Studies On Polycrystalline ZnO Nano-film Deposited By SILAR Technique

Zinc oxide is a direct gap II-VI group compound semiconductor material. At room temperature, the band gap of Zinc oxide is about 3.3eV and the exciton binding energy is 60meV, which is larger than zinc sulphide (40meV) and gallium nitride (25meV). Because of these excellent characters, UV emission in Zinc oxide can be realized at high temperature. So, zinc oxide is regarded as a kind of very potential material in large band gap use.Research progress in zinc oxide at home and abroad is reviewed in this paper. Considering all the method of preparing znic oxide film presently use, a new circumstance friendly method, successive ionic layer absorption and reaction, is explored and researched.The absorption between zinc complex ion and substrate influences film formation very much. This relationship is studied in the paper. Comparing schemes, we conclude that introducing of mono-ethanolamine in precursor improves the zinc complex ion absorption with substrate obviously. There may be molecular attraction between zinc complex ion and substrate, the larger molecular weight of zinc complex the stronger attraction between them.The film character is characterized by X-ray diffractometer, field emission scanning electronic microscopic, fluorescence spectrophotometer. Based on the results of characterization, influences of technical parameters on film formation are studied. Circle number, zinc and complex compound ratio, PH value and zinc concentration are strong correlation factors when prepare the film. In the condition that [Zn²⁺]=0.05mol/L, Zn :MEA= 1:2, pH=12.0, film with good quality can be prepared.The mechanism of film crystalline grain evolvement is derived from characterization results. Hydrophilicity of Substrate and adhesion of precursor play important roles in the formation of ZnO film, which includes three stages: formation of ZnO crystalline particles, formation of ZnO polycrystalline cluster and mergence of clusters.Compare with the traditional zinc oxide prepared by SILAR method, good crystalline and continuous film is prepared in this paper. But there is much is to be improved. At the end of the paper, expectations are expected.