Degradation mechanisms of p-GaN gate AlGaN/GaN high electron mobility transistors under power cycling tests

Abstract

In this study, the degradation mechanisms of p-GaN gate AlGaN/GaN high electron mobility transistors (HEMTs) were investigated under power cycling tests (PCTs). The saturation drain current of the p-GaN gate AlGaN/GaN HEMTs decreased and the threshold voltage shifted positively after the PCTs. In addition, we find that not only the thermal resistance of the packaging layers, but also the thermal resistance of the chip in all the p-GaN gate AlGaN/GaN HEMTs increased after the PCTs. By using deep-level transient spectroscopy (DLTS), we find that the concentration of electron traps increased after the PCTs, which may increase the phonon scattering, and the thermal resistance of the chip accordingly. In addition, the electron trapping will deplete the electrons in the two-dimensional electron gas, resulting in the decrease of the saturation drain current and the positive shift of the threshold voltage. These results provide new insights to further improve the long-term reliability of p-GaN gate AlGaN/GaN HEMTs.