Formation of light-emitting nanostructures in layers of stoichiometric SiO2 irradiated with swift heavy ions

Thermally grown SiO2 layers have been irradiated with 700-MeV Bi ions with doses of (3–10) × 1012 cm−2. It is found that, even after a dose of 3 × 1012 cm−2, a photoluminescence band in the region of 600 nm appears. Its intensity levels off at a dose of ∼5 × 1012 cm−2. The nature of the emission centers is studied by the methods of infrared transmission, Raman scattering, X-ray photoelectron spectroscopy, ellipsometry, and the reaction to passivating low-temperature anneals. It is established that irradiation brings about a decrease in the number of Si-O bonds with a relevant increase in the Si-Si bonds. It is assumed that the photoluminescence is caused by nanostructures containing an excess Si and/or having a deficit of O. The reaction of reduction of SiO2 proceeds in ion tracks due to high levels of ionization and heating within these tracks. The dose dependence is used to estimate the diameter of a track at 8–9 nm.