Influence of transfer residue on the optical properties of chemical vapor deposited graphene investigated through spectroscopic ellipsometry

Matković, Aleksandar; Ralević, Uroš; Chhikara, Manisha; Jakovljević, Milka; Jovanović, Dragoljub; Bratina, Gvido; Gajić, Radoš

doi:10.1063/1.4819967

Cited by 40 publications

(35 citation statements)

References 45 publications

(46 reference statements)

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“…7 and ESI †). Comparing these results with the others previously reported, 16,18,28 it is evident that although a better agreement can be achieved in the near UV region, it fails in the visible range. Therefore, a variable graphene thickness would not be the reason for the inappropriate n, k values obtained after data analyses using the sample structure proposed in Fig.…”

Section: Optical Propertiessupporting

confidence: 82%

Determination of a refractive index and an extinction coefficient of standard production of CVD-graphene

et al. 2015

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The refractive index and extinction coefficient of chemical vapour deposition grown graphene are determined by ellipsometry analysis. Graphene films were grown on copper substrates and transferred as both monolayers and bilayers onto SiO 2 /Si substrates by using standard manufacturing procedures. The chemical nature and thickness of residual debris formed after the transfer process were elucidated using photoelectron spectroscopy. The real layered structure so deduced has been used instead of the nominal one as the input in the ellipsometry analysis of monolayer and bilayer graphene, transferred onto both native and thermal silicon oxide. The effect of these contamination layers on the optical properties of the stacked structure is noticeable both in the visible and the ultraviolet spectral regions, thus masking the graphene optical response. Finally, the use of heat treatment under a nitrogen atmosphere of the graphene-based stacked structures, as a method to reduce the water content of the sample, and its effect on the optical response of both graphene and the residual debris layer are presented. The Lorentz-Drude model proposed for the optical response of graphene fits fairly well the experimental ellipsometric data for all the analysed graphene-based stacked structures.

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Section: Optical Propertiessupporting

confidence: 82%

Determination of a refractive index and an extinction coefficient of standard production of CVD-graphene

et al. 2015

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“…The same researchers have performed ellipsometry in situ to study the evolution of processes on fixed substrates, such as the drying of deposited very thin graphene films [101], using a Sopra GES5E-IRSE (Sopra SAS, Avenue de l’Europe, 92400, Courbevoie, France). Similar ellipsometers with a reaction chamber for in situ monitoring of surface processes on the laboratory scale are manufactured by Sentech (SE 400adv) (SENTECH Instruments GmbH, Berlin, Germany) and Horiba (Uvisel In-Situ) (HORIBA UK Limited, 2 Dalston Gardens, Stanmore Middlesex HA7 1BQ, UK).…”

Section: Thickness Monitoringmentioning

confidence: 99%

Recent Prospects in the Inline Monitoring of Nanocomposites and Nanocoatings by Optical Technologies

et al. 2016

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Nanostructured materials have emerged as a key research field in order to confer materials with unique or enhanced properties. The performance of nanocomposites depends on a number of parameters, but the suitable dispersion of nanoparticles remains the key in order to obtain the full nanocomposites’ potential in terms of, e.g., flame retardance, mechanical, barrier, thermal properties, etc. Likewise, the performance of nanocoatings to obtain, for example, tailored surface affinity with selected liquids (e.g., for self-cleaning ability or anti-fog properties), protective effects against flame propagation, ultra violet (UV) radiation or gas permeation, is highly dependent on the nanocoating’s thickness and homogeneity. In terms of recent advances in the monitoring of nanocomposites and nanocoatings, this review discusses commonly-used offline characterization approaches, as well as promising inline systems. All in all, having good control over both the dispersion and thickness of these materials would help with reaching optimal and consistent properties to allow nanocomposites to extend their use.

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“…Graphene layer transfer often involves the use of polymer support, typically polymethylmethacrylate (PMMA), which is challenging to subsequently remove from the graphene. [34][35][36][37][38][39][40][41][42] Similar residues arise from lithographic patterning of graphene using resist layers. [43][44][45] Technologically relevant, large area CVD graphene is polycrystalline with a range of inherent defects, and upon transfer mono-and few-layer graphene tends to wrinkle.…”

mentioning

confidence: 98%

Effects of polymethylmethacrylate-transfer residues on the growth of organic semiconductor molecules on chemical vapor deposited graphene

Kratzer

Bayer

Kidambi

et al. 2015

Applied Physics Letters

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Scalably grown and transferred graphene is a highly promising material for organic electronic applications, but controlled interfacing of graphene thereby remains a key challenge. Here, we study the growth characteristics of the important organic semiconductor molecule para-hexaphenyl (6P) on chemical vapor deposited graphene that has been transferred with polymethylmethacrylate (PMMA) onto oxidized Si wafer supports. A particular focus is on the influence of PMMA residual contamination, which we systematically reduce by H2 annealing prior to 6P deposition. We find that 6P grows in a flat-lying needle-type morphology, surprisingly independent of the level of PMMA residue and of graphene defects. Wrinkles in the graphene typically act as preferential nucleation centers. Residual PMMA does however limit the length of the resulting 6P needles by restricting molecular diffusion/attachment. We discuss the implications for organic device fabrication, with particular regard to contamination and defect tolerance.

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Influence of transfer residue on the optical properties of chemical vapor deposited graphene investigated through spectroscopic ellipsometry

Cited by 40 publications

References 45 publications

Determination of a refractive index and an extinction coefficient of standard production of CVD-graphene

Determination of a refractive index and an extinction coefficient of standard production of CVD-graphene

Recent Prospects in the Inline Monitoring of Nanocomposites and Nanocoatings by Optical Technologies

Effects of polymethylmethacrylate-transfer residues on the growth of organic semiconductor molecules on chemical vapor deposited graphene

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