Vacancy diffusion on Si(100)-(2×1)

Abstract

The mechanism of migration of missing-dimer vacancies on Si(100)-(2\ifmmode\times\else\texttimes\fi{}1) has been investigated theoretically. The migration involves a wavelike concerted motion of four atoms: Two rebonded atoms in the second layer more up to the top layer, while two dimerized atoms in the top layer simultaneously descent into the second layer. The migration is extremely anisotropic, with the fast direction along the dimer rows. The predicted direction of fast diffusion and the activation energy are consistent with experiment.