Analytical Modeling of Gate-Stack DG-MOSFET in Subthreshold Regime by Green’s Function Approach

An accurate analytical model of the gate-stack symmetric double-gate (DG) MOSFET using Green's function approach is developed in this brief. An exact analytical solution to 2-D Poisson's equation is derived in the subthreshold regime of operation, considering 2-D mixed boundary conditions and multizone techniques. It is observed that the Green's function approach of solving 2-D Poisson's equation in both oxides (t
_ox1
and t
_ox2
) and silicon region can accurately predict channel potential and subthreshold current (I
_sub
) of gate-stack DG-MOSFET. We further extend our model to mitigate the fringe-induced barrier lowering (FIBL) effect in the gate-stack device, by optimizing the interfacial layer thickness. It is observed that selection of interfacial SiO
₂
layer as ~0.75 times of equivalent oxide thickness is necessary to completely mitigate the FIB' effect of SiO
₂
-HfO
₂
-based gate-stack DG-MOSFET.