Gate recessed GaN based HEMT with Si3N4 passivation for microwave applications

A novel AlGaN/GaN-based HEMT using gate recess technology is designed and simulated by deploying both Si₃N₄/SiO₂ passivation layers on SiC substrate using Synopsys Tcad tools. The drain current of the proposed device is measured to be 726mA at a threshold voltage of -1.2V from the study of the DC characteristics of the device. The RF characteristics of the GaN/AlGaN HEMT is analyzed by the AC analysis of the proposed device using a two port network. The transconductance of the device obtained by the AC analysis is found to be 178mS/mm at a gate voltage, V_gs of -0.4V. The current gain cut off frequency (ft) of the AlGaN/GaN HEMT is found to be 70GHz at a gate voltage of -0.4V. The power gain cut off frequency of the device is found to be 200GHz from the small signal AC analysis of the device. Hence, the gate-recessed AlGaN/GaN based HEMT is found to be a suitable device for high frequency applications.