Preparation Of SnO₂ Film By PECVD And Application On CdS/CdTe Solar Cells

SnO₂ is a kind of wide bandgap materials, it has been widely applied in many fields such as solar cell, electric heating devices, transparent electrodes and gas sensors, due to its excellent properties, i.e. wide bandgap, high transparency in visible region, high stability. This thesis research the production of intrinsic SnO₂ film by PECVD and the application of this film on CdTe thin films solar cells as HRT buffer layer. This means which inserting a HRT buffer layer between the TCO and CdS has been proved that increasing the cells'efficiency more. Intrinsic SnO₂ film has not only the same work function with TCO but also the good ohmic contact with CdS film, so it can be used as a kind of HRT materials. In this paper, intrinsic SnO₂ films were successfully fabricated by PECVD and annealed in N₂/O₂ gas. The prepared films were characterized by X-ray diffraction, UV-Visibile absorption and XPS. It was found that intrinsic SnO₂ films were amorphous structure at 200℃and turned to the polycrystalline at 400℃. The high SnCl₄ content result in low transparent, on the other hand, it bring high conductance. Finally, the effect of HRT buffer layer in cells had been studied. As analyzed the result of HRT buffer layer effecting with SnO₂:F and CdS layer, the conclusion had been obtained, which was useful that electron moving through CdS layer to SnO₂:F layer. In the same manufacture process, two group of CdTe cells which one had HRT buffer layer and another had not HRT buffer layer were compared. The result was indicated that the cells which have HRT layer have better properties than other group, so its efficiency increased evidently. As for this experiment, the cells'efficiency with HRT buffer layer increase more 14.4% than the cells without HRT buffer layer.