High-field step-stress and long term stability of PHEMTs with different gate and recess lengths

The reliability of high power AlGaAs/InGaAs/GaAs PHEMTs has been investigated. The influences of high temperature and of elevated drain voltage have been studied separately, using long term operation at elevated temperature and a 23-hour drain-voltage step-stress at room temperature. Results pertaining to different combinations of gate length and gate-drain ledge are reported and discussed, indicating safe operation values and showing that a wider gate-drain recess increases the device reliability.