the films with spectroscopic ellipsometry (thickness, refractive index, growth rate) over 4" wafers and with X-ray photoelectron spectroscopy. All films resulted in a high degree of homogeneity, independent of the deposition temperature. Investigations with capacitance-voltage and conductance-voltage measurements showed a very low interface states density for the PE-ALD films. KW - Atomic layer deposition KW - Plasma enhanced atomic layer deposition KW - X-ray photoelectron spectroscopy KW - spectroscopic ellipsometry KW - dielectric properties KW - Al2O3 Y1 - 2014 UR - http://www.dpg-verhandlungen.de/year/2014/conference/dresden/part/ds/session/49/contribution/3?lang=en SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Kot, Małgorzata A1 - Das, Chittaranjan A1 - Henkel, Karsten A1 - Wojciechowski, Konrad A1 - Snaith, Henry J. A1 - Schmeißer, Dieter T1 - Room temperature atomic layer deposited Al₂O₃ on CH₃NH₃PbI₃ characterized by synchrotron-based X-ray photoelectron spectroscopy T2 - Nuclear Instruments and Methods in Physics Research B N2 - An ultrathin Al₂O₃ film deposited on methylammonium lead triiodide (CH₃NH₃PbI₃) perovskite has the capability to suppress the carrier recombination process and improve the perovskite solar cells efficiency and stability. However, annealing at temperatures higher than 85°C degrades the CH₃NH₃PbI₃ perovskite film. The X-ray photoelectron spectroscopy study performed in this work indicates that it is possible to grow Al₂O₃ by atomic layer deposition on the perovskite at room temperature, however, besides pure Al₂O₃ some OH groups are found and the creation of lead and iodine oxides at the Al₂O₃/CH₃NH₃PbI₃ interface takes place. KW - Synchrotron-based X-ray photoelectron spectroscopy KW - Perovskite solar cells KW - Atomic layer deposition KW - Al₂O₃ Y1 - 2017 U6 - https://doi.org/10.1016/j.nimb.2017.01.082 SN - 0168-583X SN - 1872-9584 VL - 411 SP - 49 EP - 52 ER - TY - GEN A1 - Morales, Carlos A1 - Mahmoodinezhad, Ali A1 - Schubert, Andreas Markus A1 - Wenger, Christian A1 - Henkel, Karsten A1 - Flege, Jan Ingo T1 - Functional ultra-thin oxide films deposited by atomic layer deposition on structured substrates T2 - Verhandlungen der DPG - SurfaceScience21 N2 - In the last decades, atomic layer deposition (ALD) has gained prominence in the materials and surface science communities owing to its high potential for integration as a scalable process in microelectronics. ALD's largest strengths are its well-controlled layer-by-layer deposition and growth conformity on 3D structures. Yet, the ALD technique is also well known to lead to amorphous and defective, non-stoichiometric thin films, resulting in modified materials properties that may even preferentially be used in certain applications. To study these issues, we have developed an in-situ ALD reactor attached to an X-ray photoelectron spectroscopy (XPS) system, capable of switching between both pump and flow-type operation. This novel tool allows to cover the entire range of compounds and recipes used in ALD, thus clarifying the role of such defects at different deposition stages, growth conditions and film/substrate interfaces. To exemplify these sorts of studies, we show the deposition of Al2O3 5-10 nm films on nanostructured Si, and their use as substrates for functional CeOx ALD deposits. KW - Atomic layer deposition KW - sensors KW - structured substrates KW - in-situ X-ray photoelectron spectroscopy Y1 - 2021 UR - https://www.dpg-verhandlungen.de/year/2021/conference/surfacescience/part/o/session/74/contribution/5 VL - 2021 PB - Deutsche Physikalische Gesellschaft e.V. CY - Bad Honnef ER - TY - GEN A1 - Kosto, Yuliia A1 - Morales, Carlos A1 - Devi, Anjana A1 - Henkel, Karsten A1 - Flege, Jan Ingo T1 - Activity of cerium oxide thin films prepared by atomic layer deposition using custom and commercial precursors T2 - Verhandlungen der DPG N2 - Atomic layer deposition (ALD) allows preparation of conformal coatings with possibility to control their thickness at the submonolayer level, making it a good tool for depositing active layers on 3D structures. Our group is working on cerium oxide-based materials for hydrogen detection, which is difficult at ambient conditions due to the low sensitivity and long response time of the sensors. The cerium oxide layers prepared by ALD contain a lot of defects and provide an opportunity to overcome these complications. Thickness and morphology of the oxide films play an important role in defining the Ce3+/Ce4+ ratio, as well as the interface with the used substrate. Here, we compare cerium oxide thin films deposited by ALD techniques on SiO2 and Al2O3 substrates. The results reveal that the interface to the substrate can considerably influence the reactivity of the cerium oxide toward hydrogen and oxygen. Preparation of the oxides using two different precursors (commercial Ce(thd)4 and custom Ce(dpdmg)3) has been demonstrated to affect the redox properties of the films, their reactivity, and the reversibility. KW - Atomic layer deposition KW - Cerium oxide KW - hydrogen detection Y1 - 2023 UR - https://www.dpg-verhandlungen.de/year/2023/conference/skm/part/o/session/42/contribution/4 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER -