0.25/spl mu/m In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As/InAs/sub 0.3/P/sub 0.7/ composite channel HEMTs with an f/sub T/ of 115GHz

In this paper we report growth, fabrication and characterization of In/sub 0.52/Al/sub 0.4/sAs/In/sub 0.53/Ga/sub 0.47/As/InAs/sub 0.3/P/sub 0.7/ composite channel HEMTs with a gate length of 0.25 /spl mu/m. In comparison with InAlAs/InGaAs/InP composite channel HEMTs, these devices have better band structure for transferring electrons to the composite channel under high electric field, thus exhibit excellent DC and microwave performance with a peak extrinsic transconductance of 888.3 mS/mm, an f/sub T/ of 115 GHz, and an f/sub max/ of 137 GHz. To our knowledge, this is the first report of InAlAs/InGaAs/InAsP composite channel HEMTs. The f/sub T/ is the highest ever reported for any composite channel HEMTs with the same gate length.