| This paper is a part of the "ninth five-years plans for science and technology" --<>. Focused on CdTe/CdS thin films and its heteroj unction, the thesis hasdeveloped the research for the three purposes:1 .To investigate the effects of CdCl2 vapor treatment on the structure, band gap andconductivity of CdS films.2.To find the optimal annealing conditions of CdTe films. 3.To explore the role of oxygen in ambient during Close Space Sublimation depositionof CdTe films.Through the systematically investigation, we have obtained the following achievements:1 .It has been found for the first time that CdS films annealed without CdCl2 at 410℃ show the exist of Cd. The band gap of the CdS films becomes narrower from 2.51eV for as grown sample to 2.40 eV for annealed one, which is near to 2.42eV for CdS single crystal. The CdS films annealed at 410℃ for 30 minutes with CdCl2 have the largest ratio of photo conductivity to dark conductivity and show the best electrical property.2.The optimal annealing conditions (380℃ with CdCl2) of CdTe films have been found. It has been observed that the recrystallization of CdTe films happens at about 380℃ when annealing. From photoluminescence spectra and I-V curves, we have concluded that the CdTe/CdS devices annealed at 380℃ include the lowest defect density in both the surface of CdTe films and the CdTe/CdS interface. They also show the best electrical performance. CdCl2 is helpful to decrease the defect density and increase the short circuit current.3.The CdTe films deposited in Ar+O2 atmosphere appear more compact than in Ar atmosphere. The presence of oxygen during close space sublimation of CdTe obviously promotes the open current voltage of the device.
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