The Preparation And Photoluminescence Of ZnO Low-dimension Nanostructures

ZnO is a direct wide band gap semiconductor, which has band gap of 3.37eV at room temperature, and a very large binding energy of exciton (60meV). ZnO nanostructures, as promising candidates for future electroptical devices, have been attracted much attentions. In this thesis, we investigate the deep-level defect related visible emissions in P-passivated nanocrystalline ZnO, and control the visible emissions by applying different annealing time or temperatures; synthesize uniform single-crystalline ZnO nanosheets and study the enhanced luminescence at high temperature; study the structural phase transitions of the ZnO bulk, nanosheets and nanotube sample, respectively, under hydrostatic pressures, measure the pressure coefficient and the hydrostatic deformation potential of band gap of ZnO , and investigate the properties of emission-centers for different emissions in ZnO nanotube. The details are as follows:(1) P-passivated nanocrystalline ZnO films on InP substrates were prepared by thermal oxidation of Zn films. By a simple thermal annealing cycle process, uniform photoluminescence samples with controllable visible emission and intense UV emission were obtained at different annealing conditions. It is shown that applying different annealing time or temperatures provide a very practical technique to control the deep-level defect emission. A core-shell structure model of the surface passivation, was helpfully used to discuss the P-passivation mechanism.(2) Uniform single-crystalline ZnO nanosheets were synthesized by a vapor transport process. The nanosheets with a hexagonal structure have uniform plane surfaces with lateral dimensions up to several tens of microns and a thickness of ~ 100 nm. Photoluminescence spectra of the sheets exhibit intense ultraviolet excitonic emission without observable defect-related visible emission at temperatures from 80...