Failure of the Scalar Dielectric Function Approach for the Screening Modeling in Double-Gate SOI MOSFETs and in FinFETs

This paper shows that modeling of the screening effect based on the scalar dielectric function (SDF) fails in double-gate (DG) MOS transistors and in FinFETs. This leads to simulation results inconsistent with the experiments, especially at high channel inversion densities where the mobility is limited by the surface roughness scattering. These results suggest that one should not use the SDF to model transport in DG silicon-on-insulator MOSFETs or FinFETs, but rather resort to the full tensorial dielectric function. This paper clearly identifies, using multi-subband Monte Carlo simulations as well as analytical derivations for the screened matrix elements of the surface roughness scattering, the simplifying assumptions in the derivation of the SDF that do not hold in a DG MOSFET.