Regensburg 2022 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 25: Poster 1
HL 25.35: Poster
Mittwoch, 7. September 2022, 18:00–20:00, P2
Investigation of pinhole defects in ALD TiO2−x corrosion protection layers on III-V semiconductor photocathodes — •Nicola Taffertshofer, Tim Rieth, and Ian Sharp — Walter Schottky Institute and Physics Department, Technical University of Munich, Am Coulombwall 4, 85748 Garching, Germany
The application of semiconducting photoabsorbers for photoelectrochemistry (PEC) provides a relevant path to solar fuel generation. However, a major challenge is the chemical instability of many potentially suitable semiconductors in PEC applications. Titania (TiO2−x) protection layers with defined properties can be conformally deposited by atomic layer deposition (ALD) and have been shown to improve chemical stability of photoelectrodes in PEC cells. Despite these benefits, TiO2−x ALD protection layers exhibit structural imperfections, including pinholes, that limit the long-term stability of underlying semiconductor photoelectrodes under PEC conditions. In our work, we quantify the pin-hole density in TiO2−x ALD protection layers, synthesized under different growth conditions, by combining controlled etching experiments with inductively coupled plasma mass spectrometry (ICP-MS). Using the high sensitivity of ICP-MS, the unprotected substrate area associated with existing and emerging pinholes can be deduced by an increase of the substrate elements concentrations dissolved in liquid. Overall, this method provides crucial information for the development of pinhole mitigation strategies in the TiO2−x ALD growth process and, hence, is an important step towards an increased lifetime of photoelectrodes.