AlN/3C–SiC Composite Plate Enabling High‐Frequency and High‐Q Micromechanical Resonators

Abstract
An AlN/3C–SiC composite layer enables the third-order quasi-symmetric (QS3) Lamb wave mode with a high quality factor (Q) characteristic and an ultra-high phase velocity up to 32395 ms−1. A Lamb wave resonator utilizing the QS3 mode exhibits a low motional impedance of 91 Ω and a high Q of 5510 at a series resonance frequency (fs) of 2.92 GHz, resulting in the highest fs·Q product of 1.61 × 1013 Hz among the suspended piezoelectric thin film resonators reported to date.