Direct graphene growth on Co3O4(111) by molecular beam epitaxy.
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.
Department of Chemistry, University of North Texas, Denton, TX 76203-5017, USA.
Mi
M
Zhou
Frank L
FL
Pasquale
Peter A
PA
Dowben
Alex
A
Boosalis
Mathias
M
Schubert
Vanya
V
Darakchieva
Rositza
R
Yakimova
Lingmei
L
Kong
Jeffry A
JA
Kelber
D003035:Cobalt / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D013057:Spectrum Analysis; D013696:Temperature
D010087:Oxides; D003035:Cobalt; D006108:Graphite; C060728:cobalt oxide