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HL: Fachverband Halbleiterphysik

HL 22: Nitrides: Preparation and characterization I

HL 22.6: Vortrag

Dienstag, 13. März 2018, 15:15–15:30, EW 203

Photoelectrochemical characterization of p-type GaN for application as a photocatalyst for CO₂ reduction — •Viktoria Kunzelmann, Andreas Zeidler, Ian Sharp, and Martin Stutzmann — Walter Schottky Institute and Physics Department, Technische Universität München, Garching, Germany

The photocatalytic conversion of CO₂ into useful hydrocarbons can provide an excellent sustainable way to store energy. Finding a suitable semiconductor for efficient CO₂ reduction is challenging as it must fulfill several requirements: it must provide high energy electrons to split the inert CO₂ molecule, the band edges must straddle the desired redox levels and it needs to be stable under operating conditions. Gallium nitride (GaN) is promising as a photocatalyst as it fulfills most of these requirements. GaN is also known for its superior chemical stability, however, surface oxidation during photoelectrochemistry is still a major issue, especially for n-type GaN. To diminish oxidation effects, p-doped GaN could be used as it exhibits surface electrons during photoexcitation due to the downward surface band bending. Understanding the charge transfer processes across the p-GaN/electrolyte interface is essential to optimize the material properties. Hence, in this work we focus on the photoelectrochemical investigation of p-GaN electrodes and the effect of different surface treatments on the (photo)current-voltage characteristics as well as on the stability during operation. Changes in the chemical composition caused by photoelectrochemistry are studied by XPS, and changes in the surface photovoltage are monitored by contact potential difference measurements.