Structural and electronic properties of graphene nanoflakes on Au(111) and Ag(111)

Abstract

We investigate the electronic properties of graphene nanoflakes on Ag(111) and Au(111) surfaces by means of scanning tunneling microscopy and spectroscopy as well as density functional theory calculations. Quasiparticle interference mapping allows for the clear distinction of substrate-derived contributions in scattering and those originating from graphene nanoflakes. Our analysis shows that the parabolic dispersion of Au(111) and Ag(111) surface states remains unchanged with the band minimum shifted to higher energies for the regions of the metal surface covered by graphene, reflecting a rather weak interaction between graphene and the metal surface. The analysis of graphene-related scattering on single nanoflakes yields a linear dispersion relation E(k), with a slight p-doping for graphene/Au(111) and a larger n-doping for graphene/Ag(111). The obtained experimental data (doping level, band dispersions around EF, and Fermi velocity) are very well reproduced within DFT-D2/D3 approaches, which provide a detailed insight into the site-specific interaction between graphene and the underlying substrate.

Local electronic properties of the graphene-protected giant Rashba-split BiAg2 surface

“…A subsequent deposition of ≈70Å of Ag on GNF/Ir(111) and annealing of this system at 450 • C for 30 min leads to the formation of a GNF/Ag(111)/Ir(111) system with graphene flakes floating on top. Earlier experimental results [26] and the present STM/STS data confirm the high quality of such a system. In the next step, an almost stoichiometric BiAg 2 alloy is prepared underneath the GNFs via the adsorption of Bi atoms on GNF/Ag/Ir(111) at 200 • C and subsequent annealing at the same temperature for 30 min.…”

“…S4 of the Supplemental Material). This effect is contrary to the previously observed results for graphene adsorption on Au(111) [25,26], Ag(111) [26,36,37], Cu(111) [38], and Ir(111) [16,39], where an upward energy shift for the metallic surface states was reported and explained by a stronger localization of the wave function of the metallic surface state producing an increase of Pauli repulsion at the interface. This effect leads to an increase of the energy of the electrons and consequently to the upward energy shift of the surface state.…”

“…Adsorption of graphene merely leads to a rigid shift of the respective surface states to smaller binding energies [16,25,26], which was explained by the stronger localization of the surface state wave function, leading to a corresponding energy shift. At the same time, the intercalation of Au in the graphene/Ni(111) interface leads to the appearance of induced spin-orbit splitting of the graphene π states (up to ≈100 meV) as a result of the hybridization of these states and valence band states of the underlying heavy metal [23,24].…”

Putting David Craig’s Legacy to Work in Nanotechnology and Biotechnology

“…[362] Both D3 and MBD have been shown to be very effective for many different types of problems, from ice cluster energies through crystal cohesion energies to basic chemistry and to surface adhesion to interactions with graphite and nanotubes. [260][261][262][263][264][265][266][267][268][269][270]341] This occurs despite fundamental limitations in the description of the interactions (Table 2). Success comes from the fact that these methods are designed to model interaction energies and geometries and are usually only applied for these purposes.…”

“…This includes a molecular n-bit shift register made by the controlled synthesis of large porphyrin assemblies on substrates containing leads fabricated using current silicon device technology. [259] The established synthetic strategies involve scanning tunnelling microscopy (STM)-induced reactions of molecules [260][261][262][263][264][265][266][267][268][269][270] on silicon surfaces performed with atomic precision, [271,272] that are subsequently linkable to porphyrins.…”