Stress influence on substitutional impurity segregation on dislocation loops in IV-IV semiconductors
Résumé
The influence of stress on the distribution of slow-diffusing substitutional impurities in the vicinity of a dislocation loop in Si and Ge bulk was theoretically investigated, at the atomic scale, using the Si and Ge Stillinger-Weber potentials via Monte Carlo and kinetic Monte Carlo simulations. The dislocation loop was modeled by an extra atomic plane introduced between two (111) planes. The calculations were performed at high temperature, for which impurity diffusion was enabled. The influence of atomic size effect on Cottrell atmosphere formation was investigated considering the difference of atomic volume between Si and Ge. The dislocation loop elastic field was found to prevent the accumulation of substitutional atoms in the vicinity of the dislocation. However, the calculations suggest that substitutional impurities can occupy interstitial sites close to the dislocation loop. In this case, the elastic field surrounding the dislocation loop can promote Cottrell atmosphere formation mainly if the impurity exhibits a larger atomic radius than the matrix atoms (Si or Ge). (C) 2015 Elsevier B.V. All rights reserved.