Simulation and comparative analysis of the DC characteristics of submicron GaN HEMTs for use in CAD software

摘要

Bearing in mind the requirements of design engineers, a nonlinear model is developed to simulate the temperature-dependent I-V characteristics of submicron high-electron-mobility transistors (HEMTs). Self- and ambient heating effects are incorporated into the model expression to cater for both the negative and positive conductance of the device, after the onset of the saturation current. It is shown that the accuracy of numerical models previously developed for metal-semiconductor field-effect transistors (MESFETs) deteriorates when simulating the I-V characteristics of gallium nitride (GaN) HEMTs, primarily due to the self-heating effects. The validity of the proposed model is checked for GaN HEMTs with gate length (Lg) ranging from 0.12 to 0.7m in the temperature range of T=298 to T=773K. It is demonstrated that the proposed model simulates, with a good degree of accuracy, the output characteristics of such devices exhibiting negative conductance in the saturation region of operation. It is observed that, for devices exhibiting negative conductance in the saturation region, the peak transconductance (gm) occurs at a relatively higher negative gate bias while the peak value reduces with increasing ambient temperature. The root-mean-square errors reveal that the proposed model is better than other similar models reported in the literature, with an improvement varying from 17 to 50% depending on the device characteristics.