SURFACE-DIFFUSION OF IN ON SI(111) - EVIDENCE FOR SURFACE-IONIZATION EFFECTS

Second harmonic microscopy has been used to quantify the surface diffu sion of In on Si(111). At temperatures near 50% of the bulk melting te mperature and in the coverage range 0<theta<0.7, the activation energy E(diff) and pre-exponential factor D-0 lie at 42+/-0.5 kcal/mol and 3 X10(3+/-0.3) cm(2)/s, respectively. These parameters, which are quite large, are explained semiquantitatively by reference to an adatom-vaca ncy model recently developed for related systems. The present work, wh en compared with the results of these other systems, offers significan t evidence for the effects of adatom-vacancy ionization. (C) 1996 Amer ican Vacuum Society.