Dresden 2014 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 7: Energy materials: Water splitting, batteries, and supercapacitors (HL with MM/CPP)

MM 7.6: Talk

Monday, March 31, 2014, 12:00–12:15, POT 081

Photostability of GaN-metal interfaces in aqueous media — •Carina Ehrig^{1, 2}, Ralf Krause¹, Christoph Brabec², and Günter Schmid¹ — ¹Siemens AG, CT RTC MAT IEC-DE, Erlangen — ²Lehrstuhl für Werkstoffe der Elektronik- und Energietechnik, FAU Erlangen-Nürnberg, Erlangen

Gallium nitride (GaN) is a well-established semiconductor in optoelectronic applications. It has a wide band gap of 3.4 eV and is thus excitable in the near UV range. A promising application of GaN is its use as a photo electrode driving electrochemical reactions such as photocatalytic water splitting for generation of hydrogen without consumption of fossil fuel or emission of CO₂. The corrosion resistance of those photo electrodes in aqueous media is one of the main factors determining their lifetimes and thus plays an important role for their applicability for highly efficient solar energy conversion. It has been demonstrated in photocatalytic experiments, that under UV-illumination n-type GaN acts as oxygen evolving photo anode and p-type GaN as hydrogen evolving photo cathode.

In the present work, the corrosion resistance of metal-coated n-GaN and p-GaN photoelectrodes in aqueous media is investigated by electrochemical measurements. The influence of an externally applied potential under light excitation as well as the effect of long-term photo-induced stress are studied. It is observed that without illumination the GaN surfaces and GaN-metal interfaces are rather stable, whereas they undergo different corrosion processes when exposed to UV light.