Abstract: Transparent and compact ZnO thin films with high c-axis preferred orientation were galvanostatically deposited in Zn(NO ₃)₂ solutions on the ITO substrate after an electrochemical pretreatment process. The crystallinity, microstructure of surface and cross section, and optical properties of obtained films were characterized by X-ray diffraction, scanning electron microscope and optical transmittance spectra. Results show that the deposition time has significant influences on the quality of ZnO films. At the later stage of film deposition (120min), ZnO film exhibits obvious decrease in the crystalline degree, surface smoothness, and transmittance, with the increase of crystallite sizes, which indicates that the deposition time must be optimized to obtain the electrodeposited ZnO film with high quality. In addition, the film thickness linearly changes with deposition time, illustrating the possibility to control the film thickness by deposition time.

Key words: ZnO film, electro-deposition, pretreatment, microstructure