| Novel materials are well known as an important role in the domains of science and technology. They will accelerate the advance in science and technology, and enhance the economic strength in a country, and also improve people's everyday life. Optoelectric and info materials are more important than other materials in our times. Cadmium sulfide and its thin films are optoelectric &info materials. They are so many potential applications that study on them may boost the development of optoelectric & information industry, and yet prosper economy in our country.In this dissertation the fabrications of CdS thin films were introduced. The recent advances and applications were reviewed. It presented the deposition process of CdS thin films by chemical bath deposition (CBD) and treatment after prepared. The initial growth rates dependence on experimental conditions were investigated. The mechanism of chemical bath deposition of CdS thin films was theoretically analyzed, and then proposed a modification to its mechanism, which is based on the successive absorption and decomposition of inter mediate species. The growth behaviors and properties of CBD-CdS thin films can be explained and predicted on basis of the reaction mechanism proposed. In the paper properties of the samples were also studied in detail. Some results obtained are as follows:(1) Chemical bath deposition of CdS thin films is usually based on the decomposition of the thiourea in alkaline solution containing a cadmium salt, and then CdS precipitations were produced as thin films on the substrate. The CBD technique is a simple, inexpensive and convenient method for large area deposition, and yet a low-temperature deposition technique. And the thin films have few defects and a uniform stoichiometry, and also excellent electrical and optical properties. (2) The growth behaviors of CBD-CdS thin films may be influenced by the experimental conditions. We have obtained the optimum conditions to deposit CdS thin films in the CBD process. The optimum ranges were: initial [SC(NH2)2]/[CdCl2] ratios higher than 1.5, ammonia concentration in the range of 0.1 to 3M, NH4Cl concentration varying from 0.01 to 0.1M, temperature in range of 60 to 90℃, and pH values between 10 to 12, and deposition time general duration from 20 to 30 min. The investigational results on the films growth are of much innovation. (3) Properties of the CdS thin films can be improved with ultrasonication and treatment, and by slowly releasing the reagent of CdCl2 with the contact of another reagent, SC(NH2)2. They can remove the absorbed colloidal particles and make thin films uniform and fine. Then they can enhance the heterogeneous reactions, and decrease the CdS particles by the homogeneous growth in the solution. (4) After the films were analyzed using XRD, GAXRD, SEM, and UV, we observed that the crystalline structure of the films wasn't influenced on the experimental conditions. But the surface morphologies and energy gaps were dependence on the ammonia concentration, pH values, and temperature,and duration time. However, the optical and electrical properties of CdS thin films are influenced, too.(5) CdS thin films have a number of particular applications. They can be utilized as photovoltaic devices, sensors, and light emitting devices, optical integrated circuits and storage.
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