Comparison of electronic structure and template function of single-layer graphene and a hexagonal boron nitride nanomesh on Ru(0001)

Thomas Brugger, Sebastian Günther, Bin Wang, J. Hugo Dil, Marie-Laure Bocquet, Jürg Osterwalder, Joost Wintterlin, and Thomas Greber

Phys. Rev. B 79, 045407 – Published 12 January 2009

Abstract

The structure of a single-layer graphene on Ru(0001) is compared with that of a single-layer hexagonal boron nitride nanomesh on Ru(0001). Both are corrugated $s p^{2}$ hybridized networks and display a $π$ band gap at the $\bar{K}$ point of their $1 \times 1$ Brillouin zone. In contrast to $h -BN / Ru (0001)$ , $g / Ru (0001)$ has a distinct Fermi surface. Together with the band structure measurements this indicates that $0.1 e$ per $1 \times 1$ unit cell are transferred from the Ru substrate to the graphene. Photoemission from adsorbed xenon on $g / Ru (0001)$ identifies two $Xe 5 p_{1 / 2}$ lines, separated by 240 meV, which reveals a corrugated electrostatic potential energy surface like on $h -BN / Rh (111)$ . These two Xe species are related to the topography of the template and have different desorption energies.

Received 10 November 2008

DOI:https://doi.org/10.1103/PhysRevB.79.045407

Authors & Affiliations

Thomas Brugger¹, Sebastian Günther², Bin Wang³, J. Hugo Dil^1,4, Marie-Laure Bocquet^3,2, Jürg Osterwalder¹, Joost Wintterlin², and Thomas Greber^1,*

¹Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
²Department Chemie, Ludwig-Maximilian Universität, Butenandtstrasse 5-13, D-81377 München, Germany
³Laboratoire de Chimie, Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS, F-69007 Lyon, France
⁴Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland

^*greber@physik.uzh.ch

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Vol. 79, Iss. 4 — 15 January 2009

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Figure 1
(Color online) Views of the height modulated graphene $(g)$ and $h -BN$ nanomesh (BN) on Ru(0001), as obtained from a DFT calculation for both systems. $M$ and $V$ denote mounds and valleys of the graphene, $H$ and $W$ holes and wires of the $h -BN$ nanomesh. The six ball model panels illustrate the three different regions [(fcc,top), (top,hcp), and (hcp,fcc)] which can be distinguished in both systems (see text).Reuse & Permissions
Figure 2
(Color online) Band structures of graphene and $h -BN$ nanomesh on Ru(0001) along $\bar{Γ} \bar{K}$ . (a) $He {II}_{α}$ photoemission of $g / Ru (0001)$ . [(b) and (c)] DFT of $g / Ru (0001)$ for the low $[(C_{A}, C_{B}) \sim (top, hcp)]$ and high $[(C_{A}, C_{B}) \sim (hcp, fcc)]$ regions, respectively. (d) $He {II}_{α}$ photoemission of $h -BN / Ru (0001)$ . [(e) and (f)] DFT of $h -BN / Ru (0001)$ for the low $[(B, N) \sim (fcc, top)]$ and high $[(B, N) \sim (hcp, fcc)]$ regions, respectively. The vertical lines at $\bar{K}$ indicate the boundaries of the $1 \times 1$ surface Brillouin zones for Ru (red dashed), $h -BN$ (blue solid), and graphene (green solid). The size of the filled circles in (b), (c), (e), and (f) represents the $p_{z}$ weight of the adsorbate atoms on the bands, where blue describes $C_{A}$ (top) in (b), and N in (e) (top) and (f) (fcc). Red describes hollow site atoms [ $C_{B}$ in (b) and B in (e)]. Black circles depict the average of the two inequivalent adsorbate atoms. Thick yellow curves are guides for the eyes.Reuse & Permissions
Figure 3
(Color online) $He {II}_{α}$ energy distribution curves at $k_{∥} = 1.12 Å^{- 1}$ for graphene (red open circles) and $h -BN$ nanomesh (black open diamonds) on Ru(0001) extracted from the band structure data of Figs. 2a, 2d, respectively. The curves are vertically offset for clarity.Reuse & Permissions
Figure 4
(Color online) $He {II}_{α}$ Fermi surface maps. (a) $g / Ru (0001)$ . (b) $h -BN / Ru (0001)$ . The hexagons indicate the surface Brillouin zones of Ru(0001) (red dashed), graphite [green solid in (a)], and $h -BN$ [blue solid in (b)]. (c) and (d) show the normalized intensities of azimuthal cuts along the dashed yellow sectors in (a) and (b), respectively.Reuse & Permissions
Figure 5
(Color online) Xe adsorption on $g / Ru (0001)$ . (a) Calculated electrostatic potential map $3.8 Å$ above the outermost carbon atoms. [(b) and (c)] $He I_{α}$ excited $Xe 5 p_{1 / 2}$ spectra for two Xe coverages during thermal desorption. At high coverage two spectral components may be distinguished, as can be seen from the two Gaussians that are fitted to the data. (d) Spectral weights of the two Xe species as a function of temperature. Blue open circles stand for the high binding energy and red open diamonds for the low binding energy component.Reuse & Permissions

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