Charge control, DC, and RF performance of a 0.35- mu m pseudomorphic AlGaAs/InGaAs modulation-doped field-effect transistor

The authors describe a study of charge control in conjunction with DC and RF performance of 0.35- mu m-gate-length pseudomorphic AlGaAs/InGaAs MODFETs. Using C-V measurements, they estimate that a two-dimensional electron gas (2DEG) with density as high as 1.0*10/sup 12/ cm/sup -2/ can be accumulated in the InGaAs channel at 77 K before the gate begins to modulate parasitic charges in the AlGaAs. This improvement in charge control of about 10-30% over a typical AlGaAs/GaAs MODFET may partially be responsible for the superior DC and RF performance of the AlGaAs/InGaAs MODFET. At room temperature, the devices give a maximum DC voltage gain g/sub m//g/sub d/ of 32 and a current gain cutoff frequency f/sub T/ of 46 GHz. These results are state of the art for MODFETs of similar gate length. >