Dresden 2014 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 12: Energy materials: Water splitting, batteries, and supercapacitors (with CPP/MM)
HL 12.6: Vortrag
Montag, 31. März 2014, 12:00–12:15, POT 081
Photostability of GaN-metal interfaces in aqueous media — •Carina Ehrig1, 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.