Fabrication And Properties Of Functionalized ZnO Films

The fabrication processes, microstructure and properties of ZnO functionalized films are investigated. Hydrophobic ZnO films are constructed by chemical solution deposition (CSD), hydrothermal method and electrophoretic deposition, respectively, with zinc acetate, zinc nitrate, NaOH, urotropine and Polyethylene Glycol (PEG) as raw materials. Crystal structure and chemical composition of ZnO films are analyzed by XRD. Microstructure, grain size and morphology are observed by SEM. Microstructural variation resulting from Co2+ dopants is studied by Laman spectroscopy. The relationship between structure and hydrophobic properties is investigated. ZnO films with water contact angle of 165o are achieved after treatment with alkylsilicane.(1) ZnO nanorod array films are fabricated by CSD. The effect of buffer layer, the concentration of NaOH, rate of reaction, and temperature on morphology of ZnO films is investigated. The result indicates that the increase in thickness will improve the uniformity and crystallization of buffer layer, and more and more ZnO nanorods grow along c axis. The increase in concentration of NaOH increases pH value, which results in the growth of narrower and denser nanorods. The increase in rate of reaction decreases the uniformity and regularity of nanorods. ZnO films with water contact angle of 165o are achieved at a deposition time of 75mins after treatment with alkylsilicane.(2) ZnO array films are fabricated by hydrothermal method. The effect of buffer layer, urotropine and the content of cobalt acetate on deposited films are investigated. ZnO nanorods by hydrothermal method grow along c axis at a concentration of 0.1M of urotropine. ZnO buffer layer with zinc acetate as raw material is dense and uniform. Therefore, ZnO array films by hydrothermal method have a preferential orientation. The doping of Co2+ changes the rate of growth of ZnO crystalline faces and hinders the preferential orientation along c axis, which results in the low symmetry of hexagonal structure.(3) ZnO films are fabricated by electrophoretic deposition. The effect of current density, deposition time and buffer layer on crystalline phase, microstructure, transmittance and wettability is investigated with flake-shaped particles suspension as electrophoretic solution. The result indicates that the current density has a large effect on the morphology of films. Flake-shaped particles align parallel to ITO substrate at a small deposition current, and these particles align normal to the substrate at a large deposition current. The deposited films consist of nano-scaled reticular structure and micro-scaled spheres. The uniformity of ZnO films is improved by adding buffer layer. The specific surface area is increased by the heat treatment at a low temperature, which provides an opportunity for improving hydrophobicity and gas-sensitivity.