ZnO Based Semiconductor-Metal Hetero-Nanostructures

One of the promising avenues in the current semiconductor science and technology research is the development of the novel semiconductor heterogeneous functional materials. It is extremely important to explore materials and devices with new properties and functions. This thesis aims to grope for new structure, open out new phenomena and provide a thorough insight into their physical mechanisms. Two aspects have been emphasized; one is the material design and preparation of ZnO/Au/Si heterogeneous epitaxial film, and besides, having further considerations of the stress, optical properties and the polarity control; the other one is the preparation of the Zn₂SiO₄ nanowires, the Zn₂SiO₄-Zn nanocable heterostructures and the investigation of their fascinating optical properties.First-principles computation based on the density functional theory were performed to investigate the initial growth of ZnO films on Au layer, the results of which provided an intrinsic geometric structure of the formation of the Zn-polar ZnO film. And then, the properties of ZnO grown under different conditions were characterized. The results proved that the Au nanocrystallites can play as the role of crystal nucleus, and that ZnO on Au layer displayed a film structure that had no grain boundary and showed a surface composed of hexagonal hillocks. Furthermore, X-ray diffraction, Raman, and cathodoluminescence data supported that the hexagonal hillock grains were well aligned in the c axis. We believed that Zn was rich on the top of the hillocks where the nuclei initiated. Zn and O reach the stoichiometric ratio when the nuclei grew gradually to the side. The islands of ZnO joined together, and then formed a ZnO film of good quality without grain boundary. With Au as the buffer layer, the misfit stress is minimized, the UV emission is improved, and Zn-polarity is controlled. All of these might affect the electrical conductivity of ZnO.Chemical vapor deposition was used to grow Zn₂SiO₄ nanowires and Zn₂SiO₄-Zn nanocable arrays. Morphological, chemical and crystallographic characterizations of the as-grown samples were carried out by SEM, EDS, TEM and...