Problems associated with large-scale pattern growth of graphene constitute one of the main obstacles to using this material in device applications. Recently, macroscopic-scale graphene films were prepared by two-dimensional assembly of graphene sheets chemically derived from graphite crystals and graphene oxides. However, the sheet resistance of these films was found to be much larger than theoretically expected values. Here we report the direct synthesis of large-scale graphene films using chemical vapour deposition on thin nickel layers, and present two different methods of patterning the films and transferring them to arbitrary substrates. The transferred graphene films show very low sheet resistance of ∼280 Ω per square, with ∼80 per cent optical transparency. At low temperatures, the monolayers transferred to silicon dioxide substrates show electron mobility greater than 3,700 cm2 V-1 s-1 and exhibit the half-integer quantum Hall effect, implying that the quality of graphene grown by chemical vapour deposition is as high as mechanically cleaved graphene. Employing the outstanding mechanical properties of graphene, we also demonstrate the macroscopic use of these highly conducting and transparent electrodes in flexible, stretchable, foldable electronics.
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Acknowledgements We thank J. H. Han, J. H. Kim, H. Lim, S. K. Bae and H.-J. Shin for assisting in graphene synthesis and analysis. This work was supported by the Korea Science and Engineering Foundation grant funded by the Korea Ministry for Education, Science and Technology (Center for Nanotubes and Nanostructured Composites R11-2001-091-00000-0), the Global Research Lab programme (Korea Foundation for International Cooperation of Science and Technology), the Brain Korea 21 project (Korea Research Foundation) and the information technology research and development programme of the Korea Ministry of Knowledge Economy (2008-F024-01).
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