Carbon-Mediated Aggregation of Self-Interstitials in Silicon

The carbon-mediated aggregation of silicon self-interstitials is investigated with a novel approach based on large-scale parallel molecular dynamics. The presence of carbon in the silicon matrix is shown to lead to concentration-dependent self-interstitial cluster pinning, dramatically reducing cluster coalescence and thereby inhibiting the nucleation process. The extent of cluster pinning increases with cluster size for the range of cluster sizes observed in the simulation. The effect of carbon on single self-interstitials is shown to be of secondary importance, and the concentration of single self-interstitials as a function of time is essentially unchanged in the presence of carbon. A quasi-single component mean-field interpretation of the atomistic simulation results further confirms these conclusions and suggests that the experimentally observed effect of carbon on transient-enhanced diffusion (TED) could be due to carbon-cluster interactions