The effect of deposition conditions on structure properties of radio frequency reactive sputtered polycrystalline ZnO films

Polycrystalline ZnO films were prepared by radio frequency reactive sputtering technique with Zn target on glass wafers under different pressure ratio K (defined asP(O2)/(P-Ar + P-O2)) and substrate temperature T-s. X-ray diffraction technique (XRD) was employed to analyze the effect of deposition conditions on the structure of the films. With increase in T-s from room temperature to 400degreesC, the films appear to have a preferred orientation with the c-axis perpendicular to the substrate. Pressure ratio K has an effect on orientation of the films, which have highly preferred orientation when K = 40%. The grain size is in the range 13.2-42.8 nm calculated from XRD data. The packing density, the compressive stress in (0 0 2) plane and the average optical transmittance in visible region of the films deposited under the optimal condition are 97%, -1.06 x 10(9) N/m(2) and 92%, respectively. It is found also that carbon is the main contamination in films observed by X-ray photoelectron spectroscopy. The films are close to stoichiometric relation. (C) 2002 Elsevier Science Ltd. All rights reserved.