Study on the Roles of Charge Trapping and Fixed Charge on Subthreshold Characteristics of FeFETs

Charge trapping (CT) and fixed charge (FC) are considered in the model of transient negative capacitance (TNC). The roles of CT and FC on subthreshold characteristics of ferroelectric FET (FeFET) are investigated by experiment and simulation. The simulation results show that both CT and FC can modulate the subthreshold characteristics of FeFET by shifting the operation point dynamically and statically, respectively. In addition, ferroelectric hysteresis can be reduced by the compensation due to CT and minor loop formation due to FC in a certain V
_g
sweep range. As a result, sub-60 mV/decade subthreshold swing (SS) with nearly hysteresis-free operation observed in experiments can be qualitatively reproduced by our simulation framework of TNC if both CT and FC are well-considered.