0.2 /spl mu/m AlGaAs/InGaAs pseudomorphic HEMT fabricated by optical lithography

Al/sub 0.2/Ga/sub 0.8/As/ln/sub 0.25/Ga/sub 0.75/As pseudomorphic high electron mobility transistors (PHEMTs) with a 0.2-/spl mu/m gate length have been fabricated. Based on a shadow deposition technique, the sub-half-micron gate length technology using optical lithography has been developed. This process exhibits large cross-sectional area of the gate to reduce the gate resistance of devices. The gate resistance of 46 /spl omega//mm of gate width was obtained for a 5000 A thick Ti/Au gate. In addition, a PHEMT fabricated with this technique yielded cut-off frequency of f/sub T/ = 36 GHz and maximum oscillation frequency of f/sub max/ = 93 GHz.