Toward a 10 GHz High-Order Surface Acoustic Wave Resonator: A Finite-Element Study on LiNbO3/SiC Heterostructure Incorporating Embedded Electrodes.

The escalating demand for high-frequency acoustic devices in 5G/6G communications imposes stringent requirements on surface acoustic wave (SAW) resonators, including high operating frequency, large electromechanical coupling coefficient K2, and high quality factor Q. However, conventional SAW devices suffer from severe trade-offs among these metrics. This work proposes and theoretically analyzes an embedded-electrode LiNbO3/SiC heterostructure SAW resonator tailored for high-order modes, with its frequency response evaluated via finite-element modeling. A quasi-three-dimensional periodic model consisting of LiNbO3/IDT/SiC structure is established, and the effects of LiNbO3 crystallographic orientation, normalized LiNbO3 thickness, and embedded-Al-electrode thickness on the resonator performance are then systematically investigated. For the selected design with Euler angle β = 30°, the optimal normalized LiNbO3 thickness is found to be hLN/λ=0.2. Under this crystal orientation, the optimized normalized embedded-electrode thickness is hIDT/λ = 0.06. The optimized resonator achieves a resonant frequency of fr = 12.792 GHz, a phase velocity of V = 12,792 m/s, a K2 of 9.16%, and a Q of 1004.4. These investigation results validate the proposed LiNbO3/IDT/SiC heterostructure as a viable platform for pushing SAW technology into the 10 GHz regime, thereby bridging the gap between acoustic-wave devices and millimeter-wave RF systems for next-generation communications.