  Physical phenomena underlying operation of ferroelectric field-effect
transistors (FeFETs) is treated within a unified simulation framework. The
framework incorporates the Landau mean-field treatment of free energy of a
ferroelectric and the polarization dynamics according to Landau-Khalatnikov
(LK) equation. These equations are self-consistently solved with the
one-dimensional metal-oxide-semiconductor (MOS) structure electrostatics and
the drift-diffusion solution for the current in the semiconductor channel.
Numerical simulations demonstrate, depending on the ferroelectric (FE)
thickness, both regimes of hysteresis switching (relevant for a non-volatile
memory) and of higher on-currents and steeper subthreshold slope (SS) with a
negligible hysteresis (relevant for logic) via the negative capacitance effect.
