Large-Scale electronic transport calculations of finite-length carbon nanotubes bridged between graphene electrodes with lithium-intercalated contact

We perform density-functional-theory-based large-scale calculations of finite-length carbon nanotubes with caps bridged between grapheme electrodes. The electronic transport properties vary with the length of the nanotubes and the contact structure. Despite the use of thin nanotubes expected to show n-type behavior, the Fermi level of the shorter nanotubes is uniformly pinned to the cap state, forming a large conduction gap. Although the longer nanotubes still have a medium conduction gap after forming a Schottky-like contact, the lithium intercalation in the contact area brings about a good ohmic property due to not only doping but also the orbital hybridization.