Rapid degradation induced by hot electrons in AlGaAs/GaAs HEMTs

We report on the degradation induced by hot electrons when AlGaAs/GaAs HEMTS are biased at high drain-to-source voltages in impact ionization regime. Degradation consists in a rapid and permanent decrease of drain current, in an increase of drain parasitic resistance and in an increase of transconductance frequency dispersion. Degradation mechanism is most likely associated with the development of deep levels in the access region between gate and drain where electric field is maximum. Our results show that this degradation can be a real concern expecially for high power devices.