A Novel Modified AlN/Sapphire Layered Structure for Spurious-Free Surface Acoustic Wave Resonator with High Coupling Coefficient

This work presents a modified AlN/Sapphire layered SAW structure localized partial removal of AlN thin film and sapphire, respectively. The SAW propagation and resonance characteristics of the proposed structure with periodic grooves and voids are analyzed using finite element method (FEM). Compared with conventional AlN-based SAW, the proposed structure with optimization configuration and parameters effectively improves the K ² while maintaining a high V, meanwhile eliminates spurious modes. It is demonstrated that the Sezawa mode on the proposed SAW resonator structure offers operating frequencies above 5GHz, K ² values above 6.5%, and an excellent impedance ratio of 98dB, which makes it a potential candidate for advanced 5G applications.