Study on the Degradation Mechanism of GaN MMIC Power Amplifiers Under On-State With High Drain Bias

In this work, the electrical performance degradation and circuit burnout in gallium nitride (GaN)-based microwave monolithic integrated circuit (MMIC) power amplifiers (PAs) under on-state with high drain bias have been studied in-depth. It is found that when the drain bias increases from 30 to 90 V, the saturation drain current decreases by 16%, and the output power drops significantly by 4.5 dB. With the aid of photon emission measurements (PEMs) and scanning electron microscopy (SEM), it is found that catastrophic burnout occurs in the power-stage GaN HEMTs and the MIM capacitors, respectively. For the GaN HEMT, electrons in the channel can gain enough energy with the transverse high electric field to become hot electrons. One part of hot electrons can surmount the AlGaN/GaN interface barrier and then induce leakage paths in the AlGaN layer, resulting in a significant leakage current. The other part of hot electrons will collide with the lattice near the drain edge (DE) and induce significant electron trapping, which will result in a significant longitudinal local electric field. When a critical electric field is achieved, catastrophic burnout occurs. The results obtained from the TCAD simulation verified it. For the MIM capacitor, the failure is attributed to the dielectric breakdown at the edge of the capacitor, which also plays an important role in the circuit deterioration.