Optical properties of nanostructured ZnO crystal synthesized by pulsed-laser ablation

The optical properties of ZnO nanorods and nanowires grown by a newly developed nanoparticle-assisted pulsed-laser deposition were studied by using photoluminescence (PL) and a surface photovoltage (SPV) spectroscopy. SPV spectroscopy can detect an optical absorption spectrum by the illumination-induced change in the surface potential due to the drift, accumulation, and recombination of photoexcited carriers. Thus, SPV spectroscopy is expected to be a powerful tool for nanostructured semiconductors because the light scattering at the crystal boundaries cannot affect the observed signal. In this paper, the optical-absorption edge including exciton formation and the presence of a defect level induced by copper impurities in ZnO nanorods and nanowires crystals are discussed.