High-performance, 0.1 μm InAlAs/InGaAs high electron mobility transistors on GaAs

This letter describes the material characterization and device test of InAlAs/InGaAs high electron mobility transistors (HEMTs) grown on GaAs substrates with indium compositions and performance comparable to InP-based devices. This technology demonstrates the potential for lowered production cost of very high performance devices. The transistors were fabricated from material with room temperature channel electron mobilities and carrier concentrations of μ=10000 cm
²
/Vs, n=3.2×10/sup 12/ cm/sup -2/ (In=53%) and μ=11800 cm
²
/Vs, n=2.8×10/sup 12/ cm/sup -2/ (In=60%). A series of In=53%, 0.1×100 μm
²
and 0.1×50 μm
²
devices demonstrated extrinsic transconductance values greater than 1 S/mm with the best device reaching 1.074 S/mm. High-frequency testing of 0.1×50 μm
²
discrete HEMT's up to 40 GHz and fitting of a small signal equivalent circuit yielded an intrinsic transconductance (g/sub m,i/) of 1.67 S/mm, with unity current gain frequency (f
_T
) of 150 GHz and a maximum frequency of oscillation (f
_max
) of 330 GHz. Transistors with In=60% exhibited an extrinsic g/sub m/ of 1.7 S/mm, which is the highest reported value for a GaAs based device.