EPITAXIAL-GROWTH AND INTERFACE PARAMETERS OF SI LAYERS ON GAAS(001) AND ALAS(001) SUBSTRATES

Thin Si epitaxial layers (1-14 monolayers) were fabricated by molecular beam epitaxy on GaAs (001) and AlAs (001) substrates also obtained by molecular beam epitaxy on GaAs(001) wafers. In situ studies by monochromatic x-ray photoemission show initial layer-by-layer Si growth on both substrates with only minor Si indiffusion. Reflection high energy electron diffraction analysis shows good epitaxy with some indication of three-dimensional growth at Si coverages higher than 4-8 monolayers. Comparison of our results with recent heterojunction theories suggests that the best predictions for the band offsets are obtained with the model solid approach using deformation potentials to describe the effect of strain. The Si epitaxial layers are found to remain stable upon growth of AlAs or GaAs layers on top of the Si layers.