Graphene adhesion on mica: Role of surface morphology

Руденко, А. Н.; Keil, Frerich J.; Katsnelson, M. I.; Lichtenstein, A. I.

doi:10.1103/physrevb.83.045409

Cited by 70 publications

(99 citation statements)

References 43 publications

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“…The calculated bandgap was about 3.2 eV, being much smaller than the experimental value of 7.85 eV. 23,24 Due to the well-known shortcomings of the DFT calculation in the generalized gradient approximation (GGA), our electronic structure underestimates the bandgap energy. Similarly, previous literature indicated that the DFT-calculated bandgaps are much smaller than experimentally measured ones for various semiconductors, including ZnO and ZrO 2 (Supporting Information, Text S1).…”

Section: ■ Results and Discussionmentioning

confidence: 68%

Tunable Bandgap Narrowing Induced by Controlled Molecular Thickness in 2D Mica Nanosheets

et al. 2015

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Bandgap engineering of atomically thin 2D crystals is critical for their applications in nanoelectronics, optoelectronics, and photonics. Here, we report a simple but rather unexpected approach for bandgap engineering of muscovite-type mica nanosheets (KAl 3 Si 3 O 10 (OH) 2 ) via controlled molecular thickness. Through density functional calculations, we analyze electronic structures in 2D mica nanosheets and develop a general picture for tunable bandgap narrowing induced by controlled molecular thickness. From conducting atomic force microscopy, we observe an abnormal bandgap narrowing in 2D mica nanosheets, contrary to wellknown quantum size effects. In mica nanosheets, decreasing the number of layers results in reduced bandgap energy from 7 to 2.5 eV, and the bilayer case exhibits a semiconducting nature with ∼2.5 eV. Structural modeling by transmission electron microscopy and density functional calculations reveal that this bandgap narrowing can be defined as a consequence of lattice relaxations as well as surface doping effects. These bandgap engineered 2D mica nanosheets open up an exciting opportunity for new physical properties in 2D materials and may find diverse applications in 2D electronic/optoelectronic devices. ■ INTRODUCTIONTwo-dimensional (2D) nanosheets with atomic or molecular thickness are emerging as important new materials because of their particular properties and potential applications in nextgeneration electronic devices. 1−12 One attractive aspect of these exfoliated nanosheets is that various nanostructures can be fabricated using them as 2D building blocks. Sophisticated functionalities or nanodevices may be designed through combining different nanosheets with a precise control over their arrangement on a molecular scale. The discovery of graphene can be considered a defining point in the research and development of such 2D material systems. 1,2,12 This breakthrough has opened up the possibility of exploring the fascinating properties of 2D nanosheets of other inorganic layered materials; 2−11 the reduction to single or a few atomic layers will offer new properties and novel applications. 13 To expand the utility of these 2D nanosheets, the electronic properties must be tailored through bandgap engineering and/ or doping process. Bandgap engineering of 2D nanosheets is particularly important for their applications in nanoelectronics, optoelectronics, and photonics. One key issue in the developments of 2D nanosheets is to produce semiconductor nanosheets with a narrow bandgap or a semiconductor-tometal transition, since it allows the use of field effect transistors (FETs) as well as the effective operation for low-energy absorptions and excitation of semiconductor optoelectronics. A possible indication of the bandgap engineering came from MoS 2 nanosheets, which exhibited a crossover behavior from an indirect to a direct-gap semiconductor in the monolayer limit. 14 However, the bandgap narrowing of nanomaterials is almost always difficult to achieve, since most nanomaterials would show ...

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Section: ■ Results and Discussionmentioning

confidence: 68%

Tunable Bandgap Narrowing Induced by Controlled Molecular Thickness in 2D Mica Nanosheets

et al. 2015

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“…When in contact with the mica surface graphene conserves its unique properties27, even when mica has been shown to induce doping of graphene1526. In a previous study we have shown that graphene above the double water layer is only slightly n-type doped.…”

Section: Resultsmentioning

confidence: 94%

Graphene Visualizes the Ion Distribution on Air-Cleaved Mica

Bampoulis

Sotthewes

Siekman

et al. 2017

Sci Rep

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The distribution of potassium (K+) ions on air-cleaved mica is important in many interfacial phenomena such as crystal growth, self-assembly and charge transfer on mica. However, due to experimental limitations to nondestructively probe single ions and ionic domains, their exact lateral organization is yet unknown. We show, by the use of graphene as an ultra-thin protective coating and scanning probe microscopies, that single potassium ions form ordered structures that are covered by an ice layer. The K+ ions prefer to minimize the number of nearest neighbour K+ ions by forming row-like structures as well as small domains. This trend is a result of repulsive ionic forces between adjacent ions, weakened due to screening by the surrounding water molecules. Using high resolution conductive atomic force microscopy maps, the local conductance of the graphene is measured, revealing a direct correlation between the K+ distribution and the structure of the ice layer. Our results shed light on the local distribution of ions on the air-cleaved mica, solving a long-standing enigma. They also provide a detailed understanding of charge transfer from the ionic domains towards graphene.

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“…Here, the authors argued in favour of a Kondo effect with full screening, as three conductionband channels coupled to the impurity spin. Finally, in a refined quantum-chemical calculation [19] based on a complete active-space self-consistent field approach, albeit on small clusters, it was found that Co in an h position favours a higher-spin state of S = 3/2.…”

Section: Magnetic Adatoms On Graphenementioning

confidence: 98%

The physics of Kondo impurities in graphene

Fritz¹,

Vojta²

2013

Rep. Prog. Phys.

144

197

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Abstract. This article summarizes our understanding of the Kondo effect in graphene, primarily from a theoretical perspective. We shall describe different ways to create magnetic moments in graphene, either by adatom deposition or via defects. For dilute moments, the theoretical description is in terms of effective Anderson or Kondo impurity models coupled to graphene's Dirac electrons. We shall discuss in detail the physics of these models, including their quantum phase transitions and the effect of carrier doping, and confront this with existing experimental data. Finally, we point out connections to other quantum impurity problems, e.g., in unconventional superconductors, topological insulators, and quantum spin liquids.arXiv:1208.3113v2 [cond-mat.str-el]

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Graphene adhesion on mica: Role of surface morphology

Cited by 70 publications

References 43 publications

Tunable Bandgap Narrowing Induced by Controlled Molecular Thickness in 2D Mica Nanosheets

Tunable Bandgap Narrowing Induced by Controlled Molecular Thickness in 2D Mica Nanosheets

Graphene Visualizes the Ion Distribution on Air-Cleaved Mica

The physics of Kondo impurities in graphene

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