Charge neutrality and band-gap tuning of epitaxial graphene on SiC by molecular doping

Coletti, Camilla; Riedl, Christian; Lee, Dong Su; Krauß, Benjamin; Patthey, L.; Klitzing, K. von; Smet, J. H.; Starke, Ulrich

doi:10.1103/physrevb.81.235401

Cited by 415 publications

(465 citation statements)

References 48 publications

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“…in the same manner as for prior work on 2D-2D tunneling). 2,3 Doping of graphene can be accomplished by a variety of means, 16,17,18,19 and chemical potentials shifted by 0.1 eV or more from the Dirac point, both n-type and p-type, are not uncommon. In this respect the simulations presented here appear to be applicable to physically realizable situations.…”

Section: Discussionmentioning

confidence: 99%

Single-particle tunneling in doped graphene-insulator-graphene junctions

Feenstra

Jena

Gu³

2012

Journal of Applied Physics

157

260

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The characteristics of tunnel junctions formed between n-and p-doped graphene are investigated theoretically. The single-particle tunnel current that flows between the twodimensional electronic states of the graphene (2D-2D tunneling) is evaluated. At a voltage bias such that the Dirac points of the two electrodes are aligned, a large resonant current peak is produced. The magnitude and width of this peak are computed, and its use for devices is discussed. The influences of both rotational alignment of the graphene electrodes and structural perfection of the graphene are also discussed.

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Section: Discussionmentioning

confidence: 99%

Single-particle tunneling in doped graphene-insulator-graphene junctions

Feenstra

Jena

Gu³

2012

Journal of Applied Physics

157

260

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“…In the case of SLG this has been variously accomplished via decoration with metal adatoms, 13 substitutional doping with nitrogen or boron atoms, 14 edge modification using electrothermal reactions with ammonia, 15 decorating SLG with ultrathin layers of Si islands, 16 and surface transfer doping via the adsorption of large organic molecules; 17,18 with some of these methods resulting in the opening of a band gap in SLG. In the case of the latter study, ref.…”

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confidence: 99%

Molecular Doping and Band-Gap Opening of Bilayer Graphene

2013

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The ability to induce an energy band gap in bilayer graphene is an important development in graphene science and opens up potential applications in electronics and photonics. Here we report the emergence of permanent electronic and optical band gaps in bilayer graphene upon adsorption of  electron containing molecules. Adsorption of n-or p-type dopant molecules on one layer results in an asymmetric charge distribution between the top and bottom layers and in the formation of an energy gap. The resultant band gap scales linearly with induced carrier density though a slight asymmetry is found between n-type dopants, where the band gap varies as 47 meV/10 13 cm -2 , and p-type dopants where it varies as 40 meV/10 13 cm -2 .Decamethylcobaltocene (DMC, n-type) and 3,6-difluoro-2,5,7,7,8,8-hexacyano-quinodimethane (F2-HCNQ, p-type) are found to be the best molecules at inducing the largest electronic band gaps up to 0.15 eV. Optical adsorption transitions in the 2.8 -4 m region of the spectrum can result between states that are not Pauli blocked. Comparison is made between the band gaps calculated from adsorbate-induced electric fields and from average displacement fields found in dual gate bilayer graphene devices. A key advantage of using molecular adsorption with  electron containing molecules is the high binding energy can induce a permanent band gap and

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“…While doping graphene by adsorbates or more elaborate chemical means has made rapid progress, [1][2][3][4][5][6][7] opening a band-gap in graphene has been problematic. Two routes to wide-band-gap semiconducting graphene have been pioneered: electron confinement and chemical functionalization.…”

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confidence: 99%

Wide-Gap Semiconducting Graphene from Nitrogen-Seeded SiC

et al. 2013

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All carbon electronics based on graphene has been an elusive goal. For more than a decade, the inability to produce significant band-gaps in this material has prevented the development of graphene electronics. We demonstrate a new approach to produce semiconducting graphene that uses a submonolayer concentration of nitrogen on SiC sufficient to pin epitaxial graphene to the SiC interface as it grows. The resulting buckled graphene opens a band-gap greater than 0.7eV in the otherwise continuous metallic graphene sheet. The goal of developing all-carbon electronics requires the ability to dope graphene and convert it between metallic and wide band-gap semiconducting forms. While doping graphene by adsorbates or more elaborate chemical means has made rapid progress, 1-7 opening a band-gap in graphene has been problematic. Two routes to wide-band-gap semiconducting graphene have been pioneered: electron confinement and chemical functionalization. Electron confinement in lithographically patterned narrow graphene ribbons has been plagued by lithographic limits and edge disorder, 8-11 although recent results from sidewall grown graphene ribbon are showing new progress that could lead to band-gaps larger than 0.6eV. 12,13 Functionalized graphene band-gaps can be produced by imposing a periodic potential in the graphene lattice through ordered adsorbates 14,15 or ordered impurities replacing carbon atoms. 16 In this work we demonstrate a novel approach to bandgap engineering in graphene using a nitrogen seeded SiC surface. Rather than using chemical vapor deposition (CVD) or plasma techniques to dope graphene by post seeding the films with nitrogen, 5-7,17 we show that a submonolayer concentration of nitrogen adsorbed on SiC, prior to graphene growth, causes a large band-gap to open in the subsequently grown, continuous graphene sheets. Using X-ray photoemission spectroscopy (XPS), scanning tunneling microscopy (STM), and angle resolved photoemission spectroscopy (ARPES), we show that a submonolayer concentration of bonded nitrogen at the graphene-SiC interface leads to a 0.7eV semiconducting form of graphene.The band-gap is not due to chemical functionalization since the concentrations used in these studies are expected to have little effect on graphene's band structure. 16,18 Instead, STM topographs and dI/dV images, showing that the graphene is buckled into folds with 1-2nm radii of curvature, suggests two possible origins for the gap: either a quasi-periodic strain 19 or electron localization in the 1-2 nm wide buckled ribbons. 20

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Charge neutrality and band-gap tuning of epitaxial graphene on SiC by molecular doping

Cited by 415 publications

References 48 publications

Single-particle tunneling in doped graphene-insulator-graphene junctions

Single-particle tunneling in doped graphene-insulator-graphene junctions

Molecular Doping and Band-Gap Opening of Bilayer Graphene

Wide-Gap Semiconducting Graphene from Nitrogen-Seeded SiC

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