11 research outputs found
Orientation-dependent binding energy of graphene on palladium
Using density functional theory calculations, we show that the binding
strength of a graphene monolayer on Pd(111) can vary between physisorption and
chemisorption depending on its orientation. By studying the interfacial charge
transfer, we have identified a specific four-atom carbon cluster that is
responsible for the local bonding of graphene to Pd(111). The areal density of
such clusters varies with the in-plane orientation of graphene, causing the
binding energy to change accordingly. Similar investigations can also apply to
other metal substrates, and suggests that physical, chemical, and mechanical
properties of graphene may be controlled by changing its orientation.Comment: 5 pages, 6 figure
A hybrid MBE-based growth method for large-area synthesis of stacked hexagonal boron nitride/graphene heterostructures
Van der Waals heterostructures combining hexagonal boron nitride (h-BN) and graphene offer many potential advantages, but remain difficult to produce as continuous films over large areas. In particular, the growth of h-BN on graphene has proven to be challenging due to the inertness of the graphene surface. Here we exploit a scalable molecular beam epitaxy based method to allow both the h-BN and graphene to form in a stacked heterostructure in the favorable growth environment provided by a Ni(111) substrate. This involves first saturating a Ni film on MgO(111) with C, growing h-BN on the exposed metal surface, and precipitating the C back to the h-BN/Ni interface to form graphene. The resulting laterally continuous heterostructure is composed of a top layer of few-layer thick h-BN on an intermediate few-layer thick graphene, lying on top of Ni/MgO(111). Examinations by synchrotron-based grazing incidence diffraction, X-ray photoemission spectroscopy, and UV-Raman spectroscopy reveal that while the h-BN is relaxed, the lattice constant of graphene is significantly reduced, likely due to nitrogen doping. These results illustrate a different pathway for the production of h-BN/graphene heterostructures, and open a new perspective for the large-area preparation of heterosystems combining graphene and other 2D or 3D materials