Dresden 2026 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 12: Heterostructures, Interfaces and Surfaces: Photonics

HL 12.7: Talk

Monday, March 9, 2026, 18:15–18:30, POT/0051

Persistent UV-Induced Work Function Control at Atomic Layer Deposited TiO₂ /Ta₂O₅ Bilayer Interfaces — •Julius Kühne^{1, 2}, Tim Rieth^1,2, Katarina S. Flashar^1,2, Johannes Dittloff^1,2, Lukas Wolz², Johanna Eichhorn², Verena Streibel^1,2, and Ian D. Sharp^1,2 — ¹Walter Schottky Institute, Technical University of Munich, Am Coulombwall 4, 85748 Garching — ²Physics Department, TUM School of Natural Sciences, Technical University of Munich, Am Coulombwall 4, 85748 Garching

While atomic layer deposition (ALD) enables precise fabrication of ultrathin metal-oxide films, the mechanisms governing charge-carrier dynamics and band alignment at their interfaces often remain poorly understood. Oxide bilayers grown by ALD offer a versatile platform to characterize and tune defects that dictate interface energetics and charge transfer. Here, we examine the optical tuning of interface energetics in ultrathin ALD TiO₂/Ta₂O₅ bilayer films. A persistent -0.4 eV work-function (WF) shift is observed via contact potential difference (CPD) measurements after 275 nm illumination, with polarity reversal upon bilayer sequence inversion. This response arises from long-lived deep-trap filling, suggesting oxygen-vacancy migration. Capacitance-voltage (C-V) profiling, in-plane transport, and Kelvin probe force microscopy (KPFM) confirm vertical and lateral charge redistribution, while X-ray photoelectron spectroscopy (XPS) probe defect states. The results indicate that WF modulation originates from charge trapping by deep-trap states at the interface, offering insight into defect-driven effects in oxide heterointerfaces.

Keywords: Atomic Layer Deposition; TiO2; Ta2O5