ZnO nanoparticles embedded in sapphire fabricated by ion implantation and annealing

Abstract

ZnO nanoparticles were fabricated in sapphire (α-Al2O3 single crystal) by Zn ion implantation (48 keV) at an ion fluence of 1 × 1017 cm−2 and subsequent thermal annealing in a flowing oxygen atmosphere. Transmission electron microscopy (TEM) analysis revealed that metallic Zn nanoparticles of 3–10 nm in dimensions formed in the as-implanted sample and that ZnO nanoparticles of 10–12 nm in dimensions formed after annealing at 600 °C. A broad absorption band, peaked at 280 nm, appeared in the as-implanted crystal, due to surface plasma resonance (SPR) absorption of metallic Zn nanoparticles. After annealing at 600 °C, ZnO nanoparticles resulted in an exciton absorption peak at 360 nm. The photoluminescence (PL) of the as-implanted sample was very weak when using a He–Cd 325 nm line as the excitation source. However, two emission peaks appeared in the PL spectrum of ZnO nanopraticles, i.e., one ultraviolet (UV) peak at 370 nm and the other a green peak at 500 nm. The emission at 500 nm is stronger and has potential applications in green/blue light-emitting devices.