Quarter-micrometer gate ion-implanted GaAs MESFET's with an f/sub 1/ of 126 GHz

The fabrication and characterization of a 0.25- mu m-gate, ion-implanted GaAs MESFET with a maximum current-gain cutoff frequency f/sub t/ of 126 GHz is reported. Extrapolation of current gains from bias-dependent S-parameters at 70-100% of I/sub dss/ yields f/sub 1/'s of 108-126 GHz. It is projected that an f/sub 1/ of 320 GHz is achievable with 0.1- mu m-gate GaAs MESFETs. This demonstration of f/sub 1/'s over 100 GHz with practical 0.25- mu m gate length substantially advances the high-frequency operation limits of short-gate GaAs MESFETs. >