Identification of the arsenic-antisite-arsenic-vacancy complex in electron-irradiated GaAs

We report the observation by electron paramagnetic resonance of a new irradiation-induced defect in $n$-type GaAs. It is characterized by the spin Hamiltonian parameters $S=\frac{1}{2}$, $g=1.97\mathrm{}\pm 0.06$, $A=0.068\mathrm{}\pm 0.004$ ${\mathrm{cm}}^{-1\mathrm{}}$, $I=\frac{3}{2}$ (100%) and attributed to the complex formed by an arsenic-antisite defect and an arsenic vacancy on a first-nearest-neighbor position ${\mathrm{As}}_{\mathrm{Ga}}{\mathrm{As}}_3{V}_{\mathrm{As}}$. We consider it to be the precursor defect to the isolated antisite defect ${\mathrm{As}}_{\mathrm{Ga}}$ ${\mathrm{As}}_4$, which is subsequently formed by the trapping of a mobile arsenic interstitial by this complex. Contrary to this last defect, the level associated with the 0→ + transition of the antisite-vacancy complex is shallow with an ionization energy $E\le 0.35$ eV from the conduction band.