Dresden 2026 – scientific programme
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DS: Fachverband Dünne Schichten
DS 6: Thin Oxides and Oxide Layers
DS 6.5: Talk
Tuesday, March 10, 2026, 11:00–11:15, REC/C213
Depth Profiling of Oxygen Migration in Ta/HfO2 Stacks During Ionic Liquid Gating — •Martin Wortmann1,2, Beatrice Bednarz3, Olga Kuschel3,4, Fabian Kammerbauer3, Mathias Kläui3, Andreas Hütten1, Joachim Wollschläger4, Gerhard Jakob3, and Timo Kuschel1,3 — 1Bielefeld University, Bielefeld, Germany — 2Bielefeld University of Applied Sciences and Arts, Bielefeld, Germany — 3Johannes Gutenberg University Mainz, Mainz, Germany — 4Osnabrück University, Osnabrück, Germany
Ionic-liquid gating enables electric-field-driven ion transport at thin-film interfaces to manipulate structural, electronic, optical, and magnetic properties [1]. Oxygen is driven from a donor oxide layer into an underlying acceptor metal layer, but the resulting spatial distribution and voltage dependence of oxygen migration remain poorly understood. Here, we investigate the formation of Ta2O5 at the interface between the HfO2 donor and Ta acceptor layers as a function of gate voltage, time, and HfO2 thickness using oxidation-state depth profiling by combining X-ray reflectivity measurments with multi-line angular-resolved X-ray photoelectron spectroscopy [2,3]. The results elucidate both the quantitative oxygen distribution as well as the underlying mechanism [4].
[1] Bednarz et al., Appl. Phys. Lett. 124, 232403 (2024)
[2] Wortmann et al., Small Methods 8, 2300944 (2023)
[3] Wortmann et al., Appl. Surf. Sci. 713, 164356 (2025)
[4] Bednarz et al., arxiv: 2509.05748 (2025)
Keywords: ionic liquid gating; oxygen doping; X-ray photoelectron spectroscopy; X-ray reflectivity; depth profile