An investigation was made of vacancy-assisted self-diffusion in germanium by means of kinetic lattice Monte Carlo simulations below the melting point, for a vacancy concentration of 1018/cm3. At higher temperatures, fewer clusters formed, but there was less variation in the number of clusters than at lower temperatures as the time increased. Equilibrium diffusivities in the clustering region were 102 lower than those of free vacancies in the initial stage of kinetic lattice Monte Carlo simulations. They were expressed in terms of three temperature regimes: 6.5 x 10-4exp[-0.35/kT]cm2/s above 1100K, 5.2 x 105exp[-2.32/kT]cm2/s at 900 to 1100K and 6.0 x 10-7exp[-0.19/kT]cm2/s below 900K. The effective mean migration energy, 1.1eV, coincided closely with the 1.0 to 1.2eV found in experiments and was very different from the migration energy of a free vacancy.

Vacancy Clustering and Diffusion in Germanium using Kinetic Lattice Monte Carlo Simulations. J.W.Kang, Y.G.Choi, J.H.Lee, S.H.Lee, H.J.Oh: Molecular Simulation, 2009, 35[3], 234-40