Catalyst assisted vapor phase transport growth and characterization of ZnO nanowires

Zinc Oxide (ZnO) nanowires (NWs) were grown on p-silicon (p-Si) substrates coated with around 10 nm thick metal films of Au, Al and Cu using vapor phase transport growth method.  The effect of these metal catalysts and the substrate temperatures on the morphologies of ZnO NWs were studied using field emission scanning electron microscopy (FESEM). The growth of ZnO NWs with high aspect ratio was observed at substrate temperatures above 600 oC. The structural and optical properties of the as grown ZnO NWs were characterized using X-ray diffraction (XRD) and photoluminescence spectroscopy (PL) techniques, respectively. XRD study revealed that, the grown samples possess hexagonal wurtzite structure with (002) preferential orientation. The metal droplets were observed at the tips of ZnO NWs when Au was used as catalyst, but not in the case of Al and Cu. The PL spectra exhibited two peaks, one in the UV region and the other in the visible region. The low-cost Al and Cu metal catalyst assisted growth of metal contamination-free ZnO NWs may be suitable for  the device applications.