The vacancy-pair diffusion mechanism in cubic materials was revisited, with emphasis placed on the limits of the ratio of the tracer diffusion coefficients, in order to demonstrate the operation of the mechanism. The vacancy-pair mechanism put very strict upper and lower bounds on the ratio. Extensive high-precision Monte Carlo simulations were used to calculate tracer correlation factors, ratios of tracer diffusivities and percolation effects (in compounds). The three major cubic lattices (NaCl, CsCl, zincblende) were analyzed, and the correct limits for the ratios of the tracer diffusivities were found to be 5.6, 11.2 and 2.6, respectively. For the CsCl structure, correlation factors were re-determined using the matrix method to obtain good agreement with Monte Carlo results. Self-diffusion in PbSe (NaCl structure) InSb, GaSb, CdTe and HgCdTe (zincblende structure) was re-analyzed. It was shown that the vacancy-pair mechanism was unlikely to contribute to self-diffusion in CdTe and HgCdTe but remained a valid possibility for self-diffusion in PbSe, InSb and GaSb.

Limits of the Ratios of Tracer Diffusivities for Diffusion by Vacancy Pairs: Application to Compound Semiconductors. I.V.Belova, D.Shaw, G.E.Murch: Journal of Applied Physics, 2009, 106[11], 113707