All-carbon vertical van der Waals heterostructures: Non-destructive functionalization of graphene for electronic applications

TL;DR

This paper introduces a non-destructive method to functionalize graphene by assembling all-carbon van der Waals heterostructures, enabling electronic applications with preserved transport properties and responsive chemical functionalities.

Contribution

It presents a novel assembly technique for functionalizing graphene with amino-terminated carbon nanomembranes without impairing its electronic properties.

Findings

Functional amino groups are close to graphene sheets.

Transport characteristics remain unaffected by functionalization.

Device response to protonation demonstrates chemical sensitivity.

Abstract

We present a route to non-destructive functionalization of graphene via assembly of vertical all-carbon van der Waals heterostructures. To this end, we employ singlelayer graphene (SLG) sheets grown by low-pressure methane CVD on Cu foils and large-area dielectric ~1 nm thick amino-terminated carbon nanomembranes (NH2-CNMs) generated by electron-beam-induced crosslinking of aromatic self-assembled monolayers. We encapsulate SLG sheets on oxidized silicon wafers with NH2-CNMs via mechanical stacking and characterize structural, chemical and electronic properties of the formed heterostructures by Raman spectroscopy and X-ray photoelectron spectroscopy as well as by electric and electromagnetic transport measurements. We show that functional amino groups are brought in close vicinity of the SLG sheets and that their transport characteristics are not impaired by this functionalization; moreover, we demonstrate a functional response of the heterostructure devices to the protonation of the amino groups in water. Due to its relative simplicity, the suggested approach opens broad avenues for implementations in graphene-based electronic devices where non-destructive chemical functionalization of graphene is required (e.g., for engineering electrical transducers for chemical and bio-sensing) or as complementary dielectric to graphene in hieratical heterostructures.