Studying the growth conditions, the alignment and structure of ZnO nanorods

By using a simple vapor-phase transport and condensation process, we have grown ZnO nanowires, nanorods and nanoneedles on various substrates such as Si, SiO2 and c-sapphire with a gold catalyst. The catalytic growth of ZnO nanorods/nanowires is controlled by the conventional vapor–liquid–solid (VLS) mechanism. We also note in some cases the presence of ZnO nanostructures in catalyst-free regions. By using a variety of substrates and growth times and temperatures, we can begin to understand some of the important parameters in controlling the morphology of the nanostructures. Scanning electron microscope (SEM) observations, X-ray diffraction (XRD) analysis and photoluminescence (PL) spectra showed that the ZnO nanowires were monocrystalline, with a hexagonal wurtzite structure.