BREAKDOWN WALKOUT IN PSEUDOMORPHIC HEMTS

In this work we show for the first time evidence of gate-drain breakdo wn walkout due to hot electrons in pseudomorphic AlGaAs/InGaAs/GaAs HE MT's (PHEMT's). Experiments performed on passivated commercial PHEMT's show that hot electron stress cycles induce a large and permanent inc rease of the gate-drain breakdown voltage. Three-terminal and two-term inal stress conditions are compared, the former producing a much large r walkout due to hot electrons flowing in the channel, Experimental re sults indicate that a build-up of negative charge in the region betwee n gate and drain is responsible for the breakdown walkout, due to a lo cal widening of the depletion region and a reduction of the peak elect ric field.