Effects of dielectric overlay upon surface acoustic wave propagation undermetallic grating structure

This paper describes surface acoustic wave (SAW) propagation under a period ic metallic grating structure overlaid with an SiO2 film. An analysis was m ade by modifying the software FEMSDA, in which the finite element method is applied to both the grating electrodes and SiO2 overlay. For Rayleigh-type SAW propagating on 128 degrees YX-LiNbO3, changes in the reflection coeffi cient and effective velocity are calculated as a function of the SiO2 film thickness overlaying an Al grating structure. It is shown that the SiO2 fil m overlaying the top surface of the grating electrodes affects both the SAW reflection coefficient and effective SAW velocity more significantly than the film overlaying the electrode gaps.