Growth And Defect-related Luminescence Of One Dimensional In-doped ZnO Nanomaterials

In order to realize the pervasive application of ZnO-based nano-scale optoelectronic devices, preparing high-quality ZnO nanomaterials and improving the optical and electrical properties are extremely essential. Growth orientation, surface morphology and the behavior of defects are the key points for achieving high crystallinity and good performance of ZnO nanomaterials. In this thesis, ZnO nanowires with different In doping concentration were fabricated, the structure, photoluminescence properties and defect complexes of ZnO nanostructures were analyzed. The primary results are described in the following:(1) ZnO nanowires with different In doping concentration have been grown by CVD. The preferred orientation of c-axial has been suppressed, and an infrequent [0223] growth orientaion and zigzag surface formed by (1010) and (1011) facets have been observed, indicating that In doping could alter the growth direction and surface morphology of ZnO nanowires. ZnO nanowires with large surface-to-volume ration and low surface traps have been obtained and exhibited a good photocatalytic performace. A surface band-bending model has been proposed to interpret this result.(2) A strong emission at3.1eV and the controversial A-line have been observed in the low temperature PL spectra of In-doped ZnO nanowires, and were both related to In doping. The3.1eV emission showed a rapid temperature quenching effect and disappeared at T>180K. The activation energy of the3.1eV emission was～49meV as determined from the PL quenching effect.(3) The little change of the intensity after coating the nanowires with Al2O3allowed us to conclude that the3.1eV emission and A-line was unlikely from the surface. A-line most probably origined from the stacking faults induced by In doping, and the3.1eV emission was related to VZn based on the annealing results(4) The InZn-VZn complexes have been suggested to existed in In-doped ZnO nanowires and have been the orign of3.1eV emission. Ionization energy of this defect complex has been calculated to be0.23eV. The temperature quenching effect and the orign of the activation energy (～49meV) have been interpreted by building a energy band diagram involving InZn-VZn complexes.