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Laboratory of Nanostructures Studies and Surface Imagery (LENSIS)
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Groupe Photemission, Photodiffraction et Spectromicroscopie

The group's research activities focus on the analysis of electronic structure and the chemistry of surfaces and interfaces using spectroscopic and diffraction techniques of photoelectrons.

Contact: N. Barrett

Members of the laboratory.

 

 

Nanostructured surfaces constitute substrates very interesting for the deposition of thin layers, because one can hope that this substrate nanostructuration will be transmitted to the deposited layer. A nanostructuration at an atomic scale can be obtained by heat treatments adapted under controlled atmosphere, by interaction with a laser, or by homoepitaxy (i.e. by the deposition of a material identical to the substrate).

Groupe SIMA

Les activités de recherche du groupe SIMA portent sur le contrôle atomique des surfaces, interfaces et nanostructures, les propriétés électroniques, structurales, la croissance de films, les processus élémentaires aux surfaces et interfaces. Une description complète des activités du groupe se trouve sur le lien suivant: http://www.sima.u-psud.fr

Contact: P. Soukiassian.

 

Last update : 01/13 2017 (485)

More ...
Chemisorption : « Back to the Group page « Back to the Oxides page   In view of the potential of transition metal (TM) oxides for photocatalytic applications, the adsorption and dissociation of water on their surfaces has been widely studied. Surface chemistry can strongly influence the adsorption mechanism. For example, the SrO-terminated perovskite oxide SrTiO3 (STO) favors dissociative adsorption, whereas on the TiO2-terminated surface, molecular adsorption is more stable.
Electrical boundary conditions : « Back to the Group page « Back to the Oxides page   The new physics emerging from two-dimensional films in the limit of a few unit cells has a host of exciting applications. However, understanding the ferroelectric properties of such engineered thin film systems requires taking into account not only the material but also its interfaces with electrodes, substrates or atmosphere; in other words, the electrical boundary conditions.
Screening : « Back to the Group page « Back to the Oxides page   Surface polarization charge in ferroelectric (FE) materials can be screened by a variety of mechanisms: intrinsic (charge carriers or defects in the bulk), extrinsic (chemical environment or adsorbates), domain ordering, or even a combination of the above. Chemisorption of OH- and protons can lead to important changes in the electrical boundary conditions and water film can play an active role in domain switching.
Switching the polarization :       « Back to the Group page « Back to the Oxides page       Switching requires a metallic contact, raising fundamental issues about the interface between the FE and the electrode. Polarization leads to fixed charge of opposite sign at the two metal-FE interfaces.

 

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