Lamé-Mode Resonator with Trapezoidal Grooves Based on Sc0.3Al0.7 N/AlN Composite Film Achieving Coupling Coefficient of 18.7%

This work proposes a novel Lamé-mode resonator with trapezoidal grooves, using a 30% scandium-doped aluminum nitride ($\mathrm{Sc}_{0.3}\mathrm{Al}_{0.7}\mathrm{~N}$) and aluminum nitride (AIN) composite film ($\left.\mathrm{Sc}_{0.3}\mathrm{Al}_{0.7}\mathrm{~N}/\mathrm{AlN}\right)$ as the piezoelectric layer (cTGLMR). The slope angle of trapezoidal grooves is 80°. With the increase of groove depth, electromechanical coupling coefficient $(k_{eff}^{2})$ achieves the maximum value of 18.7% and figure of merit $(FoM$) reaches up to 150 when the groove depth is $0.6\mu\mathrm{m}$. The impact of design parameters on these resonators are systematically investigated by using finite element analysis (FEA). This structure shows broad application prospect for wide bandwidth filters.