Improvement of microcrystalline silicon solar cell by insertion of buffer layer to TCO/p interface

We have developed a buffer layer to suppress the darkening of TCO (SnO/sub 2/) caused by the reduction reaction of atomic hydrogen during the p-type microcrystalline silicon (/spl mu/c-Si) deposition in the superstrate solar cell. It was found that the very thin (below a few nm) sputtered Si (sp-Si) with a surface oxide layer suppresses the darkening and improves crystallinity of p-layer. It was also found that the spectral response particularly in the short wavelength region is better than that for the cell using ZnO overcoating, even if the band gap of Si is narrower than that of the ZnO. The short circuit current (Isc) for the /spl mu/c-Si cell using the sp-Si was higher value (17.7 mA/cm/sup 2/ for 1 /spl mu/m thick i-layer) as compared to Isc of 15.7 and 14.9 mA/cm/sup 2/ for the cell of using the ZnO buffer layer and without using a buffer layer.