Hot electron degradation effects in 0.14 mu m A1InAs/GaInAs/InP HEMTs

We report on hot electron stress measurements on 0.14 mu m MOCVD grown A1InAs/GaInAs/InP HEMTs. The stress measurements increase the drain-source current and hence induce a temporary negative shift in the threshold voltage in unpassivated HEMTs. A permanent negative shift in the threshold voltage has been obtained in passivated HEMTs. The observed degradation (temporary/permanent) is due to the storage of positive charges (created by the impact ionization in the channel) in the Schottky A1InAs layer (temporary) or at the interface of semiconductor-passivation layer (permanent). For a given drain-source bias. a shift in the threshold voltage is larger in the gate-source bias region where the device has a maximum transconductance value, c. 1999 Elsevier Science Ltd. All rights reserved.