Microscopic study of cluster formation in the Ga on GaAs(001) system

Abstract

A microscopic study of the cluster morphology for the system Ga on GaAs(001) is presented. Clusters are shown to have significant volume fractions below the surface level of the surrounding substrate. A thermodynamic model qualitatively describes this phenomena based on a comparison between (a) arsenic desorption from the GaAs surface, limited either by bulk diffusion of arsenic or surface diffusion of gallium to the nearest cluster and (b) dissolution of GaAs in Ga clusters with subsequent diffusion of the As to the cluster surface and desorption. A quantitative rate prediction based on this model is in an order of magnitude agreement with the experimental data.