Browsing by Author "Y. BERREDJEM"

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    Investigation of CuIn1-xGaxSe2 thin films co-evaporated from two metal sources for photovoltaic solar cells
    (JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 2017-06-07) A. BOURAOUI; Y. BERREDJEM; A. AIN-SOUYA; A. DRICI; A. AMARA; M. KANZARI; F. CHAFFAR AKKARI; N. KHEMIRI; J. C. BERNEDE
    CuIn1-xGaxSe2 (CIGS) thin films were grown by co-evaporation using two sources for the metal elements (Cu, Ga and In). A Mo coated soda lime glass substrates heated at 500 °C was used for the deposition. X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirm that these films are polycrystalline with a chalcopyrite structure and showed homogeneous grain size estimate about 25 nm. X-ray photoelectron spectroscopy (XPS) was performed to analyse the binding energy values of Ga3d and O1s onto CIGSe layers. The conductivity measurements in the temperature range of 40-400 K were carried out for 0.05 x  0.23. The effect of grain boundary scattering on the electrical transport played an important role in describing the transport processes in these films. The bowing factor is discussed taking into account the deposition techniques of CIGS films. It has been noticed that the open circuit voltage (Voc) is influenced by Ga content and the energy gap value of the absorber CIGS thin layers and yielded a poor efficiency of solar cells.
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    SPATIO-TEMPORAL VARIABILITY OF WATER POLLUTION IN THE WATERSHED OF WADI ECHAREF, SEDRATA, ALGERIA
    (Poll Res, 2019-12-14) M. A. BELLAZI; N. ZENATI; N. BELAHCENE; M.F. SAMAR; Y. BERREDJEM; A.E. GHEID
    In order to monitor the spatio-temporal variability of water pollution in Wadi Echaref water shed, seven physico-chemical parameters are measured repeatedly over time (05 campaigns) in six selected sampling stations along this hydro system. The latter is subject to a pollution generated by discharges of domestic and industrial wastewater from two cities of Sédrata and M’daourouch. It receives daily more than 5313 m3/day of waste water, 5000 of which are treated by the STEP (waste water treatment plant) of Sédrata and more than 313 m3 are discharged directly without any prior treatment. In order to study the temporal stability of the spatial structure and measure the date station interaction in the 5 mesological tables obtained, we used partial triadic analysis. The study of the obtained results’ temporal structure reveals the existence of a common structure among the different dates that reflect a downstream upstream type of spatial expression described by the variables that characterize the pollution. The stations (S1, S2, S3 and S4) located downstream the domestic and industrial discharges of the cities of Sédrata and M’Daourouch, are still opposed to other stations, highlighting that these stations remain polluted during the study period, as evidenced by the concentration of Nickel, Silver and Cobalt.