Anisotropic Lateral Growth of GaAs by Molecular Beam Epitaxy

A large anisotropy of the lateral growth rate on (001) GaAs is observed in molecular beam epitaxy of GaAs. The growth rate along [11̄0] is much larger than that along [110], which is contrary to that of metal-organic chemical vapor deposition. The growth rate along [11̄0] increases with increasing substrate temperature or decreasing As4 pressure. These results and the fact that the surface diffusion constant of Ga along [11̄0] is larger than that along [110] indicate that the lateral growth is limited by the surface diffusion of Ga. A model taking account of the diffusion length and terrace widths is shown to explain the anisotropic growth rate.