Photoluminescence of SnO₂ nanoparticles embedded in Al ₂O₃

Tetragonal Sn nanoparticles of ∼15 nm diameter are produced in Al ₂O₃ by direct Sn implantation at room temperature. After thermal annealing at 1000 °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.