Computed Optical Absorption and Photoluminescence Spectra of Neutral Oxygen Vacancies inα-Quartz

We report ab initio configuration interaction calculations of the optical transitions of a Si${\mathrm{O}}_2$ neutral oxygen vacancy $\left(V_{\mathrm{O}}\right)$ using cluster models. The transition from the $V_{\mathrm{O}}$ ground state and the consequent radiative decay explain the 7.6 eV absorption and the 4.4 eV photoluminescence bands reported in the literature. We suggest that the transition from a metastable structure of $V_{\mathrm{O}}$ is responsible for the 5.0 eV absorption band. The model accounts for the fact that the 4.4 eV fluorescence is stimulated by excitations in both UV and vacuum UV regions with different decay kinetics.