Differential charge boost in hysteretic ferroelectric–dielectric heterostructure capacitors at steady state

Abstract

A ferroelectric material in a ferroelectric–dielectric heterostructure can provide a charge boost, as often discussed in the context of negative capacitance, and, in doing so, can reduce the power dissipation in field-effect transistor technology. However, there is an ongoing debate on whether the charge boost in such a heterostructure is a transient phenomenon or a steady state one. In this Letter, we use the positive-up-negative-down (PUND) measurement technique on a ferroelectric–dielectric (FE–DE) capacitor to show that the charge boost is a steady-state effect—i.e., the charge boost remains intact after the initial transient effects subside and all the voltages in the system reach constant values and steady states. We also demonstrate differential charge boost in steady state using a staircase voltage pulse measurement technique. An experimentally calibrated multi-domain SPICE model of an FE–DE stack is used to accurately simulate the PUND and staircase voltage hopping methods.