Anodic film formation on illuminated n-GaAs electrodes studied by time-resolved photoelectrochemistry

Abstract

The transient currents occurring when turning on and off the illumination on an n-GaAs electrode were measured as a function of the light intensity, the electrode potential and the nature and concentration of the redox couple under conditions of photocorrosion. Our observations (using pulse lengths of 100–1000 ms) indicate the formation of a film protecting the material from further photocorrosion. The film disappears in the dark (indicating corrosion of the underlying material). A kinetic scheme to interpret the observations is presented.