Photoluminescence of SnO2 nanoparticles embedded in Al2O3

Tetragonal Sn nanoparticles of ~15 nm diameter are produced in Al2O3 by direct Sn implantation at room temperature. After thermal annealing at 1000 deg C in oxygen, the implantation-induced amorphous region recrystallized and the Sn nanoparticles turned into SnO2 nanoparticles with an average diameter of ~30 nm as revealed by transmission electron microscopy. While no absorption and photoluminescence (PL) are observed from the metallic Sn nanoparticles, SnO2 nanoparticles exhibit an absorption edge at ~280 nm and three emission bands at 410 nm, 520 nm and 700 nm, respectively. In addition to the previously reported blue and green emission from SnO2 nanostructures, a red PL band was observed due to the unique surface state of SnO2 nanoparticles embedded in Al2O3 substrate fabricated by ion implantation.