New Insights into the Physical Origin of Negative Capacitance and Hysteresis in NCFETs

Stepwise internal potential jumps caused by multiple-domain polarization flips in metal/ferroelectric/metal/paraelectric/metal stack

“…However, physical understanding of NC effects is still under intensive debate [25][26][27][28][29][30][31][32][33][34][35][36] . Experimentally observed NC effects are different from each other, and also from the concepts initially proposed.…”

“…In fact, it has been argued that NC region of FE material is intrinsically unstable or even impossible 32,33 . In addition, the SS improvements observed in FETs mostly suffer from critical problems that a large hysteresis is detected, a high voltage is needed and an operation frequency is limited in actual experiments [34][35][36] .…”

Deep insight into the voltage amplification effect from ferroelectric negative capacitance

“…Different with quasi-static NC theory, it has been recently presented that the NC effect can be modeled as a transient phenomenon caused by the FE polarization switching [4,5]. In [5], we have demonstrated the first direct experimental observation of NC phenomenon in a standalone FE capacitor, verifying its dynamic behavior. It is shown that the time-induced polarization is the origin of NC phenomenon.…”

“…The traditional quasi-static NC theory considers that the NC can be derived from the negative curvature of energycharge relationship of ferroelectric, which is unstable for standalone FE capacitor and can be stabilized by connecting an appropriate positive capacitor to reach a capacitance matching condition for VA [3]. Different with quasi-static NC theory, it has been recently presented that the NC effect can be modeled as a transient phenomenon caused by the FE polarization switching [4,5]. In [5], we have demonstrated the first direct experimental observation of NC phenomenon in a standalone FE capacitor, verifying its dynamic behavior.…”

“…In this study, based on [5], we provide more detailed insights into the dynamic behavior of NC for the VA of FE-FET and present a comprehensive study on the condition of VA. First, the experimental observation of VA in the gate stack structure is presented, showing its dynamic behavior. Then, the specific condition of VA is studied taking the ferroelectric dynamic behavior into consideration.…”