Influence of the crystal orientation on the electrochemical behaviour of n-GaAs in Au(i)-containing solutions

Abstract

The electrochemical reduction of Au(CN)₂⁻ at (111) and () n-GaAs at pH 14 was studied by rotating disk voltammetry. The two surface orientations appeared to have different voltammetric behaviour in the presence of the complex. This difference can be ascribed to the mechanism of hydrogen evolution at GaAs electrodes. The nucleation mechanism was examined by chronoamperometry. It was found that the nucleation mechanism of Au on n-GaAs depends on the surface composition. Moreover, at potentials where thermodynamically stable Ga is formed at the surface (V < −1.65 V vs. SCE), the reduction of Au(CN)₂⁻ is believed to occur at the Ga/electrolyte interface, leading to the observed change in nucleation mechanism at () n-GaAs. n-GaAs/Au contacts were formed by electrodeposition and metal evaporation but the resulting Schottky barriers had poor ideality (n > 1.4).