Doping domains in graphene on gold substrates: First-principles and scanning tunneling spectroscopy studies

Abstract

We have studied graphene/gold interface by means of density functional theory (DFT) and scanning tunneling spectroscopy (STS). Weak interaction between graphene and the underlying gold surface leaves unperturbed Dirac cones in the band-structure, but they can be shifted with respect to the Fermi level of the whole system, which results in effective doping of graphene. DFT calculations revealed that the interface is extremely sensitive to the adsorption distance and to the structure of metal's surface, in particular strong variation in doping can be attributed to the specific rearrangments of substrate's atoms, such as change of the crystallographic orientation, relaxation or other modifications of the surface. On the other hand, STS experiments have shown the presence of energetic heterogeneity in terms of the changes in the local density of states (LDOS) measured at different places on the sample. Randomly repeated regions of zero-doping and p-type doping have been identified from parabolic shape characteristics and from well defined Dirac points, respectively. The doping domains of graphene on gold seem to be related to the presence of various types of the surface structure accross the sample. DFT simulations for graphene interacting with Au have shown large differences in doping induced by considered structures of substrate, in agreement with experimental findings. All these results demonstrate the possibility of engineering the electronic properties of graphene, especially tuning the doping across one flake which can be useful for applications of graphene in electronic devices.

Scanning probe microscopy study of chemical vapor deposition grown graphene transferred to Au(111)

“…This is consistent with previous reports for graphene exfoliated from graphite and transferred ex M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT situ to Au(111) [5], yet in contrast to the p-type doping reported for graphene grown in situ on Au(111) via vapor deposition [27]. This discrepancy may be related to a different adsorption distance [28] of the graphene on Au(111) in the different preparation approaches. Intercalation with water molecules, which occurs during ex situ transfer of the graphene, has been found to lead to a stronger n-type doping of graphene on Au(111) [5].…”

“…Previously, graphene was grown on Au (111) by deposition of elemental carbon and subsequent annealing, yielding dendritic graphene islands [17] that eventually can evolve into quasi-single crystalline graphene films [27]. Compared to more rough, granular substrates [28], graphene on atomically flat substrates, either grown by CVD or obtained by transfer, is interesting for studies of doping with, e.g., nitrogen, as it allows to conveniently retrieve dopants using atomically resolved STM [9][10][11]30].…”

One-dimensional potential for image-potential states on graphene

“…Overall the fit of this work describes also the calculated values (green open squares in figure 6) very well. The surfaces included in the fit all have a graphene-metal distance of around 3.4 Å [34][35][36][37][38]. The surfaces of Ni, Ru and Pd were not included in the fit and are shown by blue dashed circles.…”

Moiré superlattices in strained graphene-gold hybrid nanostructures

“…These contacts are made by sputtering or ebeam evaporation and consist of polycrystalline grains. The interaction of graphene with such a polycrystalline gold layer was investigated recently by transferring graphene flakes on a sputtered, 8 nm gold layer [22]. Based on STS measurements, it was concluded that the gold substrate is the mixture of (111) crystallites and amorphous-type regions.…”