Characteristics of ZnO thin films prepared by radio frequency magnetron sputtering

Abstract

We investigated in this study structural and nanomechanical properties of zinc oxide (ZnO) thin films deposited onto Langasite substrates at 200 degrees C through radio frequency magnetron sputtering with an radio frequency power at 200 W in an O-2/Ar gas mixture for different deposition time at 1, 2, and 3 h. Surface morphologies and crystalline structural characteristics were examined using X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The deposited film featured a polycrystalline nature, with (100), (002), and (101) peaks of hexagonal zinc oxide at 31.75 degrees, 34.35 degrees, and 36.31 degrees. As the deposition time increased, the ZnO film became predominantly oriented along the c-axis (002) and the surface roughness decreased. Through Berkovich nanoindentation following a continuous stiffness measurement technique, the hardness and Young's modulus of ZnO thin films increased as the deposition time increased, with the best results being obtained for the deposition time of 3 h. In addition, surface acoustic wave properties of ZnO thin films were also presented. (C) 2007 Elsevier Ltd. All rights reserved.