We report nanocrystalline carbon impurities coexisting with graphene synthesized via chemical vapor deposition on platinum. For certain growth conditions, we observe micron-size island-like impurity layers which can be mistaken for second graphene layers in optical microscopy or scanning electron microscopy. The island orientation depends on the crystalline orientation of the Pt, as shown by electron backscatter diffraction, indicating growth of carbon at the platinum surface below graphene. Dark-field transmission electron microscopy indicates that in addition to uniform single-crystal graphene, our sample is decorated with nanocrystalline carbon impurities with a spatially inhomogeneous distribution. The impurity concentration can be reduced significantly by lowering the growth temperature. Raman spectra show a large D peak, however, electrical characterization shows high mobility (∼8000 cm2/Vs), indicating a limitation for Raman spectroscopy in characterizing the electronic quality of graphene.
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Research Article| July 23 2014
Carbon impurities on graphene synthesized by chemical vapor deposition on platinum
Jinglei Ping (平驚雷);
Jinglei Ping, Michael S. Fuhrer; Carbon impurities on graphene synthesized by chemical vapor deposition on platinum. J. Appl. Phys. 28 July 2014; 116 (4): 044303. https://doi.org/10.1063/1.4891200
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