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323 results on '"Boukhachem, A."'

23. Structural Defect Impact on Changing Optical Response and Raising Unpredicted Ferromagnetic Behaviour in (111) Preferentially Oriented Nanocrystalline NiO Films

Author

Amira Ben Gouider Trabelsi, Fatemah. H. Alkallas, Aicha Ziouche, Abdelwaheb Boukhachem, Mostefa Ghamnia, and Habib Elhouichet

Subjects
NiO sprayed thin film, spectroscopic ellipsometry (SE), intrinsic defects, vibrating sample magnetometer (VSM), Crystallography, QD901-999
Abstract

NiO thin films deposed on a glass substrate, “NiO/glass”, are successfully prepared using a spray pyrolysis technique (SPT) at 460 °C and characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray, Atomic force microscopy (AFM), spectroscopic ellipsometry (SE), Photoluminescence (PL) and diverse electric and magnetic studies. The structural investigation shows that the synthesized films crystallized in a cubic structure with (111) preferential orientation. The NiO layers exhibit a uniform grain of regular sizes with aggregates randomly distributed across their surface. The optical properties of the NiO thin films evidenced a normal optical dispersion as well as good transparency of the NiO films. An unpredicted ferromagnetic aspect was raised due to the high oxygen presence in the synthetized material. A high thermal dependency of the conductivity, as well as a semiconductor behavior of the grown NiO material, is also demonstrated.

Published
2022
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42. Investigation of some physical properties of ZnO nanofilms synthesized by micro-droplet technique

Author

N. Hamzaoui, A. Boukhachem, M. Ghamnia, and C. Fauquet

Subjects
Physics, QC1-999
Abstract

In this paper, ZnO nanocrystals were synthesized using a simple micro-droplets technique from a solution prepared by dissolving zinc acetate di-hydrate [Zn(CH3COO)2, 2H2O] in methanol. Microdroplets were deposited on glass substrates heated at 100 °C, the obtained samples of ZnO films were investigated by XRD, AES, AFM, ellipsometry and PL. XRD patterns reveal the wurtzite structure of ZnO where the lattice parameters a and c, calculated from XRD signals, show a nanometric character of ZnO nanoparticles. The chemical composition of ZnO film surfaces was verified by Auger electron spectroscopy (AES). From Auger signals, oxygen (O-KLL) and zinc (Zn-LMM) Auger transitions indicate well the presence of Zn-O bonding. The surface topography of the samples was measured by atomic force microscopy (AFM) where ZnO nanoparticles of average size ranging between 20 and 80 nm were determined. Some optical properties as dielectric constants, refractive index, extinction coefficient as well as the optical band gap were determined from ellipsometry analysis. The dispersion of the refractive index was discussed in terms of both Cauchy parameters and Wemple & Di-Dominico single oscillator model. The photoluminescence (PL) measurements exhibited two emission peaks. The first at 338 nm, corresponding to the band gap of ZnO, is due to excitonic emission while the second around 400 nm, is attributed to the single ionized oxygen vacancies. Keywords: ZnO nanoparticles, Micro droplets technique, AFM, Auger spectroscopy, Ellipsometry, Photoluminescence (PL)

Published
2017
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