Intrinsic temperature compensation of highly resistive high-Q silicon microresonators via charge carrier depletion

We report on a novel temperature compensation technique that exploits the dependence of TCF on the free charge carriers in silicon bulk acoustic resonators (SiBARs). The free charge carriers are considerably minimized by creating single and multiple pn-junction based depletion regions in the body of the resonator. The TCF of a highly resistive (>1000 Ω-cm) conventional rectangular SiBAR has been reduced from -32 ppm/°C to -3 ppm/°C. We previously exploited the dependence of TCF on silicon resonator geometry for TCF compensation. However, at large charge carrier depletion levels achieved in this work, the TCF is found to become independent of silicon resonator geometry.