Interstitial-mediated mechanisms of As and P diffusion in Si: Gradient-corrected density-functional calculations

Abstract

Gradient-corrected density-functional calculations are used to determine the structure, stability, and diffusion of arsenic-interstitial and phosphorus-interstitial pairs in the positive, neutral, and negative charge states. For both cases, our calculations show that the neutral pair will be dominant under intrinsic conditions while the neutral and negative pairs will both be important in extrinsic $n$-type materials. The overall diffusion activation energies of neutral ${\mathrm{As}}_{s}\text{\ensuremath{-}}{\mathrm{Si}}_{i}$ and ${\mathrm{P}}_{s}\text{\ensuremath{-}}{\mathrm{Si}}_{i}$ pairs are predicted to be $3.75\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ and $3.43\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$, respectively, in good agreement with experimental observations in intrinsic regions.