Investigation Of The Growth Of ZnO Nanorod Arrays And Their Emission Manipulation

Interest in ZnO is stimulated by its prospects in optoelectronics applications, due to its wide band gap (3.37eV) and large exciton binding energy (60meV). ZnO also has much simpler crystal-growth technology, resulting in a potentially lower cost for ZnO-based devices, compared to many other materials. Combining these superior electrical and optoelectronic properties with a characteristic large surface area and high degree of orientation, ZnO nanomaterials, especially those in the form of well-aligned nanorod thin films, show extensive applications in luminescence, catalysis, piezoelectric transducers, gas sensors, and solar cells. ZnO nanowires (NWs) are promising candidates for the preparation of advanced devices due to their large surface-to-volume ratio and the photon confinement effect.We review the ZnO nanomaterials’development and researching situation in the optical filed. And among the fabrication methods, we choose the hydrothermal and electrochemical methods which are economical and environmentally friendly, only requiring low temperature, but gives high yield as our preparation method. Then, we choose the suited samples to the visible emission control. The primary significant results of this thesis are summarized as following:(1) We assembled the ZnO nanorods with the hydrothermal and electrochemical methods, and discuss the parametric influence to the rods’ morphology and properties. Vertically well-aligned ZnO nanorod arrays with highly crystalline wurtzite structures were synthesized on ITO glass substrates by a two-step hydrothermal method. Additionally and importantly, ZNAs prepared by the hydrothermal method at a relatively low growth temperature usually contain abundant intrinsic point defects which can act as donors or acceptors.(2) Photoluminescence spectra showed a near-band-edge (NBE) emission peak and an intense broad visible emission band for as-grown and annealed samples. These visible emission bands exhibited dependences on post-annealing conditions and excitation energies. Emission shifting in the visible region was investigated and explained in terms of the presence of defects. Based on these findings, we demonstrate that the visible emission in these materials can be tailored by controlling the defects in ZnO. Under different annealing conditions, it is possible to manipulate the emission in the visible region, which has important implications for the production of optoelectronic devices.