Failure Behavior and Mechanism of p-GaN Gate AlGaN/GaN HEMTs in the Third Quadrant under Repetitive Surge Current Stress

Abstract

In this article, the failure behavior and mechanism of p-GaN gate AlGaN/GaN high-electron-mobility transistors (HEMTs) in the third quadrant under repetitive surge current stress are investigated. Repetitive stress tests with different surge current peak values (Ipeak) are carried out. At high Ipeak , as the stress cycle increases, the evolution of the peak value of surge voltage induced by surge current shows an obvious turning phenomenon and a significant increasing trend. When the surge voltage reaches a certain value, the gate-to-source breakdown occurs, and then, the device is burned out. We propose that the degradation of the third-quadrant conduction characteristics results in the change of surge voltage, and excessive electric field intensity induced by high gate-to-drain voltage (VGD ) causes the gate Schottky junction breakdown. It is confirmed by further experiments, electrical performance characterization, and simulation. Inconsistent degradation of the two-dimensional electron gas (2DEG) channel in various regions causes the aforementioned turning phenomenon. As the stress cycle increases, the channel degradation in the gate-to-source/drain access region occupies a dominant position. In this situation, the VGD increases continuously, which will enhance the tunneling effect at the Schottky junction, until breakdown occurs. Besides, the device shows better surge current reliability at higher gate-to-source voltage. These results provide important insights into the improvement of GaN HEMTs reliability.