Abstract:The primary objective of this study is the development of transparent thin film materials in the IR enabling strong infrared absorption of organic compounds in the vicinity of metal nanoparticles by the surface plasmon effect. For developing these optical micro-sensors, heterostructures combining gold nanoparticles and chalcogenide planar waveguides are fabricated and adequately characterized. Single As 2 S 3 and Ge 25 Sb 10 Se 65 amorphous chalcogenide thin films are prepared by radiofrequency magnetron sputtering. For the fabrication of gold nanoparticles on a chalcogenide planar waveguide, direct current sputtering is employed. Fabricated single layers or hetero-structures are characterized using various techniques to investigate the influence of deposition parameters. The nanoparticles of gold are functionalized by a self-assembled monolayer of 4-nitrothiophenol. Finally, the surface enhanced infrared absorption spectra of 4-nitrothiophenol self-assembled on fabricated Au/Ge-Sb-Se thin films hetero-structures are measured and analyzed. This optical component presents a ~24 enhancement factor for the detection of NO 2 symmetric stretching vibration band of 4-nitrothiophenol at 1336 cm −1 . 232-239 (1999). 19. L. Tichý, H. Ticha, P. Nagels, R. Callaerts, R. Mertens, and M. Vlcek, "Optical properties of amorphous As-Se and Ge-As-Se thin films," Mater. Lett. 39(2), 122-128 (1999). 20. J. Charrier, M. L. Anne, H. Lhermite, V. Nazabal, J. P. Guin, F. Charpentier, T. Jouan, F. Henrio, D. Bosc, and J. L. Adam, "Sulphide GaxGe25-xSb10S65(x=0,5) sputtered films: Fabrication and optical characterizations of planar and rib optical waveguides," J. Appl.

Semiconductor materials have received substantial attention as photocatalysts for controlling water pollution. Among these materials, perovskite-structured SrSnO 3 is a promising candidate for this application, whereas BaSnO 3 exhibits very low activity. In the present work, Sr 1-x Ba x SnO 3 (x = 0, 0.25, 0.50, 0.75 and 1) was synthesized by solid-state reaction and was applied in the photocatalytic discoloration of the organic dye Remazol Golden Yellow. The perovskite structure was obtained for all compositions of the solid solutions with both Sr The two materials appear to feature different mechanisms of photodegradation: the direct mechanism prevails in the case of BaSnO 3 , whereas the indirect mechanism appears to play a key role in the case of SrSnO 3 .

We have used a set of complementary experimental techniques to characterize an epitaxial structure (25 nm Fe)/GaAs(001) annealed at 450 °C under ultrahigh vacuum conditions. The solid state interdiffusion leads to the formation of an epitaxial reaction layer made of Fe2As patches embedded in a Ga rich Fe3Ga2−XAsX ternary phase. The epitaxial character of this layer explains how the usually reported epitaxial growth of Fe on GaAs performed in the temperature range of 175 to 225 °C is possible in spite of the species intermixing occurring at the interface. Moreover, the observed grains of Fe2As explain the decrease of magnetization at the interface in such contact, since Fe2As is an antiferromagnetic alloy.

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International audienceA coplanar waveguide (CPW) stub resonator has been fabricated on a pulsed-laser deposited KTa(0.5)Nb(0.5)O(3) (KTN) thin film (600 nm-thick) onto a r-plane sapphire substrate. It was designed to operate at 10 GHz when the applied bias voltage is zero. We show experimentally that the resonance frequency is shifted by 44% under a 70 kV/cm DC applied electric field. In addition, the dielectric characteristics of the KTN film have been assessed through post-processed measurements of CPW 50-Omega transmission lines using the conformal mapping method

International audienceThe development of infrared sensing platform requires adapted materials. In this work, we used sputtered gold nanoparticles on a chalcogenide glass to demonstrate that these infrared materials can be used as substrate for surface enhanced infrared absorption (SEIRA) spectroscopy. The sputtering parameters were optimized to get the highest possible enhancement. To assess it, a self-assembled monolayer of 4-nitrothiophenol was used. These preliminary results are promising and pave the way for various configurations of waveguide for integrated optical components

TiO 2 thin films were grown by pulsed laser deposition on a wide variety of oxide single-crystal substrates and characterized in detail by four-circle X-ray diffraction. Films grown at 873 K on (100)-oriented SrTiO 3 and LaAlO 3 were (001)-oriented anatase, while on (100) MgO they were (100)-oriented. On (110) SrTiO 3 and MgO, (102) anatase was observed. On M-plane and R-plane sapphire, (001)-and (101)-oriented rutile films were obtained, respectively. On C-plane sapphire, the coexistence of (001) anatase, (112) anatase and (100) rutile was found; increasing the deposition temperature tended to increase the rutile proportion. Similarly, films grown at 973 K on (100) and (110) MgO showed the emergence, besides anatase, of (110) rutile. All these films were epitaxically grown, as shown by ' scans and/or pole figures, and the various observed orientations were explained on the basis of misfit considerations and interface arrangement.

Potassium niobate thin films were grown by pulsed laser deposition on various substrates. Influence of deposition conditions on films characteristics was studied. Structural investigation evidenced that single phase polycrystalline randomly oriented films were grown on sintered alumina whereas epitaxial films were grown on (100)SrTiO 3 and (100)MgO substrates. The microstructure was highly controled by the structural characteristics. Interdigited capacitors built from KNbO 3 films on two different substrates (alumina andMgO) showed the strong influence of the structural characteristics on the dielectric behaviour.The variation of the equivalent capacitance measured on the interdigital capacitor on MgO was 6.4 % at 2.5 GHz while it was 1.5 % on alumina, in both cases for a moderate applied field of ~ 15 kV.cm -1 . The results show the potentiality of this ferroelectric materials for use in frequency agile microwave electronics.