Influence of Si-O bonding arrangements at kinks on second-harmonic generation from vicinal Si(111) surfaces

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Abstract
The tensorial characteristic of optical second-harmonic generation (SHG) has been used to study Si-O bonding arrangements at kinks on vicinal Si(111) surfaces with a polar angle of 4° from [111] along an azimuth rotated away from the high-symmetry [1¯ 1¯2] or [112¯] directions by different degrees. The onefold contribution to the SHG rotational anisotropy exhibits a component arising from Si-O bonds with a net orientation parallel to the step edges. This specific component reflects the kinked-step structure of the vicinal Si(111) surface. For a remote plasma-enhanced chemical-vapor-deposited oxide film, the kink-induced onefold component changes after a rapid thermal annealing at 1000 °C indicating a relaxation of Si-O bonds at the corners of steps. The results are discussed in comparison with a microscopic model of the oxidized misoriented surface.