On/off switchable high-Q capacitive-piezoelectric AlN resonators

Voltage-controlled on/off switching based on electrode collapse around a 301-MHz capacitive-piezoelectric AlN contour-mode disk resonator has been demonstrated while still allowing on-state Q´s as high as 8,800 - the highest yet demonstrated around 300MHz in sputtered AlN. The key to on/off switching of this device is the structure of its capacitive-piezoelectric transducer, which provides a suspended electrode atop the suspended AlN resonator that can be pulled electrostatically towards the substrate, pinning the combined resonator-electrode structure to the substrate, thereby opening new conduits for energy loss that suppress signal transmission. This on/off switchability obviates the signal path micromechanical switches needed by conventional attached-electrode AlN resonator counterparts. The Q approaching 9,000, together with the demonstrated on/off switchability and electromechanical coupling k_eff² up to 0.78%, make this capacitive-piezoelectric resonator a strong contender among resonator technologies targeting RF channel-selecting communication front-ends.