D. Babonneau

Université de Poitiers, Poitiers, Poitou-Charentes, France

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Publications (104)223 Total impact

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    ABSTRACT: We investigated composite films of gold nanoparticles (NPs)/liquid crystal (LC) defects as a model system to understand the key parameters, which allow for an accurate control of NPs anisotropic self-assemblies using soft templates. We combined spectrophotometry, Raman spectroscopy and grazing incidence small-angle X-ray scattering (GISAXS) with calculations of dipole coupling models and soft sphere interactions. We demonstrate that dense arrays of elementary edge dislocations can strongly localize small NPs along the defect cores, resulting in formation of parallel chains of NPs. Furthermore, we show that within the dislocation cores, the inter-NPs distances can be tuned. This phenomenon appears to be driven by the competition between "soft (nano-)sphere" attraction and LC-induced repulsion. We evidence two extreme regimes controlled by the solvent evaporation: i) when the solvent evaporates abruptly, the spacing between neighboring NPs in the chains is dominated by Van der Waals interactions between interdigitated capping ligands, leading to chains of close-packed NPs. ii) when the solvent evaporates slowly, strong interdigitation between the ligands is avoided, leading to a dominating LC-induced repulsion between NPs associated with the replacement of disordered cores by NPs. The templating of NPs by topological defects, beyond the technological inquiries may enable creation, investigation and manipulation of unique collective features for a wide range of nanomaterials.
    No preview · Article · Nov 2015 · ACS Nano
  • G. Abadias · L. Simonot · J. J. Colin · A. Michel · S. Camelio · D. Babonneau
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    ABSTRACT: The Volmer-Weber growth of high-mobility metal films is associated with the development of a complex compressive-tensile-compressive stress behavior as the film deposition proceeds through nucleation of islands, coalescence, and formation of a continuous layer. The tensile force maximum has been attributed to the end of the islands coalescence stage, based on ex situ morphological observations. However, microstructural rearrangements are likely to occur in such films during post-deposition, somewhat biasing interpretations solely based on ex situ analysis. Here, by combining two simultaneous in situ and real-time optical sensing techniques, based on surface differential reflectance spectroscopy (SDRS) and change in wafer curvature probed by multibeam optical stress sensor (MOSS), we provide direct evidence that film continuity does coincide with tensile stress maximum during sputter deposition of a series of metal (Ag, Au, and Pd) films on amorphous SiOx. Stress relaxation after growth interruption was testified from MOSS, whose magnitude scaled with adatom mobility, while no change in SDRS signal could be revealed, ruling out possible changes of the surface roughness at the micron scale.
    No preview · Article · Nov 2015 · Applied Physics Letters
  • S. Yazidi · A. Fafin · S. Rousselet · F. Pailloux · S. Camelio · D. Babonneau
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    ABSTRACT: Self-organized Aux-Ag1–x nanoparticles were produced by grazing-angle deposition using alternating sources on alumina nanoripple patterns. Structural and far-field optical studies showed that periodic chains of Aux-Ag1–x alloy nanoparticles with small interparticle gaps and strong plasmonic dichroism can be successfully created after thermal annealing under vacuum between 400 °C and 700 °C. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
    No preview · Article · Sep 2015 · physica status solidi (c)
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    ABSTRACT: It is reported on a reactive magnetron sputtering-based deposition method to synthesize, at room temperature, photochromic nanocomposite thin films consisting of Ag nanoparticles sandwiched between nanoporous TiO2 layers. The fabrication process is compatible with large-scale production and functional flexible substrates. It is shown that when TiO2 is deposited in the metallic mode, the formation of Ag metal nanoparticles induces localized surface plasmon resonances in the visible range and therefore the as-deposited samples are colored. In contrast, when TiO2 is deposited in the compound mode, the trilayer samples are colorless because silver oxidizes during TiO2 deposition. It is demonstrated that the colorless samples can be colored under ultraviolet (UV) laser exposure at 244 nm due to the reduction of oxidized silver and the formation of metallic Ag nanoparticles. Moreover, irradiation at 647 nm wavelength of colored samples (as-prepared or after UV exposure) gives rise to changes in the particle morphology that strongly modifies the film absorbance and results in a color transition from blue to orange. The choice of the irradiation wavelength allows controlling the color saturation of the sample up to the complete discoloration by using a visible laser at 488 nm. All these photochromic mechanisms are repeatable during cyclic processes.
    Full-text · Article · Aug 2015 · Advanced Materials Interfaces
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    Full-text · Dataset · Jul 2015
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    ABSTRACT: The progress of organic electronics demands an increased participation of nanotechnology, and it has already been shown that the presence of metallic nanoparticles and/or nanostructured thin films can enhance the device performance. Nevertheless, to gain control over the device final performance, it is crucial to achieve a profound understanding of the nanostructure development and assembly. We investigate the growth kinetics of silver (Ag) on a tris(8-hydroxyquinolinato)aluminum (Alq3) thin film via sputter deposition. The increase of the average electron density of the Ag nanostructured film is observed to follow a sigmoidal shape development as a function of the deposited Ag thickness, as a consequence of dominant island-mediated growth. The nanoclustered film is percolated at around a thickness of 5.0 ± 0.1 nm. At this film thickness the effective film density is about 50%. Moreover, our simulation results indicate that the shape of the nanoclusters changes from truncated spheres to cylinders upon surpassing the percolation threshold.
    Full-text · Article · Feb 2015 · The Journal of Physical Chemistry C
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    ABSTRACT: Ultradense macroscopic arrays of ferromagnetic alloy nanowires exhibit unique properties that make them attractive both for basic physics studies and for prospective nanodevice applications in various areas. We report here on the production of self-organized equiatomic FePt nanowires produced by glancing-angle ion-beam codeposition on alumina nanoripple patterns at room temperature and subsequent annealing at 600 [degree]C. This study demonstrates that periodically aligned FePt nanowires with tunable size ([similar]10-20 nm width and [similar]0.5-10 nm height) can be successfully grown as a consequence of shadowing effects and low mobility of Fe and Pt on the rippled alumina surface. Moreover, the structure and magnetic properties of the FePt nanowires, which undergo a phase transition from a disordered A1 (soft) structure to a partially ordered L10 (hard) structure, can be modified upon annealing. We show that this behavior can be further exploited to change the effective uniaxial anisotropy of the system, which is determined by a strong interplay between the shape and magnetocrystalline anisotropies of the nanowires.
    Full-text · Article · Jan 2015 · Nanoscale
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    ABSTRACT: Nanostructured systems made of islands deposited onto oxide surfaces have both fundamental and technological interests and are used in the field of electronic, linear or non-linear optic, and optoelectronic. The final properties of these systems depend on the shape and the size of nanoparticles and also on their organization. On this general framework, we aim at producing self-organized nanostructures using vicinal surfaces [1],[2]. Vicinal surfaces are obtained by cutting a single crystal with a small deviation of the surface normal with respect to a crystallographic plane leading to a surface with terraces separated by steps. Suitable templates for the growth of self-organized nanostructures are created thanks to the re-arrangement of the steps during thermal treatment (step bunching). Different types of nanostructured surfaces can be elaborated and used as templates since the substrates exhibit a one-dimensional (1D) or two-dimensional (2D) periodic patterns (fig. 1a). The surface morphology and the periodicity can be tuned with the thermal treatment parameters (i.e. annealing time, temperature and atmosphere) and also with the sample parameters (i.e. miscut and azimuthal angles). Ordered stepped oxide surfaces are characterized ex-situ after each treatment on a laboratory scale by Atomic Force Microscopy (AFM), which provide a direct image of the surface morphology (step height, step curvature, terrace width...) over a small probed area (a few µm 2 ). Quantitative analysis of the surface morphology has been studied by grazing incidence small angle scattering using a specific set-up implemented recently onto the BM02 beamline at ESRF (Grenoble, France). Prior to the SAXS measurements, the samples were strictly oriented according to the primary beam direction using a 3-axis sample holder. 3D reciprocal space maps around the (000) node were then recorded onto a 2D pixel detector through 360 0 rotation of the samples around the azimuthal angle. Modelling of 2D sections of the (000) reciprocal space node were realized using the FitGISAXS software [3]. Typical experimental and calculated maps are reported fig. 1b and 1c. We demonstrate that the 2D ordered surface is consistent with a rectangular centred periodic lattice decorated by truncated tetrahedrons (see fig. 1d).
    Full-text · Presentation · Aug 2014
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    ABSTRACT: The extraordinary character of Surface Plasmon modes of disordered metallic systems has been predicted theoretically. We here demonstrate through Electron Energy Loss Spectroscopy that percolating fractal metal films sustain numerous strongly confined Surface Plasmon modes.
    Full-text · Conference Paper · Jun 2014
  • Vivek Antad · L. Simonot · D. Babonneau
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    ABSTRACT: Structural and optical modifications induced by low-energy (≤80 eV) bias-plasma annealing of silver nanoclusters (2–25 nm) grown by magnetron sputtering deposition are reported. By combining postmortem structural characterizations and real-time optical measurements, we show that etching effects associated with enhanced Ag mobility result in progressive and irreversible changes of both the morphology and organization of the nanoclusters (i.e., decrease of the cluster size and intercluster distance as well as increase of their out-of-plane aspect ratio). Surface plasmon resonance bands of the nanoclusters are also modified by plasma treatment, which causes a blue-shift together with an amplitude decrease and a narrowing of the band. In addition, the kinetics of plasma-induced modifications can be easily controlled by varying the applied bias voltage. Therefore, plasma annealing could emerge as an efficient alternative to more traditional thermal annealing treatments for tuning the plasmonic properties of noble metal nanoclusters with great flexibility.
    No preview · Article · Feb 2014 · Journal of Nanoparticle Research
  • S Camelio · E Vandenhecke · S Rousselet · D Babonneau
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    ABSTRACT: Low-energy ion beam sputtering of alumina thin films followed by growth of metallic nanoparticles by glancing angle deposition is optimized in order to produce arrays of silver nanoparticle chains with a strong plasmonic dichroism. A systematic study is undertaken in order to establish the influence of the angle of silver deposition and the ordering of the pre-patterned rippled surface on the morphology and organization of the nanoparticles, and on their associated optical properties. High ion fluence for ripple formation and low glancing angle for metal deposition favor the formation of aligned and elongated particles with sub-nanometer gaps. Numerical simulations show that these nanoparticle arrays generate high electric field enhancements for an excitation parallel to the particle chains, and therefore can be used for surface enhanced spectroscopies.
    No preview · Article · Dec 2013 · Nanotechnology
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    ABSTRACT: We report on the identification and nanometer scale characterization over a large energy range of random, disorder-driven, surface plasmons in silver semicontinuous films embedded in silicon nitride. By performing spatially resolved electron energy loss spectroscopy experiments, we experimentally demonstrate that these plasmons eigenmodes arise when the films become fractal, leading to the emergence of strong electrical fields (“hot spots”) localized over few nanometers. We show that disorder-driven surface plasmons strongly depart from those usually found in nanoparticles, being strongly confined and randomly and densely distributed in space and energy. Beyond that, we show that they have no obvious relation with the local morphology of the films, in stark contrast with surface plasmon eigenmodes of nanoparticles.
    Full-text · Article · Sep 2013 · Physical Review B

  • No preview · Conference Paper · Jul 2013
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    Full-text · Article · Apr 2013 · Physical Review B
  • M. Garel · D. Babonneau · Alexandre Boulle · A. Coati · Y. Garreau

    No preview · Article · Jan 2013
  • V Antad · L Simonot · D Babonneau
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    ABSTRACT: Real-time surface differential reflectance spectroscopy in the visible range is used to study the optical response of silver nanoclusters, prepared by magnetron sputtering deposition, during cyclic treatments in different oxygen atmospheres and low-energy bias argon plasma. Changes in the reflectance show that the exposure to non-ionized (or partially ionized) oxygen causes a red-shift and damping (or complete vanishing) of the resonance, while bias plasma annealing induces the opposite effects, due to oxygen desorption and structural reshaping of the nanoclusters. These results open up new opportunities for developing plasmon-based devices with high tunability of the surface plasmon resonance (energy, width and amplitude) due to an interplay between morphological and chemical modifications of the nanoclusters.
    No preview · Article · Jan 2013 · Nanotechnology
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    ABSTRACT: Sub-wavelength arrays of silver nanoparticles embedded in a dielectric matrix are elaborated by a low-cost bottom-up technique, which combines substrate pre-patterning by defocused ion-erosion (resulting in the generation of one-dimensional nanoripples) with subsequent Volmer-Weber growth by physical vapor deposition at glancing incidence. The arrays are constituted by regular chains (∼20 nm period) of small particles (size less than 10 nm) with elongated shape in the direction of the ripples. This shape anisotropy and the resulting interparticle coupling inside the chains (gap between the particles less than 10 nm) are responsible for the plasmonic dichroism of the array leading to polarization-selective broad-band absorption in visible and near infrared. This dichroism can be tuned by adjusting the amount of deposited metal, the elaboration temperature, the nature of the dielectric host and the deposition geometry. The technique is at last employed to elaborate 3D nanostructures.
    No preview · Article · Jan 2013 · Nanoscience and Nanotechnology Letters
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    ABSTRACT: Surface plasmons (SP) are collective oscillations of the conduction electrons of noble metals at metal-dielectric boundaries and are commonly described as classical dispersive electromagnetic waves. Confined geometries of metallic nanoparticles induce a resonant behavior and gives rise to SP modes that dictate their optical properties. Among all SP related phenomena, the special case of optical excitations in disordered films has drawn during the last few years much theoretical [4] as well as experimental [1][5] attention. The peculiar broadband absorption properties of such systems are now commonly attributed to a SP mediated strong localization of light at the nanoscale within deep sub-wavelength areas called "hot spots" (HS). However, despite the great deal of work in the past 15 years, no comprehensive study of such films has been carried out – especially, full properties of the HS have never been studied experimentally. Thus many fundamental questions on the physics of SP and in particular HS in disordered films remain frustratingly open [4]. Now, most of these questions might find answers when accessing the full spectral information at the (predicted) relevant scale of the HS, namely less than 20 nm. In this contribution, we will show how the extension of spatially resolved electron energy loss spectroscopy (EELS) for SP characterization from the now commonly performed nanoparticle SP analysis [2] to that of disordered films has helped us to unveil the HS spectral properties of disordered films. As an example, Figure 1 shows a STEM High Angle Angular Dark Field (HAADF) image of a silver (in grey) disordered film embedded in a (dark looking) Si 3 N 4 matrix, evidencing the random character of its morphology. Another HAADF image of a smaller substrate area, on which hyperspectral imaging measurements are performed, is displayed. EEL spectra extracted from three different positions of the electron probe are presented. Resonances associated to SP modes are underlined by the presence of peaks in the spectra. The change in the peak energies and widths for such close probing sites suggests a complex optical character, which is confirmed by strong fluctuations in the energy filtered EEL probability maps displayed in figure 2. However, these maps show that the electromagnetic energy is confined in sub-wavelength areas whose spatial location varies with the energy loss. This is equivalent to the Electromagnetic Local Density of states (EMLDOS) maps obtained with SNOM [1], but with far better spatial resolution and full spectral information [3]. Fitting each spectrum by a sum of Gaussian functions allows discriminating all the SP modes that can be blurred by picturing the EMLDOS. We show in figure 3 the results of such data processing for the lowest energy peak. The hot spots are still visible in the amplitude maps, and associated to spatial regions where the peak energy and width are well defined, but changing from one to another. Therefore, not only EELS hyperspectral imaging allows to spatially probe the EMLDOS fluctuations in a disordered system [5] with nanometer resolution, but also provides a direct identification of the SP modes through physical observables resonant energy and width. Finally, we will try to show in which amount the observed HS behavior is very specific to random films, as opposite to a random collection of nanoparticles. [6] [6] We thank Z. Mahfoud for help in data treatment, and R. Carminati and J.J. Greffet for enjoyable discussions.This work is partially supported by the Centre National de la Recherche Scientifique and the Délégation Générale de l'Armement. Figure 1. Left: Overall view STEM HAADF image of a silver disordered film embedded in a Si 3 N 4 matrix. Middle: Magnified view of the area indicated in the white dashed square. Right: EEL Spectra acquired at three probe positions indicated by the colored squares.
    Full-text · Conference Paper · Sep 2012

  • No preview · Article · Aug 2012
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    Johann Toudert · Lionel Simonot · Sophie Camelio · David Babonneau
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    ABSTRACT: We calculate, in the quasistatic coupled dipole approximation, the analytical expressions of the effective dielectric tensor of a single layer of polydisperse ellipsoidal nanoparticles with two of their principal axes in the layer's plane and embedded in a homogeneous dielectric medium. The organization (isotropic or anisotropic) and orientation (without or with a preferential in-plane orientation) of the nanoparticles is taken into account, together with their (possibly correlated) in-plane size, in-plane projected shape, and height distributions. In particular, we propose to describe the response of a layer of nanoparticles presenting a height distribution by using a vertically graded effective medium model. The expressions are tested in the case of finely characterized dielectric/silver/dielectric granular trilayers grown by means of vapor deposition in which the silver coalesced nanoparticles present correlated in-plane size and in-plane projected shape/height distributions and a moderate surface coverage of about 25$%$. A satisfactory quantitative agreement is obtained between the simulated and measured surface plasmon extinction bands of the metal nanoparticles. This agreement is permitted by the capability of the effective medium model of taking into account the ellipsoidal shape of the nanoparticles. The significant role of the size and shape distributions is also demonstrated.
    Full-text · Article · Aug 2012 · Physical Review B

Publication Stats

1k Citations
223.00 Total Impact Points


  • 1999-2015
    • Université de Poitiers
      • Département Physique & Matériaux
      Poitiers, Poitou-Charentes, France
  • 1998-2014
    • French National Centre for Scientific Research
      • • Institut Néel
      • • Institut Pprime
      Lutetia Parisorum, Île-de-France, France
    • Université Paris-Sud 11
      • Laboratoire de Physique des Solides
      Orsay, Île-de-France, France