High Temperature Stable Acoustic Surface Wave Substrates of SiO₂/LiNbO₃Structure with Super High Coupling

In this study, in order to improve the temperature coefficient of frequency (TCF), the propagation characteristics of SiO2/Rotated Y-cut, X-propagating LiNbO3 leaky surface acoustic wave (SAW) substrates with a large electromechanical coupling coefficient (k2), zero attenuation and zero TCF are theoretically investigated. The results showed a large k2 of more than 0.2 (zero k2 of Rayleigh mode), zero TCF and zero propagation attenuation for leaky SAW in the case of a short boundary at a thin film thickness of H/λ\fallingdotseq0.15–0.25 (H: SiO2 film thickness, λ: SAW wavelength). The experimental results agreed with the theoretical ones.