SMOOTH MONOLAYER AS-TERMINATED AND GA-TERMINATED GAAS(100) SURFACES

Recent layer-by-layer migration enhanced epitaxy growth of high qualit y GaAs(100) films at low temperatures suggested that smooth missing-di mer-free monolayer As- and Ga-terminated surfaces are attainable durin g the growth process or the grown films will contain a high concentrat ion of antisite defects. Using the local-orbital density-functional mo lecular-dynamics method, we find that the smooth monolayer As-terminat ed surface may be the (2x4) surface with a three-dimer unit and a shif ted dimer. The smooth monolayer Ga-terminated surface may be the (1x2) dimerized surface.