Analysis of Hot Carrier Degradation in 0.25-mu m Schottky Gate AlGaN/GaN HEMTs

In this work, we report hot carrier-induced degradation in normally-on AlGaN/GaN high electron mobility transistors (HEMTs) with a 0.25-mu m gate. To analyze the hot carrier effect, the semi-on state stress test was carried out and the DC and pulsed I-V characteristics were analyzed. The stress condition was set at the gate voltage of -3.8 V and the drain voltage of 40 V, where the drain current was at 10% of the maximum. After a stress test, the positive shift of the threshold voltage was observed and the drain current was decreased by 19%. In addition, the gate and drain lag phenomena were pronounced when measured by the pulse with a 1.23% duty cycle. The device degradation can be attributed to the hot electron-induced trapping during the semi-on stress test, which imposed the high electric field and the low channel temperature in the device.