A pseudomorphic AlGaAs/n/sup +/-InGaAs metal-insulator-doped channel FET for broad-band, large-signal applications

Molecular beam epitaxy (MBE)-grown L/sub g/=1.7- mu m pseudomorphic Al/sub 0.38/Ga/sub 0.62/As/n/sup +/-In/sub 0.15/Ga/sub 0.85/As metal-insulator-doped channel FETs (MIDFETs) are presented that display extremely broad plateaus in both f/sub T/ and f/sub max/ versus V/sub GS/, with f/sub T/ sustaining 90% of its peak over a gate swing of 2.6 V. Drain current is highly linear with V/sub GS/ over this swing, reaching 514 mA/mm. No frequency dispersion in g/sub m/ up to 3 GHz was found, indicating the absence of electrically active traps in the undoped AlGaAs pseudoinsulator layer. These properties combine to make the pseudomorphic MIDFET highly suited to linear, large-signal, broadband applications.<
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