Hot electron degradation effects in Al0.25Ga0.75 As/In0.2Ga0.8As/GaAs PHEMTs

This paper reports on hot electron stress experiments performed on 0.25 μm AlGaAs/InGaAs/GaAs pseudomorphic HEMTs. Devices have been subjected to high drain bias stress cycles with drain voltages ranging between 5 and 8 V up to a cumulative stress time of 18 hours. The effect of the stress on the device DC characteristics is studied. In particular, stressed devices show an increase of the gate-drain breakdown voltage (breakdown walkout) and changes of the drain current in the saturation region that depend, both in magnitude and polarity, on the stress conditions: moderate stress bias and time yield an increase of the drain current, whereas more severe conditions tend to lower it