Field effect and local gating in nitrogen-terminated nanopores (NtNP) and nanogaps (NtNG) in graphene

TL;DR

This study uses DFT and NEGF calculations to show that nitrogen termination in graphene nanopores and nanogaps significantly influences molecular energy levels, enhancing their potential for single-molecule biosensing.

Contribution

It reveals how electrode termination affects molecular energy levels and demonstrates nitrogen-terminated graphene structures as promising for biosensing applications.

Findings

Nitrogen termination shifts molecular energy levels closer to Fermi energy.

Electrode termination induces in-gap field effects impacting transport.

Nitrogen-terminated structures are promising for single-molecule sensing.

Abstract

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.