Effect of Oxidation Temperature on the Photoluminescence of Sn Implanted and Annealed SiO₂/Si

We report the effect of oxidation temperature on the photoluminescence (PL) of Sn nanoparticles (NPs) embedded in SiO₂/Si matrix. First, Sn NPs were synthesized in SiO₂ by 50 keV Sn⁻ ions implantation to a fluence of 2 × 10¹⁶ cm⁻² followed by annealing in N₂ atmosphere at 650 °C. Then, the Sn NPs were oxidized by annealing in air at 400–1000 °C. The samples before air-annealing showed PL emissions with an intense blue-violet band at around 393 nm. Annealing of the above pre-annealed (annealed in N₂ ambient) sample at 400°C, in air, was found to result in a significantly enhanced PL in the blue-violet band. Increasing the oxidation temperature to 600°C has been found to result in a drastic reduction in PL intensity indicating a reduction in the number of neutral oxygen vacancy centers due to oxygen incorporation into the samples. This annealing also resulted in a phase transformation of Sn NPs to SnO₂ NPs, which was confirmed by high resolution transmission electron microscopy measurements. Further, increasing the oxidation temperature has been found to result in a very slow decrease in PL intensity is mainly due to the reduction of SnO₂ NP surface disorders.