Temperature dependence of Ga-assisted oxide desorption on GaAs(001)

Abstract

Removal of native oxide by conventional thermal desorption causes large scale degradation of the initial surface layer. Ga assisted oxide removal at 440-500°C has been shown to reduce damage and so-called μpit formation. We examine surfaces prepared by this technique over the 400-580°C range with dynamic reflection high-energy electron diffraction (RHEED) and in situ scanning tunnelling microscopy (STM) analysis. Surfaces with oxide clusters, pure GaAs and Ga droplets are found to exist sequentially for sub-monolayer increases in Ga deposition. The STM imaging shows that two distinct, temperature dependent cleaned surfaces exist within the prescribed range. Ga mobility is believed to underpin the mechanisms that produce each surface whilst step-edge density defines the resulting pit density. © 2010 IOP Publishing Ltd.