Emerging of Ag particles on ZnO nanowire arrays for blu-ray hologram storage

Noble-metal/metal-oxide-semiconductor nanostructures as an important material platform have been applied in massive data storage. ZnO exhibits excellent optical modulation ability. However, plasmon induced charge separation effect in Ag/ZnO system is very weak due to the low chemical activity on the surface of the oxide. Herein, we prepare ZnO nanowire arrays via hydrothermal method, and measure their absorption spectra, photoluminescence spectra and electron paramagnetic resonance, proving the existence of oxygen defects in ZnO. Accordingly, an idea of "electron reverse transfer" is proposed that blu-ray (403.4 nm) induces reduction of Ag+ ions through the excitation of ZnO. Rod-like and spherical silver nanoparticles emerge on the surface and in the gap of ZnO nanowire arrays, respectively, after the visible light stimulus. It is found that nanowire density, oxygen defects and surface roughness are dependent on hydrothermal time. The optimized diffraction efficiency of 0.08% is obtained for reconstructing hologram in the nanoconmposite film. This work provides a bright way for construction of ZnO-based optoelectronic integrated devices.