Compact Model for Ferroelectric Negative Capacitance Transistor With MFIS Structure

We present a physics-based compact model for a ferroelectric negative capacitance FET (NCFET) with a metal-ferroelectric-insulator-semiconductor (MFIS) structure. The model is computationally efficient, and it accurately calculates the gate charge density as a function of the applied voltages. For the first time, an explicit expression for the channel current in bulk NCFET is also deduced taking into account the spatial variation of ferroelectric polarization in the longitudinal direction. Using current continuity condition in the channel, we find that different regions of the ferroelectric may operate in a positive or a negative capacitance state depending on the external biases. The model captures the impact of ferroelectric thickness scaling and variation in the ferroelectric material parameters, and has been validated against the implicit approach involving full numerical computations as well as experimental data. We also compare the device characteristics of the MFIS structure with those of the metal-ferroelectric-metal-insulator-semiconductor structure.