Magnetic circular dichroism and optical detection of electron paramagnetic resonance of theSbGaheteroantisite defect in GaAs:Sb

In an investigation of GaAs doped with Sb to a concentration of ≊1×${10}^{19}$ ${\mathrm{cm}}^{\mathrm{-}3}$, the electron-paramagnetic-resonance (EPR) signal of the ${\mathrm{Sb}}_{\mathrm{Ga}}$ heteroantisite defect has been optically detected by monitoring the microwave-induced changes in the magnetic-circular-dichroism (MCD) absorption signal. All hyperfine transitions expected for the two Sb isotopes ${(}^{121}$Sb and ${}_{}{}^{123}{}_{}{}^{}\mathrm{Sb}$) were observed and the identification of the ${\mathrm{Sb}}_{\mathrm{Ga}}$ defect is thus confirmed. The g value is 2.02 and the hyperfine constants are 0.220 ${\mathrm{cm}}^{\mathrm{-}1}$ (for ${}_{}{}^{121}{}_{}{}^{}\mathrm{Sb}$) and 0.120 ${\mathrm{cm}}^{\mathrm{-}1}$ (for ${}_{}{}^{123}{}_{}{}^{}\mathrm{Sb}$). The MCD signal of the ${\mathrm{Sb}}_{\mathrm{Ga}}$ defect has been measured being tagged to the EPR signal, and a comparison with the corresponding spectrum for the ${\mathrm{As}}_{\mathrm{Ga}}$(EL2) defect is made. The existing models fail to give a satisfactory explanation for the MCD spectra.