Journal
NANO LETTERS
Volume 13, Issue 6, Pages 2668-2675Publisher
AMER CHEMICAL SOC
DOI: 10.1021/nl400815w
Keywords
Graphene; hexagonal boron nitride; chemical vapor deposition; heterostack; moire pattern
Categories
Funding
- Swiss National Science Foundation
- Grants-in-Aid for Scientific Research [25287075] Funding Source: KAKEN
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Two limiting factors for a new technology of graphene-based electronic devices are the difficulty of growing large areas of defect-free material and the integration of graphene with an atomically flat and insulating substrate material. Chemical vapor deposition (CVD) on metal surfaces, in particular on copper, may offer a solution to the first problem, while hexagonal boron nitride (h-BN) has been identified as an ideal insulating substrate material. The bottom-up growth of graphene/h-BN stacks on copper surfaces appears therefore as a promising route for future device fabrication. As an important step, we demonstrate the consecutive growth of well-aligned graphene on h-BN, both as single layers, by low-pressure CVD on Cu(111) in an ultrahigh vacuum environment. The resulting films show a largely predominant orientation, defined by the substrate, where the graphene lattice aligns parallel to the h-BN lattice, while each layer maintains its own lattice constant. The lattice mismatch of 1.6% between h-BN and graphene leads to a moire pattern with a periodicity of about 9 nm, as observed with scanning tunneling microscopy. Accordingly, angle resolved photoemission data reveal two slightly different Brillouin zones for electronic states localized in graphene and in h-BN, reflecting the vertical decoupling of the two layers. The graphene appears n-doped and shows no gap opening at the (K) over bar point of the two-dimensional Brillouin zone.
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