| ZnO is a II-VI compound semiconductor with a wide direct bandgap of 3.3 eV at room temperature, exciton binding energy of 60meV, and a hexagonal wurtzite structure of space group P63mc. Its lattice parameters are and . Due to their excellent physical and chemical properties, ZnO films have many realized and potential applications such as surface acoustic wave devices , planar optical waveguides, transparent electrodes, ultraviolet photodetectors, piezoelectric devices, varistors, gas sensors, UV/violet/blue-LEDs (light emitting diodes) and –LDs (laser diodes), etc. And they can be integrated with some materials readily. In recent years, the researches and developments of ZnO films have attracted great attention and interest from researchers and the industry. To achieve the requirements of different applications, many techniques, such as molecular beam epitaxy, magnetron sputtering, metalorganic chemical vapor deposition , and pulsed laser deposition, spray pyrolysis, sol-gel process, reactive deposition and thermal oxidation of Zn films have been used to deposit ZnO films. Each of these techniques has its merits and demerits. The key to the application of ZnO films is high quality for the purpose, and the cost must be considered. In this work, the films were prepared using both thermal evaporation and DC reactive magnetron sputtering techniques. For various applications, highly preferred c-axis orientation of ZnO films is usually important. Thermal evaporation is the easiest deposition technique and applicable to industrial production. Films with a small or large-area coating can be obtained by the method. Zn films were deposited by thermal evaporation technique and then ZnO films with highly preferred c-axis orientation were prepared through thermal oxidation of the metallic Zn films. The thermal evaporation and oxidation were optimized. The process, characteristic and influence elements for preferred orientational growth of the films were discussed. Uniform and compact ZnO films with the highly preferred c-axis orientation and the high transmittance in visible region can be prepared by magnetron sputtering under optimized condition. It is the most investigated and widely used method. The magnetron sputtering principle and influence of deposition conditions on film quality and surface are discussed. The surface morphology and microstructure of the films were characterized by SEM and the morphology of the nano-ZnO particle by TEM. The crystallographic structure of the films and the particles was analyzed with XRD. The optical transmittance of the films was recorded using ultra-violet-visible double beam spectrophotometer. The electrical resistivity, carrier concentration and Hall mobility of the films were measured using four probe instrument and Hall effect instrument. The gas sensing effects were measured using self-made gas sensing effect apparatus.The studies on optical property of ZnO and ZAO films are an important topic for their application and for preparation conditions to be optimized. The relation between optical constants was discussed. The refractive index, the extinction coefficient, the absorption coefficient, the optical energy gap and the thickness of the films were calculated from transmittance spectrum. ZAO film, which has comparable electrical and optical properties to the ITO, are emerging as a potential substitute for ITO films due to its cheap and abundant raw material, nontoxic feature, cost-effective, easy fabrication and good stability. Widening oxygen partial pressure region and controlling film uniformity are important for commercial production. The influence of oxygen flow rate on preferred c-axis orientation of ZAO films was given. The ZAO film with columnar growth parallel to c-axis orientation was obtained. The effects of oxygen flow rate on the resistivity, the carrier concentration, the Hall mobility, the transmittance, the grain size and the lattice constants of ZAO films was determined, whose mechanisms were analyzed. The dependences of the spatial distribution of...
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