A SUPERLOW-NOISE ALGAAS/INGAAS/GAAS DOPED CHANNEL HETEROJUNCTION FIELD-EFFECT TRANSISTOR (DC-HFET) WITH 0.15-MU-M GATE LENGTH

A doped channel heterojunction field-effect transistor (DC-HFET) has been developed using an AlGaAs/InGaAs/GaAs pseudomorphic system which has an electron confinement effect superior to that of an AlGaAs/GaAs system. An excellent minimum noise figure (NF(min)) of 0.65 dB and associated gain (Ga) of 11.3 dB were realized at 12 GHz (drain current (I(ds)) = 18 mA, drain voltage (V(ds)) = 2 V). The NF had weak dependences on the I(ds) and frequency, as in the case of high electron mobility transistors (HEMTs). The transconductance (g(m)) at I(ds) = 10 mA was 385 mS/mm and maximum g(m) reached 570 mS/mm (I(ds) = 50 mA).