The Preparation Of ZnO Nano Structure On The Modified Si Substrate

As the3rd generation of semiconductor, Zinc oxide (ZnO) is a typical wide band gap metal oxide semiconductor of Ⅱ-Ⅵ group, which has potentials in excellent short wave light emitting and due to its large band gap energy of3.37V and promising blue-ultraviolet emitting materials due to its large exciton binding energy of60meV at room temperature. Besides the photoelectric capability, many other excellent properties, ZnO has attracted much attention from researchers because of its stable physical and chemical performance.As to low-dimension of nano array structures, when grain size becomes to micrometer or even nanometer, the material will have some certain unique characteristics due to its large specific surface area and the smaller size. In recent years, it is reported that low-dimension ZnO nano materials like OD nano particles and1D nanostructure, including ZnO nanowires, nanorods, nanotubes, nanoneedles, has been synthesized successfully. In addition, because ZnO thin film has excellent physical and chemical properties in photoelectric, gas sensor, pressure sensitive, piezoelectric etc, it will have prospective application in the field of photoelectric, piezoelectric, gas-sensitive and pressure sensitive devices.The orientation of the ZnO thin film growth is an important research subject. Because ZnO has a preference to grow along polar surface, it is easy to prepare c-axis oriented thin film. In theory, a-axis oriented ZnO thin film can improve the luminous efficiency of light-emitting diodes (LED) greatly, but the synthesis methods seldom are reported due to high cost.Based on the problems discussed above, in this thesis, we try to use a novel and cheap experimental methods for the preparation of the a-axis oriented of ZnO thin film. First of all, we explore the suitable experiment conditions (temperature, time, surfactant, solution concentration) the largest aspect ratio of ZnO nanorods can be synthesized by the methods of reverse micelle micro-emulsion and hydrothermal, and then discuss the formation mechanism of ZnO nanorods. Secondly, the cleaning methods of ZnO nanorods are determined, and make the particles more dispersed without cohesiveness between two particles. Thus, it will be possible to prepare the ZnO nano array by the method of gravitational sedimentation. Thirdly, we modify (100) silicon substrate by wet etching technology and etch good "V" shaped grooves, which can restrict the ZnO nano particle arrangement orientation along the grooves and then can prepare ZnO nano array. Next, the cleaned ZnO nanorods with largest aspect ratio are put in acetone, and explore the condition of gravitational sedimentation for depositing ZnO nanorods in the "V" shaped grooves neatly to form the ZnO nano array which can be used as seed layer. Finally, the prepared ZnO seed layer can be used to synthesize a-axis oriented ZnO thin film by the method of chemical bath deposition (CBD), and its growth mechanism is also discussed. In addition, to investigate how the ZnO thin film orientation can be influenced by ZnO nanotubes array, the experiments about the ZnO nanorods etching in KCl solution with different concentration, reaction temperature and time are carried out too.