  Single-molecule biosensing, with a promise of being applied in protein and
DNA sequencing, could be achieved using tunneling current approach.
Electrode-molecule-electrode tunneling current critically depends on whether
molecular levels contribute to electronic transport or not. Here we found
employing DFT and Non-Equilibrium Green's Function formalism that energies of
benzene molecular levels placed between graphene electrodes are strongly
influenced by electrode termination. Termination-dependent dipoles formed at
the electrode ends induce in-gap field effect that is responsible for shifting
of molecular levels. We show that the HOMO is closest to Fermi energy for
nitrogen-terminated nanogaps (NtNGs) and nanopores (NtNPs), promoting them as
strong candidates for single-molecule sensing applications.
