Comparison of Drain Current Transient Characteristics of AlGaN/GaN HEMTs in the Linear and Saturation Regions after OFF-state Stress

This work presents drain current transient characteristics of AlGaN/GaN HEMTs in the linear and saturation regions after OFF-state stress. Due to the various RF input power and DC quiescent point, a broad range sweep happens for switching-mode RF power amplifier application. As the device switches from OFF-state stress into an ON-state linear region, the temperature dependence of the de-trapping is observed in this work. A single trap with an activation energy (EA) of around 0.52 eV is extracted for the device. On the contrary, the device switches from OFF-state stress into an ON-state in the saturation region, and the de-trapping mechanism is dominated by electric field-assisted tunneling. In addition, the trap ($\sim$0.52eV) is added to the buffer layer in Silvaco TCAD simulation to verify the observation. By this method, it is possible to estimate the trap density to correlate with the experiment.