Raman Imaging and Electronic Properties of Graphene

Molitor, F.; Graf, David; Stampfer, Christoph; Ihn, Thomas; Ensslin, Klaus

doi:10.1007/978-3-540-74325-5_14

Cited by 7 publications

(6 citation statements)

References 12 publications

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“…The sp 3 sites introduce a different arrangement of the carbon atoms, but do not break the network [27,30,31,32]. This peak is always present in defects in graphene, even if it is often difficult to measure due to the superposition with the G peak [33,34]. The D + D ’ is also a defect activated peak and is only visible in the presence of high amount of defects [12,18].…”

Section: Resultsmentioning

confidence: 99%

NO2 and NH3 Sensing Characteristics of Inkjet Printing Graphene Gas Sensors

Travan

Bergmann

2019

Sensors

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Graphene is a good candidate for filling the market requirements for cheap, high sensitivity, robust towards contamination, low noise, and low power consumption gas sensors, thanks to its unique properties, i.e., large surface, high mobility, and long-term stability. Inkjet printing is a cheap additive manufacturing method allowing fast, relatively precise and contactless deposition of a wide range of materials; it can be considered therefore the ideal technique for fast deposition of graphene films on thin substrates. In this paper, the sensitivity of graphene-based chemiresistor gas sensors, fabricated through inkjet printing, is investigated using different concentrations of graphene in the inks. Samples have been produced and characterized in terms of response towards humidity, nitrogen dioxide, and ammonia. The presented results highlight the importance of tuning the layer thickness and achieving good film homogeneity in order to maximize the sensitivity of the sensor.

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Section: Resultsmentioning

confidence: 99%

NO2 and NH3 Sensing Characteristics of Inkjet Printing Graphene Gas Sensors

Travan

Bergmann

2019

Sensors

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“…4 in Ref. 23. The symmetric hole and electron charging-dependent stiffening of the E 2g ⌫ phonon was recently explained as the effect of a͒ Author to whom correspondence should be addressed.…”

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confidence: 94%

Raman imaging of doping domains in graphene on SiO2

Stampfer¹,

Molitor²,

Graf³

et al. 2007

Applied Physics Letters

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217

216

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We present spatially resolved Raman images of the G and 2D lines of single-layer graphene flakes. The spatial fluctuations of G and 2D lines are correlated and are thus shown to be affiliated with local doping domains. We investigate the position of the 2D line-the most significant Raman peak to identify single-layer graphene-as a function of charging up to ͉n͉Ϸ4 ϫ 10 12 cm −2 . Contrary to the G line which exhibits a strong and symmetric stiffening with respect to electron and hole doping, the 2D line shows a weak and slightly asymmetric stiffening for low doping. Additionally, the linewidth of the 2D line is, in contrast to the G line, doping independent making this quantity a reliable measure for identifying single-layer graphene. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2816262͔Graphene has attracted increasing attention over the last few years. 1,2 Its unique electronic properties, 3,4 mainly due to the linear energy versus momentum dispersion and the electron hole symmetry near the charge neutrality point, make it an interesting nanomaterial for high mobility electronics. 5,6 Raman spectroscopy has proven to be a powerful tool to distinguish single-layer graphene from few-layer graphene and graphite. [7][8][9][10][11] The particular electronic structure of graphite and graphene leads to Kohn anomalies in the phonon dispersion at the ⌫ and K points. 12-14 Additionally, the BornOppenheimer approximation, which is usually employed for the calculation of phonon frequencies, is no longer valid because the vibration period is much smaller than the electronmomentum relaxation time. Furthermore, a pronounced stiffening of the Raman G line upon positive or negative charging ͑p or n doping͒ of the graphene sheet is observed. [15][16][17] In this paper, we investigate how spatially resolved Raman spectroscopy can be used to probe doping domains and local charge fluctuations. While electron-hole puddles ͑i.e., local charge fluctuations͒ have been predicted to be responsible for the finite conductance at vanishing ͑av-erage͒ charge carrier density 18 and have recently been observed using a scanning single electron transistor, 19 the identification of different doping domains might be desirable to investigate graphene devices. Here, we report on Raman measurements on back gate controlled charged graphene and on Raman imaging of doping fluctuations of isolated graphene flakes. We focus on the correlation between the shifts of the G line and 2D line ͑or D * line͒. The latter one is the most significant Raman peak in single-layer graphene. 7,9 Within the low charging regime ͑up to ±4 ϫ 10 12 cm −2 ͒ obtained in our experiments, the 2D line stiffens for both electron and hole charging while its linewidth ͑in contrast to the G line͒ is not affected by charging. A good correlation between the shift of G and 2D lines is observed. However, the spectral resolution and lateral resolution are not sufficient to resolve electron-hole puddles, as shown in Ref. 19. Therefore, we refer to charging ͑i.e., doping͒ domains ra...

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“…Graphene is a two-dimensional material composed of carbon atoms packed through sp 2 hybridization 13 . Graphene has attracted significant attention due to its extraordinary mechanical 14 , thermal 15 , optical 16 and electronic properties 17 . In addition to graphene, graphene based composites are now also being extensively produced and investigated due to their unique properties 18 .…”

Section: Introductionmentioning

confidence: 99%

First Report on High Entropy Alloy Nanoparticle Decorated Graphene

Rekha

Mallik

Srivastava

2018

Sci Rep

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This is the first report on synthesis of multimetal high entropy alloy (HEA) nanoparticle-few layer graphene composite. A two-step methodology for synthesizing multi-component HEA nanoparticle-graphene composite is provided. In the first step, high purity graphite powder was mechanically milled with metal powders (Ni, Cr, Co, Cu, Fe) to produce multimetal-graphite composite. This composite was then sonicated with sodium lauryl sulphate (SLS) for 2 hours to produce a dispersion of graphene decorated with multi-component nanoparticles with face centred cubic structure. Potentiodynamic polarization and electrochemical impedance spectroscopy methods revealed that the HEA nanoparticle graphene composite possess excellent corrosion resistance properties which was better than the corrosion resistance exhibited by milled and exfoliated graphene. The HEA nanoparticle-graphene composite can be used for corrosion resistant coating applications.

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Raman Imaging and Electronic Properties of Graphene

Cited by 7 publications

References 12 publications

NO2 and NH3 Sensing Characteristics of Inkjet Printing Graphene Gas Sensors

NO2 and NH3 Sensing Characteristics of Inkjet Printing Graphene Gas Sensors

Raman imaging of doping domains in graphene on SiO2

First Report on High Entropy Alloy Nanoparticle Decorated Graphene

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