We report a combined study by optical absorption (OA) and electron paramagnetic resonance (EPR) spectroscopy on the $E_{\alpha }^{\prime }$ point defect in amorphous silicon dioxide $\left(a\text{−}\mathrm{Si}{\mathrm{O}}_2\right)$. This defect has been studied in $\beta$-ray irradiated and thermally treated oxygen-deficient $a\text{−}\mathrm{Si}{\mathrm{O}}_2$ materials. Our results have pointed out that the $E_{\alpha }^{\prime }$ center is responsible for an OA Gaussian band peaked at $\sim 5.8\mathrm{eV}$ and having a full width at half maximum of $\sim 0.6\mathrm{eV}$. The estimated oscillator strength of the related electronic transition is $\sim 0.14$. Furthermore, we have found that this OA band is quite similar to that of the $E_{\gamma }^{\prime }$ center induced in the same materials, indicating that the related electronic transitions involve states highly localized on a structure common to both defects: the $\mathrm{O}{\mathrm{Si}}^{\mathbf{\cdot }}$ moiety.

• Received 7 February 2008

DOI:https://doi.org/10.1103/PhysRevB.77.155214