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

Abstract

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 (C_HfO2) connected in series with a FE ZrO₂ capacitance (C_ZrO2), which is higher than the value predicted by the series capacitance formula (C_ZrO2⁻¹ + C_HfO2⁻¹)⁻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.