Comparing the weak and strong gate-coupling regimes for nanotube and graphene transistors

We present an experimental and theoretical comparison of the weak and strong gate-coupling regimes that arise for carbon nanotube (CNT) and graphene field-effect transistors (FETs) in back-gated and liquid-gated configuration, respectively. We find that whereas the back-gate efficiency is suppressed for a liquid-gated CNT FET, the back gate is still effective in case of a liquid-gated graphene FET. We calculate the gateinduced Fermi-level shifts and induced charge densities. In both strong and weak coupling regimes, nonlinearities occur in the gate dependence of these parameters, which can significantly influence the electronic transport.