First-principles investigation of the oxygen negative- U center in GaAs

摘要: We investigated the atomic configuration of oxygen negative-$U$ center in GaAs, which has a Ga-O-Ga structure, based on first-principles calculations. calculated stable configurations and formation energies for two structures. One is $\mathrm{Ga}\ensuremath{-}{\mathrm{O}{\ensuremath{-}V}_{\mathrm{As}}}\ensuremath{-}\mathrm{Ga},$ been proposed as structure center. The other ${\mathrm{G}\mathrm{a}\ensuremath{-}\mathrm{O}}_{i}\ensuremath{-}\mathrm{Ga},$ we propose this paper. Five charge states from $+1$ to $\ensuremath{-}3$ were considered. For both $\mathrm{Ga}\ensuremath{-}{\mathrm{O}{\ensuremath{-}V}_{\mathrm{As}}}\ensuremath{-}\mathrm{Ga}$ depend states. cannot explain experimentally obtained tendency local-vibrational-mode absorption frequencies different energy function Fermi level indicates that does not have nature. In contrast, results ${\mathrm{G}\mathrm{a}\ensuremath{-}\mathrm{O}}_{i}\ensuremath{-}\mathrm{Ga}$ well experimental such Thus, it concluded GaAs $\mathrm{Ga}\ensuremath{-}{\mathrm{O}{\ensuremath{-}V}_{\mathrm{As}}}\ensuremath{-}\mathrm{Ga}.$