A general review of recent research progress in fabricating transparent conductive ZnO thin films by means of intentional doping and codoping with In, Ga, A1, Mg, Li, F, H, N, and P, divided into metals and nonmetals, is presented in this article. The main emphasis is placed on introducing and discussing the recent research achievements on the mechanisms of the incorporation of these impurities, and their effects on the electrical and optical properties. Lastly, this article concludes with a summary of the present state of investigations on doping elements in fabricating functional ZnO thin films for photoelectric applications, and with our personal view of the perspective of future studies on doped ZnO thin films.
Transparent thin films of ZnO have been prepared on ordinary glass substrates by the inorganic sol-gel method using citric acid as chelating agent and zinc nitrate as the starting material. A novel structure on zinc citrate complex was put forward by using DTA-TG and FT-IR absorbanee spectrum of citrate gels. Phase formation, morphology and optical properties of ZnO films are investigated by XRD, AFM and UV-vis transmittance spectra. The experimental results show that ZnO thin films derived from zinc citrate sol-gel method showed a （002） oriented hexagonal wurtzite structure, good crystalline property, a uniform range of grain size （40 nm）, smooth surface of films, band gap of 3.28 eV and optical transmittances ratio over 90% in the visible range.
QIN Xiu-Juan SUN Xue-Liang BU Li-Min ZUO Hua-Tong HANSI Hui-Zhi
