How perfect can graphene be?

TL;DR

This paper demonstrates that naturally occurring graphene flakes on bulk graphite exhibit exceptionally high electronic quality, surpassing current fabrication methods, which challenges existing technological limits in graphene production.

Contribution

It reveals that ultra-pure graphene can be found naturally on graphite surfaces, showing unprecedented electronic properties that set new benchmarks for graphene quality.

Findings

Graphene flakes on bulk graphite have carrier mobility over 10^7 cm^2/(V.s).

Natural graphene exhibits lower disorder than fabricated samples.

This discovery challenges the perceived limits of current graphene fabrication technologies.

Abstract

Fabrication of graphene structures has triggered vast research efforts focused on the properties of two-dimensional systems with massless Dirac fermions. Nevertheless, further progress in exploring this quantum electrodynamics system in solid-state laboratories seems to be limited by insufficient electronic quality of manmade structures and the crucial question arises whether existing technologies have reached their limits or major advances are in principle possible. Here we show that graphene in a significantly purer state can be found in nature on the surface of bulk graphite, in form of flakes decoupled from the substrate material. Probing such flakes with Landau level spectroscopy in the THz range at very low magnetic fields, we demonstrate a superior electronic quality of these ultra low density layers (n~3x10^9 cm^-2) expressed by the carrier mobility in excess of 10^7 cm^2/(V.s). This finding represents an important challenge for further improvements of current graphene technologies.