In order to enhance the conversion efficiency of pin-type a-Si:H solar cells, we introduced δ - doped boron layers as window material with a conventional glow - discharge decomposition method. We found that the doping efficiency was relatively high and that the photosensitivity. ($\sigma_{ph}/\sigma_{dark}$) of δ - doped p-type materials was much higher than that of uniformly B-doped p-type a-Si:h. The conversion efficiency of the solar cell with δ - doped p-layer was obtained as 7.81% when the total thickness of p-layer is 40Å and the number of boron layers is 2 or 3. The blue response of δ - doped solar cell was better than that of conventional pin-type solar cells. The conversion efficiency was increased up to 9.78% by reverse bias annealing at 215℃. It is due to the increase of $V_\infty$ and improvement of spectral response in the short wavelength region.
