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 °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.