Controlling graphene corrugation on lattice-mismatched substrates

By means of synchrotron-radiation-based core-level spectroscopies we demonstrate that the degree of corrugation in graphene nanomesh on lattice-mismatched transition-metal substrates critically depends on the strength of chemical bonding at the interface. The degree of interfacial orbital hybridization between graphene and metal states is rising in the series Pt(111)-Ir(111)-Rh(111)-Ru(0001). This growing strength of hybridization is accompanied by a gradual change in graphene morphology from nearly flat to strongly corrugated. We provide a comparison of the pore size and period for the cases of graphene and $h\text{-BN}$ nanomesh on Rh(111).

Figure 1

(Color online) (a) $\text{C}1s$ NEXAFS spectra from monolayer graphite adsorbed on several lattice-mismatched TM surfaces. The $\text{C}1s$ spectrum from HOPG is shown for comparison. [(b)–(e)] Corresponding LEED patterns $\left(E=60\text{eV}\right)$; substrate-related spots are marked with crosses.

Figure 2

(Color online) $\text{C}1s$ photoelectron spectra taken in normal emission from monolayer graphite adsorbed on several lattice-mismatched TM surfaces. Photon energy is 400 eV. For MG/Ru(0001) the $\text{Ru}3d$ signal is subtracted (see text and Fig. 3). The $\text{C}1s$ photoelectron spectrum from HOPG is shown for comparison. Schematics illustrate resulting graphene morphology.

Figure 3

(Color online) (a) $\text{Ru}3d$ PES from clean Ru(0001) excited with $h\nu =400\text{eV}$ and decomposed in surface-related and bulk-related contributions; (b) “raw” $\text{C}1s$ and $\text{Ru}3d$ spectrum from MG/Ru(0001) excited with $h\nu =400\text{eV}$ fitted with several “bulk” $\text{Ru}3d$ shapes to model the substrate contribution (the result of subtraction is shown below); (c) raw $\text{C}1s$ and $\text{Ru}3d$ spectrum from MG/Ru(0001) excited with $h\nu =325\text{eV}$.

Figure 4

(Color online) (a) Intensity evolution of C1 and C2 components of the $\text{C}1s$ photoelectron spectrum from graphene nanomesh on Rh(111) as a function of kinetic energy; (b) the same for N1 and N2 components of the $\text{N}1s$ spectrum from $h\text{-BN}$ nanomesh on Rh(111) (from Ref. 10). All PES measurements performed at normal emission.