Off-state breakdown walkout in high-power PHEMT's

PECVD nitride passivated high-power AlGaAs/InGaAs PHEMTs processed with different surface conditions and on epitaxial wafers from different vendors were fabricated to study the off-state breakdown walkout. It has been shown that breakdown walkout of passivated high-power PHEMTs depends on the surface process conditions and to a less degree on the starting wafers. The breakdown walkout shows no noticeable recovery after annealing at 240/spl deg/C for 400 hours, indicating a permanent improvement. The results suggest an alternative to optimize the PHEMT's process for reliability and to improve the breakdown voltage.