  This paper investigates and compares through a comprehensive TCAD analysis 2D
and 3D simulations for ferroelectric based FETs. We provide clear evidence that
the multiple read conductance values experimentally observed in FeFETs stem
from source to drain percolation current paths, which are governed by the
polarization patterns in the ferroelectric domains. Such a physical picture
makes 3D simulations indispensable to capture even the qualitative features of
the device behaviour, not to mention the quantitative aspects.
