Comparative Performance Analysis of Multi-Barrier GaN HEMTs with β-Ga2O3 Buffer and InGaN Back-Barrier Layers

A TCAD-based comparative study of AlGaN, InAlN, and quaternary InAlGaN barrier GaN HEMTs integrated with an InGaN back-barrier and β-Ga2O3 buffer layer on a SiC substrate is presented. The influence of barrier composition on carrier confinement, electrostatic behavior, and high-frequency characteristics is systematically investigated. The quaternary In0.10Al0.20Ga0.70N barrier device exhibits improved polarization-induced carrier confinement and enhanced 2DEG density of 6.38 × 10^13 cm–2. Owing to the optimized band alignment and reduced carrier spillover, the device achieves a maximum drain current of 2.15 A/mm, peak gm of 330 mS/mm, and fT of 530 GHz. In addition, lower intrinsic capacitances of 0.356 pF/mm for C_GS~ and 0.112 pF/mm for C_GD are obtained, leading to improved RF switching characteristics. The proposed structure also demonstrates excellent OFF-state behavior with leakage current in the order of 10–15 A/mm and a breakdown voltage of 67 V. The obtained results indicate that quaternary barrier and back-barrier engineering provide an effective pathway for next-generation microwave and power electronic systems.