Study on the impact of the resonant cavity and lateral acoustic edge reflector for AlSc0.095N-based S0 mode Lamb-wave resonators

Abstract

In this paper, the impact of the resonant cavity and lateral acoustic edge reflector on the performance of the S0 mode Lamb-wave resonators based on Aluminum nitride film doped with scandium concentration of 9.5 % (AlSc0.095N) were systematically studied. Through the theoretical analysis and experimental verification, we found that the Q value of the resonator can be improved by defining a miniaturized resonant cavity due to the enhanced acoustic reflection effect at the anchor boundary. The effect of lateral reflection boundary width on the spurious modes, Q values, and electromechanical coupling coefficient (k2eff) of the resonators was analyzed. In addition, the k2eff and Q values of the interdigitated transducer (IDT)-IDT resonators are higher than those of the IDT-Floating resonators, due to the larger electromechanical conversion efficiency and smaller interface loss. The experimental results show that the Q and k2eff values of the optimized IDT-Floating and IDT-IDT resonators reach 853, 1.70 % and 1362, 2.69 %, respectively, meanwhile, they have clean spectrums.