Effect of Hydrogen on Defects of AlGaN/GaN HEMTs Characterized by Low-Frequency Noise

The effect of hydrogen on defects in AlGaN/GaN high-electron-mobility transistors (HEMTs) was investigated by using low-frequency noise (LFN) method. The results show that drain-to-source current of AlGaN/GaN HEMTs after hydrogen treatment is significantly larger than that of the fresh AlGaN/GaN HEMTs. The maximum variation of drain-to-source current is up to 80 mA at the gate-to-source voltage of 0 V and drain-to-source voltage of 5 V. The suppression of current collapse was also observed, and the gate-lag characteristic becomes better for the AlGaN/GaN HEMTs after hydrogen treatment. Extracted by the LFN method, the trap density decreases by about one order of magnitude in the AlGaN/GaN HEMTs after hydrogen treatment, and this would lead to less depleted electrons in the channel 2-D electron gas. The mechanism for the reduction of trap density could be attributed to H-passivated defects at AlGaN surface, AlGaN barrier layer, and heterostructure interface. The results of this paper may be useful in the design and application of AlGaN/GaN HEMTs.