Silicon carbide phononic crystals for high f.Q micromechanical resonators

This paper demonstrates silicon carbide phononic crystal cavities for RF and microwave micromechanical resonators. We demonstrate design and simulation of silicon carbide/air phononic crystals used as Bragg acoustic mirrors to confine energy in a silicon carbide cavity. Aluminum nitride piezoelectric transducers are used for drive and sense of silicon carbide overtone cavities at 2.3 GHz with quality factors exceeding 3,500 in air. This approach enables decoupling of the piezoelectric material from the cavity quality factor, resulting in high f.Q products at microwave frequencies. The silicon carbide phononic crystal cavities are fabricated in a CMOS-compatible process, for integration in wireless communication systems.