Band Engineering and Magnetic Doping of Epitaxial Graphene on SiC (0001)

Jayasekera, Thushari; Kong, Byoung Don; Kim, Ki Wook; Nardelli, Marco Buongiorno

doi:10.1103/physrevlett.104.146801

Cited by 64 publications

(51 citation statements)

References 28 publications

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“…[12][13][14] The geometry of the graphene/SiC interface and the bonding that takes place in this region play a dominant role in the determination of the electronic properties of the active graphene layers: interface modifications can lead to a fine-tuning of the doping and band alignment of the system and provide a clear insight into the mechanisms of charge transfer and interface stability. 15 These findings, when placed in the more general context of ambient exposed graphene samples, provide the framework for the interpretation of the experimental results and a generalization to a universal behavior that should be expected in many other common situations. The goal of our study is to provide a quantitative and systematic evaluation of the impact of ambient exposure in epitaxial graphene samples.…”

Section: Methodsmentioning

confidence: 65%

Charge transfer equilibria in ambient-exposed epitaxial graphene on (0001¯) 6 H-SiC

Sidorov

Gaskill

Nardelli

et al. 2012

Journal of Applied Physics

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The transport properties of electronic materials have been long interpreted independently from both the underlying bulk-like behavior of the substrate or the influence of ambient gases. This is no longer the case for ultra-thin graphene whose properties are dominated by the interfaces between the active material and its surroundings. Here, we show that the graphene interactions with its environments are critical for the electrostatic and electrochemical equilibrium of the active device layers and their transport properties. Based on the prototypical case of epitaxial graphene on (000 1) 6 H-SiC and using a combination of in-situ thermoelectric power and resistance measurements and simulations from first principles, we demonstrate that the cooperative occurrence of an electrochemically mediated charge transfer from the graphene to air, combined with the peculiar electronic structure of the graphene/SiC interface, explains the wide variation of measured conductivity and charge carrier type found in prior reports. V C 2012 American Institute of Physics. [http://dx

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Section: Methodsmentioning

confidence: 65%

Charge transfer equilibria in ambient-exposed epitaxial graphene on (0001¯) 6 H-SiC

Sidorov

Gaskill

Nardelli

et al. 2012

Journal of Applied Physics

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“…Figure 2(b) shows the band structures (left) without and (right) with the SOC for graphene/intercalated Bi/SiC. Not only does the gap not open, but the Bi also introduces an undesirable impurity state near the Fermi level, similar to light metal intercalations such as lithium 27 .…”

Section: Resultsmentioning

confidence: 99%

Topological insulators in transition-metal intercalated graphene: The role ofdelectrons in significantly increasing the spin-orbit gap

Tang

Chen

et al. 2013

Phys. Rev. B

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We study the effect of transition metal intercalation of graphene on the formation of twodimensional topological insulator with experimentally measurable edge states. Our first-principles calculations reveal that the spin-orbit coupling (SOC) gap in Re-intercalated graphene on SiC(0001) substrate can be as large as 100 meV. This value is five orders of magnitude larger than that of pristine graphene. Similar effect should also exist in Mn-or Tc-intercalated graphene. A tight-binding model Hamiltonian analysis establishes the role of orbital coupling between graphene p states and transition metal d states on the formation of the SOC gap. Remarkably, the gap can be larger than atomic SOC, as is the case for Mn. This finding opens the possibility of designing topological insulators comprised of only relatively light elements. Our study also reveals that the presence of the substrate should induce a splitting between the K and K' valleys with the potential to integrate spintronics with valleytronics.

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“…Other computational details are the same as in Ref. 17. All calculations include 1 Na atom per 8 graphene carbon atoms in a computational unit cell that includes a carbon-rich buffer layer strongly bonded to the SiC surface but leaving several unsaturated dangling bonds.…”

Section: Methodsmentioning

confidence: 99%

“…15,16 Theoretical studies demonstrated that modifications in the chemical composition of the buffer can lead to significant changes of the graphene bands, allowing for a fine tuning of the electronic structure of the system with band offsets up to 1.5 eV and even inducing magnetism of the graphene. 17 Alkali metal adsorption on graphene has been used extensively to study the effects of electron doping. Potassium deposition on graphene on SiC(0001) has enabled detailed studies of quasiparticles 18 and the discovery of plasmarons 19 in graphene.…”

Section: Introductionmentioning

confidence: 99%

Multiple coexisting intercalation structures of sodium in epitaxial graphene-SiC interfaces

et al. 2012

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We show using scanning tunneling microscopy, spectroscopy, and ab initio calculations that two intercalation structures coexist for Na in epitaxial graphene on SiC(0001). Intercalation takes place at room temperature, and Na electron dopes the graphene. It inserts in between single-layer graphene and the interfacial layer and also penetrates beneath the interfacial layer and decouples it to form a second graphene layer. Decoupling is accelerated by annealing and is verified by Na deposition onto the interface layer combined with computational modeling of the two new decoupled buffer layer structures.

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Band Engineering and Magnetic Doping of Epitaxial Graphene on SiC (0001)

Cited by 64 publications

References 28 publications

Charge transfer equilibria in ambient-exposed epitaxial graphene on (0001¯) 6 H-SiC

Charge transfer equilibria in ambient-exposed epitaxial graphene on (0001¯) 6 H-SiC

Topological insulators in transition-metal intercalated graphene: The role ofdelectrons in significantly increasing the spin-orbit gap

Multiple coexisting intercalation structures of sodium in epitaxial graphene-SiC interfaces

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