Molecular-beam-epitaxial growth of GaAs on high-temperature hydrogen-annealed (100) silicon

Superior-quality GaAs epitaxial layers have been grown by molecular beam epitaxy on high-temperature hydrogen-ambient annealed silicon (100) substrates. Rutherford back-scattering and channelling of 2.1 MeV He+ ions and transmission electron microscopy techniques have been used to characterise these layers. Comparative studies indicate that the epitaxial layers grown on hydrogen-ambient annealed substrates have a superior surface morphology and a lower interface disorder than those on chemically cleaned (100) substrates. Cross-sectional transmission electron micrographs show the presence of a high density of threading dislocations, stacking faults and twins in the GaAs layers grown on the chemically cleaned silicon (100) substrates. In contrast, a significant reduction in the density of these defects is observed in the layers grown on the preannealed substrates.