High current density and low on-resistance in ultra-wide bandgap Al0.65Ga0.35N-channel MOS-HEMTs for kV power switching

Achieving high on-currents (ID,MAX) and low on-resistances (RON) is a cardinal challenge for ultra-wide bandgap (UWBG) semiconductor materials, such as Al-rich AlxGa1−xN. In this work, we demonstrate state-of-the-art ID,MAX and RON (450 mA/mm and 30.5 Ω mm for LSD = 10 μm) in UWBG Al0.85Ga0.15N/Al0.65Ga0.35N channel high electron mobility transistors. We demonstrate the first microscopic imaging of ohmic contacts to reverse-graded AlxGa1−xN heterostructures and demonstrate high-performance power transistors with a Baliga figure of merit of 629 MW/cm2. We further characterize the high temperature breakdown of these device structures up to 150 °C, showing that high breakdown voltages are maintained with low degradation in RON. Cumulatively, these results show the potential of AlxGa1−xN-channel HEMTs for high voltage and high temperature applications.