A computational approach to optimize the linearity in dual-gate InAlGaN/AlN/GaN HEMTs

This paper investigates the effect of the proposed dual gate structures in enhancing the linearity of InAlGaN/AlN/GaN high-electron-mobility transistors (HEMTs) using TCAD analysis. Through the comprehensive analysis of the dual gate structure with the additional gate placed between the gate-source (DG-GS) and gate-drain (DG-GD) regions, the impact on the linearity performance has been compared with that of a standard single gate (SG) structure. The dual gate configuration exhibits a flatter and broader transconductance (g(m)) profile than the SG configuration. The reduction in the third-order intermodulation levels is confirmed with the polynomial fitting method. The f(T)/f(max) of the DG-GS case is simulated to be 52/102 GHz, which shows that such configuration does not deteriorate the RF performance. Comprehensive simulations are carried out to study the device physics and assess the mechanism behind the linearity improvement. The large signal model has been developed to examine the large signal RF performance as well as linearity performance metrics. An improvement of 9.6 dB in the carrier-to-intermodulation (C/I) ratio and that of 2.4 degrees in the amplitude-to-phase modulation at 6 dB backoff from P-sat have been observed as compared to the SG configuration. Such characteristics have evidenced that the optimized dual-gate configuration with the second gate placed between the source and gate can effectively improve the linearity performance of the InAlGaN/AlN/GaN HEMT configurations.