Analysis of Degradation Behavior and Mechanism of p-GaN Gate HEMT Under High-Power Microwave Irradiation

In this work, the degradation behavior of electrical characteristics of p-gallium nitride (GaN) gate HEMTs under high-power microwave (HPM) irradiation has been studied. The trap analysis of p-GaN gate HEMTs before and after HPM irradiation based on the 1/f noise method was carried out. The experimental results show that the threshold voltage of the p-GaN gate HEMTs under HPM irradiation is obviously lower than that of the fresh device and the subthreshold swing is larger than that of the fresh device. The maximum variation of gate leakage current increases by an order of magnitude. As the HPM power and the irradiation time increase, the degradation phenomenon of the p-GaN gate HEMT device becomes more severe. The 1/f noise results show that the input-referred flat-band spectral noise density in the p-GaN gate HEMTs had doubled under HPM irradiation. This indicates that the trap density in the p-GaN gate HEMTs has also doubled under HPM irradiation, which would lead to an increase in the subthreshold swing and gate leakage current of the device. Further study shows that HPM couples high-frequency potential differences between the pins of the device (the same frequency as HPM). The degradation of the device may be due to this high-frequency ac gate stress. The experimental results may be useful in the application of p-GaN gate HEMTs in complex electromagnetic environments.