Browsing by Author "Hafdallah, A."

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    Realization and study of ZnO thin films intended for optoelectronic applications
    (Oum-El-Bouaghi University, 2011) Herissi, L.; Hadjeris, L.; Moualkia, H.; Abdelmalek, N.; Hafdallah, A.; Attaf, N.; Aida, M. S.
    The objective of this study is the realization of zinc oxide (ZnO) thin films intended for optoelectronic applications. For this purpose, thin films were prepared by spray pyrolysis technique from zinc acetate solutions of different molarities (0.025 M, 0.05 M and 0.1 M) used as precursors on Si and glass substrates heated between 200 and 500 °C. The nozzle to substrate distance was varied between 20 and 30 cm. Structural, optical and electrical properties of the films have been studied. The results indicated that the films deposited were transparent in the visible region, well adherent to the substrates and presented surface roughness. All samples were polycrystalline in nature, having hexagonal würtzite type crystal structure. A (002) preferred orientation was observed at 450°C and a 0.025M molarity. The optical energy gap measured was about 3.3 eV. The refractive index values presented small variations with the deposition conditions and were located between 1.8 and 2.0. The electrical properties showed that the samples are natively n‑type semiconductor and the electrical conductivity at room temperature varied between 10-5 and 102 (Ω.cm)‑1.
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    Substrate effect temperature on Cu2ZnSnS4 thin films deposited by ultrasonic technique
    (Oum-El-Bouaghi University, 2011) Daranfed, W.; Fassi, R.; Hafdallah, A.; Ynineb, F.; Attaf, N.; .Aida, M.S; Hadjeris, L.; Rinnert, H.; Bougdira, J.
    Cu2ZnSnS4 (CZTS) thin films are a potential candidate for absorber layer in thin film solar cells. CZTS films were deposited by spray ultrasonic technique. An aqueous solution composed of copper chloride, zinc acetate, tin chloride and thiourea like precursors is sprayed on heated glass substrates at various temperatures. The substrate temperature was changed from 280°C to 360°C in order to investigate its influence on CZTS films properties. The DRX analyses indicated that Cu2ZnSnS4 films have nanocrystalline structure with (112) preferential orientation and a crystalline size, ranged from 30 to 50 nm with increasing substrate temperature. The obtained films are composed of SnS, ZnO, ZnS and Cu2ZnSnS4 phases. The optical films characterization was carried by the measurement of UV-visible transmission. The optical gap was deduced from the absorption spectra. Broad emissions at around 1.27 eV was observed in the photoluminescence spectrum measured at 77 K.