Single and dual p-doped channel In/sub 0.52/Al/sub 0.48/ As/In/sub x/Ga/sub 1-x/As (x=0.53, 0.65) FET's and the role of doping

The properties of lattice-matched (x=0.53) and strained (x=0.65) In/sub 0.52/Al/sub 0.48/As/In/sub x/Ga/sub 1-x/As p-doped channel FETs are reported. The role of doping density is studied with the help of two designs (dual-channel with low doping and single-channel with high doping). The strained dual-channel devices demonstrated an improvement of mobility from 108 cm/sup 2//V-s (53% In) to 265 cm/sup 2//V-s (65% In) at 300 K. The corresponding intrinsic transconductance enhancement is from 23 Ms/mm (53% In) to 46.5 mS/mm (65% In) using 1.0 mu m-long gates. The cutoff frequency (f/sub t/) also improves from 1.0 to 1.4 GHz. The impact of strain in the highly-doped single-channel device is small. The band structure under lattice-matched and strained conditions and the position of the Fermi level according to doping seem to be the main factors determining the reported features.>