Tuning Performance of Silicon Carbide Micro-Resonators

Silicon carbide microresonators have been designed, fabricated and tested. Three designs have been studied: cantilever, bridge and ring resonators. The devices have been actuated electrothermally and sensed piezoelectrically. The resonant frequency as well as the amount of frequency shift as a function of DC bias voltage for the three designs have been characterized electrically using two-port measurements. It has been found that the DC tuning sensitivities of the ring and bridge resonators (between 58,000 ppm/V and 62,000 ppm/V) are significantly higher than for the cantilever (240 ppm/V). Simulations have shown that a larger temperature change, hence a larger compressive stress induced in the SiC layer exists in the bridge design compared to the cantilever design as the DC bias voltage is increased. The higher DC tuning sensitivity for the bridge design could be a result of the combination of the location of the electrode thus causing higher thermally induced compressive stress as well as the clamped-clamped beam configuration.