Closed Form Current and Conductance Model for Symmetric Double-Gate MOSFETs using Field-dependent Mobility and Body Doping

A closed-form inversion charge-based long-channel drain current model is developed for a symmetrically driven, lightly doped Symmetric Double-Gate MOSFET (SDGFET). It is based on the drift-diffusion transport mechanism and considers velocity saturation using the Caughey-Thomas model with exponent n=2, vertical field mobility degradation and body doping. It is valid in subthreshold as well as above-threshold. Its main feature is that the physical model for velocity saturation has been retained as an integral part of the model derivation, instead of adding its effect at the end by considering an averaged electric field. The model is also extended to model the Channel Length Modulation effect in the post-velocity saturation regime. Comparisons of currents and conductances are made with 2D device simulation results and a reasonable match is shown all the way from subthreshold to strong inversion.