Analysis of longitudinal leaky surface acoustic waves on quartz thin plate bonded to similar-material substrate

The propagation and resonance properties of longitudinal leaky surface acoustic waves (LLSAWs) on bonded structures consisting of a quartz (Qz) thin plate and a Qz support substrate with different Euler angles were investigated theoretically. By using both an X-cut Qz thin plate and a Qz support substrate with optimal Euler angles, we obtained LLSAWs with a larger coupling factor, a smaller attenuation, and a lower temperature coefficient of frequency than those on a single Qz substrate. Furthermore, from the resonance properties simulated by the finite element method, the bonded structures were found to exhibit a large admittance ratio and a high quality factor, which could not be obtained when using a single Qz substrate; the bandwidth, however, was as small as 0.016%-0.086%.