Growth and formation mechanism of c-oriented ZnO nanorod arrays deposited on glass

ZnO nanorod arrays have been grown on glass substrates. X-ray diffraction demonstrated that most of the nanorods in the arrays are of wurtzite crystal structure with preferable [0 0 1] growth direction. The morphology and the microstructure of the arrays and the nanorods were investigated by using scanning electron microscopy and transmission electron microscopy. A wetting layer of ZnO was observed between the nanorods and the substrate. On the (0 0 1) surfaces of some nanorods, the initial stage of nucleation and the subsequent development of the nuclei were observed, revealing the process of the nanorod growth. Electron energy-dispersive X-ray spectroscopy revealed that the wetting layer and the nanorods exhibit different stoichiometric ratio. The kinetics of the formation of the structures was discussed within the framework of the Stranski–Krastanov mechanism. In addition, photoluminescence spectra of the as-grown ZnO nanorod arrays indicate their possible applications in ultraviolet (UV) emission devices.