Research On Controllable Growth And Luminescence Properties Of ZnO Nanostructure

Nanotechnology gradually draws much attention and has made considerable progress in recent years. At present nanotechnology, as well as molecular biotechnology and industrialization of information technology, has already become the most cutting-edge subjects of21st century. Nanotechnology is a comprehensive subject which involves the applications in physics, chemistry, biology and medicine etc. and injects new vitality into many traditional subjects. Materials in nano-scale always appears special property differed from the bulk of macroscale. For instance, surface effect, size effect, quantum size effect and macroscopic quantum tunneling effect seen in nanoscaled materials leads to different properties of mechanics, thermotics, electricity and optics from bulk. And with the striking increase of the global information industry, communication technology which is on basis of photoelectron and microelectronics has got unprecedented development. Among researches of photo-electricity, semiconduct laser is one of the most practical studies. Semiconduct laser which has advantage in low mass, small volume, long lifetime, easy fabricated and inexpensive, can be widely applied in areas of concern such as laser printing, high-density optical storage, optical gyro, radar, ranging etc.. Zinc oxide (ZnO) is a kind of wide direct band gap semiconductor with the band gap of3.37eV. Due to its high exciton binding energy (60mV), which is much more higher than room temperature thermal energy (26meV), ZnO is one of the most effective materials for ultraviolet light emitting diodes and lasing diodes at room temperature. Meanwhile, ZnO is also abundant reserved, non-toxic, easy to preparing nanostructures, environment friendly. In kinds of nanostructured zinc oxide, one dimension ZnO attracts most attentions because of its single crystal structure and large specific surface area. ID ZnO nanostructures have served as building blocks for application in light-emitting devices, photodetectors, photocatalysts, solar cells and hydrophobic surfaces. Due to ZnO has lots of excellence, ZnO becomes the new hot spot in the short wavelength semiconductor laser device.In this paper, two kinds of metal layers are also utilized as reflecting mirrors to decrease the optically pumped ultraviolet laser threshold. On the basis of as-grown ZnO nanorods, we fabricate ZnO/p-GaN heterojunction LED. We fabricate the one dimensional ZnO nanostructure by hydrothermal and electrochemical method, and realize the controllable growth of ZnO nanostructure, and obtaine the following results:1. ZnO nanowires are fabricated by the hydrothermal method. Using two different metal layers (Au and Ag) are utilized as reflecting mirrors, to increase the reflectivity of ZnO nanowires and substrate, which resulted in the decrease the optically pumped ultraviolet laser threshold of ZnO nanowires. The ultraviolet stimulated emission of F-P cavity modes are generated with the threshold intensity of26.8kW/cm2and31.2kW/cm2respectively. The thresholds are lower than values of the previous reports of40kW/cm2.2. To prepare the ZnO nanorods and p-GaN heterostructure light emitting diode, thus the blue-violet electroluminescence of395nm originated from the ZnO nanorods is obtained. On this basis, ZnO nanorods are decorated CdSe/ZnS quantum dots with photoluminescence emission peak was625nm, the visible region light emitting diode is effectively observed from this device.3. ZnO nanowires are fabricated by the hydrothermal method, by controlling the reaction temperature, reaction time and concentration of hydrothermal reactions, we successfully control the length, diameter and density of ZnO nanowires. ZnO nanowires are annealed in air at different temperatures, the good thermal stability has observed. Research on the morphology of ZnO nanowires at high annealing temperature. At high annealing temperature the morphology of ZnO nanorods changed greatly. At1000℃the hexagonal-shaped nanorods are totally changed into cylinder-like nanorods. And the adjacent nanorods are combined together to form a whole one. We attribute the shape deformation to the surface reaction in ZnO nanorods. ZnO nanorods are fabricated by the electrochemical method, by controlling the reaction time and concentration of electrochemical reaction, we successfully control the length, diameter and density of ZnO nanorods.