Electronic decoupling and hole-doping of graphene nanoribbons on metal substrates by chloride intercalation

TL;DR

This study demonstrates that chloride intercalation beneath graphene nanoribbons on gold surfaces can electronically decouple and heavily dope the ribbons, enabling better investigation of their intrinsic properties.

Contribution

The paper introduces a novel chloride intercalation method to decouple GNRs from metal substrates and induce hole doping, facilitating in situ electronic characterization.

Findings

Chloride intercalation forms a dielectric gold chloride adlayer.

Intercalation decouples GNRs from the metal substrate.

GNRs experience substantial hole doping after intercalation.

Abstract

Atomically precise graphene nanoribbons (GNRs) have a wide range of electronic properties that depend sensitively on their chemical structure. Several types of GNRs have been synthesized on metal surfaces through selective surface-catalyzed reactions. The resulting GNRs are adsorbed on the metal surface, which may lead to hybridization between the GNR orbitals and those of the substrate. This makes investigation of the intrinsic electronic properties of GNRs more difficult, and also rules out capacitive gating. Here we demonstrate the formation of a dielectric gold chloride adlayer that can intercalate underneath GNRs on the Au(111) surface. The intercalated gold chloride adlayer electronically decouples the GNRs from the metal and leads to a substantial hole doping of the GNRs. Our results introduce an easily accessible tool in the in situ characterization of GNRs grown on Au(111) that allows for exploration of their electronic properties in a heavily hole-doped regime.