An Improved Compact Model of T-Gate HEMT Based on Effective Gate Length

Abstract

Advanced SPICE Model for high electron mobility transistor (ASM-HEMT) is one of the industry standard models for GaN-based high electron mobility transistors (HEMTs), in which there still lack analytical models for the distribution of the physical properties inside the device, especially a model for the distribution of the transverse electric field ( ${E}_{\text {X}}$ ) and carrier concentration ( ${n}_{\text {S}}$ ) that can be linked to the drain current ( ${I}_{\text {DS}}$ ) and gate charge ( ${Q}_{\text {G}}$ ). Besides, the modeling of operations in the saturation region in ASM-HEMT is dependent on empirical parameters without physical significance. In this work: 1) effective gate length ( ${L}_{\text {G,eff}}$ ) as a core parameter for saturation region modeling is calculated to capture the velocity saturation occurring in HEMTs; 2) distribution of ${E}_{\text {X}}$ and ${n}_{\text {S}}$ varying with gate and drain biases in the linear and saturation regions is modeled; 3) a field plate (FP) aware T-gate HEMT model is developed to capture the reduction of the peak electric field and the additional parasitic effect caused by the FP. The model is verified by characterizing the ${I}_{\text {DS}}$ and Miller capacitance ( ${C}_{\text {GD}}$ ) of the fabricated T-gate HEMTs, with RMSE lower than 7.5%, indicating a high degree of agreement.