Water-vapour-assisted growth of ZnO nanowires on a zinc foil and the study of the effect of synthesis parameters

Dense and large-aspect-ratio ZnO nanowires have been synthesized by thermal oxidation of a Zn foil under the flow of moist nitrogen. The effects of annealing temperature and time have been systematically studied in detail. It was observed that the length, diameter and number density increase with time and temperature before they saturate at the optimum synthesis condition of 600 °C annealing temperature and 16 h annealing time. The nanowires have been characterized by a scanning electron microscope, a transmission electron microscope, UV–Vis absorption and room temperature photoluminescence. The nanowires grow uniquely along the [1 1 0] direction up to ∼14–16 µm length and are of good crystalline and optical quality. It was found that the formation of nanowires enhances greatly in the presence of water vapour. We have also shown by TEM observations that nanowires grow by surface diffusion of Zn ions from root to tip