First high performance InAlAs/InGaAs HEMTs on GaAs exceeding that on InP

InAlAs/InGaAs HEMTs lattice-mismatched on GaAs substrates have been fabricated with a 0.6-/spl mu/m thick step-graded In/sub y/Al/sub 1-y/As buffer layer. Peak extrinsic transconductance of 1060 mS/mm is measured for the device, which has a gate-length of 0.16 /spl mu/m. This is comparable to if not higher than that of HEMTs lattice-matched on InP substrates. The maximum oscillation frequency of 147 GHz, the highest ever reported for InAlAs/InGaAs HEMTs lattice-mismatched on GaAs substrates, is recorded for a device with a 0.2-/spl mu/m-long, 100-/spl mu/m-wide gate, despite the fact that it is not a T-shape gate.<
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