Photoresponse of the FR3 electron-spin-resonance signal in GaAs

The photoresponse of the FR3 electron-spin-resonance (ESR) signal in GaAs has been studied. Excitation and quenching of the FR3 ESR is shown to result from the optically induced charge exchange between the FR3 center and the ${\mathrm{As}}_{\mathrm{Ga}}$ antisite. The FR3 ESR can be persistently excited with photons in the range $1.0 \mathrm{eV}<h\nu <1.3\mathrm{} \mathrm{eV}$. It is demonstrated that this behavior is a direct consequence of the metastability of the ${\mathrm{As}}_{\mathrm{Ga}}$ antisite. Conclusive evidence for the acceptor nature of the FR3 center is presented, the corresponding level lying between $E_v+0.03\mathrm{}$ eV and $E_v+0.52\mathrm{}$ eV.