Role of extended vacancy-vacancy interaction on the ripening of voids in silicon

We elucidate the mechanism driving the ripening of vacancy clusters in silicon by means of lattice kinetic Monte Carlo simulations using different binding models. A modified Ising model, also taking into account second neighbor interaction, results in vacancy cluster energetics, in quantitative agreement with recent tight binding molecular dynamics calculations. We show that, when this model is used, the ripening process is also driven by the migration of small vacancy clusters, and not solely by free vacancies. This produces a faster vacancy agglomeration and a strong modification of the cluster size distribution.