Effect of Hydrogen on Electrical Characteristics of AlGaN/GaN HEMTs After HTO Stress

In this article, we investigate the effect of hydrogen on the electrical characteristics of AlGaN/GaN HEMTs subjected to high-temperature operation (HTO) stress and the related failure mechanism. The measurement results of dc electrical characteristics show that the device undergoes significant degradation after HTO stress, which is manifested as decreased drain-source current, positive drift of threshold voltage, decreased maximum transconductance, increased subthreshold slope (SS), increased gate leakage current, and deteriorated gate-lag characteristics. The effect of hydrogen on the device is not uniform. In the output and transfer characteristics, the recovery occurs after hydrogen treatment, but the gate leakage current continues to increase and the gate-lag characteristics do not change significantly after hydrogen treatment. Based on the electroluminescence (EL) measurement, it is found that the hot electron effect in HTO stress was not significant, and the low-frequency noise (LFN) measurement results show little change. Based on the above measurements, we believe that the degradation of the device after HTO stress mainly stems from the generation of deep-level defects and trap-related behavior, while hydrogen treatment forms a layer of dipolar at the metal-semiconductor interface, pulling down the Schottky barrier height and increasing the 2DEG concentration.