egradation and failure mechanisms of P-GaN HEMTs in single and complex radiation environments

In this work, the mechanisms of total ionizing dose effect (TID) and single-event burnout (SEB) failure in P-type gallium nitride gate high electron mobility transistors (P-GaN HEMTs) was investigated based on experiment and simulation. In the TID experiments, three groups of samples with different voltage bias were irradiated up to a maximum of 1 Mrad(Si) using 60Co γ-rays with an average energy of 1.25 MeV, at a dose rate of 100 rad(Si)/s. Positive threshold voltage shifts of different magnitudes are observed, while the gate leakage current increases insignificantly in all of them. We believe that electron and hole trapping at the P-GaN/AlGaN interface and in the AlGaN barrier layer is the main reason for the threshold voltage shift. For the SEB experiments, a tantalum (Ta) ion beam was used for irradiation at an energy of 854.3 MeV and Linear Energy Transfer (LET) value of 86.8 MeV·cm2/mg in silicon. When the drain-source voltage was 350 V, we observed a significant surge in drain current, while the gate current did not show an uncontrollable increase. The simulation results indicate that the local electric field enhancement due to charge enhancement effect and charge collection phenomenon as well as the intensification of collisional ionization are the main causes of device damage and failure. In addition, we subjected one of the three groups of samples that had undergone TID experiments to Ta ion single-event effect (SEE) experiments once again. The synergistic experimental results show the superposition effect of the two experiments.