  Recent measurements on ultra-thin body Negative Capacitance Field Effect
Transistors have shown subthreshold behaviors that are not expected in a
classical MOSFET. Specifically, subthreshold swing was found to decrease with
increased gate bias in the subthreshold region for devices measured over
multiple gate lengths down to 30 nm. In addition, improvement in the
subthreshold swing relative to control devices showed a non-monotonic
dependence on the gate length. In this paper, using a Landau-Khanatnikov
ferroelectric gate stack model calibrated with measured Capacitance-Voltage, we
show that both these anomalous behaviors can be quantitatively reproduced with
TCAD simulations.
