Theoretical investigation of Cottrell atmosphere in silicon

The distribution of fast-diffusing interstitial impurities (Ni, Cu, etc.) in the vicinity of a dislocation loop in Si bulk is theoretically investigated, at the atomic scale, using the Si Stillinger–Weber potential via Monte Carlo and kinetic Monte Carlo simulations. The Si dislocation loop is modeled by an extra Si plane introduced between two Si(1 1 1) planes. Interstitial impurities are shown to gather on the dislocation loop edges only, in interstitial sites of minimum pressure. These results are in agreement with experimental atom probe tomography observations related to Ni accumulation on Si dislocation loops, and can be interpreted as a Cottrell atmosphere.