Investigation of Phonon-Carrier Interactions in Silicon-Based MEMS Resonators

In this work, a technique is introduced for isolating the energy loss associated with the interaction of charge carriers with acoustic phonons in thin film piezoelectric-on-silicon (TPoS) MEMS resonators. This method facilitates the investigation of acoustoelectric loss mechanism. The variation in quality factor (Q) and insertion loss of high frequency TPoS resonators is reported while the surface carrier concentration of the silicon layer is varied through application of a voltage to the metal-dielectric-silicon capacitor that is intrinsically formed during the conventional fabrication of TPoS resonators. A maximum of 3% improvement in the insertion loss (IL~9 dB) of a ~926 MHz resonance mode is recorded when a 4 V bias is applied to the said capacitance which is believed to stem from a reduction in interaction of acoustic phonons with carriers.