A model was proposed for vacancy mediated diffusion in disordered alloys, with particular application to Ge self-diffusion in Si1–xGex. It was argued that, if the vacancy formation energies, exhibited a strong dependence upon the configuration of nearest neighbor atoms, there will be preferential diffusion paths for some concentrations. For Si1–xGex, it was shown that the vacancy formation energies varied linearly from 2 to 3eV as the number of nearest-neighbor Ge atoms varied from 4 to 0. Thus, the equilibrium population of the various kinds of vacancies changed significantly with x, and the diffusion proceeded via paths which did not necessarily resemble the concentration of the alloy.

Vacancy-Mediated Diffusion in Disordered Alloys - Ge Self-Diffusion in Si1–xGex. P.Venezuela, G.M.Dalpian, A.J.R.da Silva, A.Fazzio: Physical Review B, 2002, 65[19], 193306