Surface Transformations and Growth of Nanocrystals on Au-covered GaAs Crystals

Abstract

We present a simple method of nanocrystal growth during the heating of Au-covered GaAs single crystals in a closed quartz ampoule, previously evacuated to 10-1 Pa. The process is the final stage of surface transformations in such crystals which include the disruption of initially continuous, 50 nm thick Au layer and formation of Au-particle fractals in the relatively low 300-500 °C temperature range and a next step, when a variety of crystalline nanowires and even nanotubes grows on the crystal surface during the further short-period heating up to 550-650 °C. These nanostructures were identified by SEM and TEM measurements as b-Ga2O3 and a non-stoichiometric arsenic oxide. It is supposed that the growth of few nanometer thick arsenic oxide tubes follows the vapour-solid mechanism, whereas the catalytic Au-metal growth of thicker b-Ga2O3 nanowires was dominated by the vapour-liquid-solid mechanism.