A numerical study was made of self-diffusion mechanisms in silicon by using a semi-empirical Stillinger-Weber potential to calculate the formation and migration energies and entropies. It was found that self-diffusion in bulk Si was mediated by vacancies at low temperatures, but that interstitials played an increasingly important role as the temperature increased: in agreement with experimental data. This behaviour was shown to change markedly under a biaxial strain, ϵ, which simulated the effect of the epitaxial growth of a Si thin film. The present methodology permitted the classification of vacancy or interstitial self-diffusion within a (T,ϵ) diagram. This revealed a transition, from vacancy to interstitial diffusion at low temperatures, beyond a critical tensile strain which corresponded to the Si/Ge size mismatch.

Strain Effect on Self-Diffusion in Silicon - Numerical Study. P.Ganster, G.Tréglia, A.Saúl: Physical Review B, 2009, 79[11], 115205