FORMATION OF LUMINESCENT NANOSTRUCTURES BY REDUCTION OF SiO2 IN TRACKS OF SWIFT HEAVY IONS

Abstract

320 nm-thick SiO2 layers were thermally grown on the Si substrates. The layers were irradiated with 167 MeV Xe ions or with 700 MeV Bi to the doses ranging between 1012 cm-2 and 1014 cm-2. After irradiation the yellow-orange photoluminescence (PL) band appeared and grew with the ion doses. In parallel, optical absorption, Raman scattering and X-ray photoelectron spectroscopy were carred out. The results obtained are interpreted as the formation of the light-emitting nanostructures inside the tracks of swift heavy ions through the disproportionation of SiO2. Ionization losses of the ions are regarded as responsible for the processes observed. Difference between the dependences of the PL intensity on the doses of Xe and Bi ions are ascribed to their different stopping energy, therewith the diameters of the tracks of Xe and Bi ions were assessed as <3 nm and ~10 nm, respectively. Shift of the PL bands, induced by Xe and Bi ions, agrees with the predictions of the quantum confinement theory.