Metamorphic InAlAs/InGaAs HEMT's on GaAs substrates with a novel composite channels design

We report on fabrication and performance of novel 0.13 mu m T-gate metamorphic InAlAs/InGaAs HEMT's on GaAs substrates with composite InGaAs channels, combining the superior transport properties of In(0.52)Ga(0.48)AS With low-impact ionization in the In0.32Ga0.68As subchannel, These devices exhibit excellent de characteristics, high drain currents of 750 mA/mm, extrinsic transconductances of 600 mS/mm, combined with still very low output conductance values of 20 mS/mm, and high channel and gate breakdown voltages, The use of a composite InGaAs channels leads to excellent cut-off frequencies: f(max) of 350 GHz and an f(T) 160 GHz at V-DS = 1.5 V, These are the best microwave frequency results ever reported for any FET on GaAs substrate.