High-breakdown-voltage AlGaN-channel metal-insulator-semiconductor heterostructure field-effect transistors employing a quaternary AlGaInN barrier layer and an Al2O3 gate insulator

In this study, Al2O3-gate-insulated metal-insulator-semiconductor (MIS) heterostructure field-effect transistors (HFETs) were fabricated using an Al0.61Ga0.37In0.02N/Al0.18Ga0.82N two-dimensional-electron-gas heterostructure, and their electrical properties were characterized. It was confirmed that the thermally stable quaternary AlGaInN barrier layer contributed to a good ohmic contact resistance of 10.5 Ω mm. This value seemed to be considerably small as an AlGaN-channel heterostructure. The fabricated MIS-HFETs showed good pinch-off characteristics and exhibited a maximum drain current (IDSmax) of approximately 180 mA/mm at the gate bias of +2 V. A high off-state breakdown voltage of 2.5 kV was obtained for the device with a gate-to-drain length of 20 μm.