Signature of Dirac Fermion Injection From Hole-Doped Graphene Into Two-Dimensional Semiconductors

We fabricated field-effect transistors (FETs) based on two-dimensional (2D) semiconductors with hole-doped graphene as source contacts. The graphene-contacted MoS₂ FET exhibited n-type transport with the subthreshold swing (SS) below the Boltzmann limit of 60 mV/decade at room temperature. In contrast, the graphene-contacted WSe₂ FET displayed ambipolar transport, where the sub-60 mV/decade switching was observed only in the electron branch. These observations imply the injection of Dirac fermions from hole-doped graphene into the 2D semiconductors.