Integration of InAlAs/InGaAs/InP enhancement- and depletion-mode high electron mobility transistors for high-speed circuit applications

A process for the monolithic integration of enhancement- and depletion-mode high electron mobility transistors (E/D-HEMTs) on InAlAs/InGaAs/InP is reported. The E-HEMTs with a 1.0-/spl mu/m gate length exhibit a threshold voltage of +255 mV and a maximum dc extrinsic transconductance of 503 mS/mm at room temperature, while a threshold voltage of -317 mV and a transconductance of 390 mS/mm are measured for the D-HEMTs of the same gate length. The devices show excellent RF performance, with a unity current-gain cutoff frequency (f/sub t/) of 35 GHz and a maximum frequency of oscillation (f/sub max/) of 95 GHz for both the E- and D-HEMT's. To the best of the authors' knowledge, this is the first demonstration of an E/D-HEMT technology on lattice-matched InP that is suitable for circuit integration.