A facile method for fabricating Au-nanoparticles-decorated ZnO nanorods with greatly enhanced near-band-edge emission

Doping with noble metal nanoparticles (NPs) has been proved to be an effective method to tune the photoluminescence (PL) properties of semiconductor materials. Since high processing temperatures make it difficult to avoid metal oxidation, low-temperature synthesis of metal NPs is preferred. Taking ZnO nanorods on fused silica substrates as a model system, a facile low-temperature fabrication method was adopted to deposit Au metal NPs coated ZnO nanorods in this work. The synthesis consisted of two steps: First, ZnO nanorods were grown on the fused silica substrates by a seed-assisted chemical solution method. Then, Au NPs were deposited on the surfaces of ZnO nanorods by an in situ photochemical metal-deposition. A homogeneous distribution of Au NPs with an average diameter around 30 nm has been obtained on the well-aligned ZnO nanorods. The near-band-edge (NBE) UV emission of the ZnO nanorods is enhanced by up to seven times, accompanied with a decrease in the deep-level (DL) emission intensity. The mechanism of the PL enhancement is discussed with respect to the surface plasmon resonance (SPR) effect and the band bending at Au/ZnO interface.