Interface States in AlGaN/GaN Metal-Insulator-Semiconductor High Electron Mobility Transistors

Frequency-dependent capacitance and conductance measurements are performed on AlGaN/GaN high electron mobility transistors(HEMTs)and NbAlO/AlGaN/GaN metal-insulator-semiconductor HEMTs(MISHEMTs)to extract density and time constants of the trap states at NbAlO/AlGaN interface and gate/AlGaN interface with the gate-voltage biased into the accumulation region and that at the AlGaN/GaN interface with the gate-voltage biased into the depletion region in different circuit models.The measurement results indicate that the trap density at NbAlO/AlGaN interface is about one order lower than that at gate/AlGaN interface while the trap density at AlGaN/GaN interface is in the same order,so the NbAlO film can passivate the AlGaN surface effectively,which is consistent with the current collapse results.