600-V p-GaN Gate HEMT With Buried Hole Spreading Channel Demonstrating Immunity Against Buffer Trapping Effects

A 600-V p-GaN gate HEMT with buried hole spreading channel (BHSC) is demonstrated to suppress the buffer trap related dynamic {R}_{\text {ON}} degradation. The BHSC is located at the interface between u-GaN and buried AlGaN. In the on-state, the holes injected from the p-GaN gate can effectively spread along the BHSC and screen the negative buffer charges. The hole spreading effect is verified by a detection of hole current from the sidewall of BHSC. The screening effect is verified by a positive substrate stress test that intentionally induces severe buffer trapping, which is widely known to cause severe dynamic {R}_{\text {ON}} degradation in traditional GaN HEMTs. However, the propose device exhibits an immunity against buffer trapping owing to the screening effect of the holes along BHSC. The dynamic performance with as short as \sim 20~\mu \text{s} delay after a 400-V substrate stress is characterized. Nearly zero buffer trap related dynamic {R}_{\text {ON}} degradation is achieved.