Solution grown polysilicon for photovoltaic devices

A process has been developed for the low temperature deposition of polysilicon films from a thin layer of Si-metal melt, onto SiO₂ or glass substrates. Substrate temperatures ranged from 450° to 650°C. The wetting behavior of the liquid layer onto the substrate has been found very important. Morphological results are very good if a Ti wetting layer is used; films with grain size of up to 25 μm are deposited. These films show highly preferred (111) orientation, good hole mobility (approx. 100 cm²V^-1s^-1), but very poor photoconductivity. Not using a wetting layer results in a smaller grain size, poorer electron mobility (up to 60 cm²V^-1s^-1), but improved photoconductivity. Trends are found linking electrical properties to deposition temperature and thickness of solvent layer used. Some improvement is found by ECR plasma hydrogenation.