Ab Initio Study of Elementary Processes in Silicon Homoepitaxy–Adsorption and Diffusion on Si(001)

Abstract

Ab initio total-energy calculations of the reconstructed Si(001) with adatoms for various adsorption sites have been performed. The results are interpreted in terms of adatom-substrate interactions to understand microscopic mechanisms of the surface diffusion of Si adatoms. The spatial variation of the adsorption energy suggests strong anisotropy in the direction of the adatom diffusion on Si(001)–the most probable direction of diffusion is along the dimer rows. The surface dimer breaks when the adatom moves along the lateral projection of the dimer bond.