ZnO nanoparticles embedded in sapphire fabricated by ion implantation and annealing

ZnO nanoparticles were fabricated in sapphire (??-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.