Direct MOCVD epitaxy of GaAsP on SiGe virtual substrate without growth of SiGe

Abstract

GaAsP has important applications for solar cells and light-emitting diodes on silicon substrates. Here we demonstrate that GaAsP can be directly grown by metal-organic chemical vapor deposition on previously-prepared lattice-matched SiGe virtual substrates, without prior in-situ growth of SiGe. By optimizing the growth pressure and AsH3 pre-exposure time, the surface morphology of GaAsP is improved and the pinhole densities are reduced by two orders of magnitude from 2.4×107/cm2 to 1.2×105/cm2. The physics is suggested to be an optimization between complete As-termination and AsH3 etching effect of SiGe surface.