Highly Uniform Bilayer Graphene on Epitaxial Cu-Ni(111) Alloy

Yuichiro Takesaki, Kenji Kawahara, Hiroki Hibino, Susumu Okada, Masaharu Tsuji, Hiroki Ago

    Research output: Contribution to journalArticle

    30 Citations (Scopus)

    Abstract

    Band gap opening in bilayer graphene (BLG) under a vertical electric field is important for the realization of high performance graphene-based semiconductor devices, and thus, the synthesis of uniform and large-area BLG is required. Here we demonstrate the synthesis of a highly uniform BLG film by chemical vapor deposition (CVD) over epitaxial Cu-Ni (111) binary alloy catalysts. The relative concentration of Ni and Cu as well as the growth temperature and cooling profile was found to strongly influence the uniformity of the BLG. In particular, a slow cooling process after switching off the carbon feedstock is important for obtaining a uniform second layer, covering more than 90% of the total area. Moreover, low-energy electron microscopy (LEEM) study revealed the second layer grows underneath the first layer. We also investigated the stacking order by Raman spectroscopy and LEEM and found that 70-80% of bilayer graphene has Bernal stacking. The metastable 30°-rotated orientations were also observed both in the upper and lower layers. From our experimental observations, a new growth mode is proposed; the first layer grows during the CH4 supply on Cu-Ni alloy surface, while the second layer is segregated from the bulk alloy during the cooling process. Our work highlights the growth mechanism of BLG and offers a promising route to synthesize uniform and large-area BLG for future electronic devices.

    Original languageEnglish
    Pages (from-to)4583-4592
    Number of pages10
    JournalChemistry of Materials
    Volume28
    Issue number13
    DOIs
    Publication statusPublished - Jul 12 2016

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    Graphene
    Cooling
    Electron microscopy
    Binary alloys
    Growth temperature
    Semiconductor devices
    Feedstocks
    Raman spectroscopy
    Chemical vapor deposition
    Energy gap
    Carbon
    Electric fields
    Catalysts

    All Science Journal Classification (ASJC) codes

    • Chemistry(all)
    • Chemical Engineering(all)
    • Materials Chemistry

    Cite this

    Highly Uniform Bilayer Graphene on Epitaxial Cu-Ni(111) Alloy. / Takesaki, Yuichiro; Kawahara, Kenji; Hibino, Hiroki; Okada, Susumu; Tsuji, Masaharu; Ago, Hiroki.

    In: Chemistry of Materials, Vol. 28, No. 13, 12.07.2016, p. 4583-4592.

    Research output: Contribution to journalArticle

    Takesaki, Y, Kawahara, K, Hibino, H, Okada, S, Tsuji, M & Ago, H 2016, 'Highly Uniform Bilayer Graphene on Epitaxial Cu-Ni(111) Alloy', Chemistry of Materials, vol. 28, no. 13, pp. 4583-4592. https://doi.org/10.1021/acs.chemmater.6b01137
    Takesaki, Yuichiro ; Kawahara, Kenji ; Hibino, Hiroki ; Okada, Susumu ; Tsuji, Masaharu ; Ago, Hiroki. / Highly Uniform Bilayer Graphene on Epitaxial Cu-Ni(111) Alloy. In: Chemistry of Materials. 2016 ; Vol. 28, No. 13. pp. 4583-4592.
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