How close can one approach the Dirac point in graphene experimentally?

Nano Lett. 2012 Sep 12;12(9):4629-34. doi: 10.1021/nl301922d. Epub 2012 Sep 4.

Abstract

The above question is frequently asked by theorists who are interested in graphene as a model system, especially in context of relativistic quantum physics. We offer an experimental answer by describing electron transport in suspended devices with carrier mobilities of several 10(6) cm(2) V(-1) s(-1) and with the onset of Landau quantization occurring in fields below 5 mT. The observed charge inhomogeneity is as low as ≈10(8) cm(-2), allowing a neutral state with a few charge carriers per entire micrometer-scale device. Above liquid helium temperatures, the electronic properties of such devices are intrinsic, being governed by thermal excitations only. This yields that the Dirac point can be approached within 1 meV, a limit currently set by the remaining charge inhomogeneity. No sign of an insulating state is observed down to 1 K, which establishes the upper limit on a possible bandgap.

MeSH terms

  • Computer Simulation
  • Electron Transport
  • Graphite / chemistry*
  • Models, Chemical*
  • Static Electricity

Substances

  • Graphite