| Summary: | 碩士 === 義守大學 === 電機工程學系 === 91 === The propagation characteristics of bulk and multilayered piezoelectric substrates are studied in this work. Firstly, the bulk ST-quartz and LiNbO3 substrates are investigated. The dependences of surface acoustic wave (SAW) phase velocity, temperature coefficient of frequency (TCF), and electro-mechanical coupling coefficient ( ) on the cutting axis and the propagation direction are analyzed and discussed. Next, the multilayered substrates, using YX-LiNbO3, 128oYX- LiNbO3、STX-quartz and ST35oX-quartz as the bulk substrates and ZnO and AlN as the thin film, are investigated. It includes four interdigital transducers (IDTs) structures to analyze the propagation characteristics.
LiNbO3 shows high SAW phase velocity, large , and large TCF. STX-quartz presents zero TCF, but has low and SAW phase velocity. The multilayered structures are designed to improve the propagation characteristics of bulk substrates. The multilayered substrates with AlN film shows low and high SAW phase velocity. The multilayered substrates with ZnO film have high and low SAW phase velocity. The structure, which interdigital transducers (IDTs) are deposited on the interface between film and bulk substrate, presents the better propagation characteristics.
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