Clustering in the Epitaxial Growth of GaAs on Si.

We report ion scattering and TEM investigations of the first layers of GaAs grown on clean Si(111). Based on observations of pure Ga cluster growth on As terminated Si(111) we purpose a model for GaAs growth on Si, where Ga atoms are mobile and tend to cluster, but are immobilized by arriving As. These results establish conditions necessary for uniform film growth of GaAs/Si at the important film/substrate interface.