Fabrication of Ag nanoclusters in single-crystal MgO by high-energy ion implantation

Ag nanoclusters are created in single-crystal MgO by ion implantation of 2×1017 Ag ions/cm2 at an energy of 200 keV and subsequent thermal annealing. The defect evolution is investigated by means of optical absorption spectroscopy. Optical absorption spectra show an absorption peak around 460 nm which belonged to the surface plasmon resonance absorption of Ag clusters in as-implanted and annealed samples in reducing atmosphere. With the increase in annealing temperature, the optical absorption peaks blueshift at lower temperature, then redshift for temperature higher than 600 °C and return to position after annealing at 900 °C. A new absorption peak belonging to Fn center is observed after annealing at 700 °C. Transmission electron microscopy (TEM) study indicates that the surface of MgO is amorphized and the ion-implanted layer is partly damaged; the damaged layer is recovered by annealing in reducing atmosphere at 900 °C.