Origin of Steep Subthreshold Swing Within the Low Drain Current Range in Negative Capacitance Field Effect Transistor

Negative capacitance FET (NCFET) can achieve the steeper subthreshold swing (SS) than conventional MOSFET for the reduction of supply voltage V
_DD
, while many experimental results indicate that NCFETs show the steeper SS only within a limited drain current range. In this work, the physical origin and parameter impacts of drain current range corresponding to steeper SS in NCFET are investigated, based on the modeling of domain switching dynamics of ferroelectric (FE). It is found that the larger remnant polarization is beneficial for the steeper SS with the larger drain current range. Besides, simulation results indicate that only within the limited window of sweeping rate and FE switching time, the drain current range can be enlarged for the steeper switching in NCFET.