ANALYSIS OF MOLECULAR-BEAM EPITAXIAL-GROWTH OF INAS ON GAAS(100) BY REFLECTION ANISOTROPY SPECTROSCOPY

The molecular-beam epitaxial growth of InAs on GaAs(100) was investigated in situ using reflection anisotropy spectroscopy (RAS) and simultaneously reflection high-energy electron diffraction. The RAS spectra of the GaAs c(4 x 4) and (2 x 4) and the InAs (4 x 2) and (2 x 4) reconstructions are reported. During InAs deposition, the RAS signal shows significant changes for InAs coverages as low as 1/6 of a monolayer. At this coverage surface reconstructions are responsible for the signal variation. For InAs coverages larger than four monolayers, the RAS signal is essentially determined by the anisotropic roughness of the three-dimensional growing surface. This is verified using a three-layer model which gives an excellent description of the experimental spectra at large coverages.