Silicon carbide phononic crystal cavities for micromechanical resonators

This paper demonstrates silicon carbide phononic crystal cavities for RF and microwave micromechanical resonators. We demonstrate design, fabrication, and characterization of Silicon Carbide/air phononic crystals used as Bragg acoustic mirrors to confine energy in a lateral SiC cavity. Aluminum nitride transducers drive and sense SiC overtone cavities in the 2-3GHz range with fxQ products exceeding 3×10¹³ in air. This approach enables decoupling of the piezoelectric AlN material from the SiC cavity, resulting in high Q resonators at microwave frequencies. The SiC cavities are fabricated in a CMOS-compatible process, enabling integration with wirelesss communication systems.