Very high frequency performance of nanometre scale GaAs MESFETs

GaAs MESFETs with gate lengths from 250 to 30 nm were fabricated and characterized at microwave frequencies. The MESFETs, fabricated on MBE (molecular beam epitaxy) grown layers, were optimized, as far as possible, to reduce short-channel effects. It was found that the inverse proportionality of the gate length with f/sub T/ does not hold for sub-100-nm gate-length GaAs MESFETs. In addition, deviation from the simple mod h/sub 21/ mod versus frequency relationship was observed as the gate length was reduced to less than 100 nm.