Anomalous energetics and defect-assisted diffusion of Ga in silicon

We study via first-principles calculations the energetics and diffusion of Ga in c-Si. In contrast to B and In, the favored Ga/self-interstitial complex is the tetrahedral interstitial Ga-T. Thus in the presence of self-interstitials Ga becomes interstitial, and is electrically deactivated as an acceptor. Studying the native-defect assisted diffusion, we find a self-interstitial-assisted mechanism to be favored; vacancy-assisted diffusion has a sizably larger activation energy, in agreement with the observed transient enhanced diffusion behavior. (C) 2004 American Institute of Physics.