Frequency scaling and transducer efficiency in internal dielectrically transduced silicon bar resonators

In this paper, we present experimental results of frequency scaling and transducer optimization in internal dielectrically transduced silicon bar resonators. We show that selective positioning of the dielectric transducers inside the resonator can preferentially excite targeted harmonics while suppressing undesired modes. Furthermore, measurements across multiple resonators show lower motional impedance as resonant frequency increases and as the dielectric thickness approaches the acoustic half-wave length in silicon. With dielectric films at positions of maximum strain (minimum displacement) in the resonator, a 6.2 GHz resonator is demonstrated with a Q of 4277. We also report an f·Q product of 3.1·1013 at 4.7 GHz, the highest f·Q product in polysilicon reported to date.