The complete set of 4 macroscopic transport coefficients which described the coupled diffusion of impurity atoms and vacancies was derived from the atomistic mechanisms by taking accurate account of the effects of microscopic forces between dopants and vacancies. The aim of the simulations was to determine the validity of models such as the pair diffusion model or the non-Fickian diffusion model. These gave contradictory predictions of fundamental properties such as the directions of dopant and vacancy fluxes, as driven by a vacancy gradient, and of the relationship between 2 of the 4 transport coefficients. Simulations were performed, for various assumed interaction potentials, that established a functional dependence of factors such as the enhancement of dopant diffusivity over tracer diffusion for an arbitrary interaction. In the case of As, a large scatter in the experimental data prevented an equally definite conclusion from being drawn. A qualitative confirmation of the pair diffusion theory, that dopant and vacancy fluxes had the same direction if caused by a vacancy gradient, was possible.

Atomistic Analysis of the Vacancy Mechanism of Impurity Diffusion in Silicon. S.List, H.Ryssel: Journal of Applied Physics, 1998, 83[12], 7585-94