Modified boundary condition at Si-SiO_2 interface for modeling of threshold voltage and subthreshold swing of short-channel SOI MESFET's

摘要

Superposition technique to solve the two dimensional (2-D) Poisson's equation is a widely used method for the analytical modeling of potential distribution and threshold voltage of short-channel FET devices. In this method, the solution of the 2-D Poisson's equation is considered as the superposition of the solutions of the 1-D Poisson's equation used for the long channel devices and a homogeneous Laplace equation which is used to include the effects of the short-gate length on the potential function of the device. Such a method was used by Chiang et. al. [1] to model the threshold voltage and subthreshold swing of short-channel SOI MESFET's. However, the boundary condition described in [1] at the Si-SiO_2 interface may yield ψ_S (x, t_(Si)) = 0 for all values of x, eliminating short-channel effects that may play an important role. Further, Chiang et. al. have chosen an approximate solution of their Eq.