High Temperature Characteristics of Insulated-Gate AlGaN/GaN Heterostructure Field-Effect Transistors with Ultrathin Al2O3/Si3N4 Bilayer

The device performance of AlGaN/GaN-based metal–insulator–semiconductor heterostructure field-effect transistors (MIS-HFETs) with an ultrathin (1 nm/0.5 nm) Al2O3/Si3N4 bilayer has been investigated at elevated temperatures up to 200°C. The devices exhibited excellent transconductance characteristics with high maximum transconductances and ultralow gate current leakages under reverse gate bias conduction at both room and high temperatures due to the employment of an ultrathin bilayer with large dielectric constants and the large conduction band offset between Al2O3 and nitrides. The excellent characteristics observed at high temperatures might indicate the very high interfacial quality between nitrides and bilayer insulator. The results in this report demonstrate that Al2O3/Si3N4 bilayer insulator is a superior candidate for nitride-based MIS-HFET devices operating at high temperatures.