Research for Surface Waves and SAW devices on Piezoelectric Crystals

• Main Authors: Hao-Wei Chuang, 莊豪偉
• Other Authors: Yuan-Fang Chou
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/15090182928601968987

碩士 === 國立臺灣大學 === 機械工程學研究所 === 91 === Hao-Wei Chuang, M. S. National Taiwan University, July, 2003 Research for Surface Waves and SAW devices on Piezoelectric Crystals Major Professor: Yuan-Fang Chou Abstract This article analyzes the properties of the surface wave on different piezoelectric crystals and discusses the bulk acoustic wave (BAW) effect on different piezoelectric crystals when exciting surface acoustic wave by interdigital transducers. There is a kind of wave whose amplitude decays with the depth from the surface, called surface wave, on isotropic materials. Assume the propagation type exists in piezoelectric crystals, we can use the wave equations of piezoelectric solids and the boundary conditions to obtain the wave velocity and the coincident displacement and electric potential. Then we consider the temperature variation affection to phase velocity to obtain the temperature coefficient of frequency when there is constant electrode distance on piezoelectric crystals. Finally we estimate the BAW affection to SAW devices on different materials. From this research, there are two important results. One is the temperature coefficients of frequency on ST-X quartz and (0°,140°,25°) langasite are smaller than those of others. The other is that the BAW affection to SAW devices of ST-X quartz is larger than that of Y128°-X lithium niobate and YZ cut lithium niobate.