Degradation Behavior and Mechanism of GaN HEMTs With P-Type Gate in the Third Quadrant Under Repetitive Surge Current Stress

In this article, the degradation behavior and mechanism of GaN high-electron-mobility transistors (HEMTs) with p-type gate in the third quadrant under repetitive surge current stress are studied. The electrical properties of devices under various surge current conditions are investigated. It can be found that the turning point exists in the degradation trend of threshold voltage (V-TH), gate leakage current (I-gss), and OFF-state drain leakage current (I-dss). The turning phenomenon is related to the peak value of the surge current (I-peak) and the stress cycle. We propose that two competing mechanisms that take place on carrier transport paths cause the degradation behavior. When I(peak )is low, the electron trapping effect is the main degradation mechanism. As I-peak exceeds a certain value, as the stress cycle increases, the hole trapping effect will be greatly enhanced and even cause the reversal of the degradation rate of V-TH , I-gss , and I-dss . Furthermore, at higher I-peak , new donor traps can be generated in the gate, causing the permanent and negative shift of V-TH . Based on the simulation, further experiments, and V-TH recovery characteristics, the competing mechanism is confirmed. These results provide deep insights and references for the reliable applications of GaN HEMTs.