Investigation of Switching Characteristics Degradation of GaN HEMT Under Power Cycling Aging

GaN HEMT devices have wide application prospects because of their high electron mobility and excellent electrical characteristics. However, due to the lack of reliability analysis of the switching characteristics, GaN HEMT devices are unable to realize their maximum potential in practical applications. In this paper, GaN HEMT devices are aged based on power cycling. The switching degradation behavior of GaN HEMT devices after aging is characterized by double pulse test. The test results show that the switching delay increases, the Miller platform lengthens, and the opening ringing decreases after power cycle aging. In order to explore the degradation mechanism, the effects of parasitic capacitance on the switching characteristics are characterized by double pulse test of parallel capacitors. Based on the analysis of the parasitic capacitance model, the degradation trend of each parasitic capacitance caused by trap after aging is deduced and verified by experiment. The results show that the trap increase of AlGaN layer caused by inverse piezoelectric effect and hot-electron effect is the main reason for the change of parasitic capacitance after aging, while the on-state and off-state capacitance of GaN HEMT devices have completely different composition mechanism and change trends, which lead to different trends and degrees of degradation of each switching characteristic. This can provide a valuable reference for the reliability of GaN HEMT devices in long-term applications.