Electronic Conduction Through Monolayer Amorphous Carbon Nano-Junctions

TL;DR

This study investigates how disorder in monolayer amorphous carbon affects electronic conduction, revealing that near the Fermi level conduction involves surface-like states, while away from it, states become localized or insulating.

Contribution

It provides the first computational analysis of electronic transmission in MAC nano-fragments, highlighting the role of surface states, delocalized states, and quantum interference due to disorder.

Findings

States near Fermi energy exhibit surface state characteristics.

Current at band edges is carried by localized interior states.

Quantum interference among frontier orbitals is common in MAC fragments.

Abstract

In molecular electronic conduction, exotic lattice morphologies often give rise to exotic behaviors. Among 2D systems, graphene is a notable example. Recently, a stable amorphous version of graphene called Monolayer Amorphous Carbon (MAC) was synthesized. MAC poses a new set of questions regarding the effects of disorder on conduction. In this Letter, we perform ensemble-level computational analysis of the coherent electronic transmission through MAC nano-fragments in search of defining characteristics. Our analysis, relying on a semi-empirical Hamiltonian (Pariser-Parr-Pople) and Landauer theory, showed that states near the Fermi energy ($E_F$) in MAC inherit partial characteristics of analogous surface states in graphene nano-fragments. Away from $E_F$, current is carried by a set of delocalized states which transition into a subset of insulating interior states at the band edges. Finally, we also found that quantum interference between the frontier orbitals is a common feature among MAC nano-fragments.