REFLECTION HIGH-ENERGY ELECTRON-DIFFRACTION STUDY OF THE GAASSIGAAS SYSTEM

Surface structures occurring as a function of coverage during the deposition of Si on GaAs (001) and the further changes brought about by subsequent GaAs overgrowth using molecular beam epitaxy (MBE) have been studied with reflection high-energy electron diffraction (RHEED). Deposition of Si in the presence of an AS4 flux causes the surface reconstruction to change systematically from 2 X 4 to symmetric 3 X 1 via an asymmetric 3 X 1 stage. The process is reversed during the overgrowth of GaAs. The change in surface periodicity in the [110] direction from two-fold to three-fold is explained by a superpositioning model. The implications of this for the growth and incorporation mechanisms of Si on GaAs are discussed.