Effect of hydrogen on electrical properties and defects of AlGaN/GaN HEMTs

In this paper, the electrical characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) were investigated after hydrogen treatment at room temperature, and the physical mechanism of hydrogen action on AlGaN/GaN HEMTs was analyzed. The ON–OFF ratio of the devices increases from 2.2 × 103 to 3.2 × 103 and the maximum transconductance also increases after hydrogen treatment, while the threshold voltage remains almost unchanged. The gate-lag characteristics of the devices after hydrogen treatment have been improved by comparing with the fresh ones. The internal defects density for the AlGaN/GaN HEMTs after hydrogen treatment is found to show more obvious decrease compared to that of the fresh ones through the characterization method of low-frequency noise. This mechanism could be attributed to the passivation of defects in the SiNx layer and at the SiNx/AlGaN interface between drain and gate electrodes by H atoms due to the forming bonds, such as N–H and Si–H. The results may be serve as useful guidelines for realizing improved design in practical applications of AlGaN/GaN HEMTs.