A novel approach to modelling the properties of HEMTs operating in the saturation region

Abstract

Currently, the ASM-HEMT model, QPZD model and EPFL model are all based on the three-terminal potential as the core, and relate the electrical characteristics such as I-V and C-V to Vd, Vs and Vg, so as to accurately build the HEMT model with high accuracy and fast convergence. However, there has not yet been a model based on three-terminal potentials that can quickly model the velocity saturation effect as well as the carrier concentration distribution and the electric field distribution inside the HEMT, which makes the existing models have to rely on a number of empirical parameters in the modelling process, which lacks the actual physical significance. In previous publications, models for the electric field, carrier concentration distribution based on the effective length of the gate were presented. In this paper, the model proposed in previous publications is improved to enable: (1) the calculation of the current Ids without relying on the Newton iterative method with fast simulation convergence behavior; (2) The Vdsat when the HEMT reaches saturation at different Vgo is redefined instead of using Vdsat = Vgo; (3) The expression of the v-E relationship is redefined relying on the different transport of carriers, which solves the problem of the large model error of the electric field distribution in the region below the gate, and makes the model's accuracy of the I-V characteristic further improved. The model was validated by characterising the I-V and E-V of the HEMT through TCAD simulation with RMSE below 5%.