Raman Spectroscopy of Graphene Edges

Casiraghi, Cinzia; Hartschuh, Achim; Qian, Huihong; Piscanec, S.; Georgi, Carsten; Fasoli, Andrea; Новоселов, К. С.; Basko, D. M.; Ferrari, Andrea C.

doi:10.1021/nl8032697

Cited by 968 publications

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References 65 publications

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“…This result corroborates with our assumption that the value estimated for ℓ D in Ref. [20] corresponds to the low limit for L φ determined by the uncertainty principle. This limit is accurate for high phonon population regimes.…”

supporting

confidence: 91%

“…In addition to the peaks identified in the previous spectrum, we now also observe the defect-induced D band centered at ≃ 1350 cm −1 [18]. Due to momentum conservation, the TO phonons giving rise to this band only become Raman active if the electrons or holes involved in the scattering process undergo elastic scattering by a lattice defect, which in this case is provided by the graphene edge [19,20,26]. Therefore, the closer the position of a photo-excited electron to the graphene edge, the higher is its probability to be involved in D band scattering.…”

mentioning

confidence: 70%

“…In one interpretation, D band localization is predicted to depend on the virtual electron-hole lifetime and L φ on the electron-phonon scattering rate [20]. According to this interpretation, there is no direct relationship between D band localization and L φ .…”

mentioning

confidence: 99%

“…In this letter, we use Raman scattering to experimentally determine the phase-breaking length of photo-excited electrons near the edges of graphene, where electrons undergo inelastic scattering with optical phonons. The measurements were performed using a novel optical defocusing method, which makes it possible to measure the localization of the disorder-induced Raman D band [18] with a resolution of a few nanometers.The relationship between the spatial confinement of the D band and the phase-breaking length has been debated recently [19,20]. In one interpretation, D band localization is predicted to depend on the virtual electron-hole lifetime and L φ on the electron-phonon scattering rate [20].…”

mentioning

confidence: 99%

“…The relationship between the spatial confinement of the D band and the phase-breaking length has been debated recently [19,20]. In one interpretation, D band localization is predicted to depend on the virtual electron-hole lifetime and L φ on the electron-phonon scattering rate [20].…”

mentioning

confidence: 99%

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Low Temperature Raman Study of the Electron Coherence Length near Graphene Edges

2011

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In mesoscopic physics, interference effects play a central role on the transport properties of conduction electrons, giving rise to exotic phenomena such as weak localization, Aharonov-Bohm effect, and universal conduction fluctuations. Mesoscopic objects have a size on the order of the phasebreaking length L φ , the length conduction electrons travel while keeping phase coherence. In this letter, we use vibrational spectroscopy in combination with a novel optical defocusing method to measure L φ of photo-excited electrons in graphene which undergo inelastic scattering by optical phonons. We extract L φ from the spatial confinement of the defect-induced Raman D band near the edges of graphene. Temperature dependent measurements in the range of 1.55 K to 300 K yield L φ ∝ 1/ √ T , in agreement with previous magneto-transport measurements.PACS numbers: 78.67. Wj,72.80.Vp,42.62.Fi Over the past decades, silicon based materials spurred the development of ever smaller and faster transistor devices and the production of ever larger information storage. However, as the material dimensions become comparable to the length scale of electronic wavefunctions it is necessary to explore alternative materials with enhanced performance. Low-dimensional carbon materials, such as carbon nanotubes and graphene, form a particularly promising alternative to silicon based materials [1,2]. Monolayer graphene exhibits unique electronic transport properties, such as high electron mobility at room temperature (≥ 10 4 cm 2 /Vs) and tunable carrier densities as high as 10 13 cm −2 [3]. These properties have led to extensive research and motivated the development of proof-of-concept devices, such as single electron transistors (SETs), field-effect transistors (FETs), and even graphene-based memory [6][7][8]. Although single-crystal graphene is metallic (unable to confine electrons electrostatically), it can become semiconducting when produced in a narrow (≤ 10 nm) ribbon-like geometry, a manifestation of electronic quantum confinement [1].Conduction electrons confined to nanometer length scales cease to show a purely diffusing behavior as predicted by the Boltzmann transport theory. In this regime, the dephasing length of conduction electrons becomes larger than the device itself, and interference effects give rise to weak localization, Aharonov-Bohm effect, and universal conduction fluctuations [12][13][14][15]. These interference effects extend over the length L φ , the electron phase-breaking length [16,17]. In this letter, we use Raman scattering to experimentally determine the phase-breaking length of photo-excited electrons near the edges of graphene, where electrons undergo inelastic scattering with optical phonons. The measurements were performed using a novel optical defocusing method, which makes it possible to measure the localization of the disorder-induced Raman D band [18] with a resolution of a few nanometers.The relationship between the spatial confinement of the D band and the phase-breaking length has been debated recen...

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confidence: 70%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Low Temperature Raman Study of the Electron Coherence Length near Graphene Edges

2011

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Large‐Area Graphene and Carbon Nanosheets for Organic Electronics: Synthesis and Growth Mechanism

Joh

Bae

Lee

et al. 2015

Nanomaterials, Polymers, and Devices

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Synthesis and Characterization of Graphene

Das

Sudhagar

Kang

et al. 2015

Carbon Nanomaterials for Advanced Energy Systems

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Graphene is an important nanoscale material with unique electronic and optical properties. Due to its many potential applications, grapheme was the subject of a Nobel Prize in physics 2010; Andre Geim and Kostya Novoselov of Manchester University received the Nobel Prize for demonstrating the ability to create single atom thick graphene layers from bulk graphite. Since then, many alternative synthesis techniques and device applications of graphene have been explored. An important and unique property of graphene is its excellent thermal properties.Graphene has a two dimensional structure and the thermal properties are significantly different than three dimensional bulk materials. Using graphene by itself or as a composite for thermal management presents new opportunities for its impact on numerous applications including green technologies for power generation. . Due to the strength of its 0.142 Nm-long carbon bonds, graphene is the strongest material ever discovered, with an ultimate tensile strength of 130,000,000,000 Pascals (or 130 gigapascals), compared to 400,000,000 for A36 structural steel. Not only is graphene extraordinarily strong, it is also very light at 0.77milligrams per square meter (for comparison purposes, 1 square meter of paper is roughly 1000 times heavier). It is often said that a single sheet of graphene (being only 1 atom thick), sufficient in size enough to cover a whole football field, would weigh under 1 single gram. These values are theoretical values. To test these values requires flawless graphene which currently is very hard to be commercially produced. (Graphanea, n.d.) Optical properties Graphene's ability to absorb a rather large 2.3% of white light is also a unique and interesting property, especially considering that it is only 1 atom thick. This is due to its aforementioned electronic properties; the electrons acting like massless charge carriers with very high mobility.( Graphanea, n.d.

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Raman Spectroscopy of Graphene Edges

Cited by 968 publications

References 65 publications

Low Temperature Raman Study of the Electron Coherence Length near Graphene Edges

Low Temperature Raman Study of the Electron Coherence Length near Graphene Edges

Large‐Area Graphene and Carbon Nanosheets for Organic Electronics: Synthesis and Growth Mechanism

Synthesis and Characterization of Graphene

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