A simulation study on the DC characteristics of the Ga0.52In0.48P/In0.2Ga0.8As/Ca0.52In0.48P double heterojunction pseudomorphic high electron mobility transistor

The effect of device channel thickness on the transconductance performance of a Ga0.52In0.48P/In0.2Ga0.8As/ Ga0.52In0.48P double heterojunction pseudo morphic high electron mobility transistor (DH-pHEMT) grown on GaAs substrat e was investigated using a two-dimensional (2D) device simulator. The elect ron sheet concentration values for different channel thickness were calcula ted using an analytical model. Simulation results revealed that devices wit h narrower channels exhibited transconductances that were comparable to tho se of devices with wide channels, due to a trade-off between the electron s heet concentration and the gate-to-channel separation. Subsequently, the de vices were fabricated and their measured results agreed with the transcondu ctance trend predicted by simulation. A second transconductance peak of low er magnitude was observed for the Ga0.52In0.48P/In0.2Ga0.8As/Ga0.52In0.48P DH-pHEMT at more negative biases. This phenomenon was investigated and desc ribed qualitatively by a model, which involves the incorporation of interfa cial quaternary layers at the lower In0.2Ga0.8As channel-Ga0.52In0.48P inte rface. (C) 2000 Elsevier Science Ltd. All rights reserved.