Zinc Oxide Nanostructures by Oxidation of Zinc Films Deposited on Oxidized Silicon Substrate

In this work, we report the preparation and characterization of nanostructured ZnO film prepared by a novel technique of oxidation of zinc film. Zinc thin films of thicknesses 100, 200 and 500 nm were deposited on oxidized Si wafer by thermal evaporation technique. The as-deposited films were then annealed in a furnace for 6 hours under normal atmospheric condition. The annealing was carried out in the temperature range 100-500 °C. Electron microscopic studies indicated that the film of 100 nm thickness consisted of hexagonal nanodisks while the 200 nm film resulted in stack of nano hexagonal disks of ZnO after annealing. On the other hand, the 500 nm film contained mixture of nanoflakes and nanowires of ZnO following annealing. The growth of ZnO nanostructures depends on annealing temperature and the Zn film thickness. The nanostructures of ZnO can be grown on large area (2 inch oxidized silicon wafer in present case) thus making it feasible to use these for device fabrication such as gas sensors. The X-ray diffractogram (XRD) study has been carried out to investigate the crystal structure. Possible mechanism is proposed to explain the growth of these ZnO nanostructures.