High-performance enhancement-mode Al2O3/InAlGaN/GaN MOS high-electron mobility transistors with a self-aligned gate recessing technology

The paper reports high-performance enhancement-mode MOS high-electron mobility transistors (MOS-HEMTs) based on a quaternary InAlGaN barrier. Self-aligned gate technology is used for gate recessing, dielectric deposition, and gate electrode formation. An improved digital recessing process is developed, and an Al2O3 gate dielectric grown with O2 plasma is used. Compared to results with AlGaN barrier, the fabricated E-mode MOS-HEMT with InAlGaN barrier delivers a record output current density of 1.7 A/mm with a threshold voltage (VTH) of 1.5 V, and a small on-resistance (Ron) of 2.0 Ω·mm. Excellent VTH hysteresis and greatly improved gate leakage characteristics are also demonstrated.