Buffer layers inhomogeneity and coupling with epitaxial graphene unravelled by Raman scattering and graphene peeling

Wang, Tianlin; Huntzinger, Jean-Roch; Bayle, Maxime; Roblin, Christophe; Decams, Jean-Manuel; Zahab, Ahmed-Azmi; Contreras, Sylvie; Paillet, Matthieu; Landois, Périne

doi:10.1016/j.carbon.2020.03.027

Cited by 21 publications

(15 citation statements)

References 52 publications

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“…The presence of graphene films on the SiC surface was confirmed by Raman spectroscopy, as shown in Figure 2 . Before and after functionalization, the Raman spectra of the chips in the region of 1300–3000 cm −1 were dominated by sharp G and 2D lines characteristic of monolayer graphene [ 21 ] and wide asymmetric bands centered at approximately 1380 and 1550 cm −1 corresponding to the buffer layer [ 22 ]. After functionalization, a new D line at ~1350 cm −1 appeared in the spectra.…”

Section: Resultsmentioning

confidence: 99%

Investigation of the Morphology and Electrical Properties of Graphene Used in the Development of Biosensors for Detection of Influenza Viruses

et al. 2021

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In this study, we discuss the mechanisms behind changes in the conductivity, low-frequency noise, and surface morphology of biosensor chips based on graphene films on SiC substrates during the main stages of the creation of biosensors for detecting influenza viruses. The formation of phenylamine groups and a change in graphene nano-arrangement during functionalization causes an increase in defectiveness and conductivity. Functionalization leads to the formation of large hexagonal honeycomb-like defects up to 500 nm, the concentration of which is affected by the number of bilayer or multilayer inclusions in graphene. The chips fabricated allowed us to detect the influenza viruses in a concentration range of 10−16 g/mL to 10−10 g/mL in PBS (phosphate buffered saline). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) revealed that these defects are responsible for the inhomogeneous aggregation of antibodies and influenza viruses over the functionalized graphene surface. Non-uniform aggregation is responsible for a weak non-linear logarithmic dependence of the biosensor response versus the virus concentration in PBS. This feature of graphene nano-arrangement affects the reliability of detection of extremely low virus concentrations at the early stages of disease.

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Section: Resultsmentioning

confidence: 99%

Investigation of the Morphology and Electrical Properties of Graphene Used in the Development of Biosensors for Detection of Influenza Viruses

et al. 2021

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“…To prevent the formation of MLG the wafers were heated only to T gr = 1600 • C (zero growth time). The Raman spectra reveal features in the 1200-1700 cm −1 range, typical for the buffer layer[26,28,36]. The band around 1330 cm −1 appears to be on par in terms of intensity with the band around 1580 cm −1 for all samples.…”

mentioning

confidence: 81%

“…[35], where v F = 1.02 × 10 6 m s −1 is the Fermi velocity and N s is the carrier sheet density. 1585 cm −1 (G B ) can be used to evaluate the content of sp 3 hybridization [26] or discuss correlations associated with buffer structure in general [28]. We will comeback to this question when comparing buffer layers grown on n-type and SI SiC.…”

Section: Methodsmentioning

confidence: 99%

“…However, this approach has not been explored despite the intense investigation of buffer layer properties and optimization. [4,[26][27][28] In this work, we report a comprehensive study on the effect of introducing Ar at different temperatures on the buffer layer formation and properties in high-temperature sublimation for both n-type and semi-insulating 4H-SiC. The free charge carrier density and mobility parameters of the corresponding MLG and quasi-free standing MLG are determined for different environmental treatment conditions and discussed.…”

Section: Introductionmentioning

confidence: 99%

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Critical View on Buffer Layer Formation and Monolayer Graphene Properties in High-Temperature Sublimation

Stanishev¹,

Armakavicius²,

Bouhafs³

et al. 2021

Preprint

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In this work we have critically reviewed the processes in high-temperature sublimation growth of graphene in Ar atmosphere using enclosed graphite crucible. Special focus is put on buffer layer formation and free charge carrier properties of monolayer graphene and quasi-freestanding monolayer garphene on 4H-SiC. We show that by introducing Ar at different temperatures, TAr one can shift to higher temperatures the formation of the buffer layer for both n-type and semi-insulating substrates. A scenario explaining the observed suppresed formation of buffer layer at higher TAr is proposed and discussed. Increased TAr is also shown to reduce the sp3 hybridization content and defect densities in the buffer layer on n-type conductive substrates. Growth on semi-insulating substrates results in ordered buffer layer with significantly improved structural properties, for which TAr plays only a minor role. The free charge density and mobility parameters of monolayer graphene and quasi-freestanding monolayer graphene with different TAr and different environmental treatment conditions are determined by contactless terahertz optical Hall effect. An efficient annealing of donors on and near the SiC surface takes place in intrinsic monolayer graphene grown at 2000∘C, and which is found to be independent of TAr. Higher TAr leads to higher free charge carrier mobility parameters in both intrinsically n-type and ambient p-type doped monolayer graphene. TAr is also found to have a profound effect on the free hole parameters of quasi-freestanding monolayer graphene. These findings are discussed in view of interface and buffer layer properties in order to construct a comprehensive picture of high-temperature sublimation growth and provide guidance for growth parameters optimization depending on the targeted graphene application.

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“…To avoid heating and damage to the sample, the laser power was limited to 4 mW. Two main features in the presented spectra, namely the sharp and intense G and 2 D lines, are originating from the graphene film [ 37 ], while the complex background with several maxima in the 1300–1600 cm −1 range corresponds to the buffer layer, which is an interface carbon layer located between the graphene film and the 4 H -SiC substrate [ 38 ].…”

Section: Study Of the Parameters Of The Obtained Epitaxial Filmsmentioning

confidence: 99%

Graphene on SiC Substrate as Biosensor: Theoretical Background, Preparation, and Characterization

et al. 2021

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This work is devoted to the development and optimization of the parameters of graphene-based sensors. The graphene films used in the present study were grown on semi-insulating 6H-SiC substrates by thermal decomposition of SiC at the temperature of ~1700 °C. The results of measurements by Auger and Raman spectroscopies confirmed the presence of single-layer graphene on the silicon carbide surface. Model approach to the theory of adsorption on epitaxial graphene is presented. It is demonstrated that the Green-function method in conjunction with the simple substrate models permit one to obtain analytical results for the charge transfer between adsorbed molecules and substrate. The sensor structure was formed on the graphene film by laser. Initially, a simpler gas sensor was made. The sensors developed in this study demonstrated sensitivity to the NO2 concentration at the level of 1–0.01 ppb. The results obtained in the course of development and the results of testing of the graphene-based sensor for detection of protein molecules are also presented. The biosensor was fabricated by the technology previously developed for the gas sensor. The working capacity of the biosensor was tested with an immunochemical system constituted by fluorescein and monoclonal antibodies (mAbs) binding this dye.

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Buffer layers inhomogeneity and coupling with epitaxial graphene unravelled by Raman scattering and graphene peeling

Cited by 21 publications

References 52 publications

Investigation of the Morphology and Electrical Properties of Graphene Used in the Development of Biosensors for Detection of Influenza Viruses

Investigation of the Morphology and Electrical Properties of Graphene Used in the Development of Biosensors for Detection of Influenza Viruses

Critical View on Buffer Layer Formation and Monolayer Graphene Properties in High-Temperature Sublimation

Graphene on SiC Substrate as Biosensor: Theoretical Background, Preparation, and Characterization

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