Development of highly conductive boron-doped microcrystalline silicon films for application in solar cells

We have examined the deposition of highly conductive boron-doped microcrystalline silicon (pc-Si:H) films for application in solar cells. Depositions were conducted in a very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) chamber. In the deposition processes, various substrate temperatures (T-S) were applied. Highly conductive p-type microcrystalline silicon films were obtained at substrate temperature lower than 210 degrees C. The factors that affect the conductivity of the films were investigated. Results suggest that the dark conductivity, which was determined by the Hall mobility and carrier concentration, is influenced by the structure. The properties of the films are strongly dependent on the substrate temperature. With TS increasing, the dark conductivity (sigma(d)) increases initially; reach the maximum values at certain T-S and then decrease. Also, we applied the boron-doped mu c-Si:H as p-layers to the solar cells. An efficiency of about 8.5% for a solar cell with mu c-Si:H p-layer was obtained.