Piezoelectric acoustic boundary waves propagating along the interface between SiO2and LiTaO3

The propagation characteristics of the layered structure of thick Si02 film on 126° rotated Y-cut X-propagation LiTa03 are studied. The existence of the new piezoelectric acoustic boundary waves (Stoneley type waves) has been found. The waves are tightly bound to the thick Si02 film-LiTa03 substrate interface. Piezoelectric acoustic boundary waves appear beyond H/λ = 0.5, where H is the film thickness and λ is the acoustic boundary wave length. At H/λ = 1.0, the energy concentration coefficient, η = |Us|² / l |Ui|² is 0.08, where Us and Ui, are displacement at the surface and interface, respectively, and piezoelectric coupling coefficient K² is 0.02. The experimental results agree with the calculated results.