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  • 1
    Online Resource
    Online Resource
    Some Insights into the Relaxation Mechanisms of Germanium Growing on (001) Si by Ultrahigh Vacuum Chemical Vapor Deposition
    The Electrochemical Society ; 2006
    In:  ECS Meeting Abstracts Vol. MA2006-02, No. 31 ( 2006-06-30), p. 1461-1461
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2006-02, No. 31 ( 2006-06-30), p. 1461-1461
    Abstract: Abstract not Available.
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2006-02/31/1461
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2006
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  • 2
    Online Resource
    Online Resource
    Kinetics of Selective Epitaxial Growth of Si and Relaxed Ge by Ultrahigh Vacuum Chemical Vapor Deposition in Si(001) Windows
    The Electrochemical Society ; 2006
    In:  ECS Meeting Abstracts Vol. MA2006-02, No. 31 ( 2006-06-30), p. 1463-1463
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2006-02, No. 31 ( 2006-06-30), p. 1463-1463
    Abstract: Abstract not Available.
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2006-02/31/1463
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2006
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  • 3
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    Online Resource
    (Invited) Combining Absorption, Wavelength-Dependent Raman and Fluorescence-Excitation Spectroscopy with High-Resolution Transmission Electron Microscopy for Determining the Chiral Purity of Sorted SWCNT Samples
    The Electrochemical Society ; 2021
    In:  ECS Meeting Abstracts Vol. MA2021-01, No. 11 ( 2021-05-30), p. 566-566
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2021-01, No. 11 ( 2021-05-30), p. 566-566
    Abstract: Single-wall carbon nanotubes (SWCNTs) possess unique electronic and optical properties that depend strongly on their exact chiral structure. Recent progress in the structure sorting of specific SWCNT chiralities, with increasing chiral purity[1], demands an effective characterization methodology to be developed to accurately determine the chiral composition of any SWCNT chirality. Very often, optical spectroscopy is used to assess the chiral composition of a sample, but absorption cross-sections, PL quantum efficiencies and Raman cross-sections are all depending on the exact chiral structure,[2] and can be strongly influenced by other factors such as the specific internal and external environment of the SWCNTs.[3] In this work, we systematically compare the chirality distribution obtained from 3 different optical spectroscopic techniques, i.e. absorption, wavelength-dependent Raman and fluorescence-excitation spectroscopy with the chirality distribution obtained from high-resolution transmission electron microscopy for both chirality-sorted and unsorted SWCNT samples. This combined approach demonstrates the importance of using a multi-technique characterization strategy for a reliable determination of SWCNT chirality distribution.[4] [1] J.A. Fagan, Nanoscale Adv. 1, 3307 (2019) and references therein [2] V.N. Popov, Nano Lett. 4, 1795 (2004) [3] S. Cambré et al , Angew. Chem. – Int Ed. 50, 2764 (2011); ACS nano 6, 2649 (2012) [4] A. Castan et al, Carbon 171, 968 (2021)
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2021-0111566mtgabs
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2021
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  • 4
    Online Resource
    Online Resource
    (Invited) Spectroscopic Properties of Black Phosphorus Crystals and Layers
    The Electrochemical Society ; 2021
    In:  ECS Meeting Abstracts Vol. MA2021-01, No. 14 ( 2021-05-30), p. 670-670
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2021-01, No. 14 ( 2021-05-30), p. 670-670
    Abstract: Black Phosphorus stands out in the 2D-materials panorama by its unique semiconducting properties: direct bandgap which can be tuned by the layer number in a wide range of wavelengths from visible (monolayer) to midinfrared (bulk) [1] . This tunability combined the anisotropy of the structure therefore offers promising perspectives in various fields such as electronics and photonics. However, the fast photooxidation in ambient condition, coupled to a high sensitivity to quantum confinement and dielectric environment in ultrathin BP, make very difficult the investigations on its intrinsic optical properties [2]. Further, as screening effects may strongly affect electronic and spectroscopic properties of 2D materials, it is highly desirable to investigate intrinsic properties of free-standing layers as well the ones of the bulk material which remain poorly known. To start with, we have investigated the infrared photoluminescence of BP single crystals at very low temperature [3]. Near-band-edge recombinations are observed at 2 K, including dominant excitonic transitions at 0.276 eV and a weaker one at 0.278 eV. The free-exciton binding energy is calculated with an anisotropic Wannier-Mott model and found equal to 9.1 meV. On the contrary, the PL intensity quenching of the 0.276 eV peak at high temperature is found with a much smaller activation energy, attributed to the localization of free excitons on a shallow impurity. This analysis leads us to attribute respectively the 0.276 eV and 0.278 eV PL lines to bound excitons (I°X) and free excitons (X) in BP. As a result, the value of bulk BP electronic bandgap is refined to 0.287 eV at 2K, to serve as reference for future work on thin BP layers [3] . As far as the thinnest layers are concerned, which cannot manipulated in air, we have shown that Angular resolved Electron energy loss spectroscopy implemented in Transmission Electron Microscopy (Ar-EELS-TEM) offers a unique way to investigate dielectric response of free-standing layers related to valence band and plasmon excitations with the advantage to get access to their q dispersion and their symmetry properties [4]. By combining this technique with suitable ab initio calculations, we have studied the dielectric response of free-standing BP layers as a function of the number of layers. We found optical bandgap values of 1.9 eV, 1.4 eV and 1.1 eV for the mono- bi- and trilayer respectively. Moreover, by combining our results with a simple variational model, we correlate the exciton energy with the dielectric screening. We hence demonstrate that the variations of the electronic gap are sizeably larger than the variations of the binding energy. Finally, we probe and analyze the volume and surface plasmons dispersion as a function of momentum for the 1-3 BP layers and bulk and highlight a deviation and linearization of the parabolic dispersion with strong anisotropic fingerprints [5] . [1] G. Zhang et al., Nat. Com., 8, 14071, (2017) [2] A. Favron, E. Gaufres et al Nature Mat. 14 (2015) 826. [3] E. Carré et al, 2D Materials (2020) :doi.org/10.1088/2053-1583/abca81 [4] F. Fossard et al, Phys. Rev. B 96, 115304 (2017) [5] E. Gaufres et al, Nanoletters 19, 8303 (2019); DOI: 10.1021/acs.nanolett.9b03928
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2021-0114670mtgabs
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2021
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  • 5
    Online Resource
    Online Resource
    Optical Properties of Dyes Confined into Carbon and Boron Nitride Nanotubes for Multimodal Bio-Imaging
    The Electrochemical Society ; 2018
    In:  ECS Meeting Abstracts Vol. MA2018-01, No. 6 ( 2018-04-13), p. 677-677
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2018-01, No. 6 ( 2018-04-13), p. 677-677
    Abstract: Nanotubes attracted a lot of interest as 1D nano-porous materials for the encapsulation and aggregation control of organic dyes molecules. Indeed, the 1D confinement drives the stacking of the molecules inside and enables original aggregation effects on their optical properties (1,2). When encapsulated inside carbon nanotube, organics dyes such as 6T, exhibits for example a strong and specific Raman scattering but their luminescence is efficiently quenched by the nanotube (3). Here we show that the same dyes, when encapsulated inside boron nitride nanotubes (6T@BNNT) exhibits strong luminescence (4). Photoluminescence imaging experiments on individualized 6T@BNNT show that the encapsulation also circumvent the photobleaching issue over days under continuous photo-excitation. Finally we show that these hybrid materials, with specific luminescence and/or Raman fingerprints, can act as robust nanoprobes with reduced toxicity in living system such as Daphnia Pulex , for multimodal imaging from the visible to the near infrared range. (4) (1) E. Gaufrès et al Nature Photon. (2014) (2) S. Cambré et al Nature Nano (2015) (3) E. Gaufrès et al ACS Nano (2016) (4) E. Gaufrès et al (submitted)
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2018-01/6/677
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2018
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  • 6
    Online Resource
    Online Resource
    Optical Properties of a-Sexithiophene Dyes Aggregated inside Carbon and Boron Nitride Nanotubes
    The Electrochemical Society ; 2017
    In:  ECS Meeting Abstracts Vol. MA2017-01, No. 9 ( 2017-04-15), p. 696-696
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2017-01, No. 9 ( 2017-04-15), p. 696-696
    Abstract: The inner cavity of nanotubes attracted a lot of interest as template for the encapsulation of elongated dyes molecules, such as polythiophenes. Indeed, the 1D confinement drives the stacking of the molecules inside and enables original aggregation effects on their optical properties (1,2). When encapsulated inside carbon nanotube, the 6T exhibits for example a strong and specific Raman scattering but its luminescence is efficiently quenched by the nanotube (3). Here we show that the same dye, when encapsulated inside boron nitride (6T@BNNT) exhibits strong luminescence with signature of inter-molecules coupling (4). Photoluminescence imaging experiments on individualized 6T@BNNT deposited on substrate show that the encapsulation also prevents the bleaching of the molecules under strong photoexcitation, harsh oxidizing exposure and annealing in air up to 350°C. (1) E. Gaufrès et al Nature Photon. (2014) (2) S. Cambré et al Nature Nano. (2015) (3) E. Gaufrès et al ACS Nano (2016) (4) E. Gaufrès et al (submitted)
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2017-01/9/696
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2017
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  • 7
    Online Resource
    Online Resource
    Selective Epitaxial Growth Of Si And Relaxed Ge By UHV-CVD In Si(001) Windows
    The Electrochemical Society ; 2006
    In:  ECS Transactions Vol. 3, No. 7 ( 2006-10-20), p. 593-598
    Details
    In: ECS Transactions, The Electrochemical Society, Vol. 3, No. 7 ( 2006-10-20), p. 593-598
    Abstract: Relaxed germanium was deposited following a low temperature-high temperature procedure by ultrahigh vacuum chemical vapor deposition in Si trenches opened through a SiO 2 mask. The resulting growth is selective, the germanium fills the Si trenches and evolves towards a roof-shaped morphology limited by (001), {113} and {111} facets. The evolution in height of the Ge structure depends on the trench width, and can be understood by considering a growth rate in the 〈 113 〉 direction equal to 22% of that measured along the 〈 001 〉 axis. At last, a surprisingly strong Ge diffusion under the SiO 2 mask was revealed by selective chemical etching. Such a phenomenon was unexpected because no diffusion through the Si/Ge interface was previously observed on plain wafer.
    Type of Medium: Online Resource
    ISSN: 1938-5862 , 1938-6737
    URL: Article
    DOI: 10.1149/1.2355856
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2006
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  • 8
    Online Resource
    Online Resource
    Some Insights into the Relaxation Mechanisms of Germanium Growing on (001) Si by Ultrahigh Vacuum Chemical Vapor Deposition
    The Electrochemical Society ; 2006
    In:  ECS Transactions Vol. 3, No. 7 ( 2006-10-20), p. 569-583
    Details
    In: ECS Transactions, The Electrochemical Society, Vol. 3, No. 7 ( 2006-10-20), p. 569-583
    Abstract: Recent developments in the control by UHVCVD of relaxation mechanisms are reported and discussed. Considering the elastic domain, it is shown that the nucleation of Ge QDs can be accurately driven in order to form isolated single dots or regular arrays of dots, as a consequence of an additional relaxation effect at Si mesas edges. The plastic relaxation can be drastically favored at low deposition temperature : it was found to proceed during the deposition of the first two monolayers at 330ºC. The morphology of the corresponding Ge films becomes stable above a critical thickness value lying just below 27 nm. A further re-growth at 600ºC leads to a low disorder level and a low roughness, while the misfit dislocations are located at the very Ge-Si interface. At last, the growth of Ge on oxidized Si is shown as a promising alternative for growing Ge films free of misfit dislocations.
    Type of Medium: Online Resource
    ISSN: 1938-5862 , 1938-6737
    URL: Article
    DOI: 10.1149/1.2355854
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2006
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  • 9
    Online Resource
    Online Resource
    (Invited) Ultrasonication-Induced Inner Shell Extraction from Double‐Wall Carbon Nanotubes: Characterisation By Ultracentrifugation and in Situ Raman and Fluorescence-Excitation Spectroscopy
    The Electrochemical Society ; 2021
    In:  ECS Meeting Abstracts Vol. MA2021-01, No. 11 ( 2021-05-30), p. 555-555
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2021-01, No. 11 ( 2021-05-30), p. 555-555
    Abstract: We show that ultrasonication extracts inner tubes from double-wall carbon nanotubes (DWCNT), and characterize the process by density gradient ultracentrifugation (DGU) combined with in situ spectroscopic characterization in the density gradient. Our observations also cast new light on the question whether or not the inner tubes of DWCNTs fluoresce, which has been the subject of a long-standing debate, even though single‐DWCNT experiments have already shown drastic PL‐quenching for the inner CNT [1] . Indeed, in previous studies to characterise the PL from DWCNTs, they were typically solubilised using sonication, while here we see that upon sonication, the extraction of the inner tubes from the DWCNTs leads to much more, efficiently fluorescing SWCNTs. First, the DWCNTs were purified from SWCNTs and bundles using density gradient ultracentrifugation (DGU). Then, sonication is applied, after which the extracted inner tubes were separated from the DWCNTs by DGU and characterised by in situ resonant Raman and PL‐spectroscopy as a function of height in the centrifuge tube [2]. These subsequent in situ DGU experiments unambiguously prove the extraction of inner SWCNTs from DWCNTs, even by very brief sonication, and sonication-time-dependent measurements show that the process quickly saturates. [1] D. Levshov, R. Parret, H.-N. Tran, T. Michel, T.T. Cao, V.C. Nguyen, R. Arenal, V.N. Popov, S.B. Rochal, J.-L. Sauvajol, A.-A. Zahab, M. Paillet, Phys. Rev. B 96 , 195410 (2017). [2] S. Cambré, P. Muyshondt, R. Federicci, W. Wenseleers, Nanoscale 7 , 20015 (2015).
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2021-0111555mtgabs
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2021
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  • 10
    Online Resource
    Online Resource
    (Invited) Momentum-Resolved Dielectric Response of Free Standing Black Phosphorus Down to the Monolayer
    The Electrochemical Society ; 2020
    In:  ECS Meeting Abstracts Vol. MA2020-01, No. 10 ( 2020-05-01), p. 840-840
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2020-01, No. 10 ( 2020-05-01), p. 840-840
    Abstract: Atomic layers of Black Phosphorus (BP) have been recently isolated, ten years after graphene. BP stands out in the 2D-materials panorama by its unique semiconducting properties: direct bandgap which can be tuned by the layer number in a wide range of wavelengths from visible (monolayer) to midinfrared (bulk) [1]. This tunability combined the anisotropy of the structure therefore offers promising perspectives in various fields such as electronics and photonics. However, the fast photooxidation in ambient condition, coupled to a high sensitivity to quantum confinement and dielectric environment in ultrathin BP, make very difficult the investigations on its intrinsic optical properties [2] . Further, as screening effects may strongly affect electronic and spectroscopic properties of 2D materials, it is highly desirable to investigate intrinsic properties of free-standing layers as well the ones of the bulk material which remain poorly known. To start with, we have investigated photoluminescence (PL) and absorption properties of high quality BP single crystals at 2K [FTIR]. The PL intensity appears comparable to high quality InAs crystals confirming the suitability of BP for infrared applications. Two peaks are evidenced at 0.275 eV and 0.26 eV. The highest energy peak is particularly narrow (FWHM = 3.8meV) and is tentatively attributed to exciton recombination, thanks to the temperature dependence of PL spectra from 2K to 300K. Further, we have measured the gap related energy shift of the PL spectra as a function of the BP thickness in a series of mechanically exfoliated samples with thicknesses down to 10 nm, complementary to the previous measures done on thinner samples [3] . As far as the thinnest layers are concerned, which cannot manipulated in air, we have shown that Angular resolved Electron energy loss spectroscopy implemented in Transmission Electron Microscopy (Ar-EELS-TEM) offers a unique way to investigate dielectric response of free-standing layers related to valence band and plasmon excitations with the advantage to get access to their q dispersion and their symmetry properties [4]. By combining this technique with suitable ab initio calculations, we have studied the dielectric response of free-standing BP layers as a function of the number of layers. We found optical bandgap values of 1.9 eV, 1.4 eV and 1.1 eV for the mono- bi- and trilayer respectively. Moreover, by combining our results with a simple variational model, we correlate the exciton energy with the dielectric screening. We hence demonstrate that the variations of the electronic gap are sizeably larger than the variations of the binding energy. Finally, we probe and analyze the volume and surface plasmons dispersion as a function of momentum for the 1-3 BP layers and bulk and highlight a deviation and linearization of the parabolic dispersion with strong anisotropic fingerprints [5] . [1] G. Zhang et al., Nat. Com., 8, 14071, (2017) [2] A. Favron, E. Gaufres et al Nature Mat. 14 (2015) 826. [3] C. Chen et al., NanoLett., (2019) [4] F. Fossard et al, Phys. Rev. B 96, 115304 (2017) [5] E. Gaufres et al, Nanoletters (2019); DOI: 10.1021/acs.nanolett.9b03928
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2020-0110840mtgabs
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2020
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