الفهرس 
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Abstract
Copper-zinc-sulfur (Cu-Zn-S) ternary compound was reported as a promising material for variety of optical device applications. This compound was first reported and developed as absorber layer in solar cells in 2013 by N. Kitagawa et. al. [7]. They reported that this material is a p-type semiconductor material that has wide direct band gap and good absorbance to visible light. Cu-Zn-S has been used as alternative to the complex compound CZTS (Se) of four or five elements. In addition, little work has been done in investigating the effect of doping on the properties of Cu-Zn-S thin films. Thus, in this work, preparation of undoped and Ag doped Cu-Zn-S thin films have been reported using low temperature (280˚c), low cost sol gel spin coating method without sulfurization. For this objective, several films of Cu-Zn-S and Ag doped Cu- Zn-S with different Ag concentrations have been deposited on different substrates (Glass and n, p-type Silicon) with different thickness of 5 or 8 layers The effects of Ag doping and the film thickness on the structural, morphological, optical and electrical properties of the films prepared on glass substrates have been presented. It has been found that both Ag free Cu-Zn-S thin film sample (S0) and Ag doped Cu-Zn-S thin film samples with 0.5٪ (S1), 1٪(S2) and 2%(S3) show polycrystalline structure of hexagonal and cubic crystal structure using X-ray diffraction. Scanning electron microscope images show that all samples have good homogeneity and cover all the area of the substrates specially, 1٪ Ag doped sample have less porous structure. Energy dispersive spectroscopy results have been presented for reporting chemical composition of the constituting elements. Effect of annealing at two different temperatures 320˚c and 360˚c on the undoped samples and the effect of annealing at 320˚c only on the Ag doped samples for further enhancement of film crystallinity have been presented. Optical properties of undoped and Ag doped samples have been reported. It has been found that decrease in the optical bandgap energy from 2.16 eV (un-doped sample) to 1.91 eV at 2٪ Ag doping occurs. At 280˚c, the sample 1% Ag doping has the lowest resistivity value 0.66 Ωcm. At 320˚c the sample of 0.5٪ Ag doping has the lowest resistivity value 0.68 Ωcm compared to the other samples. from the results of all measurements we did on the films deposited on glass, we chose the best films to be deposited on silicon substrates (n, p types). We deposited the pure Cu-Zn-S films and Ag-doped Cu-Zn-S films with 1٪ Ag concentration on silicon substrates. Also we studied the effect of the different substrates n, p types on the structural, optical and electrical properties of the films In addition, we investigated the effect of annealing at 320 ˚C on un-doped and Ag- doped films for further enhancement of film crystallinity. It has been found that the sample S05lpsi (un-doped film in thickness of 5 layers deposited on p-type Si) has the biggest crystal size and has the most surface homogeneity compared to other samples. Optically it has been found that the bandgap energy decrease from 2.5 ev (at un-doped sample on n-type Si) to 2.14 ev (at 1٪ Ag doping sample on n-type Si) and from 2.7 eV (at un-doped sample on p-type Si) to 2.5 eV (at 1٪ Ag doping sample on p-type Si). In order to investigate the photovoltaic properties of these films deposited on silicon substrates the Current – voltage (I-V) curves in dark and during illumination of either white lamp (2800 lm) or diode laser of 405 nm have been measured to find out the values of open circuit voltage Voc and short circuit current Isc and the samples of highest Voc and Isc express the good parameters for obtaining photovoltaic cells. We found the un-doped Cu-Zn-S film sample in thickness of 5 layers prepared at 280˚c that have been deposited on p-type silicon substrate has the highest Voc values under lamp and under laser illumination of about 0.65 mv and 4.5 mv respectively. The enhancement of Ag doping appeared in increasing the short circuit current Isc value as the sample contains films of 1% Ag doped Cu-Zn-S have been deposited on p-type silicon substrate and annealed at 320 ˚c has the highest Isc under laser illumination of about 366 µA/cm². We conclude that the Ag doping enhance the photovoltaic properties of the Cu-Zn-S films by increasing the value of the short circuit current Isc.