ZnO/Ag/ZnO multilayer films deposited at room temperature

Abstract

Transparent conductive ZnO/Ag/ZnO multilayer films were prepared by simultaneous RF magnetron sputtering of ZnO and DC magnetron sputtering of silver at room temperature. A silver film with nanoscale thickness was used as intermediate metallic layers. The crystal structure of the ZnO/Ag/ZnO film was analyzed by X-ray diffraction. The electrical property of the ZnO/Ag/ZnO film was investigated by a linear array four-point probe. The transmittance spectra of the ZnO/Ag/ZnO films were measured using spectrophotometer. A strong ZnO (002) peak is seen for ZnO/Ag/ZnO film, indicating polycrystalline nature and wurtzite structure of ZnO film. Silver has (111) orientation, addition of underlayer ZnO enhances the polycrystallinity of silver layer in ZnO/Ag/ZnO multilayer film. The transmittance decreases in the short wavelength as well as in the long wavelength regions as the thickness of the silver layer is increased. The peak transmittance shifts toward the long wavelength region when the thickness of the two ZnO layers is increased. The electrical and optical properties of the ZnO/Ag/ZnO films depend strongly on the silver film thickness. ZnO/Ag/ZnO multilayer films having high transmittance of 92.5% and low sheet resistance of 4.2Ω/sq. are successfully fabricated and can be reproduced by controlling the preparation process parameters properly.