Dresden 2026 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 4: Materials for the Storage and Conversion of Energy I
MM 4.3: Vortrag
Montag, 9. März 2026, 11:00–11:15, SCH/A216
Probing Defect-State Photoionization in Ta3N5 Thin Films via Photocurrent Excitation Spectroscopy — •Luc-Fabrice Tremel1, Lukas M. Wolz1, Johannes Dittloff1, 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. A prominent example is Ta3N5, which combines a bandgap of 2.2 eV with favorable band alignment for solar water splitting. In practice, however, its photoelectrochemical performance is strongly constrained by shallow and deep defects. Here, we use photocurrent excitation spectroscopy, complemented by power-dependent photocurrent measurements, to determine how these defect states shape the spectral photocurrent response of Ta3N5. By tracking photocurrent as a function of photon energy, light intensity, and applied potential, we distinguish the sharp band-edge transition from a broadened onset dominated by defect-assisted photoionization into the conduction band. These insights into the defect-controlled photoresponse of Ta3N5 provide guidance for improved fabrication strategies and the development of higher-performing nitride-based solar-fuel devices.
Keywords: Photocurrent; Ta3N5; Defects