Characterization of Surface Layers on GaAs Single Crystals in Contact with Acid Aqueous Solutions

From ellipsometric measurements, combined with surface analysis by SEM, Auger spectroscopy and X-ray diffraction, it appears that a porous arsenic layer develops upon the p-type gallium arsenide electrode surface in acid, aqueous indifferent electrolyte solution during anodic current flow. Due to its porosity, this layer does not affect the forward current-potential characteristics of the electrode. Also under open-circuit circumstances in the same electrolyte, the arsenic layer appears to grow. The probable reactions corresponding to both arsenic deposition processes are discussed.