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Abstract
In the studies presented here, the subsequent growth of graphene on hexagonal boron nitride (h-BN) is achieved by the thermal decomposition of molecular precursors and the catalytic assistance of metal substrates. The epitaxial growth of h-BN on Pt(111) is followed by the deposition of a temporary Pt film that acts as a catalyst for the fabrication of the graphene sheet. After intercalation of the intermediate Pt film underneath the boron-nitride mesh, graphene resides on top of h-BN. Scanning tunneling microscopy and density functional calculations reveal that the moiré pattern of the van-der-Waals-coupled double layer is due to the interface of h-BN and Pt(111). While on Pt(111) the graphene honeycomb unit cells uniformly appear as depressions using a clean metal tip for imaging, on h-BN they are arranged in a honeycomb lattice where six protruding unit cells enframe a topographically dark cell. This superstructure is most clearly observed at small probe-surface distances. Spatially resolved inelastic electron tunneling spectroscopy enables the detection of a previously predicted acoustic hybrid phonon of the stacked materials. Its' spectroscopic signature is visible in surface regions where the single graphene sheet on Pt(111) transitions into the top layer of thestacking.
Highlights
The preparation of graphene on h-BN, represents an experimental challenge
This transfer procedure may lead to their low mutual hybridization rotational and translational to pronounced graphene rippling and trapped contaminants degrees of freedom allow the control of distinct stacking sym- residing at the graphene–h-BN interface.[19]
chemical vapor deposition (CVD) proceeds via the thermal decomposition of molecular precursors, which is facilitated by the catalytic activity of a metal surface
Summary
The preparation of graphene on h-BN, represents an experimental challenge. Very often, the heterostructure. CVD proceeds via the thermal decomposition of molecular precursors, which is facilitated by the catalytic activity of a metal surface. Dedkov Institut für Chemie und Biochemie Freie Universität Berlin D-14195 Berlin, Germany residual hybridization of graphene on h-BN with some metals, such as Ni, hampers the preservation of the unique free-state properties. At small probe–surface distances, STM images show that the graphene–h-BN heterostructure in addition to the moiré lattice exhibits a honeycomb superstructure. Far from the transition zones, the graphene–h-BN stacking as well as monolayer graphene (MLG) on Pt(111) remain featureless in IETS. The latter observation together with the additional graphene honeycomb superstructure hint at a finite graphene–surface coupling, which contrasts expectations of a quasi-free state of graphene on h-BN
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