Growth of Luminescent GaAsP on Si Substrate by Metalorganic Molecular Beam Epitaxy Using GaP Buffer Layer

GaAs1-x P x (0.2<x<0.7) was grown on a Si substrate with a GaP buffer layer by metalorganic molecular beam epitaxy. The surface smoothness was taken to be an indicator for the improvement of GaAsP crystallinity. The optimal growth temperature and thickness of the buffer layer for obtaining a smooth surface were determined based on results of atomic force microscopy and reflection high-energy electron diffraction. While GaAsP epilayers grown directly on Si showed no photoluminescence (PL), GaAsP grown on Si with a thin GaP buffer layer (∼100 Å) at 300°C showed PL. GaAsP epilayers of n-type were obtained with Sn-doping during growth. The electron conduction in n-type GaAsP was explained by carrier conduction in both the Γ valley and the X valley.