Gate modulation of graphene contacts - on the scaling of graphene FETs

The nature of source/drain contacts in graphene field-effect transistors (GFETs) is investigated. We argue that the energy dispersion of the graphene portion underneath of the metal electrodes is substantially altered compared to its original. Moreover, different from other materials, the Fermi levels of these graphene segments are not pinned by the metal contacts, but instead can be modulated by the gate. Our experimental findings give important insights into the critical relevance of contacts for the scaling of graphene devices.