A multi-scale analysis of stress-enhanced vacancy-mediated diffusion in strained Si was performed that explicitly included the Jahn–Teller structural distortion around vacancies. The resultant anisotropy, combined with biaxial deformations applied to (100)-oriented films, led to an orientational dependence of the vacancy formation energy. At finite temperatures, it resulted in a strong entropy effect when thermal activation permitted the occupancy of high-energy defect states. Kinetic lattice Monte Carlo simulations revealed that the effective activation energy was a strongly non-linear function of strain at small deformations. At larger deformations, it became linear as the occupancy of the excited states became insignificant.

Stress Enhanced Self-Diffusion in Si - Entropy Effect in Anisotropic Elastic Environment. K.Z.Rushchanskii, P.Pochet, F.Lançon: Applied Physics Letters, 2008, 92[15], 152110