Study on the degradation mechanism of GaN MMIC PAs under on-state stress with different drain bias

In this work, the degradation mechanisms of Gallium Nitride (GaN) Monolithic Microwave Integrated Circuit (MMIC) Power Amplifiers (PAs) under on-state stress with different drain bias have been studied. It is found that the direct current (DC) and Radio Frequency (RF) characteristics degrade significantly at high drain bias, which is mainly attributed to hot-electron effect. Using emission microscopy (EMMI) techniques, it can be concluded that the main degradation in GaN MMIC power amplifiers occurs in active components instead of passive components. The channel hot electron effect shows two impacts. The first one is the leakage current path near the drain edge, which is caused by the high-energy hot electrons that surmount AlGaN/GaN barrier. The second one is electron trapping within the active region between gate and drain, which can reduce the DC and RF performance. Finally, it is also found that the generated traps during the stress cannot recover easily even at high temperature of 250 °C, which indicates these traps are probably located at deep energy levels.