Gallium self-interstitial relaxation in GaAs : An ab initio characterization

摘要: Ga interstitials in GaAs $({I}_{\mathrm{Ga}})$ are studied using the local-orbital ab initio code SIESTA a supercell of $216+1$ atoms. Starting from eight different initial configurations, we find five metastable structures: two tetrahedral sites addition to $110\text{\ensuremath{-}}{\text{split}}_{[\mathrm{Ga}\text{\ensuremath{-}}\mathrm{As}]}$, $111\text{\ensuremath{-}}{\text{split}}_{[\mathrm{Ga}\text{\ensuremath{-}}\mathrm{As}]}$, and $110\text{\ensuremath{-}}{\text{split}}_{[\mathrm{Ga}\text{\ensuremath{-}}\mathrm{Ga}]}$. Studying competition between various configuration charges ${I}_{\mathrm{Ga}}$ at $T=0\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, that predominant gallium charged $+1$, neutral, or most $\ensuremath{-}1$ depending on doping conditions prefer occupy where it is surrounded by Our results excellent agreement with recent experimental concerning dominant charge ${I}_{\mathrm{Ga}}$, underlining importance finite size effects calculation defects.