Properties of oxide deposited on c-plane AlGaN/GaN heterostructure

GaN-based metal-insulator-field effect transistors are very promising for high-voltage power switching applications because of low gate leakage current, low interface state density, and the ability to achieve enhancement mode devices. In this reported work, properties of the SiO2/AlGaN interface were characterised using capacitors fabricated on polar c-plane (0001) AlGaN/GaN heterostructures for two different oxide deposition conditions. Using capacitance-voltage measurements, it was possible to determine the interface fixed charge density for 500 and 900 degrees C oxide deposition temperatures. The measured interface charge density data will be useful for the design of normally-off AlGaN/GaN transistors with silicon dioxide gate insulator.