Equilibrium concentration and diffusivity of vacancies and self-diffusion in Ge: An atomistic study

We developed an improved Stillinger-Weber-type potential for Ge by adjusting the three-body parameters in such a manner, that the potential yields the correct lattice constant and the correct cohesive energy, and the melting point and other properties are reproduced satisfactorily. Using this potential, the temperature dependence of equilibrium concentration and diffusivity of vacancies as well as the contribution of vacancies to self-diffusion are investigated by atomistic simulations and thermodynamic considerations. The enthalpies and entropies of formation and migration are calculated. Similar investigations are performed for self-interstitials in order to check whether their contribution to self-diffusion can be neglected, as shown experimentally. Finally, the self-diffusion coefficient and the equilibrium concentration of vacancies determined by the simulations are compared with experimental data from the literature.