Optically Detected Electron-Nuclear Double Resonance of As-Antisite Defects in GaAs

This Letter reports on the first optically detected electron-nuclear double-resonance (ENDOR) measurements of a paramagnetic semiconductor defect in which ligand hyperfine interactions could be resolved. In semi-insulating GaAs: Cr the ENDOR lines of the first-shell ${}_{}{}^{75}{}_{}{}^{}\mathrm{As}$ neighbors of the regular tetrahedral As${\mathrm{As}}_4$-antisite defect could be detected and analyzed. The ENDOR investigation reveals that at least one other As${\mathrm{As}}_4$-antisite complex contributes to the same ESR spectrum.