Dresden 2017 – scientific programme
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O: Fachverband Oberflächenphysik
O 94: Graphene: Electronic Properties, Structure and Substrate Interaction II
O 94.4: Talk
Thursday, March 23, 2017, 15:45–16:00, TRE Ma
Structure of pristine and hBN-embedded graphene quantum dots on Ir(111) — •Jiaqi Cai1, Caio Silva1,2, Wouter Jolie2, Ferdinand Farwick zum Hagen2, Christoph Schlueter3, Tien-Lin Lee3, and Carsten Busse1,2 — 1Institut für Materialphysik, Münster, Germany — 2II. Physikalisches Institut, Köln, Germany — 3Diamond Light Source Ltd, Didcot, United Kingdom
Nanometer-sized graphene flakes (graphene quantum dots, GQDs) provide a playground for the confinement of Dirac electrons [1]. On Ir(111), these GQDs are dome-shaped, with their edges bend towards and strongly bond to Ir surface atoms [2]. We prepare GQDs with an average size of 2 nm, and explore the details of the varying graphene-substrate interaction with the x-ray standing wave technique. We precisely measure the bond distances of the C atoms at the edges as well as in the interior of the GQDs.
In order to stabilize these graphene nanostructures and to reach a well-defined edge termination, we embedded the GQDs in hexagonal boron nitride (hBN). We investigate the structural changes caused by the embedding, especially at the graphene-hBN interface, where peculiar electronic effects, such as half-metallicity are predicted [3]. The GQDs edges remain strongly bonded to the substrate, and the interface is comprised of both N-C and B-C bonds.
[1] W. Jolie et al., Phys. Rev. B 89, 155435 (2014).
[2] P. Lacovig et al., Phys. Rev. Lett. 103, 166101 (2009).
[3] S. Dutta et al., Phys. Rev. Lett. 102, 096601 (2009).