Quantum Transport in Graphene Nanoribbons with Realistic Edges

TL;DR

This paper models quantum transport in graphene nanoribbons with realistic, reconstructed edges using NEGF and tight binding methods, revealing how edge structure influences electronic properties and device robustness.

Contribution

It introduces a comprehensive modeling approach for various realistic edge reconstructions, including mixed edges, advancing understanding of their impact on GNR transport properties.

Findings

Reconstructed edges affect sublattice-dependent transport.

Reconstructed armchair GNRs have larger band gaps.

Reconstructed edges are more robust against disorder.

Abstract

Due to their unique electrical properties, graphene nanoribbons (GNRs) show great promise as the building blocks of novel electronic devices. However, these properties are strongly dependent on the geometry of the edges of the graphene devices. Thus far only zigzag and armchair edges have been extensively studied. However, several other self passivating edge reconstructions are possible, and were experimentally observed. Here we utilize the Nonequilibrium Green's Function (NEGF) technique in conjunction with tight binding methods to model quantum transport through armchair, zigzag, and several other self-passivated edge reconstructions. In addition we consider the experimentally relevant cases of mixed edges, where random combinations of possible terminations exist on a given GNR boundary. We find that transport through GNR's with self-passivating edge reconstructions is governed by the sublattice structure of the edges, in a manner similar to their parent zigzag or armchair configurations. Furthermore, we find that the reconstructed armchair GNR's have a larger band gap energy than pristine armchair edges and are more robust against edge disorder. These results offer novel insights into the transport in GNRs with realistic edges and are thus of paramount importance in the development of GNR based devices.