Charge Transfer and Surface Diffusion of Lead on Ge(111)

Abstract

Small amounts of Pb significantly enhance the surface diffusion on the Ge(111)c(2 × 8) surface. Scanning tunneling microscopy at different sample bias polarities has been used to study the local geometric and electronic properties of the mixed Pb and Ge adatom structure. It was found that all Ge adatoms transfer charge to the Ge rest atoms whereas the Pb atoms exist in two different electronic configurations. Pb atoms which do not transfer charge to Ge rest atoms allow the existence of various characteristic Pb-induced defects in the c(2 × 8) reconstruction. During the formation of these defects vacancies are created which facilitate the diffusion of adatoms over large distances on the surface.