J.L. Deschanvres

Characterization of piezoelectric properties of zinc oxide thin films deposited on silicon for sensors applications

Abstract This paper reports the piezoelectric properties of zinc oxide thin films deposited on silicon wafers by a modified CVD technique based on the pyrolysis of an ultrasonic-generated aerosol. The aerosol was obtained from an organic solvent containing dissolved organometallic precursors. Direct measurement of the piezoelectric effect, as well as electromechanical resonance observations, were achieved on small beams. The coupling factor, k , of the layers reached a value of 0.09, which is comparable with the single crystal value.

New spray pyrolysis deposition and magnetic properties of ferrite thin films for microwave applications

Abstract For microwave applications we report a new spray technique based on the pyrolysis of an ultrasonic generated aerosol. Thin films of garnet and spinel ferrites (Y 3 Fe 5 O 12 , LiFe 5 O 8 , Ni 1− x Zn x Fe 2 O 4 ) are grown. The magnetic properties are discussed with respect to the experimental conditions.

High Tc superconducting films prepared by pyrolysis of an ultrasonic-generated aerosol☆

Abstract Thin films of YBa2Cu3O7 − x superconductors have been prepared using a new spray technique based on the pyrolysis of an ultrasonic-generated aerosol containing the YBaCu precursors. This deposition technique leads to a better quality of the film surface compared with the conventional spray techniques and allows accurate control of the film thickness. Films of about 0.2–1 μm in thickness have been annealed in air successively at 500 and 950 °C and then slowly cooled in oxygen to 200 °C. This method leads to well-crystallized YBa2Cu3O7 − x films with good grain size homogeneity and a texture in the 001 direction depending on the heat treatment conditions. SrTiO3, yttrium stabilized ZrO2 or MgO single crystals and ceramics have been used as substrates. In this paper we discuss the influence of experimental conditions and substrates on the microstructure, morphology and superconducting properties of the films.

High Tc superconducting films obtained by pyrolysis of an ultrasonically deposited gel

YBa2Cu3O7−x superconducting thin films have been prepared using a technique based on the pyrolysis of an ultrasonically deposited gel containing the Y-Ba-Cu precursors. This technique allows us to control accurately the film thickness and surface homogeneity. MgO single crystals have been used as substrates. Films about 0.2–10 μm in thickness have been annealed in air at 500°C, heated in oxygen at temperatures ranging from 850 to 1000°C and then slowly cooled in oxygen to room temperature. This method leads to well-crystallized YBa2Cu3O7−x films with a grain size and a texture in the 001 direction depending on the heat treatment conditions. X-ray diffraction, scanning electron microscopy and resistivity measurements are presented in this paper and discussed as a function of the film thickness and experimental conditions.

Growth of garnet thin films for magneto-optic memories by pyrosol CVD process

A description is given of the deposition of garnet thin films for magnetooptic memories. The deposition technique (pyrosol process) is based on the pyrolysis of an ultrasonic generated aerosol, which contains the dissolved organometallic precursors. Films have been deposited at temperatures ranging from 520 degrees to 600 degrees C. Y/sub 3/Fe/sub 5/O/sub 12/ polycrystalline thin films with good crystallinity were obtained on glass or fused quartz substrates after annealing the deposited films. Single-crystal thin films were grown by epitaxy on GGG single-crystal wafers as shown by grazing X-ray diffraction and Kikuchi experiments. Magnetic and magnetooptic properties of the films were very close to the bulk material properties. >

Garnet thin film deposited by a new chemical vapour deposition

Abstract For magneto-optical information storage applications we report on the deposition of yttrium-iron-garnet (YIG) thin films by an original deposition process using the pyrolysis of an aerosol produced by ultrasonic spraying (Pyrosol process). The compositions of the films are discussed with regard to the experimental conditions. As-deposited layers were amorphous. After annealing at 700 °C in air, epitaxial YIG layers are obtained on gadolinium-gallium-garnet single crystal and high-quality polycrystalline films on fused quartz. The magnetic and magneto-optical properties of these films are studied.

Growth of Bi-substituted YIG thin films for magneto-optic applications

Abstract For magneto-optical applications we report the growth of Bi-substituted YIG thin films by an original CVD technique (the pyrosol process). The composition of the deposited films is studied with respect to the experimental conditions (temperature, concentration ratio of the source solution). A Faraday rotation higher than four degrees per micrometer is obtained at λ = 520 nm.

A new route for the deposition of YBaCuO thin films

Abstract A new deposition technique has been adapted to the preparation of high Tc superconductive thin films. This low cost technique is based on the pyrolysis of a thin gel obtained by polymerization of an ultrasonically generated aerosol. The ultrasonic pulverization method allows a very precise control of the deposition conditions and leads to homogeneous coatings. After calcination in air at 500°C, the layers are annealed in oxygen at temperatures ranging from 850 to 1000°C and then slowly cooled to room temperature. This method leads to superconductive thin films of 0.2 to 10 microns in thickness with a complete superconductive transition between 90K and 70K.