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 900degC 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.