Deposition of preferred-orientation ZnO films on the ceramic substrates and its application for surface acoustic wave filters

Polycrystal ZnO films with c-axis (002) orientation have been successfully grown on the lead-based ceramic substrates by rf magnetron sputtering technique. The deposited films were characterized as a function 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 10 mTorr containing 50% argon and 50% oxygen and rf power of 70 W. The phase velocity, electromechanical coupling coefficient, and temperature coefficient of frequency of surface acoustic wave (SAW) device with ZnO/IDT/PT (IDT: interdigital transducer; PT:PbTiO₃ ceramics) structure were investigated. It shows that the preferred oriented ZnO film is beneficial for improving the electromechanical coupling coefficient of SAW device. © 2004 American Vacuum Society.