High breakdown voltage and high f/sub max/ InAlAs/InGaAs HEMTs on GaAs

A simple model to describe the dependence of both the breakdown voltage between a gate and a drain (BV/sub gd/) and maximum frequency of oscillation (f/sub max/) on a width of the gate recess in an InAlAs/InGaAs high electron mobility transistor (HEMT) is presented. The model suggests that the wide recess structure can improve both BV/sub gd/ and f/sub max/, which is experimentally confirmed. We fabricated InAlAs/InGaAs HEMTs lattice-mismatched on GaAs substrates with optimum recess-width, and these exhibited both a high BV/sub gd/ of 14 V and a high f/sub max/ of 127 GHz at a gate length of 0.66 /spl mu/m.