A substrate having a suitable electromechanical coupling factor (ks) value and a good temperature coefficient of frequency (TCF) is required for an applications of resonator surface acoustic wave (SAW) filters and rudder-type SAW filters requiring a specific bandwidth, because their bandwidth largely depends on the coupling factor of the substrate. Although a quartz substrate for SAW devices provides a good TCF, the electromechanical coupling factor obtained is small. The author speculated that an excellent TCF and an appropriate electromechanical coupling factor could be realized by combination of a quartz substrate having a positive TCF and a ZnO film having a negative TCF. As a result of theoretical and experimental investigations performed using a 29°45′ rotated Y and a 42°45′ rotated Y 35°X propagating quartz substrate, an excellent TCF (≈ 0 ppm/°C) and an appropriate coupling factor (ks = 0.1-0.11; ks2 = 0.01-0.0121) were realized with a zero degree power flow angle on the structure of IDT/ZnO/quartz or IDT/ZnO/shorted-plane/quartz for the first time.
|Number of pages||5|
|Journal||Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers|
|Issue number||5 SUPPL. B|
|Publication status||Published - 1997 May|
- Coupling factor
ASJC Scopus subject areas
- Physics and Astronomy(all)