Operation bandwidth of negative capacitance characterized by the frequency response of capacitance magnification in ferroelectric/dielectric stacks

The ferroelectric (FE) negative capacitance (NC) has emerged as a potential candidate for low-power electronics. In this study, we experimentally demonstrate the capacitance magnification of a paraelectric (PE) HfO2 capacitance (CHfO2) connected in series with a FE ZrO2 capacitance (CZrO2), which is higher than the value predicted by the series capacitance formula (CZrO2−1 + CHfO2−1)−1 and has a capacitance magnification ratio in the range 1.79–2.24. A model based on the switching of the net polarization in FE multi-domains is proposed to explain the capacitance magnification. In addition, the operation bandwidth of the NC effect was investigated by the frequency response of the capacitance magnification from 1 kHz to 10 GHz for the first time. The result reveals vanishing of the capacitance magnification at a frequency of about tens of megahertz, which suggests that the operation speed of NC is below ∼100 MHz.