Gate-Bias Induced R_ON Instability in p-GaN Power HEMTs

In this letter, we investigate the on-resistance (RON) instability in p-GaN power HEMTs induced by a positive or negative gate bias ( ${V}_{\text {GB}}$ ), following the application of a quasi-static initialization voltage ( ${V}_{\text {GP}}$ ) of opposite sign. The transient behavior of this instability was characterized at different temperatures in the 90–135 °C range. By monitoring the resulting drain current transients, the activation energy as well as time constants of the processes are characterized. Not trivially, both RON increase/decrease were found to be thermally activated and with same activation energy. We attribute the thermal activation of both (RON) increase/decrease to the charging/discharging of hole traps present in the AlGaN barrier in the region below the gate.