An all-implanted, self-aligned, GaAs JFET with a nonalloyed W/p/sup +/-GaAs ohmic gate contact

We describe a self-aligned, refractory metal gate contact, enhancement mode, GaAs junction field effect transistor (JFET) where all impurity doping was done by ion implantation. Processing conditions are presented for realizing a high gate turn-on voltage (/spl sim/1.0 V at 1 mA/mm of gate current) relative to GaAs MESFET's. The high gate turn-on voltage is the result of optimizing the p/sup +/-gate implant and anneal to achieve a nonalloyed ohmic contact between the implanted p/sup +/-GaAs and the sputter deposited tungsten gate contact. Initial nominally 1.0 /spl mu/m/spl times/50 /spl mu/m n-JFET's have a transconductance of 85 mS/mm and f/sub t/ of 11.4 GHz.<
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