Luminescence characteristics and growth mechanism of awl-like ZnO Nanostructures fabricated on Ni-coated silicon substrate via chemical vapor deposition method

Awl-like ZnO nanostructures have been fabricated by sublimation process employing chemical vapor deposition (CVD) method at 1000 °C on Ni-coated silicon substrates. Each ZnO nanostructure consists of four hexagonal awl-shaped legs, and the length and diameter of legs are about 1.8-2.6 μm and 0.6-1.3 μm, respectively. XRD and TEM results demonstrate that the awl-like ZnO nanostructure has a hexagonal structure with a preferred growth direction along the c-axis. The high crystallinity of the prepared nanostructures is confirmed by Raman spectroscopy. Room-temperature photoluminescence measurements of ZnO nanostructures exhibit a weak ultraviolet peak at 380 nm and a broad peak centered at about 523 nm, which can be attributed to the free exciton transition and oxygen vacancy, respectively. Cathodoluminescence results indicate that there may be an energy transportation process inside the nanostructures. Finally, a possible growth mechanism of the ZnO nanostructures is discussed.