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Thin Films & Nanomaterials
(Ex Nanomaterials for Photonics)



Head:

  • Rachel Desfeux, Full Professor (Thin Films / Scanning Probe Microscopy)

Teachers and researchers:

The team “Thin Films and Nanomaterials", organized around 4 Full Professors and 5 Assistant Professors, is one of the 5 teams of the "Solid State Chemistry" branching from the much larger Unit of Catalysis and Solid-State Chemistry. The team involves Solid-Chemists as well as Physicists. The team-members are tenured at the University of Artois.

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Keywords:

Oxides ; Thin Films ; Nano-particles ; Piezoelectricity ; Ferro-electricity; Optics; Pulsed-Laser Deposition; Scanning-Probe Microscopies; Spectrometry; DFT calculations

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Presentation of research:

The research led by the team spans over the synthesis, the advanced characterization as well as the modeling of both multi-functional oxides thin-films and nanoparticles for applications to nano-devices, essentially electronic and optical.


Modélisation Caractérisation Synthèse Applications
  • Synthesis

The first mission of the team is to design, develop and synthesize new materials or systems, either in the form of thin films (mainly oxides) or as colloids composed of nanoparticles and self-assembled molecular materials (liquid crystals). The studied properties mainly consist in ferro-electricity, piezoelectricity, magnetism, luminescence, and transport properties ... In the particular case of thin films, this task takes into account the role played by the nature of the substrate via the strains induced in the film, the thickness of the deposited film or even the synthesis conditions used. In the context of systems based on nanoparticles, it takes into account the volume organization of nanoparticles with new methods of trapping.
  • Characterization

The second mission is to establish the relationships between the microstructural and physical properties of the nanometer synthesized systems, using tools and methodologies that the team develops at the nanoscale level. In this respect, it primarily relies on skills and credit it has extended in scanning-probe microscopy starting from the mid-1990s, in particular through the development of distinctive modes such as MFM (Magnetic Force Microscopy) and PFM (Piezo-response Force Microscopy), and vibrational spectroscopies (Raman - Infra-Red).
  • Modelisation

The team third-mission lies in the study of experimental parameters and understanding of phenomena that govern the behavior of materials at a local level (the role of the substrate/film interface, the electronic structure ...) by developing ab-initio calculations or original models related to the functions of dispersion of colloidal materials associated with DDA (Discrete Dipole Approximation) calculation methods.


Applications : the objective is to optimize the properties of new synthetized-materials to be integrated into electronic-and-optical nano-devices or used in the field of energy. In special cases, the team calls for techniques available outside the laboratory only. These concern both FIB (Focused Ion Beam) to nanostructure thin films and to study size effects, and mapping-mode plasmon-analysis. Due to environmental constraints, it is primarily concerned with non-toxic materials such as lead-free thin films.
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Collaborations:

Our research centers around numerous collaborations, including the University of Southampton (England), the University of Saarland (Germany), The University “Tor Vergata” of Rome (Italy), the University of Kiev (Ukraine), the University of Sidi Bel Abbes (Algeria), the University of Barcelona (Spain), the CRISMAT-Caen, IEMN Lille, the UDSMM-Calais, the LRCS in Amiens…

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Highlights :



In thin films, we have developed new metastable phases from the Ln2Ti2O7 (Ln = Sm, Eu, Gd) family with layered perovskite structure. The ferroelectric character was highlighted through PFM measurements. Through structural studies, led in collaboration with the OXIN team (P. Roussel) by high resolution X-ray diffraction, structure-properties relationships have been established. Results were modeled by ab-initio calculations (2 thesis, J. Mater Chem 2012, 22, 9806; J. Mater Chem 2012, 22, 24894; Phys Rev B 2012, 86, 125136.

 

 


Our team is one of the pioneering groups in the characterization of piezoelectric/ferroelectric thin films by PFM at the nanoscale level. In this spirit, studies have been carried out on islands fabricated by Ga+ focused ion-beam in both PbZr0.4Ti0.6O3 and unlead La2Ti2O7 thin-films, in collaboration with IEMN with the help of their technological platform. These measurements have led to better understanding of the matter response to radiation in order to produce functional nano-objects (J. Appl. Phys., 2009, 105, 044101; J. Appl. Phys. 2010, 108. 042008; J. Am Ceram. Soc. To be published). In addition, PFM measurements, carried out in collaboration with the CRISMAT laboratory, on [(BiFeO3)m/(SrTiO3)n]p multi-ferroic hetero-structures have shown the potential of the interfacial strains in the super-lattice for the control of the domains-orientation as well as their density. This last result is particularly interesting for applications based on engineering domains and their walls (J. Magn. Magn. Mater., 2009, 321, 1710; Appl. Phys. Lett., 2010, 96, 022902)
We have developed a singular module to measure electrical fatigue at the nanoscale via the tip of an atomic force microscope and without any upper electrode. This development has permitted to show that the fatigue resistance within the local electromechanical properties was larger for ferroelectric PMN-PT film deposited on an oxide electrode than for a film prepared on a metal electrode. These measurements have helped to establish the relation between the electrical film-endurance and the nature of the material used as the bottom electrode (Thin Solid Films 2011, 520, 591-596)
We have shown that a low concentration of ferroelectric nanoparticles in a nematic liquid crystal significantly improves the electro-optical properties of the latter (voltage switch, birefringence). Moreover, the work, carried out in the framework of the ANR P3N2009 NANODIELLIPSO, has contributed to some sensible improvement of the ellipsometry Delta Psi 2 software which was developed by Horiba scientific to measure optical properties of nanomaterials (Review of Scientific Instruments 035103 (2010), J. Appl. Phys. 074102 (2012), one thesis ongoing).

 


 

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PhD, Lecturer, post-doc (2008-2013):

Last name, First name

Type

Thesis title

Ferri Anthony

Thesis

Shao ZhenMian

Thesis
Lecturer
Bruyer Emilie
Thesis
Lecturer
Bayart Alexandre
Thesis
Nemer Salim
Post-Doc
Detalle Mikaël
Lecturer

 

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