INITIAL-STAGE OF EPITAXIAL-GROWTH AT THE HIGH-TEMPERATURE OF GAAS AND ALGAAS ON SI BY METALORGANIC CHEMICAL VAPOR-DEPOSITION

GaAs and AlGaAs grown directly on Si were characterized by transmission electron microscopy. Both GaAs and AlGaAs grow three-dimensionally on Si at 750-degrees-C. The spacing between GaAs islands is large, while the AlGaAs islands appear to be contiguous for a nominal thickness of 22.5 nm. There is a high density of dislocations, stacking faults, and microtwins in the thin GaAs layer, but drastic reduction of such defects was observed in the planar AlGaAs nucleation layer.