Electronic structure of bilayer graphene physisorbed on metal substrates

Abstract

Graphene-metal interfaces have recently become popular for graphene growth and for making contacts in numerous thermal and photo-electronic devices. A number of studies have already been made to investigate the interfacial properties when single layer graphene is grown on metal substrates. In this study, we consider the physisorption of bilayer graphene on metals and find a significant bandgap opening which is otherwise absent in the single layer case. This gap arises from the asymmetry in the bilayer due to the charge transfer process at the interface. This charge transfer also causes doping in the bilayer graphene and a corresponding shift in the Fermi level. In this work, we present a thorough investigation into the induced bandgap and Fermi level shift when bilayer graphene is adsorbed on Cu, Al, Ag, Pt, and Au(111) surfaces first by reporting their values from Density Functional Theory (DFT) studies with Local Density Approximation functional used for exchange-correlation energy. Next, to obtain an enhanced picture of the surface physics at play (which is usually obscured by the complexities of DFT), we provide an analytical model to relate the induced bandgap and Fermi level shift to the metal work function and interface separation distance. The values predicted from the model shows a high degree of correlation with the values obtained from the DFT simulation. The results are expected to greatly facilitate the understanding of bilayer graphene adsorption on metals, which in turn may aid the study of graphene electronic devices.

Enhancing the Performance of Surface Plasmon Resonance Biosensor via Modulation of Electron Density at the Graphene–Gold Interface

“…Considering the weak chemical interaction between Au film and graphene, the latter term can be neglected . In the case of 2 SLG deposition, in addition to the charge transfer from the first layer of graphene to Au, asymmetric charges were transferred ( ∆ as ( d )) from the second graphene layer to Au, generating an asymmetric electric field through the interfaces . ∆V 2SLG/Au can be described by ∆V 2SLG/Au = ∆ tr ( d ) + ∆ c ( d ) + ∆ as ( d ), with negligible value of ∆ c ( d ).…”

Modeling the physisorption of graphene on metals

“…A striking property of graphene is its strong ability to adsorb, due to its large surface area and high polarizability. To fundamentally understand this interface problem, many van der Waals-corrected density functionals have been employed to calculate binding energies and equilibrium distances between graphene and metal surfaces [7][8][9][10][11][12][13][14][15][16][17][18][19]. In particular, Ruiz et al proposed a vdW method [20] to model the adsortion of molecules on the surface of a transition metal based on the Zaremba-Kohn theory.…”

Atomic Structures of Pt Nanoclusters Supported on Graphene Grown on Pt(111)

“…The surface structure of the Pt substrate did not alter with the formation of graphene, confirming a weak interaction between graphene and substrate (Pt). 6,7,10,12,13 Two additional reflection streaks appeared at azimuth [−110] when graphene was grown, indicated with a red notation (Figure 1c). As both graphene and Pt(111) have hexagonal surface lattices and as similar patterns were observed at the same reciprocal lattice plane, the patterns are assigned to (10) and ( 20) reflection beams from the graphene film commensurate structurally with the Pt(111) surface.…”

“…Metal nanoclusters on a graphene monolayer grown on a metal surface are intensively studied because they can serve as a model for carbon–supported metal catalysts and also as a prospective electrode in solar cells or fuel cells because of graphene’s atypical electronic properties. − The graphene monolayer has generally a superlattice at surfaces, exhibited as a Moiré pattern in scanning tunneling microscopy (STM) images, largely because the lattices of graphene and the underlying metal surfaces are structurally mismatched. − The superlattice provides a novel template to form a two-dimensional (2D) cluster array. ,, Many possible combinations of metal–graphene–metal have been investigated, including Ir, Rh, Pt, , W, Re, Fe, and Au on graphene on Ir(111); Ni on Rh(111); Pt, − Ru, Rh, Pd, Co, and Au on Ru(0001); and Pt on Pt(111). These investigations concentrated on the varied Moiré patterns, the nucleation of deposited metal atoms, the morphologies, and possible arrays of grown clusters.…”