First-principles study of vacancy-assisted as diffusion in silicon

A set of interaction potentials for vacancy-assisted As diffusion in silicon have been provided via first-principles pseudo-potential calculations. Some important reactions such as As+V reversible arrow AsV, AsV + As reversible arrow As2V, AsV + V reversible arrow AsV2, as well as V + V reversible arrow V-2 are considered. The results demonstrate that the existence of another As atom greatly reduces the migration barrier of vacancy moving between the two As atoms and speeds up the diffusion of As. The AsV pair can attract another nearby vacancy. The binding force mainly comes from the binding between two vacancies, rather than from the AsV pair. The obtained potential energy diagrams provide input information for atomistic diffusion simulations.