Abstract
Zinc oxide (ZnO) is extensively studied because of its potential applications in various fields, such as surface acoustic wave (SAW) devices, solar cells, light emitting diodes (LEDs) and laser systems. The stoichiometric ZnO films are electrical insulation and have high piezoelectric properties, which are useful for a variety of integrated piezoelectric thin film devices. For SAW devices applications, it is necessary to deposit ZnO films of smooth surface and high density to satisfy the requirements of the following manufacturing processes. Ion beam sputtering deposition, which is an atom-by-atom (or molecule-by-molecule) transport process of high-energy species in a relatively low-pressure environment, can form a film with high packing density and quality. In the current study, ZnO films have been prepared by ion beam sputtering technique on both Si (1 0 0) and free-standing diamond substrates. Highly (0 0 2) oriented ZnO films have been deposited by ion beam sputtering method of different Ar/O2 ratios and at different temperatures. The X-ray diffraction patterns of ZnO films showed sharp diffraction peaks of (0 0 2) orientation. Zn and O elements in the as-deposited ZnO films were investigated by X-ray Photoelectron Spectroscopy (XPS). In this study, the lowest full width of half maximum (FWHM = 0.27°) of (0 0 2) peak and the smooth ZnO film of several nanometers can be obtained by the optimal condition (substrate temperature = 300 °C, Ar/O2 ratio = 8/2). Good quality ZnO film on free-standing diamond film was also obtained to explore more applications.