Analysis of GaN HEMT Degradation under RF Overdrive Stress

This work concentrated at the degradation characteristics of GaN HEMT devices when exposed to RF overdrive stress. According to results of the experiment, the drain current of GaN HEMT decreases by 35.6% from 877 mA to 564mA after RF overstress. Moreover, after the experiment, the threshold voltage has a 0.26-V positive shift, and the maximum transconductance decreases. The gate leakage current increases by three times more than that of original ones. The gate-lag characteristics also deteriorates with the increase of experimental time. After measuring the high frequency performance, the return loss of the device degrades. Based on the measurement of leakage current, the height of Schottky barrier before and after the experiment was calculated and the captured charge density was extracted as ${1.11\,\times \,10^{14}\,cm^{2}}$ by combining with the threshold voltage drift.