New Insights into Read Current Margin and Memory Window of HfO2-based Ferroelectric FET with Re-exploration of the Role of Ferroelectric Dynamics and Interface Charges during Readout

The read current margin and memory window (MW) of HfO 2 -based ferroelectric FET (FeFET) are comprehensively re-evaluated by considering the impacts of the ferroelectric dynamics and interface charges during the read operation. It is found that readout methods and read time can significantly influence the evaluation of MW and read current margin due to polarization switching dynamics, revealing the limitation of prevailing MW evaluation method by pulsed IV. Moreover, when fast readout, MW of FeFET with optimized interface traps and interlayer capacitance can be theoretically potential to be higher than 2 times of coercive voltage which is the theoretical maximum value for quasi-static readout. For practical FeFET, the high trapped charge density may not only reduce MW and read current margin, but also lead to negligible dependence on read time and method. Based on the comprehensive physical discussion, the new understanding and design strategies of FeFET with high-read-margin are provided.