Quality factor enhancement in lamb wave resonators utilizing AlN plates with convex edges

A novel Lamb wave resonator utilizing an aluminum nitride (AlN) plate with convex edges to enhance the quality factor (Q) is demonstrated for the first time. The finite element analysis (FEA) simulation results show that the mechanical energy can be more efficiently confined in the center of the AlN Lamb wave resonator by using the convex edges instead of the flat edges. Specifically, the measured frequency response for a 491.8-MHz AlN Lamb wave resonator with convex edges yields a Q of 3,280 which represents a 2.6× enhancement in Q over a 517.9-MHz AlN Lamb wave resonator with flat edges. Moreover, a 419.3-MHz Lamb wave resonator on an AlN/SiO₂ composite plate with convex edges yields a Q of 4,792, representing a 3.8× increase in Q.