Metamorphic In0.4Al0.6As/In0.4Ga0.6As HEMT's on GaAs substrate

New In0.4Al0.6As/In0.4Ga0.6As metamorphic (MM) high electron mobility trans istors (HEMT's) have been successfully fabricated on GaAs substrate with T- shaped gate lengths varying from 0.1 to 0.25 mu m. The Schottky characteris tics are a forward turn-on voltage of 0.7 V and a gate breakdown voltage of -10.5 V, These new MM-HEMT's exhibit typical drain currents of 600 mA/mm a nd extrinsic transconductance superior to 720 mS/mm, An extrinsic current c utoff frequency f(T) of 195 GHz is achieved with the 0.1-mu m gate length d evice. These results are the first reported for In0.4Al0.6As/In0.4Ga0.6As M M-HEMT's on GaAs substrate.