Al-Rich Multi-AlGaN Barriers for Enhanced Performance in GaN-Based Monolithic Integration Platforms

This work proposes Al-rich multilayer AlGaN barriers featuring three distinct layers (AlGaN1/2/3) with strategically spindle-shaped Al mole fractions (Xb1 < Xb2 > Xb3) to decouple the improved gate control capability from enhanced conduction/breakdown properties in p-GaN HEMTs via simulation. The key Al-rich AlGaN2 (40% Xb2) enhances polarization and critical electric fields, simultaneously boosting the 2DEG/2DHG densities. Functioning as polarization-modulating transition layers, 10% Xb1 AlGaN1 and 15% Xb3 AlGaN3 enable enhanced electrostatic control of the p-GaN gate, achieving a +0.4 V Vth shift in n-FETs. Selective etching of AlGaN1 in n-FET access regions decouples polarization modulation between the p-GaN gate and access regions, allowing Al-rich AlGaN2 to dominate the 2DEG channel. This architecture yields a 20% higher ION and 28% higher VBV (1120 V at LGD = 18 μm) in n-channel p-GaN power HEMTs compared to conventional Al0.25Ga0.75N barriers.