Abstract
Vertically aligned ZnO nanowires with controllable density were successfully synthesized by nanoparticle-assisted pulsed-laser deposition (NAPLD), by which nanoparticles formed in the gas phase by the condensation of the ablated species are transported onto the substrate, and nanoparticles play an important role in density control. The effects of synthesis conditions on the density and optical properties of ZnO nanowires were investigated in detail. With the increase in repetition rate and laser energy, ZnO nanowires with a higher density can be obtained as a result of a larger quantity of nanoparticles formed in the gas phase. The density-controlled growth also depends on substrate–target distance. UV emission was observed from all the obtained nanowires at about 390 nm without visible fluorescence near 500 nm due to their excellent crystallinity and the oxygen-deficient defect.