Transport properties of hot-wire CVD μc-Si:H layers for solar cells

Transport properties of microcrystalline silicon (μc-Si:H) films prepared by hot-wire/catalytic chemical vapor deposition (HWCVD) have been investigated by steady-state photocarrier grating (SSPG) and conductivity measurements. Improved diffusion length has been obtained when the hydrogen dilution approaches the value corresponding to the amorphous–microcrystalline phase transition, i.e. 0.92±0.01. An efficiency of 5.1% has been obtained for μc-Si:H n–i–p superstrate type solar cells on a glass substrate, with a 3.5 μm thick i-layer deposited by HWCVD, using a variable hydrogen dilution (VHD) process with the final dilution value close to 0.92. Future use of a n–i–p substrate structure should improve the performance of HWCVD μc-Si:H solar cells.