The investigation of preferred orientation growth of ZnO films on the PbTiO₃-based ceramics and its application for SAW devices

Poly-crystal ZnO films with c-axis (0 0 2) orientation have been successfully grown on the lead-based ceramic substrates by RF magnetron sputtering technique. The deposited films were characterized as a function of deposition time, argon-oxygen gas flow ratio, and RF power. Crystalline structures of the films were investigated by X-ray diffraction, scanning electron microscopy and atomic force microscopy. Highly oriented films with c-axis normal to the substrates can be obtained by depositing under a total pressure of 10mTorr containing 50% argon and 50% oxygen and RF power of 70W for 3h. The phase velocity, electromechanical coupling coefficient and temperature coefficient of frequency of surface acoustic wave (SAW) device with ZnO/IDT/PT-ceramic structure were investigated. It shows that the preferred oriented ZnO film is beneficial for improving the electromechanical coupling coefficient of SAW device.