An insight into the present understanding of point defects in the simplest and the most radiation-resistant oxide glass, glassy silicon dioxide (silica) was presented. The defects and their generation processes in glassy and α-quartz forms of silicon dioxide were significantly different. The only defect, confirmed to be similar in both materials, was O vacancy. In silica, additional defects of dangling bond type were generated from precursor sites formed by strained Si-O bonds, and by modifier ions. The optical absorption spectra of silica were dominated by paramagnetic dangling bond type defects: Si dangling bond (E’-center) and O dangling bond (non-bridging O hole center, NBOHC). Radiation-induced interstitial O atoms exist in peroxy linkage (Si-O-O-Si) form, they could react with O dangling bonds to create peroxy radicals or dimerize into interstitial O2 molecules. Hydrogen doping helps to reduce the defect concentration, however, creates new precursors in the form of hydroxyl groups and may stimulate O vacancy generation. Doping by fluorine reduces the number of strained Si-O bonds and results in glass, which had higher vacuum ultraviolet transparency and higher resistance to excimer laser light than pure silica.

Defects in Oxide Glasses. L.Skuja, M.Hirano, H.Hosono, K.Kajihara: Physica Status Solidi C, 2005, 2[1], 15-24