6533b85afe1ef96bd12b9f31

RESEARCH PRODUCT

Optical absorption band at5.8eVassociated with theEγ′centers in amorphous silicon dioxide: Optical absorption and EPR measurements

subject

description

Line shape modifications induced by thermal treatment in the optical absorption and electron paramagnetic resonance (EPR) signals associated with the ${E}_{\ensuremath{\gamma}}^{\ensuremath{'}}$ center are experimentally investigated in various types of $\ensuremath{\gamma}$-irradiated amorphous silicon dioxide $(a\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{2})$. The $g$ values of the EPR main resonance line of the ${E}_{\ensuremath{\gamma}}^{\ensuremath{'}}$ center show a shift correlated with the peak energy variation of the absorption band at about $5.8\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ associated with this defect. These spectroscopic changes are proposed to originate from structural modifications of the defect environment. The correlation is theoretically explained considering that the spin-orbit interaction couples the $g$-tensor's elements and the electronic energy level distribution of the defect. Our results suggest that the optical band at $5.8\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ is due to an intracenter electron promotion from the $\mathrm{Si}\mathrm{O}$ bonding states to the dangling bond of the $\mathrm{O}{\mathrm{Si}}^{\ifmmode\bullet\else\textbullet\fi{}}$ moiety.