Anomalous DC-current-induced attenuation of Q factor in a silicon contour mode micromechanical resonator

In this work, we report the experimental observation of quality factor (Q) variation in piezoresistively sensed silicon micromechanical resonators vibrating in a lateral contour mode. By fine tuning the bias current, the gradual descending and ascending trend of Q is distinctively observable. It shows a drastic drop in Q by nearly one order of magnitude (from 10⁵ to 10⁴) at a certain bias current level. The observed Q variation is replicable even when applying a capacitive sensing configuration with bias current running through. This anomaly is consistently detected from multiple die samples including resonators aligned along both <;110> and <;100> crystal orientations in the (100) plane. A detailed quantitative study is currently underway.