Direct Observation of Ferroelectric Domain Switching Dynamics Under Negative Capacitance Conditions via In Situ Transmission Electron Microscope

The negative capacitance (NC) of ferroelectric materials has attracted extensive attention due to its potential to overcome the power consumption limitations of microelectronic devices. Due to the transient and unstable nature of the NC effect, it is difficult to probe the underlying ferroelectric domain dynamics, making the relationship between domain dynamics and NC still elusive. We used in situ transmission electron microscopy and pulse measurements to find that domain switching in monolayer ferroelectric and ferroelectric/dielectric (FE/DE) heterostructures exhibits the traditional three-step and Landau switching modes, respectively. In the monolayer FE, domain nucleation and growth contribute more to NC than domain wall motion. Moreover, external factors such as charge injection induced by polarization switching are also found to contribute to NC. Furthermore, an enhanced NC effect was observed in the FE/DE heterostructure, which mainly originates from the homogeneous and ultrafast domain switching mechanism assisted by interfacial charges. The observed phenomenon provides opportunities for NC device engineering via domain switching dynamics.