Direct graphene growth on MgO: Origin of the band gap

Sneha Gaddam, Cameron Bjelkevig, Siping Ge, Keisuke Fukutani, Peter A. Dowben, Jeffry A. Kelber

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)

Abstract

A 2.5 monolayer (ML) thick graphene film grown by chemical vapor deposition of thermally dissociated C2H4 on MgO(111), displays a significant band gap. The apparent six-fold low energy electron diffraction (LEED) pattern actually consists of two three-fold patterns with different 'A' and 'B' site diffraction intensities. Similar effects are observed for the LEED patterns of a 1 ML carbon film derived from annealing adventitious carbon on MgO(111), and for a 1.5 ML thick graphene film grown by sputter deposition on the 1 ML film. The LEED data indicate different electron densities at the A and B sites of the graphene lattice, suggesting that the observed band gap results from lifting the graphene HOMO/LUMO degeneracy at the Dirac point. The data also indicate that disparities in A site/B site LEED intensities decrease with increasing carbon overlayer thickness, suggesting that the graphene band gap size decreases with increasing number of graphene layers on MgO(111).

Original languageEnglish
Article number72204
JournalJournal of Physics Condensed Matter
Volume23
Issue number7
DOIs
Publication statusPublished - 2011 Feb 23

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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