First-Principles Study of Boron Diffusion in Silicon

Abstract

In this Letter we investigate boron diffusion as a function of the Fermi-level position in crystalline silicon using ab initio calculations. Based on our results, a new mechanism for B diffusion mediated by Si self-interstitials is proposed. Rather than kick out of B into a mobile channel, we find a direct diffusion mechanism for the boron-interstitial pair for all Fermi-level positions. Our activation energy of $3.5--3.8$ eV, migration barrier of $0.4--0.7$ eV, and diffusion-length exponent of $\ensuremath{-}0.6$ to $\ensuremath{-}0.2$ eV are in excellent agreement with experiment.