Density functional theory calculations were used to investigate the formation and diffusion of tin-vacancy pairs (SnV) in germanium. Depending upon the Fermi energy, SnV pairs could form in neutral, singly negative, or doubly negative charged states. The activation energies of diffusion, also as function of the Fermi energy, were calculated to lie between 2.48 and 3.65eV, in agreement with and providing an interpretation of available experimental work.

Diffusion of Tin in Germanium: A GGA+U Approach. H.Tahini, A.Chroneos, R.W.Grimes, U.Schwingenschlögl: Applied Physics Letters, 2011, 99[16], 162103