The effect of strain upon vacancy-mediated diffusion was investigated by comparing diffusivities in tensile-strained and relaxed Si and in compressively strained and relaxed Si0.91Ge0.09. It was found that the diffusivity was enhanced by a compressive strain and was retarded by a tensile strain. A convincing degree of agreement was found between the present trends, and the predictions of total-energy calculations. It was possible to determine changes in activation energy per unit strain for compressive and tensile strains. It was also demonstrated that there was an appreciable enhancement, due to chemical effects, in Si0.91Ge0.09. However, contrary to interstitialcy-mediated diffusion, this chemical effect could not alone account for the enhancement. This implied that strain had a greater effect upon vacancy-mediated diffusion than upon interstitialcy-mediated diffusion.

P.Kringhøj, A.N.Larsen, S.J.Shirayev: Physical Review Letters, 1996, 76[18], 3372-4