Direct graphene growth on Co3O4(111) by molecular beam epitaxy

J Phys Condens Matter. 2012 Feb 22;24(7):072201. doi: 10.1088/0953-8984/24/7/072201. Epub 2012 Jan 6.

Abstract

Direct growth of graphene on Co(3)O(4)(111) at 1000 K was achieved by molecular beam epitaxy from a graphite source. Auger spectroscopy shows a characteristic sp(2) carbon lineshape, at average carbon coverages from 0.4 to 3 ML. Low energy electron diffraction (LEED) indicates (111) ordering of the sp(2) carbon film with a lattice constant of 2.5(±0.1) Å characteristic of graphene. Sixfold symmetry of the graphene diffraction spots is observed at 0.4, 1 and 3 ML. The LEED data also indicate an average domain size of ~1800 Å, and show an incommensurate interface with the Co(3)O(4)(111) substrate, where the latter exhibits a lattice constant of 2.8(±0.1) Å. Core level photoemission shows a characteristically asymmetric C(1s) feature, with the expected π to π* satellite feature, but with a binding energy for the 3 ML film of 284.9(±0.1) eV, indicative of substantial graphene-to-oxide charge transfer. Spectroscopic ellipsometry data demonstrate broad similarity with graphene samples physically transferred to SiO(2) or grown on SiC substrates, but with the π to π* absorption blue-shifted, consistent with charge transfer to the substrate. The ability to grow graphene directly on magnetically and electrically polarizable substrates opens new opportunities for industrial scale development of charge- and spin-based devices.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cobalt / chemistry*
  • Graphite / chemistry*
  • Oxides / chemistry*
  • Spectrum Analysis
  • Temperature

Substances

  • Oxides
  • Cobalt
  • Graphite
  • cobalt oxide