First-principles calculations were made of the energetics and diffusion of Ga in c-Si. In contrast to B and In, the favored Ga/self-interstitial complex was the tetrahedral interstitial GaT. In the presence of self-interstitials, Ga became interstitial and was electrically deactivated as an acceptor. Upon studying native-defect assisted diffusion, a self-interstitial assisted mechanism was found to be favored. Vacancy-assisted diffusion had a considerably higher activation energy; in agreement with the observed transient enhanced diffusion behavior.

Anomalous Energetics and Defect-Assisted Diffusion of Ga in Silicon. C.Melis, G.M.Lopez, V.Fiorentini: Applied Physics Letters, 2004, 85[21], 4902-4