Elaboration and Characterization of Ca Doped ZnO Films Prepared by rf-Magnetron Sputtering at Room Temperature

In this work, we studied calcium doped zinc oxide (ZnO:Ca) thin films deposited by rf-magnetron sputtering at room temperature using calcium doped nanocrystalline powder synthesized by sol-gel method. The calcium doping concentration was varied from 2.0 to 4.0 at.%. The structural characteristics of the films were investigated by X-ray diffractometry, scanning electron microscopy and atomic force microscopy, while the electric and optical properties of the films were studied by the Hall measurement and optical spectroscopy, respectively to explore the possibility of producing transparent conductive oxide films through low-cost process. It has been found that all of the films deposited were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The lowest resistivity obtained in this study was 2.34 x 10(-3) Omega.cm for ZnO:Ca films containing 3.0 at.% of calcium. Optical transmittance measurement results show a good transparency within the visible wavelength range for all the films.