ATOMIC DIFFUSION IN SILICON.

We present a unified description of atomic diffusion processes in silicon, based on the results of parameter-free total-energy calculations. An interpretation of both low- and high-temperature data is provided without the need to invoke a change in the nature of intrinsic defects as a function of temperature. The self-interstitial has negative-U properties and can migrate athermally via the Bourgoin-Corbett mechanism along several paths. Both vacancies and self-interstitials mediate self-diffusion with activation energies within the range of observed values. Both intrinsic defects also mediate the diffusion of impurities such as Al and P, but the detailed mechanisms are considerably more complex than those of self-diffusion.