Arsenic-antisite defect in GaAs: Multiplicity of charge and spin states

Abstract

We find that the As-antisite defect in GaAs which is the source of the stable EL2 and metastable $\mathrm{EL}{2}^{*}$ centers can exist in at least eight different combinations of charge and structural states, twice as many as currently envisaged. In particular, results from first-principles calculations indicate that $\mathrm{EL}{2}^{*}$ which is normally considered to be a neutral defect can also occur in $+1,$ $\ensuremath{-}1,$ and $\ensuremath{-}2$ charge states. The existence of charged states for $\mathrm{EL}{2}^{*}$ is consistent with experimental data which indicate that $\mathrm{EL}{2}^{*}$ is a more complex defect than originally anticipated.