Enhancement of characteristics of ZnO thin film surface acoustic wave device on glass substrate by introducing an alumina film interlayer

ZnO films with c-axis (0 0 0 2) orientation have been successfully grown by RF magnetron sputtering on Al2O3/glass substrates. The alumina films were deposited on glass substrates by electron beam evaporation. The crystalline structure and surface roughness of the films were investigated by X-ray diffraction and atomic force microscopy, respectively. The phase velocity and coupling coefficient of SAW device were apparently increased when we increased the thickness of alumina film. Besides, an excellent temperature coefficient of frequency of SAW device was obtained with increasing the thickness of alumina film. The experimental result is beneficial to improve the performance of the ZnO thin film SAW devices on cheap glass substrate with easier process and lower cost.