Surface diffusion of In on Si(111): Evidence for surface ionization effects

Second harmonic microscopy has been used to quantify the surface diffusion of In on Si(111). At temperatures near 50% of the bulk melting temperature and in the coverage range 0 much-gt θ much-gt 0.7, the activation energy Ediff and pre-exponential factor D0 lie at 42±0.5 kcal/mol and 3x103±0.3 cm2/s, respectively. These parameters, which are quite large, are explained semiquantitatively by reference to an adatom endash vacancy model recently developed for related systems. The present work, when compared with the results of these other systems, offers significant evidence for the effects of adatom endash vacancy ionization. copyright 1996 American Vacuum Society