Binding and formation energies of native defect pairs in GaAs

Abstract

The formation energies of native lattice-site point defects and of nearest-neighbor lattice-site defect pairs in GaAs have been calculated by use of the self-consistent Green’s-function technique. From these results, we deduce a binding energy of ∼2±1 eV for the pairs $V_{\mathrm{As}+V_{\mathrm{Ga}}}$, ${\mathrm{As}}_{\mathrm{Ga}+{\mathrm{Ga}}_{\mathrm{As}}}$, ${\mathrm{As}}_{\mathrm{Ga}+{\mathrm{V}}_{\mathrm{As}}}$, and ${\mathrm{Ga}}_{\mathrm{As}+{\mathrm{V}}_{\mathrm{Ga}}}$. We also obtain end-point energy differences for the vacancy migration hops $V_{\mathrm{Ga}\to V_{\mathrm{As}+{\mathrm{As}}_{\mathrm{Ga}}}}$ and $V_{\mathrm{As}\to V_{\mathrm{Ga}+{\mathrm{Ga}}_{\mathrm{As}}}}$. For these latter reactions, violent donor-acceptor transitions occur and the Fermi energy determines the stable form.