Pre-heating temperature dependence of the c-axis orientation of ZnO thin films

Highly c-axis oriented zinc oxide, ZnO, thin film has been obtained at a very low pre-heating temperature, 120 °C. After depositing all layers, the film is annealed at 350 °C, for 5 h. The deposition process is designed to be compatible with silicon/silicon-dioxide substrates, to make piezoelectric coatings for integrated smart sensors. The films are synthesized by the sol–gel method and deposited onto a glass substrate. The deposition solution is prepared by dissolving zinc-acetate 2-hydrate in methanol. To optimize the film quality with respect to c-axis orientation, and surface uniformity, the selected parameters are: pre-heating temperature, spin-coating speed and number of coating layers. The effect of the deposition conditions is studied by applying experimental design and response surface techniques on the characteristic (002) peak, obtained by X-ray diffraction analysis. Surface uniformity and grain size are observed by scanning electron microscopy.