A study of surface acoustic wave pressure sensor in ZnO/quartz structure

It was previously reported that a Rayleigh wave propagating on a zinc oxide film has a relatively low temperature coefficient of frequency (TCF) and a large electromechanical coupling factor (K²). In this study we investigate the performance of a SAW pressure sensor using ZnO/quartz structure. Y-cut is preferred in our study due to its positive TCF value permitting a zero TCF when combined with ZnO. ZnO thickness was determined to achieve a zero TCF and to improve the electromechanical coupling coefficient (K²=1%) seven times higher than that of quartz Y-cut X propagating direction. The development of the optimal structure to be used is presented followed by the operating frequency effect and ZnO film contribution to the pressure sensitivity.