Study of Low-Temperature Degradation of AlGaAs/InGaAs Pseudomorphic HEMT´s

AlGaAs/InGaAs PM-HEMT´s DC behaviour has been investigated at low temperature. Depending on the bias conditions a remarkable collapse of the drain current, ID, or a considerable shift in the threshold voltage VT have been observed. A complete recovery of the I-V curve has been observed at high values of the applied bias. Trapping and detrapping (by impact ionization) of electrons in deep levels present in the gate-to-drain region and under the gate are responsible for the observed behaviour.