Temperature-dependant non-catalytic growth of ultraviolet-emitting ZnO nanostructures on silicon substrate by thermal evaporation process

Needle-like nanowires, nanorods, and nanosheets containing nanowires of ZnO have been synthesized on silicon substrate by the thermal evaporation of metallic zinc powder in the presence of oxygen without the use of any catalyst or additives. It was observed that a particular type of ZnO nanostructure can be obtained in a specific temperature zone and morphology can be well controlled simply by adjusting the substrate temperature. Detailed structural analysis revealed that the formed ZnO nanostructures are single-crystalline with wurtzite hexagonal phase, grown along the [0 0 0 1] direction in preference. Raman scattering and room-temperature photoluminescence spectra showed the good crystallinity with hexagonal wurtzite phase and excellent optical properties, respectively for all the deposited ZnO nanostructures.