Ph.D. Tezi Görüntüleme

       In this study, the effects of CdS thin films produced by two techniques on the CdS/CdTe solar cells have been investigated. CdS thin films were prepared by a quasi-closed volume and chemical spray pyrolysis methods.

       First, the effects of white light illumination during the deposition of CdS thin films in a quasi-closed volume, on the structural, photoelectrical and optical properties were investigated. The films were highly c-axis oriented with an increasing intensity of (002) reflection as the illumination increases. The room temperature resistivity values of the CdS films decreased in the range of 10^7-10^4 $xcm. The photosensitivity in the fundamental absorption region and the transparency in the transmission region considerably increased as the illumination increased. Under 100 mW/cm^2 insulation, the efficiencies of the CdS/CdTe solar cells based on window materials which were deposited: (1) dark; (2) under an illumination of 150 mW/cm^2; were found to be 1.8 % and 7.3 %, respectively.

       In addition, we report the structural, electrical and optical properties of CdS thin films produced by spray pyrolysis as a function of In concentration. As the In concentration increased the preferred orientation of the films changed from the (002) plane to the (101) plane. The resistivity decreased with increasing In concentration, reached a minimum, and then increased with further increased in In concentration. In the transmittance spectra of CdS thin films shifts were observed towards lower wavelengths as the In concentration increased. Under 100 mW/cm^2 insulation, the efficiencies of the CdS/CdTe solar cells based on window materials which were deposited: (1) undoped; (2) In doped (x=0,05) ; were found to be 3.5% and 6.4 %, respectively

       Finally, a new fabrication technique of p-type CdS thin films by He-Ne laser illumination of bilayer Cu-nCdS structures at room temperature was investigated. The band gap of CdS films was estimated to be 2,41 eV from the optical transmission spectra. The formation of a p-n homojunction in CdS films or conversion of the film all over to the p-type, depending on the duration of laser illumination, was shown by I-V characteristics, the photovoltaic, the hot prope and Hall effects measurements.

       Keywords: CdS/CdTe, p-n Junction, Short Circuit Current, Open Circuit Voltage