An Advanced Ageing Methodology for Robustness Assessment of Normally-off AlGaN/GaN HEMT

The semi-on-state reliability of normally-off AlGaN/GaN high electron mobility transistor fabricated by fluorine ion plasma implantation technology is reported, focusing on an advanced dc step-stress methodology. By inserting a non-stressful fixed-bias step between each stress step, a reliable in-situ monitoring of gate and drain current degradations can be achieved without the use of conventional I-V interim measurements. A negative shift of the threshold voltage leading to an increase of the drain current is observed after the stress sequence carried out in semi-on-state regime. Currents monitoring during non-stressful steps reveal no permanent degradation up to stress step at V DS ≈ 19.5V and a self-healing mechanism occurring during non-stressful steps. By avoiding intermediate I-V control measurements after each stress step, this methodology provides a safe in-situ monitoring of degradations.