Design and simulation of GaN/AlGaN HEMTs with low leakage current and high ON/OFF current ratio

Abstract

A gate-recessed AlGaN/GaN based heterojunction field effect transistor (HFET) on SiC Substrate is designed and simulated using both Si3N4 and SiO2 passivation layers and its DC performance characteristics are analyzed using SENTAURUS TCAD Tools. The maximum ON current of the proposed device is found to be 670mA/mm at a gate voltage of -1.5 V and the maximum OFF current of the device is found to be less than 10-7 A/μm. This substantially reduced leakage current leads to a high ON/OFF Current ratio. The transconductance of the device is found to be 6e-4S/μm at a gate voltage of 0.5 V. The rise in ON current is mainly due to the increase in the accumulation of the positive charges at the Si3N4/GaN interface which leads to the increase in the sheet carrier concentration in the 2DEG channel.