Photosensitivity of SiO2–Al and SiO2–Na glasses under ArF (193 nm) laser

Photosensitivity of SiO2–Al and SiO2–Na glass samples was probed by means of the induced optical absorption and luminescence as well as by electron spin-resonance (ESR) after irradiation with excimer-laser photons (ArF, 193 nm). Permanent visible darkening in the case of SiO2–Al and transient, lifetime about one hour, visible darkening in the case of SiO2–Na was found under irradiation at 290 K. No darkening was observed at 80 K for either kind of material. This investigation is dedicated to revealing the electronic processes responsible for photosensitivity at 290 and 80 K. The photosensitivity of both materials is related to impurity defects excited directly in the case of SiO2–Na and/or by recapture of self-trapped holes, which become mobile at high temperature in the case of SiO2–Al. Electrons remain trapped on the localized states formed by oxygen deficient defects.