RHEED STUDIES OF STEPS, ISLANDING AND FACETING ON SINGULAR, VICINAL AND HIGH-INDEX SURFACES

The atomic-scale morphology of singular, vicinal and high-index surfaces and their growth mechanisms during molecular beam epitaxy (MBE) have been studied by reflection high-energy electron diffraction (RHEED). The growth mechanism of the singular GaAs (001) surface is governed by a competition between layer-by-layer growth and kinetic roughening. On vicinal GaAs (001) surfaces tilted toward the (111BAR) As plane the terrace width fluctuations increase with the decrease in misorientation, although a step flow mechanism is maintained. The GaAs (311) Ga surface shows a unique behaviour. After breaking up into (331) facets, the well-ordered corrugated surface reproduces during growth, since neither nucleation nor diffusion processes over long distances are essential. On single-layer stepped Si (001) surfaces misoriented toward [110], a preferential incorporation of Si atoms in one of the inequivalent step types is possible even for low tilt angles. It is, however, hindered by arsenic adsorption.