Nazar Abbas Shah

Abstract:

The research work is based on the growth of CdZnTe thin films by thermal evaporation technique using layer by layer method. After depositing the CdTe layer, a thin layer of ZnTe is deposited on already CdTe layer for the formation of ternary IIB-VIA semiconductor compound CdZnTe thin films by the same technique. After annealing, these CdZnTe thin films samples are characterized structurally, optically and electrically. The CdZnTe thin films with band gap energy of 1.45–1.75 eV are of current interest because of their promising applications as the top device of a two-cell tandem structure in high-efficiency thin-film solar cells and of X-ray and gamma ray detectors. Cadmium sulfide (CdS) powder (Aldrich 99.99%) is used to fabricate CdS thin films and mixed with pure zinc (Zn) powder for the CZS thin films. An angle resolved transmission show a very interesting behavior that at higher angles, the transmission is decreased in UV and VIS regions but increase in the IR region, which confirme that these thin films are more transparent in the IR range at higher angles. These results including structural, surface morphology and the optical properties are strongly correlated which validate this argument that Zn can be diffused by mechanical mixing method and the CZS thin films could be used as a window layer instead of CdS having wide band gap. Thin films of CdTe with thickness of 1-3 microns can convert sunlight energy into electrical energy. Zinc Telluride (ZnTe) polycrystalline thin films were fabricated on corning glass substrates by Close Spaced Sublimation (CSS) technique under vacuum. More than 80% transmission in the visible range makes it suitable materials for solar cell applications. Electrical results show that conductivity of CdZnTe thin films varies from 4.66 x10-06 (Ù-cm)-1 to 8.20 x10-11 (Ù-cm)-1. Due to its direct energy band gap nature, it is ideal for efficient thin film based solar cells. Larger grains of CdZnTe are formed due to CSS technique, as compared CdZnTe thin films prepared by other techniques, which is important for solar cell applications. The effects of radiations on the CdZnTe thin films can explore a new pathway for researchers.