Browsing by Author "abdelkader. Djelloul"

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    CONTROLE DES CENTRES F+ DANS LES COUCHES MINCES D’OXYDE DE ZINC
    (2000-11-06) abdelkader. Djelloul
    Dans cette étude, l’importance a été donnée à la variation de la luminescence verte dans les couches minces d’oxyde de zinc (ZnO) en fonction du traitement ultérieur dans une atmosphère d’hydrogène. Le défaut responsable de la luminescence verte dans ZnO est la lacune oxygène (VO ) sous la forme de centres F+. Il est établi que la concentration des lacunes peut être régulée à la limite de l’ordre deux pour des températures ne dépassant pas 980 K. Au-delà de cette température, se crée un autre type de défaut dans les couches de ZnO, qui est le zinc interstitiel
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    Photoluminescence, FTIR and X-ray diffraction studies on undoped and Al-doped ZnO thin films grown on polycrystalline a-alumina substrates by ultrasonic spray pyrolysis
    (2010-06-17) abdelkader. Djelloul
    Undoped and aluminum-doped zinc oxide (ZnO) thin films have been grown on polycrystalline a-alumina substrates by ultrasonic spray pyrolysis (USP) technique using zinc acetate dihydrate and aluminum chloride hexahydrate (Al source) dissolved in methanol, ethanol and deionized water. A number of techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and photoluminescence (PL) were used to characterize the obtained ZnO thin films. It was seen that the orientation changed with increase in substrate temperature. During the ZnO deposition Zn source reacted with polycrystalline a-Al2O3 substrate to form an intermediate ZnAl2O4 spinel layer. It has been interestingly found that the intensity of green emission at 2.48 eV remarkably increased when the obtained ZnO:Al films were deposited at 380 1C. The FTIR absorbance intensity of spectroscopic band at 44776 cmÿ1 is very sensitive to oxygen sublattice disorder resulting from non-stoichiometry, which is consistent with the result of PL characterization