Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 54: 2D Materials II: Growth
O 54.6: Vortrag
Mittwoch, 9. März 2016, 11:45–12:00, S053
Growing graphene underneath hBN on Rh(111) — •Uta Schlickum1, Daniel Rosenblatt1, Sebastian Koslowski1, and Klaus Kern1, 2 — 1Max-Planck-Institute for Solid State Research, 70569 Stuttgart, Germany — 2École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
The stable hexagonal monolayer of hBN is an insulator with excellent dielectric properties. It can be grown on a large variety of transition metal surfaces like Rh(111) on which it shows a hexagonal Moire super-lattice. We grow a single layer of hBN on Rh(111) by chemical vapor deposition and found beside the well known hexagonal structure a new periodic pattern resembling a lattice of a "spoked wheel" (SW). For small coverages this new phase appears at the intersection of the rims connecting three valleys of the Moire lattice, and forms large islands for higher coverage. Atomic resolution topographic images reveal that the phase boundaries do not disturb the atomic lattice periodicity of the hBN. Depending on the preparation parameters, the relative coverage of the two phases can be tuned at will. The crucial parameter determining the relative coverage is the time, the sample stays at about 600∘ C after the exposure to borazine at 800∘ C. It is well known that at 600∘ C, C impurities segregate and accumulate at the surface. This together with the fact that the hBN lattice itself remains intact crossing a phase boundary, leads us to conclude that the SW phase consists of an additional graphene layer below the hBN layer. Various experimental details, like high resolution spectroscopy, support this interpretation.