Surface acoustic wave propagation characteristics of ScAlN/diamond structure with buried electrode

In this paper, a 3D Finite Element model (FEM) of a surface acoustic wave (SAW) resonator consists of a piezoelectric thin film ScAlN /diamond layered structure with buried interdigital electrodes (IDT) was performed and analyzed using commercial software COMSOL Multiphysics, FEM software. We have done investigation on SAW propagation characteristics on the layered structures for different thickness of ScAlN film and electrode as well as different electrode materials. Simulation results showed that the maximum electromechanical coupling factor K_max² achieved up to be 14.35% for Rayleigh mode and 10% for Sezawa mode, which is more than two times larger than the previous report (5.48%). This work is useful for design of SAW devices with wideband and high frequency.