Thermal-piezoresistive pumping on double SiC layer resonator for effective quality factor tuning.

Active techniques that pump energy into MEMS mechanical resonant devices to improve their performance have attracted great research attention. Herein, we introduce a new concept of bi-layered monolithic silicon carbide resonators utilizing thermal-piezoresistive pumping to boost the quality factor. The device operates based on the electrothermal actuation as a result of a superimposed alternating and direct voltages. The structural stress modulates the electrothermal force generated in the device through the piezoresistive effect. Due to the negative piezoresistive coefficient of the actuator, the mechanical vibration of the structure is fed from the DC bias applied to the structure. The unique design of the double SiC layer allow energy pumped into the system via the thermal-piezoresistive coupling in highly doped SiC nano-film, enabling the enhancement of effective quality factor up to 15.5 %, from 12,200 to 14,100. The change in frequency related to the applied power was measured to be less than 1 % of the designed value. The saturation threshold of the pumping effect was reached at an applied power of 0.18 W. This works provides an avenue to improve the effective quality factor in MEMS bridge structure resonators by the coupling of the thermal-piezoresistive pumping and electrothermal actuation. [Display omitted] • The design allows the application of thermal piezoresistive pumping to enhance the effective quality factor. • Highly reliable and stable electrothermal actuation of SiC MEMS resonators has been achieved. • Effective quality factor tuning by electrothermal actuation on an out-of-plane vibration mode of n-type SiC resonator. [ABSTRACT FROM AUTHOR]