Study Of Fabrication ,characterization And Optical Properties Of Zinc Oxide Nanostructure

As a wide-bandgap semiconductor material with 3.37eV bandgap energy and 60meV exciton bondage energy, the wurtzite structural zinc oxide(ZnO) is ideal material applied to fabricate ultraviolet photoelectron device. Due to small size effect and quantum confinement effect, nanostructural ZnO is largely superior to its bulk material in the physics properties and promising to be used to construct micro/nano ultraviolet laser, ultraviolet emission diode and high-sensitive biology/chemistry sensor. The industrialization of nanostrual ZnO is the fabrication of the nanomaterials. Although some ZnO nanostructures with different morphologies have been fabricated by various methods by now, the factors influencing crystal growth process can't efficiently controlled, and the obtained nanostructures still exist large uncertainty in morphology and physics properties. In particular, the understanding on the growth mechanism still keeps a lower level. Therefore, the fabrication of ZnO nanostructures will still be an important part of ZnO research work in a long time.This paper reviews the nature of ZnO, fabrication methods, testing methods. Some ZnO nanostructures were successfully synthesized by chemical vapor deposition(CVD) and thermal evaporation techniques. The morphologies , crystalline qualities and optical characteristics of ZnO nanostructures were investigated by scanning electron microscopy(SEM),X-ray diffraction(XRD), Energy Dispersive X-ray Spectrometry (EDS) and Photoluminescence(PL) analytic technology, respectively. The details are as follows:1. In this paper, a simple method for fabricating ZnO nano-disks is given, and ZnO nano-disks with size about several microns and thickness about 400nm obtained on Si substrates (100) in the atmosphere, with Zn power thermally evaporated directly in the crucible. X-ray diffraction (XRD) reveals the grown samples are hexagonal ZnO crystal. Scanning electron microscopy (SEM) images show that the morphology and size of samples is closely related to the evaporation temperature of zinc. The photoluminescence (PL) spectrum at room temperature of ZnO disks has a strong green peak centered at 510 nm,which is due to the presence of oxygen vacancies in the samples. The energy-dispersive X-ray analysis (EDS) indicates samples are zinc oxide without any impurities, with Zn content higher than O ones, and have more O- vacancies. The EDX results are consistent with PL experiments.2. Tetrapod ZnO (T-ZnO) is a material with very potential applications. T-ZnO were successfully synthesized by chemical vapor deposition technique, and the possible growth mechanism were put forward. We find that the growth mechanism of T-ZnO is complex by some analysis. The morphology of ZnO has a great relationship with substrate temperature,substrate position,saturated vapor pressure. Zinc vapor and Zinc droplets have different roles in the process of ZnO growth. Finally, we made photoluminescence of T-ZnO and made a brief analysis of the PL mechanism.3. We prepared nano-structured zinc oxide wrapped with indium oxide and found that the presence of indium play an important role in the formation of sheet structures. At the same time, we studied photoluminescence properties of the prepared samples and found that there was a wealth of PL information in the composite structure. However, in order to understand the PL properties we need more experiments and theoretical analysis on this structure.