The SiC(0001)6√3 × 6√3 reconstruction studied with STM and LEED

Owman, Fredrik; Mårtensson, Per

doi:10.1016/s0039-6028(96)00919-3

Cited by 94 publications

(92 citation statements)

References 16 publications

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“…We discuss the evolution of the spectra with graphene coverage in terms of possible indirect effects of the overlying graphene layer(s). Our STM images for the 5×5 and 6√3 surface are in good agreement with prior work, 2,3 revealing adatom positions that are inconsistent with simple adatoms on a bulk-terminated SiC bilayer. Based on the adatom positions, for the 5×5 surface particularly, we suggest that a complex carbon-rich adlayer may be present below the adatoms for both surfaces.…”

supporting

confidence: 89%

Tunneling spectroscopy of graphene and related reconstructions on SiC(0001)

Nie

Feenstra

2009

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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The 5×5, 6√3×6√3-R30°, and graphene-covered 6√3×6√3-R30° reconstructions of the SiC(0001) surface are studied by scanning tunneling microscopy and spectroscopy. For the 5×5 structure a rich spectrum of surface states is obtained, with one state in particular found to be localized on top of structural protrusions (adatoms) observed on the surface. Similar spectra are observed on the bare 6√3×6√3-R30° reconstruction, and in both cases the spectra display nearly zero conductivity at the Fermi-level. When graphene covers the 6√3×6√3-R30° surface the conductivity at the Fermi-level shows a marked increase, and additionally the various surface state peaks seen in the spectrum shift in energy and fall in intensity. The influence of the overlying graphene on the electronic properties of the interface is discussed, as are possible models for the interface structure.

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supporting

confidence: 89%

Tunneling spectroscopy of graphene and related reconstructions on SiC(0001)

Nie

Feenstra

2009

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…The experimentally determined (6 √ 3 × 6 √ 3)R30 • carbon buffer layer (also known as zero layer graphene or ZLG) [28][29][30][31] is modeled using a simplified √ 3 × √ 3R30 • cell, which has previously been shown to adequately describe the interaction between the SiC substrate and subsequent graphene layers [32][33][34]. A vacuum layer of at least 17Å is included in the direction normal to the surface to electronically decouple neighboring slabs and the dipole correction is applied [35,36].…”

Section: Methodsmentioning

confidence: 99%

Changes in work function due to NO2 adsorption on monolayer and bilayer epitaxial graphene on SiC(0001)

et al. 2016

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The electronic properties of monolayer graphene grown epitaxially on SiC(0001) are known to be highly sensitive to the presence of NO 2 molecules. The presence of small areas of bilayer graphene, on the other hand, considerably reduces the overall sensitivity of the surface. We investigate how NO 2 molecules interact with monolayer and bilayer graphene, both free-standing and on a SiC(0001) substrate. We show that it is necessary to explicitly include the effect of the substrate in order to reproduce the experimental results. When monolayer graphene is present on SiC, there is a large charge transfer from the interface between the buffer layer and the SiC substrate to the molecule. As a result, the surface work function increases by 0.9 eV after molecular adsorption. A graphene bilayer is more effective at screening this interfacial charge, and so the charge transfer and change in work function after NO 2 adsorption is much smaller.

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“…27,45,47 The data presented here have been obtained on similar samples, using two different homemade UHV microscopes working at 4-5 K, one located at Max Planck Institute of Stuttgart (Germany), the other one at Universidad Autonoma de Madrid (Spain). After transport in atmosphere and transfer into the UHV systems, the samples were outgassed at 300…”

Section: Experimental Methodsmentioning

confidence: 99%

Role of pseudospin in quasiparticle interferences in epitaxial graphene probed by high-resolution scanning tunneling microscopy

et al. 2012

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Pseudospin, an additional degree of freedom emerging in graphene as a direct consequence of its honeycomb atomic structure, is responsible for many of the exceptional electronic properties found in this material. This paper is devoted to providing a clear understanding of how graphene's pseudospin impacts the quasiparticle interferences of monolayer (ML) and bilayer (BL) graphene measured by low-temperature scanning tunneling microscopy and spectroscopy. We have used this technique to map, with very high energy and space resolution, the spatial modulations of the local density of states of ML and BL graphene epitaxially grown on SiC(0001), in presence of native disorder. We perform a Fourier transform analysis of such modulations including wave vectors up to unit vectors of the reciprocal lattice. Our data demonstrate that the quasiparticle interferences associated to some particular scattering processes are suppressed in ML graphene, but not in BL graphene. Most importantly, interferences with 2q F wave vector associated to intravalley backscattering are not measured in ML graphene, even on the images with highest resolution where the graphene honeycomb pattern is clearly resolved. In order to clarify the role of the pseudospin on the quasiparticle interferences, we use a simple model which nicely captures the main features observed in our data. The model unambiguously shows that graphene's pseudospin is responsible for such suppression of quasiparticle interference features in ML graphene, in particular for those with 2q F wave vector. It also confirms scanning tunneling microscopy as a unique technique to probe the pseudospin in graphene samples in real space with nanometer precision. Finally, we show that such observations are robust with energy and obtain with great accuracy the dispersion of the π bands for both ML and BL graphene in the vicinity of the Fermi level, extracting their main tight-binding parameters.

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The SiC(0001)6√3 × 6√3 reconstruction studied with STM and LEED

Cited by 94 publications

References 16 publications

Tunneling spectroscopy of graphene and related reconstructions on SiC(0001)

Tunneling spectroscopy of graphene and related reconstructions on SiC(0001)

Changes in work function due to NO2 adsorption on monolayer and bilayer epitaxial graphene on SiC(0001)

Role of pseudospin in quasiparticle interferences in epitaxial graphene probed by high-resolution scanning tunneling microscopy

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