Silicon self-interstitial migration paths and barrier energies by the critical-path method

Abstract

Silicon self-interstitial migration paths and barrier energies have been investigated based on a first-principles critical-path calculation for atomic motions. Self-interstitials are moved through critical paths corresponding to the lowest-energy configurations for thermal diffusion. The results suggest that self-interstitial diffusion occurs mainly as a combination of interstitial-interchange and direct-interstitial mechanisms and that migration begins from stable hexagonal and tetrahedral configurations. The interstitialcy-interchange mechanism has been found to occur only rarely, because the structure becomes unstable when it attempts to move. The calculated migration barrier energies range from 1 eV to a little more than 2 eV, lying at the middle of widely ranging experimental results. Migration through the interstitial-interchange mechanism with a relatively low energy barrier compared with defect generation is attributed mainly to a successive bond remaking process.