Planar GaAs normally-off j.f.e.t. for high speed logic circuits

Planar GaAs j.f.e.t.s in the normally-off mode were fabricated by direct selective ion implantation into a semi-insulating Cr-doped substrate for n-type active regions and selective Zn diffusion for p-type gate areas. The p-n junction gate, typically 2 ?m in length and 20 ?m in width, was formed without appreciable anomalous lateral diffusion. A 15-stage ring oscillator formed with resistor-f.e.t. logic gates exhibited a propagation delay time of 73 ps per stage with a power-delay product of 320 fJ. The minimum power-delay product was 5.6 fJ with delay time of 163 ps.