Stress induced anisotropy of vacancy interaction and clustering in uniaxially loaded Si monocrystal

In this paper, we investigate the effect of uniaxial strain on the interaction of a pair of neutral vacancies in pure silicon at distances up to the fifth-nearest-neighbors. The calculation of the total energies of vacancy pairs at different pair orientations was performed using the first-principles approach. It is demonstrated that the energy of a vacancy pair is sensitive to the pair orientation with respect to the direction of applied stress. The effect of such orientational dependence of vacancy interaction on the formation of vacancy clusters in a uniaxially strained monocrystalline Si is studied using kinetic Monte-Carlo simulation. It is shown that anisotropy in vacancy–vacancy interaction leads to the formation of planar vacancy clusters with preferred orientation with respect to the strain axis.