HOT-ELECTRON DEGRADATION OF THE DC AND RF CHARACTERISTICS OF ALGAAS INGAAS/GAAS PHEMTS/

This paper reports on hot electron (HE) degradation of 0.25-mu m Ala(0 .25)Ga(0.75)As/In0.2Ga0.8As/GaAs PHEMT's by showing the effects of the hot electron stress on both the dc and rf characteristics. The change s of dc and rf behavior after stress turn out to be strongly correlate d. Both can be attributed to a decrease of the threshold voltage yield ing different effects on the device gain depending on the bias point c hosen for device operation and on the bias circuit adopted: a fixed cu rrent bias scheme will minimize the changes induced by the stress. The work also presents a study of the dependence of device degradation on the stress bias condition.