Search results for "layer"
showing 10 items of 2667 documents
Measurements of thickness dispersion in biolayers by scanning force microscopy and comparison with spectroscopic ellipsometry analysis.
2007
Measuring the thickness of biological films remains a difficult task when using differential measurements by atomic force microscopy (AFM). The use of microstructured substrates combined with a selective adsorption constitutes an alternative to tribological measurements. The statistical thickness analysis of biological layers, especially via the dispersion measurements, can provide a way to quantify the molecular orientation. AFM thicknesses were then compared with those obtained optically by spectroscopic ellipsometry (SE) and surface plasmon resonance enhanced ellipsometry (SPREE). The biolayers could then be modeled using a vertical gradient of optical index, which reflects height disper…
Studies on atomic layer deposition of MOF-5 thin films
2013
International audience; Deposition of MOF-5 thin films from vapor phase by atomic layer deposition (ALD) was studied at 225-350 degrees C. Zinc acetate (ZnAc2) and 1,4-benzenedicarboxylic acid (1,4-BDC) were used as the precursors. The resulting films were characterized by UV-Vis spectrophotometry, Fourier transform infrared spectroscopy (FTIR), optical microscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), time-of-flight elastic recoil detection analysis (TOF-ERDA), isopropanol adsorption tests, and nanoindentation. It was found out that the as-deposited films were amorphous but crystallized in humid conditions at room temperature. The crystalline films h…
Benzene monitoring by micro-machined sensors with SnO2 layer obtained by using micro-droplet deposition technique
2011
International audience; SnO2 thin layers were deposited by the way of the micro-droplet technique. The sensor substrate consisted of a thin membrane developed on oxidised silicon wafer. The sensing layers were deposited by means of the micro-droplet technique into thin layers of about 100 nm. Such devices were tested for benzene detection. The obtained results showed a very high sensitivity for this chemical compound since 500 ppb were detected. The results presented in this paper were not focused on the reactional mechanism of benzene detection but rather on the development of a cheap and sensitive sensor using sol-gel and micro-droplet processes. Since these layers were elaborated using s…
Development of gas sensors by microwave transduction with phthalocyanine film
2012
International audience; This work presents a new transduction mode for gas sensing using a passive microwave circuit at room temperature. The design of the sensor includes a microstrip line where is deposited a thin molecular layer of cobalt phthalocyanine (CoPc). The material is sensitive to ammonia and toluene. Submitted to an electromagnetic incident wave in the microwave range, the sensor response is a reflected wave. In the presence of ammonia, the reflected wave is specific to the species concentration. The sensor response is the reflected wave over the incident wave ratio at each frequency traduced by the reflected coefficient. The study deals with the influence of molecular sensitiv…
Assembly of citrate gold nanoparticles on hydrophilic monolayers
2016
Abstract Self-assembled monolayers (SAMs) as model surfaces were linked onto planar gold films thorough lipoic acid or disulfide groups. The molecules used were polyethylene glycol (EG-S-S), N -[tris-(hydroxymethyl)methyl]acrylamide polymers with and without lipoic acid (Lipa-pTHMMAA and pTHMMAA) and a lipoic acid triazine derivative (Lipa-MF). All the layers, but Lipa-MF with a primary amino group were hydroxyl terminated. The layers were characterized by contact angle measurements and atomic force microscopy, AFM. Citrate stabilized nanoparticles, AuNPs in water and phosphate buffer were allowed to assemble on the layers for 10 min and the binding was followed in real-time with surface pl…
Growth of titanium oxynitride layers by short pulsed Nd:YAG laser treatment of Ti plates: Influence of the cumulated laser fluence.
2009
International audience; Titanium oxynitride layerswere formed by surface laser treatment of Ti plates in air using a Nd:YAG laser source of short pulse duration about 5 ns. The cumulated laser fluence was varied in the 100–1200 J cm2 range and its influence on the composition and the structure of the formed layers was studied by different characterization techniques providing physico-chemical and structural information. It was shown that the laser treatment induces the insertion of light elements as O, N and C in the formed layer with the amount increasing with the laser fluence. The in-depth composition of the layers and the co-existence of different phases were also studied. The way in wh…
XPS analysis of sol-gel-generated mixed-oxide layers for biomedical application
2002
The excellent biocompatibility of titanium and its alloys is associated with the properties of their dense TiO2 layer on the surface. The adsorption of proteins of the body fluid to implant surfaces depends on the properties of the surface oxide layer, especially the electronic structure. Therefore, tailoring of the oxide layer is a method for influencing protein adsorption. In this study, titanium platelets are coated by the sol–gel process with mixed oxides containing the biocompatible elements Ti, Nb, Zr and Ta. In order to verify the composition of the produced oxide layer, which can differ from the adjusted precursor composition in the sol because of different reactivities of the precu…
Low-K factor of SiO2 layer on Si irradiated by YAG:Nd laser
2007
Abstract The change of optical and electrical properties of SiO2 layer on Si single crystal exposed to YAG:Nd laser radiation has been found experimentally. The second harmonic of YAG:Nd laser was used as a source of light. Before irradiation the SiO2 layer with thickness 0.75 μm had red color in reflecting light due to the interference. After irradiation with the laser with intensity of more than 3.5 MW/cm2 red color changed to yellow. However, samples with thickness 0.21 μm did not change color after irradiation. We explain such peculiarities of optical properties by change of optical path. Capacity (C) measurements of SiO2 layer with thickness 0.21 μm by the method of capacity–voltage ch…
Antiferromagnetism and p‐type conductivity of nonstoichiometric nickel oxide thin films
2020
Plasma‐enhanced atomic layer deposition was used to grow non‐stoichiometric nickel oxide thin films with low impurity content, high crystalline quality, and p‐type conductivity. Despite the non‐stoichiometry, the films retained the antiferromagnetic property of NiO.
Redox reactions in the Pt/TiO2–WO3/SiO2 planar system
2014
Abstract The thermal behavior of the titanium–tungsten adhesive layer (30–70 at.%) deposited on a SiO2 substrate followed by a thicker Pt layer was investigated. The resulting Pt/TiW/SiO2 planar system was annealed under air or vacuum. Morphological and chemical characterizations at different stages of the annealing, as a function of several parameters such as treatment atmosphere, annealing temperature and thickness of the Pt film were performed through surface science analyses. When annealing under air, even at mild temperature (773 K), the whole interlayer oxidizes while a low amount of tungsten diffuses through platinum film. This phenomenon is related to tungsten oxidation which acts a…