Dual-Mode Hybrid Quasi-SAW/BAW Resonators With High Effective Coupling Coefficient.

This article reports on a design journey for ScAl - N-based dual-mode hybrid quasi-surface and bulk acoustic wave (quasi-SAW/BAW) resonators. Four types of acoustic excitation configurations are proposed in these designs based on Sc AlN/6H-SiC stack architectures. The influence of Sc AlN materials, film thickness, and device configurations on the performance is investigated. After design optimization, the final dual-mode hybrid quasi-SAW/BAW resonators comprise of top electrode, partially etched Sc AlN pillars, and bottom electrode, which are stacked on a 6H-SiC substrate. The coupled quasi-SAW and BAW excited in the hybrid resonators enhance the resonance for both quasi-Rayleigh and quasi-Sezawa modes which results in a high effective coupling coefficient (K) and phase velocity ( v ). Simulation results show that the optimized hybrid quasi-SAW/BAW resonator based on Mo/Sc AlN/Mo/6H-SiC configuration with SiO filling the grooves has a remarkable K value of 14.55% and a high v above 7500 m/s, which make this kind of dual-mode hybrid quasi-SAW/BAW resonators have great potential in wideband and high-frequency applications.