Abinitiocalculations of the structure and energetics of As-vacancy complexes in silicon

For atomistic simulation of vacancy-assisted dopant diffusion in silicon one needs details of the dopant-vacancy interaction, i.e. the potential as a functional of dopant-vacancy separations. In this paper, we present a detailed study on the energetics of As-vacancy reaction in silicon and the lattice distortions surrounding the As-vacancy defect by using an ab initio plane-wave pseudopotential method and the density functional theory (DFT). A potential-energy diagram as a function of As-vacancy separation, which can be used in the atomistic diffusion simulations, is provided. We also calculate the binding energy and the formation energy of various complexes such as AsV, As 2 V and AsV 2 (V represents a vacancy). We find that the stable configuration of As 2 V is As-V-As, whereas the stable configuration of AsV 2 is As-V-V. The nature of the binding between As and a vacancy is explained in terms of the lattice distortions and the change of chemical bond configuration introduced by the As-vacancy complex.