Excitation spectroscopy on the 0.79-eV (C) line defect in irradiated silicon

We combine photoluminescence excitation measurements and conventional luminescence spectroscopy to show that the oxygen-related deep defect in irradiated silicon which emits the 0.79-eV ($C$) no-phonon line possesses local modes of 65.5-, 72.5-, 138.1-, and 145.3-meV quantum energy. These values are close to the vibration energies of interstitial oxygen ($\mathrm{S}\mathrm{i}-{\mathrm{O}}_i-\mathrm{S}\mathrm{i}$), substitutional carbon, or oxygen-carbon complexes as observed in ir absorption. Two groups of electronic excited states centered at photon energies around 0.80 or 0.82 eV, respectively, are also identified.