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

In this work, the mechanisms of single-event burnout (SEB) failure and total ionizing dose effect (TID) in P-type gallium nitride gate high electron mobility transistors (P-GaN HEMTs) were investigated based on experiments and simulation. In the SEB experiments, we observed the occurrence of SEB when the drain-source voltage was 350 V with tantalum (Ta) ions irradiation. 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 the TID experiments, three groups of samples with different gate voltage bias were irradiated using Co⁶⁰-γ rays. Positive threshold voltage shifts and gate leakage current increasing are observed. 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. 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.