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DS: Fachverband Dünne Schichten
DS 27: 2D Materials beyond Graphene (jointly with O)
DS 27.16: Poster
Dienstag, 21. März 2017, 18:30–20:30, P2-EG
Structural analysis of PTCDA domains on an epitaxial hexagonal boron nitride (hBN) monolayer via SPA-LEED and STM — •Christine Brülke1, Timo Heepenstrick1, Moritz Sokolowski1, and Sergey Subach2 — 1Institut für Physikalische und Theoretische Chemie der Universität Bonn, Wegelerstraße 12, 53115 Bonn, Germany — 2Peter Grünberg Institut, Forschungszentrum Jülich, 52452 Jülich, Germany
Epitaxial monolayers of hBN on metal surfaces are of interest as two-dimensional insulating substrates as well as templates for the formation of epitaxial layers of organic molecules. Here, we report a structural analysis of one monolayer of PTCDA on hBN/Cu(111) by spot profile analysis low energy electron diffraction (SPA-LEED) and scanning tunneling microscopy (STM). hBN grows on the Cu(111) surface in an incommensurate structure with a lattice mismatch of 2.0 % (at 100 K) corresponding to an unstrained hBN layer. The films show rotational mosaicity, however, the majority of the hBN domains are in or close to alignment with the unit cell vectors of the Cu(111) surface (± 2∘).
On this hBN layer PTCDA molecules form ordered domains with a herringbone structure with lattice constants a = (19.8 ± 0.3) Å and b = (12.4 ± 0.2) Å. This yields a size of the unit cell that deviates by 3.1 % and 2.2 % from that in the (102) plane of the α and β bulk crystals, respectively. The majority of PTCDA domains are statistically distributed in their azimuthal orientation. There is only a small preference for domains that are oriented along the unit cell vectors of the hBN layer.