An exhaustive first-principles study of the energetics of B-Si interstitial complexes, having various configurations and charge states, was used to clarify the B diffusion mechanism. Total energy calculations and molecular dynamics simulations showed that B diffused via an interstitialcy mechanism. Substitutional B captured a Si interstitial with a binding energy of 0.90eV. This complex was itself a fast diffuser, with no need to kick the B out into an interstitial channel. The migration barrier was equal to about 0.68eV. Kinetic Monte Carlo simulations confirmed that this mechanism led to a decrease in the diffusion length with increasing temperature; as observed experimentally.

Mechanism of Boron Diffusion in Silicon - an Ab Initio and Kinetic Monte Carlo Study B.Sadigh, T.J.Lenosky, S.K.Theiss, M.J.Caturla, T.Diaz de la Rubia, M.A.Foad: Physical Review Letters, 1999, 83[21], 4341-4