Integrated complementary graphene inverter

The operation of a digital logic inverter consisting of one pp- and one nn-type graphene transistor integrated on the same sheet of monolayer graphene is demonstrated. Both transistors initially exhibited pp-type behavior at low gate voltages, since air contamination shifted their Dirac points from zero to a positive gate voltage. Contaminants in one transistor were removed by electrical annealing, which shifted its Dirac point back and therefore restored nn-type behavior. Boolean inversion is obtained by operating the transistors between their Dirac points. The fabricated inverter represents an important step toward the development of digital integrated circuits on graphene.