Quality Factor Enhancement of Laterally-excited Bulk Acoustic Resonators with Reflectors

This work demonstrates a quality factor (Q) enhancement of a laterally excited bulk acoustic wave resonator (XBAR) based on a Z-cut lithium niobate (LN) thin film. Two sets of reflectors are formed in the direction of acoustic wave propagation to prevent energy leakage along the lateral direction. The fabricated XBAR achieves an operating frequency of around 6 GHz and an effective electromechanical coefficient of 26%. The XBAR with a reflector structure possesses a Q of 461, an improvement of 32% over that of XBARs without a reflector, which is consistent with the simulation results.