Electronic structures of an epitaxial graphene monolayer on SiC(0001) after gold intercalation: a first-principles study

Abstract

The atomic and electronic structures of an Au-intercalated graphene monolayer on the SiC(0001) surface were investigated using first-principles calculations. The unique Dirac cone of graphene near the K point reappeared as the monolayer was intercalated by Au atoms. Coherent interfaces were used to study the mismatch and the strain at the boundaries. Our calculations showed that the strain at the graphene/Au and Au/SiC(0001) interfaces also played a key role in the electronic structures. Furthermore, we found that at an Au coverage of 3/8 ML, Au intercalation leads to a strong n-type doping of graphene. At 9/8 ML, it exhibited a weak p-type doping, indicative that graphene was not fully decoupled from the substrate. The shift in the Dirac point resulting from the electronic doping was not only due to the different electronegativities but also due to the strain at the interfaces. Our calculated positions of the Dirac points are consistent with those observed in the ARPES experiment (Gierz et al 2010 Phys. Rev. B 81 235408).

Extraordinary epitaxial alignment of graphene islands on Au(111)

“…Only graphene on Ir(111) displays a lower level of charge transfer; however, in that case the electronic structure of graphene is complicated by interactions with the Ir bands close to the Fermi level. As these interactions are absent in graphene on Au(111), this system is well suited for investigations of quasi-free-standing graphene, an attribute that is being investigated in transferred and Au-intercalated graphene [25,[30][31][32]. Table 1.…”

Electronic structures of an epitaxial graphene monolayer on SiC(0001) after metal intercalation (metal = Al, Ag, Au, Pt, and Pd): A first-principles study

“…The study by Gierz et al 17 demonstrated that the strongly interacting first graphitic layer was decoupled from the SiC(0001) substrate via gold intercalation. The shifts of Dirac points due to gold intercalation were then theoretically studied by Chuang et al 19 The choice of elements used for intercalation depends on the atomic radius such that the atoms can fit into the supercell. On the other hand, it depends on their interatomic bond strength meaning the intercalated atoms will not break the sp 2 hybridization of the graphene.…”

“…The calculations were carried out within the generalized gradient approximation to the densityfunctional theory (DFT) 26,27 using projector augmentedwave (PAW) pseudopotential method, 28 as implemented in the Vienna Ab-initio Simulation Package (VASP). 29 As in previous studies, 4,5,11,19 a ffiffi ffi 3 p  ffiffi ffi 3 p R30 unit cell of SiC(0001) is used to match the 2  2 unit cell of graphene. The same computational settings are used as in Ref.…”

Laterally Inhomogeneous Au Intercalation in Epitaxial Graphene on SiC(0 0 0 1): A Multimethod Electron Microscopy Study

“…The study by Gierz et al [21] claimed that the strongly interacting first carbon layer was decoupled from the SiC(0 0 0 1) substrate via gold intercalation. The shift of Dirac points due to gold intercalation was then theoretically studied by Chuang et al [22]. A similar study performed by Premlal et al [23], using scanning tunneling microscopy and spectroscopy (STM/ STS), concluded that the intercalated gold cluster displays a new surface reconstruction and induces a possible hole-doping effect.…”

“…Nevertheless, we cannot exclude that a small shift of the Dirac point (below 20 meV) has occurred. Moreover, Au deposition on SiC(0 0 0 1) results in p-or n-doping, depending either on the number of graphene layers, the strain at the Au/graphene or SiC/ graphene interfaces [22], or the gold coverage [21]. In our case, we average the electronic information over the region that is slightly larger than that defined by the illumination, which includes both single and bilayer graphene.…”