Regensburg 2025 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 32: Nitrides: Preparation and Characterization I
HL 32.3: Talk
Wednesday, March 19, 2025, 10:00–10:15, H15
Understanding the Effect of Defects in Ta3N5 Thin Films on Charge Carrier Dynamics — •Jan Luca Blänsdorf1, Lukas M. Wolz1, Matthias Kuhl1, Johannes Dittloff1,2, Nina Miller1, Gabriel Grötzner1,2, Ian D. Sharp1,2, and Johanna Eichhorn1 — 1Physics Department, TUM School of Natural Sciences, Technische Universität München, Germany — 2Walter Schottky Institute, Technische Universität München, Germany
Transition-metal nitrides are a highly interesting material space for solar-energy conversion due to their suitable bandgap for visible light absorption and high theoretical solar-to-hydrogen efficiencies. An intensively studied example is Ta3N5, with a bandgap of 2.2 eV and favorable band alignment for solar water splitting. However, its photoelectrochemical performance is limited by oxygen impurities and nitrogen vacancies. Here, we used transient absorption spectroscopy on the microsecond timescale to reveal the impact of different defects on charge carrier dynamics in Ta3N5. Therefore, we synthesized Ta3N5 thin films with different concentrations of nitrogen vacancies and oxygen impurities. Their structure, defect and photoelectrochemical properties were correlated with charge carrier dynamics to identify current performance limitations.
Keywords: Photoelectrochemical water-splitting; Transient absorption spectroscopy; Tantalum nitride; Nitrogen vacancies; Deep trap states