Preparation And P-type Transition Of N-doped ZnO Films

ZnO is a direct band gap(3.37eV) semiconductor compound with high excition binding energy of 60meV and photon gain of 320cm^-1. ZnO films have broad applications in various fields such as transparent conductor, LED components, solar cell window materials, optical waveguides, monochromatic field emission display materials, high-frequency piezoelectric conversion, surface acoustic wave devices, sensors and low-voltage varistor because of their excellent properties such as piezoelectric, optoelectronics, gas sensing, and pressure-sensitive. However, non-doped ZnO films are natural n-type semiconductors because of their intrinsic defects of the stoichiometric proportion disbalance in oxygen vacancies (Vo) and Zn interstitial defects (Zni). The theoretical calculations have predicted that the nitrogen elements in ZnO films may form shallow acceptor level and make them p-type conductivity.In this paper, N-doped ZnO thin films were prepared by frequency(RF) magnetron sputtering, at the same time we also prepared N-doped ZnO thin films with the bias voltage. Their crystalline structure, superficial appearance, conductivity and some physical properties had been measured in two kinds of N-doped ZnO thin films.In chapter 1, we elaborate simply the background and the significance about N-doped ZnO thin films in domestic and foreign, then introduce the crystalline structure of related ZnO thin film, the prepared method, the disadvantage, and the industrial applications.In chapter 2, firstly we introduce the development and the principle of radio frequency(RF) magnetron sputtering, then give the deposition process of thin films, finally, we summarize the characterization techniques used in our experiments.In chapter 3 and 4, we mainly introduce how to prepare the ZnO thin films and N-doped ZnO thin films with the radio frequency magnetron sputtering and how to measure the crystal structure, superficial appearance, fluorescence spectrum, and electronic resistivity. The constituent, crystal structure and properties of the thin film had been studied with XRD, SEM; fluorescence spectrophotometer,as well as electronic resistivity.The result indicates that the N-doped ZnO thin film presents the p characteristic completely when the ration of Ar:O₂:N₂ is 15:7:8.