Reliability of InGaAs HEMTs on GaAs substrates

The authors report on the reliability results of an optimised doped channel heterojunction field effect transistor (DCHEMT) with an InGaAs channel delta-doped to 1.5*10/sup 12/ cm/sup -2/. They compare the reliability results with those obtained for a single channel HEMT (SHEMT). The transistors were fabricated with a T-gate process and with 0.5*150 mu m or 1.0*200 mu m, PdAu or TiPdAu gates. Pseudomorphic-based devices were found to have better turn-off characteristics, output conductance, and breakdown characteristics than InP-based devices or GaAlAs/GaAs HEMTs. The doped channel pseudomorphic HEMT median time before failure (MTBF) of 4*10/sup 4/ h at 110 degrees C is shown to be limited by dislocations at the InGaAs-GaAs interface and ohmic contact degradation.<<ETX>>