An improved model for the $${I{-}V}$$ I - V characteristics of submicron SiC MESFETs by evaluating the potential distribution inside the channel

Abstract

This paper presents a detailed mathematical model describing the $$I{-}V$$ characteristics of submicron SiC MESFETs. Poisson’s equation with appropriate boundary conditions has been solved to determine the potential distribution inside the channel. The location ( $$L_1$$ ) of the Schottky barrier gate with a corresponding depletion layer width ( $$u_1$$ ) where the carrier’s velocity gets saturated has been evaluated. It has been demonstrated that, both $$L_1$$ and $$u_1$$ are bias dependent, and their values change by changing the drain biasing even after the onset of current saturation. This causes a modification in the depletion layer underneath the Schottky barrier gate and, thus, changes the available channel cross-section for the flow of current. It has been shown that finite output conductance in the saturation region of operation, which is usually observed in submicron devices, can be explained with Schottky barrier depletion layer modification. The $$I{-}V$$ characteristics of submicron SiC MESFET are modeled and compared with conventional velocity saturation techniques, where the depletion layer after the onset of current saturation has been treated as a constant. It is observed that the proposed technique gave $$\sim $$ 15.9% improvement in the modeled characteristics of a submicron SiC MESFET.