Metamorphic InAlAs/InGaAs HEMTs on GaAs substrates with composite channels and f/sub max/ of 350 GHz

We have designed, fabricated, and demonstrated a novel 0.13 /spl mu/m metamorphic InAlAs/InGaAs HEMT with a composite channel on GaAs substrates, which displays high cut-off frequencies and current drive capability. Such devices exhibit very low g/sub 0/ of 20 mS/mm and state of the art f/sub max/ values of 350 GHz with an f/sub T/ of 150 GHz. The power gain enhancement is mainly due to the channel design, as confirmed by our theoretical model. Metamorphic growth technology of InAlAs/InGaAs HEMTs with a composite channel will become useful if the reliability of the device can be assured.