Investigating the effect of thermal annealing on dc performance of off-state drain-voltage step-stressed AlGaN/GaN high electron mobility transistors

The effects of a thermal annealing process on the dc performance of off-state, drain-voltage step-stressed AlGaN/GaN high electron mobility transistors (HEMTs) were investigated. After stress, the reverse bias gate leakage current increased from 7 × 10−3 to 1.96 × 10−1 mA/mm and drain current on–off ratio decreased from 1.9 × 105 to 4.52 × 103. These degradations were completely recovered after a thermal annealing at 450 °C for 10 min. Temperature-dependent drain-current subthreshold swing measurements were employed to estimate the trap densities located in the AlGaN barrier layer near-surface region of the HEMTs before and after off-state drain-voltage step-stressing and also following subsequent thermal annealing. Off-state step-stressing produced a significant increase of trap density from 2.15 × 1012 to 1.63 × 1013/cm2 V. This was reduced to 5.21 × 1012/cm2 V after thermal annealing.…