Dual-gate In0.5Ga0.5P/In0.2Ga0.8As pseudomorphic high electron mobility transistors with high linearity and variable gate-voltage swing

In0.5Ga0.5P/In0.2Ga0.8As pseudomorphic high electron mobility transistors ( PHEMTs) fabricated using single- and dual-gate methodologies have been char acterized with special emphasis on precisely controlling the device lineari ty and the gate-voltage swing. A composite channel employing a GaAs delta-d oped (delta (n(+))) sheet and an undoped In0.2Ga0.8As layer characterizes t he key features of the proposed PHEMT profile. Better carrier confinement f or both the electron and the hole due to the InGaP/InGaAs hetero-interface and superior carrier transport properties at the channel/buffer interface, together with the redistributed carrier profile, contribute to high-lineari ty performances. On the other hand, high etching selectivity between the Ga As cap and the InGaP Schottky layers makes it possible to precisely positio n both of the gates. The gate-voltage dependence of transconductance for th e first equivalent gate with several V-GS2 shows that the available gate-vo ltage swing is in the range 0-4.0 V.