A WNxgate self-aligned GaAs p-channel MESFET for complementary logic

The Schottky barrier of reactively sputtered WN x to p-type GaAs has been investigated. Postdeposition heat treatments above 500°C led to a reduction in the barrier height but for lamp annealing at 740°C the barrier heights are 0.68 eV. Self-aligned p-channel MESFET's were fabricated with WN x gates by a refractory metal process involving the above heat treatment. The Schottky-barrier heights were close to the expected values. K-values of FET's with 2 µm × 24 µm gates were 0.088 mA/V2, consistent with previously reported results. SPICE simulation studies carried out for a variety of complementary-type logic gates, indicate that power dissipation × delay time products of less than 10 fJ may be achievable over the power range 5-50 µW/gate. Thus complementary logic may be useful for applications where low power dissipation is at a premium.