Regensburg 2022 – scientific programme
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 21: Functional semiconductors for renewable energy solutions (joint session HL/KFM)
KFM 21.8: Talk
Wednesday, September 7, 2022, 17:15–17:30, H36
Defect-Engineered Atomic Layer Deposited TaOx Protection Layers for Photoelectrochemistry — •Tim Rieth, Clara Scherm, and Ian Sharp — Walter Schottky Institute and Physics Department, Technical University of Munich, Am Coulombwall 4, 85748 Garching, Germany
Photoelectrochemical (PEC) energy conversion provides a viable route to the generation of chemical fuels from solar light. In this approach, charge carriers generated within a semiconductor light absorber immersed in an electrolyte are used to drive water splitting or carbon dioxide reduction reactions. A particularly relevant PEC configuration uses photovoltaic absorbers coated with transparent and conductive protection layers that prevent chemical corrosion of the semiconductor components. However, ensuring that the protection layer simultaneously fulfills the criteria for chemical stability, electronic conductivity, and optical transparency remains a challenging task. Here, we utilize plasma enhanced atomic layer deposition (PE-ALD) to create defect engineered and ultra-thin tantalum oxide (TaOx) protection layers for PEC applications. In addition to their optical transparency, the TaOx films form continuous coatings on the photoabsorber and provide improved chemical stability compared to titanium dioxide. A sufficiently high film conductivity is obtained by intentionally introducing electronic defects from hydrogen plasma sub-cycles during the ALD process. The demonstrated defect engineering mechanism and achieved TaOx protection layers represent an advance towards efficient and stable PEC devices.