| ZnO is a direct band gap semiconductor material, which has band gap of 3.37eV at room temperature, and the binding energy of exciton as high as 60meV. Since the realization of stimulated emission of ZnO films at room temperature by optical pumping in 1996, researches on ZnO and its related materials have become one of the most promising and attractive aspects in the optoelectronic region. In this thesis, we investigate the structural, optical and electronic properties of ZnO thin films and ZnO nanotubes prepared by the plasma-molecular beam epitaxy (P-MBE). In addition, we also explore the properties of ZnO based homojunction and heterojunction device. The details are as follows: (1)ZnO thin films were prepared by P-MBE. The as-growth samples were characteriazted by in-situ reflection high-energy diffraction, X-ray diffraction, X-ray rocking curve, atomic force microscope, temperature dependent photoluminescence spectra and Hall effect measurement. The results show that the growth temperature can efficiently improve the structural, optical and electric properties of ZnO thin films, and the two-dimension growth mode at 650℃was obtained. (2)Based on the structural properties of ZnO, the aligned ZnO nanotubes were prepared by P-MBE. The single crystal chimney-like ZnO nanotube was confirmed by transmission electron microscope image and selection area electronic diffraction pattern of a single ZnO nanotube. The stimuted emission of ZnO nanotubes pumped by fs laser was observed at RT. In addition, the ZnO nanotubes grown on Si substrate show excellent field emission properties. (3)The ZnO based homo/hetero-junction devices were investigated gropingly. The obtained ZnO homojunction and heterojunction device shows the rectifying diodelike behavior from the p-n junction. According the band theory, the n-ZnO / i-MgO/p-GaN heterojunction light emission diode was designed and prepared, and the electroluminescence from ZnO layer was obtained at room temperature.
|
PDF Full Text Request