Antiresonances in the Mid-Infrared Vibrational Spectrum of Functionalized Graphene

Lapointe, François; Rousseau, Bruno; Aymong, Vincent; Nguyen, Minh; Biron, Maxime; Gaufrès, Étienne; Choubak, Saman; Han, Zheng; Bouchiat, Vincent; Desjardins, P.; Côté, Michel; Martel, Richard

doi:10.1021/acs.jpcc.7b01386

Cited by 8 publications

(18 citation statements)

References 56 publications

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“…As example, the deconvolution of the spectrum for a 12.3 at% flake is shown in Figure 3a. [32] The additional peak between the D and G modes at 1456.5 cm −1 is generally attributed to the presence of F-containing covalent groups at the basal plane of the flakes, [16] and its large width is an artefact associated with the close proximity to the more intensive D and G modes. [32] The additional peak between the D and G modes at 1456.5 cm −1 is generally attributed to the presence of F-containing covalent groups at the basal plane of the flakes, [16] and its large width is an artefact associated with the close proximity to the more intensive D and G modes.…”

Section: Fluorographenementioning

confidence: 99%

“…As example, the deconvolution of the spectrum for a 12.3 at% flake is shown in Figure a. Besides the typical D‐ and G‐mode peaks at 1335 and 1587.5 cm −1 , respectively, additional features were observed: a D* mode at 1610 cm −1 and an additional peak at 1250 cm −1 , which can be attributed to the amorphization (local polycrystallinity) of the FG material . The additional peak between the D and G modes at 1456.5 cm −1 is generally attributed to the presence of F‐containing covalent groups at the basal plane of the flakes, and its large width is an artefact associated with the close proximity to the more intensive D and G modes.…”

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confidence: 97%

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Electrical Transport in Devices Based on Edge‐Fluorinated Graphene

Koleśnik-Gray

Sysoev

Gollwitzer

et al. 2018

Adv Elect Materials

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When considering fluorinated graphene (FG)-based functional device technology, the device architectures must be chosen adequately. Typically, functionalized graphene devices can be envisaged as either large scale (area)-based thin film structures or as systems integrated from individual nanoobjects. This implies potentially significant qualitative and quantitative differences in the device response. Specifically, the presence of edges in graphene can be decisive. Considering the electrical conductivity of individual mono-and fewlayer flakes, it is dominated by the type, amount, and bonding position (basal or edge) of functional groups attached to the C(sp 2 ) matrix. In thin film-based systems, however, the charge transport also is largely affected by the properties of edge/edge, edge/plane, and plane/plane junctions. [22] Therefore, electrical characterization is a primary means to evaluate and benchmark whether or not a given derivative meets the requirements for selected applications.In the present work we study the impact of F content and bonding position on the electronic properties of graphene fluorinated by BrF 3 vapor at room temperature [8,20] in the range of 2.4-16.6 at%. We compared the electrical conductivity of thin films with the conductivity of corresponding individual FG flakes which constitute the former. We found a significant difference in the conductivity dependence on the degree of fluorination for the two device architectures: While in the case of thin films, a strong decrease in conductivity with fluorine content was observed, individual flakes showed an increase in conductivity and exhibited graphene-like bipolar transfer characteristics with electron and hole mobilities of the order of few 1000s cm 2 V −1 s −1 for F content approaching 17 at%. With further aid of scanning electron and Raman microscopy, this qualitative difference between films and single flakes was attributed to the circumstance that the preferred sites for fluorination are at the edges rather than basal planes of the FG.For the characterization of thin film devices, 3 mm long and 1 mm wide structures were defined using a hard-mask technique (Figure 1a). FG dispersions were sprayed onto Si wafers with 300 nm thermal SiO 2 on top, resulting in homogeneous and continuous films (Figure 1b), which were then electrically contacted with conducting silver paste. For electrical characterization of individual flakes, small amounts of the dispersionsThe conductivity of few-and monolayer graphene with covalently bound moieties is a key-point in the potential application of these materials in any electrical and optoelectronic device. In particular, fluorination of such graphene-based systems is of interest, as fluorine is expected to have a strong influence on the charge-carrier density due to its high electronegativity, and therefore modify the electrical transport properties significantly. Here it is shown that, depending on the device architecture, the electrical properties of fluorinated graphene-based devices are significantly d...

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Section: Fluorographenementioning

confidence: 99%

mentioning

confidence: 97%

Electrical Transport in Devices Based on Edge‐Fluorinated Graphene

Koleśnik-Gray

Sysoev

Gollwitzer

et al. 2018

Adv Elect Materials

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“…2,5 The dependence on nanotube length appears to have been confirmed 4,5,8 but the effect of dopant concentration appears to have eluded closer experimental inspection, possibly because reliable protocols for attaining and quantifying doping levels have become available only recently. 15 Fano antiresonances in the MIR spectrum of mixed-chirality carbon nanotubes and monolayer graphene have also shed some light on the coupling of low-energy intraband electronic excitations to phonons, 3,7,8 similar to the Breit-Wigner-Fano lineshapes observed in resonance Raman spectra of metallic nanotubes. [16][17][18] Specifically, the intensity of MIR Fano resonances was found to increase with both, doping level and defect density.…”

Section: Introductionmentioning

confidence: 92%

“…Plasmon and Fano resonances in carbon nanotubes have been studied extensively to better understand how these spectroscopic signatures may be used for accessing microscopic aspects of the electronic degrees of freedom in these systems as well as for probing how electronic and vibrational degrees of freedom couple with one another. [1][2][3][4][5][6][7][8][9] Plasmonic properties of carbon nanotubes and other nano-materials are also explored for their practical use, for example in surface enhanced infrared absorption 10 or infrared detectors. 11 Doping plays a decisive role in securing and tailoring the functionality of any such semiconductor-based spectroscopic or optoelectronic applications.…”

Section: Introductionmentioning

confidence: 99%

“…The proposed mechanism is based on a combination of inelastic phonon and elastic defect scattering. 3,7 What remains somewhat unclear is how doping level and sample character may affect optical spectra. The majority of prior FIR/MIR studies was performed on samples consisting of mixtures of metallic and semiconducting SWNTs or made of larger diameter semiconducting SWNTs with different chiralities.…”

Section: Introductionmentioning

confidence: 99%

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Infrared Study of Charge Carrier Confinement in Doped (6,5) Carbon Nanotubes

Eckstein¹,

Hirsch²,

Martel³

et al. 2021

Preprint

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Electronic degrees of freedom and their coupling to lattice vibrations in semiconductors can be strongly modified by doping. Accordingly, the addition of surplus charge carriers to chirality-mixed carbon nanotube samples has previously been found to give rise to a Drude-type plasmon feature as well as Fanotype antiresonances in the far-to mid-infrared spectral range (FIR/MIR). Here we investigate the FIR/MIR response of redox-chemically doped semiconducting (6,5) carbon nanotubes (s-SWNTs). We find that, contrary to expectations, the Drude-type plasmon shifts to lower wavenumbers with increasing doping level. By means of Monte-Carlo simulations of the optical response, we attribute this behavior to the confinement of excess charge carriers at low doping levels and their progressive delocalization when approaching degenerate doping. The coupling of vibrational modes to intraband excitations in the doped s-SWNTs can be probed via a double resonance process similar to that responsible for the Raman D-band. The resulting Fano antiresonances shed new light onto the character and coupling of electronic and vibrational degrees of freedom in these one-dimensional semiconductors.

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