Combining scanning probe microscopy and x-ray spectroscopy

A new versatile tool, combining Shear Force Microscopy and X-Ray Spectroscopy was designed and constructed to obtain simultaneously surface topography and chemical mapping. Using a sharp optical fiber as microscope probe, it is possible to collect locally the visible luminescence of the sample. Results of tests on ZnO and on ZnWO4 thin layers are in perfect agreement with that obtained with other conventional techniques. Twin images obtained by simultaneous acquisition in near field of surface topography and of local visible light emitted by the sample under X-Ray irradiation in synchrotron environment are shown. Replacing the optical fibre by an X-ray capillary, it is possible to collect local X-ray fluorescence of the sample. Preliminary results on Co-Ti sample analysis are presented

Cinetiques et mecanismes de depots de materiaux pour la microelectronique obtenus lors de l'interaction d'un faisceau laser avec une surface en presence d'un gaz

CNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Fabrication de motifs métalliques et semi-conducteurs connectés

AIX-MARSEILLE2-BU Sci.Luminy (130552106) / SudocSudocFranceF

Computer Simulation of Laser Induced Temperatures for the Laser Direct Writing technique

ABSTRACT Laser induced temperatures in substrates irradiated with a scanning gaussian laser beam were calculated by the finite element method. A quartz substrate of a given thickness and covered with a one - micron - thick silicon coating was assumed to be either placed on a heat sink or thermally insulated. The maximum temperature in the center of the laser spot was found to be proportional to the laser power for a spot size larger than the silicon thickness. Furthermore at a given laser power, the temperature decreased with increasing laser spot diameter and the time to reach the equilibrium temperature increases with the spot radius for radii less than the substrate thickness. The laser induced temperature was found to be affected by laser - scan speeds for speed values above the heat diffusion rate

Localized Laser-Assisted Deposition of Silicon,Silicon Nitride and Silicon Dioxide

ABSTRACT The localized laser-induced deposition of an insulator for silicon-based microelectronics seems to be an unsolved problem. In order to understand the limiting mechanism in the deposition, the formation kinetics of silicon, silicon oxide and silicon nitride using various laser wavelengths and gas mixtures have been studied Depending upon wavelength and laser-induced temperature, various chemical reactions are involved. In the presence of ammonia, the growth rate of silicon nitride dots was found to be lower than the corresponding silicon deposition rate, indicating that deposition starts with silane decomposition followed by nitridation of silicon. By evaluating the influence of the wavelengths, the existence of a photolytic aided reaction is detected in the presence of 2.4 eV photons. In the presence of oxygen molecules and under most experimental conditions, no deposition occurs. The formation of volatile intermediate compounds can explain the difficulty of locally depositing silicon dioxide

Kinetics of Laser-Assisted Chemical Vapor Deposition of Tungsten Microstructures

Tungsten microstructures (dots, strips and films) have been deposited via H 2 reduction of WF 6 on polycrystalline silicon-coated quartz substrates irradiated with a focused cw argon laser beam. The deposition rate of W dots, deduced from α-step measurements of the height of dots, was investigated as a function of irradiation time, composition of H 2 -WF 6 gas mixtures and laser-induced surface temperature. At a laser-induced surface temperature ranging from 340° to 670°C with an H 2 partial pressure varying from 50 to 700 Torr, the reaction order with respect to H 2 was equal to one-half, whereas at higher temperatures (750°-950°C) and lower H 2 partial pressures (20-80 Torr), the reaction order with respect to H 2 was found to be one. The reaction mechanism of the H 2 reduction of WF 6 on substrates irradiated with the argon laser beam is discussed

Characterization of Some Physical and Photocatalytic Properties of CuO Nanofilms Synthesized by a Gentle Chemical Technique

Pure and Li-doped CuO nanofilms were synthesized on heated glass substrates using the spray-pyrolysis technique. The deposited pure CuO nanofilms were achieved at a precursor molarity of 0.2 M using a solution prepared from copper nitrate trihydrate (Cu(NO3)2·3H2O). Doped Li–CuO nanofilms were obtained using several doping concentrations (3, 6, 9, 12 and 15%) by adding a solution prepared from lithium nitrate (LiNO3). The pure and Li–CuO samples were investigated by different techniques. XRD revealed three dominant peaks (-111), (111) and (211), which are the properties of monoclinic CuO. The increase in Li-doping concentration showed the appearance of other peaks of low intensities detected at 2θ ranging from 49 to 68°. AFM images showed a textured and inhomogeneous surface composed of spherical grains whose size decreased with increasing Li doping. UV–visible spectroscopy showed that the CuO samples were of low transparency; the transmittance was less than 50%. The band-gap energy determined from Tauc’s equation plot increased from 2.157 to 3.728 eV with the increase in Li doping. These values correspond well to the band gap of semiconducting CuO. The photocatalytic properties were accelerated by Li doping, as revealed by the discoloration of aqueous methylene-blue (MB) solution under ultraviolet irradiation

Le palmier dattier dans l'agriculture d'oasis des pays méditerranéens

Cet ouvrage contient les textes des communications faites durant les journées internationales d'Elche, Espagne, tenues du 25 au 27 avril 1995. Il fait le point de la recherche dans ce domaine, de la coopération internationale, de la commercialisation et des marché

Dosimetric characterization of a small-scale (Zn,Cd)S:Ag inorganic scintillating detector to be used in radiotherapy

International audienc

Synthesis and Investigation of Pure and Cu-Doped NiO Nanofilms for Future Applications in Wastewater Treatment Rejected by Textile Industry

Pure and Cu-doped NiO films were synthesized via a soft chemical process. They were deposited on glass substrates heated to 400 °C. Different atomic percentage ratios (2, 4, 6, 8, and 10%) of Cu-doping were used. The prepared samples were characterized by several techniques such as X-ray diffraction for crystallographic study, SEM and AFM for microstructural and morphological properties, and UV-Visible spectroscopy for optical and photocatalytical analysis. XRD results of pure and Cu-doped NiO films indicated the formation of NiO polycrystalline phases under a cubic structure with a favored orientation along the (200) plane noticed in all sprayed films. SEM images revealed the formation of NiO nanoparticles of spherical forms whose sizes increase and agglomerate with increasing Cu-doping. At 10% Cu-doping, NiO agglomeration was extended to the whole surface. AFM images showed a textured and rough surface composed of NiO nanoparticles of average size varying from 16 to 10 nm depending on Cu-doping concentration. UV-visible spectroscopy confirmed the transparency of NiO films and their semiconducting character with a band gap ranging from 3.4450 eV to 2.8648 eV. The photocatalytical properties of pure and Cu-NiO films were enhanced by Cu-doping particles as revealed by the degradation of methylene blue (MB) solution subjected to irradiation