Study of normally-off AlGaN/GaN HEMTs with recessed p-GaN gate

This article presents a comprehensive simulation analysis of a normally-off AlGaN/GaN HEMT with recessed p-GaN gate. Based on a conventional p-GaN HEMT, the structure of the device is achieved by selectively etching the AlGaN barrier layer beneath the gate and depositing a p-GaN cap layer. The TCAD tool was used to analyze transfer characteristics, output characteristics, transconductance, and breakdown voltage of the device. Besides, the large-signal power performance was also studied. The results indicate that the normally-off HEMT exhibits great performance with a threshold voltage of 2.7 V, saturation drain current at 1.52 A/mm, peak transconductance reaching 326 mS/mm, and a breakdown voltage of 610 V. When the device is driven with large-signal operation at the gate, the output power and power output efficiency increase with the increasing input power, while the power gain decreases.