Research Of Structure And Properties Of ZnO And AlN Thin Films

ZnO is a Ⅱ-Ⅵ semiconductor material with wide band-gap, which has hexagonal wurtzite structure. ZnO thin films were widely applied in solar cell, UV detector, lighting displayer, SAW device, gas sensor et al for their excellent physical properties. AlN is an important Ⅲ－Ⅴ compound semiconductor material with wide band-gap, which has wurtzite structure too. Because of their many excellent physical properties, AlN thin films were applied in blue-UV emitting materials, epitaxy buffer layer, SOI material and SAW device with GHz band. In the aspect of SAW devices, for ZnO has high coupling factor, and AlN has high SAW velocity, if ZnO thin film was deposited on AlN thin film, the multiplayer film has not only high coupling factor, but also has high SAW velocity, which was suitable for SAW of high frequency.In this paper, ZnO and AlN thin films were prepared by magnetron sputtering method, the films were figured by XRD, SEM, XPS, AFM and FTIR, UV photometer. It was concluded that, the structure of ZnO thin films were influenced by many working parameters such as substrate temperature, sputtering pressure, the distance between target and substrate and so on. Meanwhile, the deposition rate of ZnO thin films was varied at different working parameters. It was indicated by SEM spectra of ZnO thin films that the surface of the sample was leveled off, and the crystals were felsitic. It was found from the experiment that, with the increasing of substrate temperature, there were more oxygen vacancies in the films, which lead the conductance of the sample become larger , and the absorb edge of ZnO thin films shifted toward higher wavelength; with increasing of Ar:O2 ratio, there were lesser oxygen vacancies in the films, which lead the absorb edge of ZnO thin films shifted toward lower wavelength. It was discovered through the experiment that, the structure and deposition rate of AlN thin films varied with the varieties of substrate temperature, sputtering power, distance between target and substrate. XPS spectra of AlN thin film showed that Al atoms and N atoms in the sample were schomichemetry . It was concluded through the AFM spectra of AlN thin films that surface morphology and roughness were widely varied with different thickness of the films. It was showed through field emission property test of AlN thin films that, when the thickness of the film was thinner, it has more excellent field emission properties; the field emission properties of AlN thin films greatly depended on the structure of the films.