Mi Zhou et al 2012 J. Phys.: Condens. Matter 24 072201 doi:10.1088/0953-8984/24/7/072201
Mi Zhou1, Frank L Pasquale1, Peter A Dowben2, Alex Boosalis3, Mathias Schubert3, Vanya Darakchieva4, Rositza Yakimova4, Lingmei Kong2 and Jeffry A Kelber1
Show affiliationsDirect growth of graphene on Co3O4(111) at 1000 K was achieved by molecular beam epitaxy from a graphite source. Auger spectroscopy shows a characteristic sp2 carbon lineshape, at average carbon coverages from 0.4 to 3 ML. Low energy electron diffraction (LEED) indicates (111) ordering of the sp2 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 Co3O4(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 SiO2 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.
68.55.A- Nucleation and growth
79.60.Jv Interfaces; heterostructures; nanostructures
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
73.20.-r Electron states at surfaces and interfaces
68.35.B- Structure of clean surfaces (and surface reconstruction)
Condensed matter: electrical, magnetic and optical
Issue 7 (22 February 2012)
Received 12 October 2011, in final form 22 November 2011
Published 6 January 2012
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