Laser-assisted approach for synthesis of plasmonic Ag/ZnO nanostructures

We report an experimental investigation on room-temperature synthesis of porous metal - semiconductor plasmonic nanocomposites by using laser deposition and annealing with nanosecond pulses. Ag/ZnO nanostructures are elaborated by using Ag-doped ZnO targets and the effects of silver concentration and laser annealing on the morphology and optical properties of the Ag/ZnO embedded nanostructures are studied. Ag-doped ZnO thin films are deposited by pulsed laser deposition on quartz substrates and subsequently laser annealed. Homemade Ag/ZnO targets with a silver doping concentration of 2, 4 and 6 at.%, prepared by ceramic technology, are exploited in the film deposition process. Then, the influence of laser irradiation on the microstructure and plasmon resonance absorption of the samples is investigated for three values of the number of laser pulses used for annealing. As the number of laser annealing pulses increases the resonance absorption is magnified. The net-like morphology of nanowires transforms to nanoparticles with increasing the silver concentration at the fixed number of ten laser annealing pulses. The composite systems show interesting plasmonic properties, which can be easily tuned by controlling the nanostructures morphology from nanowires through nanochains to nanoparticles. The experimental optical properties are in agreement with predictions of theoretical calculations showing that the extinction efficiency of AgNPs in ZnO environment peaks at about 490 nm.