ELECTRON-IRRADIATION DURING SCHOTTKY GATE METAL EVAPORATION AND ITS EFFECT ON THE STABILITY OF INGAAS ALGAAS HEMTS/

The threshold voltage of InGaAs/AlGaAs HEMTs with molybdenum Schottky gate were observed to shift after a high forward gate current test. Ex perimental results show that this phenomenon is characteristic of moly bdenum Schottky gates on GaAs, and it is related to the deep traps nea r the interface between molybdenum (Mo) and GaAs or within the semicon ductor to the depth of 1000 Angstrom. Such deep traps were introduced because of the electron irradiation effect during the electron beam de position of Mo on GaAs. Insertion of a Ti layer thicker than 100 Angst rom between Mo and GaAs was found to be effective for suppressing the shift by the blocking effect for the electron irradiation. (C) 1997 El sevier Science Ltd.