Threshold Voltage Hysteresis and Gate Leakage in AlGaN/GaN HEMTs

Abstract

Temperature-dependent threshold voltage (V TH ) hysteresis and gate leakage current are characterized in commercial AlGaN/GaN high electron mobility transistors (HEMTs). Significant peaks in V TH hysteresis are observed at 220 ; pm ; 10 K. Gate leakage current increases with increasing temperature for as-processed devices and devices irradiated with 1.8-MeV protons at off-state bias, due to Mott hopping. In contrast, gate leakage current for devices irradiated or stressed at on-bias increases strongly with decreasing temperature below 200 K. The increased gate leakage at low temperatures and large negative bias in on-bias stressed and/or irradiated devices is attributed primarily to trap-assisted tunneling through oxygen impurities (ON) in AlGaN. Dehydrogenation of ON-H impurity centers during stress and/or on-bias irradiation evidently plays a key role in enhanced cryogenic gate leakage at large negative bias in these devices.