Figure 5.

(a) $\log \left(-Z^{″}\right)$ vs. $\log f$ plot measured by frequency sweeping at selected gate voltages; (b) $\log \left(-Z^{″}\right)$ vs. $\log f$ plot measured by gate voltage sweeping at selected frequencies; (c,d) $Q_0$ and $\alpha$ were extracted based on multi-frequency C-V profiling method.