Graphene Bilayer with a Twist: Electronic Structure

Santos, J. M. B. Lopes dos; Peres, N. M. R.; Neto, A. H. Castro

doi:10.1103/physrevlett.99.256802

Cited by 1,435 publications

(1,645 citation statements)

References 27 publications

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“…Furthermore, theoretical calculations of the electronic structure of BLG with a twist in the second layer were carried out. The results showed that the low energy dispersion of twisted two-layer graphene is linear, as in SLG, but that the Fermi velocity is significantly smaller [69]. Further investigation of the electronic structure of BLG that deviates from AB stacking is necessary in order to obtain a fundamental understanding of the relationship between stacking order and electronic properties of bi-or multi-layer graphene.…”

Section: Raman Spectroscopy Of Folded Graphenementioning

confidence: 99%

Raman spectroscopy and imaging of graphene

et al. 2008

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Graphene has many unique properties that make it an ideal material for fundamental studies as well as for potential applications. Here we review recent results on the Raman spectroscopy and imaging of graphene. We show that Raman spectroscopy and imaging can be used as a quick and unambiguous method to determine the number of graphene layers. The strong Raman signal of single layer graphene compared to graphite is explained by an interference enhancement model. We have also studied the effect of substrates, the top layer deposition, the annealing process, as well as folding (stacking order) on the physical and electronic properties of graphene. Finally, Raman spectroscopy of epitaxial graphene grown on a SiC substrate is presented and strong compressive strain on epitaxial graphene is observed. The results presented here are highly relevant to the application of graphene in nano-electronic devices and help in developing a better understanding of the physical and electronic properties of graphene.

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Section: Raman Spectroscopy Of Folded Graphenementioning

confidence: 99%

Raman spectroscopy and imaging of graphene

et al. 2008

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“…The lack of AB stacking ( Figure 3d) reduces electronic coupling between the graphene layers, so that bilayer graphene in this configuration has electronic properties similar to that of monolayer graphene. [30][31][32] Supporting Information section 6), which corresponds to a single layer. It is accepted that the electronic structure and density of states play a key role in heterogeneous ET rates, 22,33 and these results show that different graphene layers (monolayer and bilayer), with closely similar band structures, behave analogously in terms of electrochemistry.…”

Section: Introductionmentioning

confidence: 99%

Structural Correlations in Heterogeneous Electron Transfer at Monolayer and Multilayer Graphene Electrodes

et al. 2012

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ABSTRACT:As a new form of carbon, graphene is attracting intense interest as an electrode material with widespread applications. In the present study, the heterogeneous electron transfer (ET) activity of graphene is investigated using scanning electrochemical cell microscopy (SECCM), which allows electrochemical currents to be mapped at high spatial resolution across a surface for correlation with the corresponding structure and properties of the graphene surface. We establish that the rate of heterogeneous ET at graphene increases systematically with the number of graphene layers, and show that the stacking in multilayers also has a subtle influence on ET kinetics.Graphene-based materials are having a huge impact in electrochemistry and electrochemical technologies, with promising applications in areas such as supercapacitors, 1 batteries, 2 electrocatalytic supports, 3 sensors for electroanalysis 4 and transparent electrodes. 5 These important technologies typically use graphene produced by chemical vapor deposition (CVD) 6 and other scalable methods, yet important fundamentals questions concerning heterogeneous electron transfer (ET) at such materials -intrinsic to many of these applications-remain to be addressed. Electrical measurements have revealed that the electron mobility 7 and the electronic band structure 8 are sensitive to the number of graphene layers and their stacking order, with implications for electrochemistry. In this communication, we thus seek to elucidate how both the number of graphene layers and arrangement of the layers influence heterogeneous ET kinetics.Graphene grown by CVD on nickel substrates 9 (see Supporting Information section 1) was optimal for the present study because it presents a heterogeneous continuous layer of microsized multilayered flakes, which can be addressed with high resolution scanning electrochemical cell microscopy (SECCM). [10][11][12][13] Thus, on one sample it is possible to make thousands of individual electrochemical (EC) measurements at different locations and relate these to the corresponding graphene structure. This provides datasets on a scale that would be unfeasible with conventional photolithographic techniques of the type employed in recent EC studies of exfoliated graphene. [14][15][16] In order to study the unambiguous electrochemical response of graphene without any interference from a conductive substrate, CVD graphene layers were transferred to a silicon substrate with a 300 nm thermal grown oxide layer. This substrate allowed optical visualization and identification of the morphological film features characteristic of graphene, 17,18 for direct correlation with the local electrochemistry. Importantly, the approach described herein makes possible the study of graphene surfaces with minimal intrusion and avoids the need for any post-processing lithographic step, which may result in unavoidable damage and possible interference of residues. 19 Ferrocene-derivatives have proven particularly suitable for the study of the ET activity of sp 2 ca...

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“…A full-tight binding calculation showed a reduction of the Fermi velocity due to interlayer interaction 2 . For TG with small twist angles (yo15°), the experimental studies showed 1,3,6,9 that the Dirac cones for each layer persist but van Hove singularities are present due to the interlayer interaction. For large twist angles, the twisted layers effectively de-couple from each other and become indistinguishable from SLG 7 .…”

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confidence: 99%

“…T he rotational stacking of graphene layers alters their electronic characteristics resulting in novel and rich physics [1][2][3][4][5][6][7][8] . Bernal (AB)-stacked graphene rotated by 60°b etween adjacent layers is well understood and its electronic properties are radically different from single-layer graphene (SLG).…”

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confidence: 99%

Observation of the intrinsic bandgap behaviour in as-grown epitaxial twisted graphene

et al. 2015

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Twisted graphene is of particular interest due to several intriguing characteristics, such as its the Fermi velocity, van Hove singularities and electronic localization. Theoretical studies recently suggested the possible bandgap opening and tuning. Here, we report a novel approach to producing epitaxial twisted graphene on SiC (0001) and the observation of its intrinsic bandgap behaviour. The direct deposition of C 60 on pre-grown graphene layers results in few-layer twisted graphene confirmed by angular resolved photoemission spectroscopy and Raman analysis. The strong enhanced G band in Raman and sp 3 bonding characteristic in X-ray photoemission spectroscopy suggests the existence of interlayer interaction between adjacent graphene layers. The interlayer spacing between graphene layers measured by transmission electron microscopy is 0.352 ± 0.012 nm. Thermal activation behaviour and nonlinear current-voltage characteristics conclude that an intrinsic bandgap is opened in twisted graphene. Low sheet resistance (B160 O& À 1 at 10 K) and high mobility (B2,000 cm 2 V À 1 s À 1 at 10 K) are observed.

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Graphene Bilayer with a Twist: Electronic Structure

Cited by 1,435 publications

References 27 publications

Raman spectroscopy and imaging of graphene

Raman spectroscopy and imaging of graphene

Structural Correlations in Heterogeneous Electron Transfer at Monolayer and Multilayer Graphene Electrodes

Observation of the intrinsic bandgap behaviour in as-grown epitaxial twisted graphene

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