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Transparent conductive oxide (TCO) thin films are used as a front electrode in large area thin film Si solar cells. The material that is most frequently used for TCO is SnOx, since it could be deposited by atmospheric pressure chemical vapour deposition (APCVD), has high optical gap, good conductivity and favorable surface roughness. The active part of solar cell is deposited on TCO by plasma enhanced chemical vapour deposition under low gas pressure. In recent years, the working gas for thin Si films deposition contains silane highly diluted by hydrogen which puts the additional demand on TCO - it has to be resistant to the hydrogen plasma. Many experiments show that SnOx does not satisfy this demand. That is why we examine the possibility to protect the SnOx with a thin ZnO layer. Thin aluminium doped ZnO transparent conductive (TCO) films were prepared by APCVD method using Zn-acetate water/isopropanol solution as precursor. The preparation parameters (deposition temperature, doping concentration, chemical precursor concentrations and post-preparation thermal treatment) were optimized to the needs of the TCOs: maximum transparency and minimum resistance. The films were deposited on a SnOx , pre-coated on the glass substrate and exposed to the hydrogen plasma in the typical condition for thin crystalline Si deposition. The transmittance, resistivity and XPS analysis of the SnOx and ZnO:Al coated SnOx were measured before and after plasma treatment. The results suggest that the hydrogen plasma treatment does not affect the ZnO:Al protective layer in contrary to the pure SnOx. |