Investigation of the aging of power GaN HEMT under operational switching conditions, impact on the power converters efficiency

This paper investigates the aging of a 650 V, 30 A GaN HEMT power transistor under operational switching conditions. The switching stress respects the Safe Operation Area (SOA) of the tested transistor. The aging campaign lasted 1008 h and was carried out through a developed switching application with high power efficiency. The global aging results show the degradation of five parameters: drain current ID, on-state resistance R-DS(ON), transconductance g(m), gate leakage current I-GSS, and threshold voltage V-TH. The major causes that affect the reliability of the GaN HEMT are hard switching, long time of test and high intensity of the stress. The existence of trapped charge in the gate-drain access region after aging is demonstrated using pulsed measurements. The effects of this degradation on power converters are studied by modeling the static characteristics of the aged GaN HEMT using an accurate method based on the Levenberg-Marquardt Algorithm. The accuracy and consistent convergence of the developed SPICE model provide a good way to investigate the reliability of GaN HEMTs by a simulation approach.