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    Öğe
    Gadolinium doping effect on SnO2 thin films optical and electrical properties
    (Iop Publishing Ltd, 2019) Adjimi, A.; Aida, M. S.; Attaf, N.; Ocak, Y. S.
    Undoped SnO2 thin films, as well as Gd-doped SnO2 thin films, were deposited on glass substrate by spray pyrolysis technique. The effect of gadolinium concentration and substrate annealing on structural, optical and electrical properties of SnO2 films are investigated. The structural properties of these thin films were analyzed using x-ray diffraction (XRD). XRD analysis confirmed the polycrystalline tetragonal crystalline structure of the films with mainly (110) preferential growth plane. The crystallite size has been reduced from 35 nm to 15 nm with increasing Gd dopant concentration. The films optical transmittance spectra exhibit high transparency of about 76%-87% in visible region. The films optical gap is enlarged from 3.43 eV in the un-doped films to 3.71 eV when Gd doped. The films figure of merit revealed a maximum value of about 8.2 x 10(-3) (Omega/sq)(-1) at 550 nm wavelengths. The highest conducting and transparency are obtained in the film prepared with 3 wt% Gd doping ratio. Hence, we conclude that 3 wt% ratio is the optimal one required for Gd:SnO2 film production that may found optoelectronic applications, in particular, as window layer in solar cells.
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    Öğe
    Spectroscopic ellipsometry, optical, structural and electrical investigation of sprayed pure and Sn-doped ZnO thin films
    (E D P Sciences, 2012) Mokhtari, H.; Benhaliliba, M.; Aida, M. S.; Attaf, N.; Ocak, Y.
    in this work, we report the transparent pure and Sn-doped zinc oxide (ZnO). The films were deposited onto microscope glass substrate which was heated at 350+/-5C degrees by ultrasonic spray pyrolysis (U S P) deposition technique. The concentrations of Sn were selected within the range of 0-3% by step of 0.5% and the time deposition is kept at 5 min. A (002)-oriented wurtzite crystal structure was confirmed by X-rays patterns; and grain size varied within the range 7.37-14.84nm, and cristanillity is calculated goes from14.4 to 45.9%. Based on UV-VIS-IR analysis, the results revealed the high transparency of the sprayed films which exceeds 90%. The band gap energy was of 3.26-3.30 eV. The film thickness was estimated by spectroscopy ellipsometry and the found values were of 165-270nm. The refractive index is in the range of 2.75. The obtained electrical parameters were around 10(18) cm(-3), 3.6 cm(2)/Vs, 1.6 Omega.cm; 5.8cm(3)/C. finally the Sn-doping has influenced the physical parameters of as-ground ZnO films
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    Öğe
    Thermal sulfurization effect on sprayed CZTS thin filmsproperties and CZTS/CdS solar cells performances
    (Iop Publishing Ltd, 2018) Boutebakh, F. Z.; Batibay, D.; Aida, M. S.; Ocak, Y. S.; Attaf, N.
    Cu2ZnSnS4 (CZTS) thin films were successfully deposited by a simple and inexpensive technique such as ultrasonic spray pyrolysis. The effect of sulfurization temperature on CZTS films properties and on Mo/CZTS/CdS/ZnO/ZnO:Al solar cell performances were studied. The investigated sulfurization temperatures were ranged from 450 degrees C to 550 degrees C. X-ray-diffraction pattern and Raman scattering spectroscopy confirmed the formation of monophase kesterite CZTS, the best crystallinity was obtained in the sample sulfurized at 450 degrees C. Atomic forces microscopy images indicated that annealing temperature increase yields to rough films with large grain size. UV-visible optical transmittance spectroscopy reveals that films enjoy a strong absorption with an absorption coefficient as high as 104 cm(-3). Whereas, the optical band gap energy was found to decrease with sulfurization temperature. Hall effect measurements confirm the films p-type conductivity; the carriers concentration varies between 10(14) and 10(16) cm(-3) when the sulfurization temperature changes from 450 degrees C to 550 degrees C. The I-V characteristics of the realized Mo/CZTS/CdS/ZnO/ZnO:Al cells indicated that all the devices show a rectification behavior with an ideality factor ranged from 1.6 to 1.8. The current transport is dominated by the interfacial recombination process. The photovoltaic effect was observed, the best performance was achieved in the device prepared with CZTS sulfurized film at 450 degrees C, the recorded characteristics are: 0.43% efficiency, 9.8 mA cm(-2) short circuit current, 161 mV open circuit voltage and 28% fill factor. A comparison between the reported results obtained by different techniques reveals the superiority of the cells prepared with CZTS deposited by physical deposition technique such as thermal evaporation or sputtering.