Hydrogen passivation of polycrystalline silicon solar cells by means of catalytic reactions

Due to emitter damage at the surface, hydrogen passivation of polycrystalline silicon solar cells by implantation or exposure to hydrogen plasma ultimately limits the yield. A method which uses the titanium-hydrogen system and does not increase the surface recombination at the emitter has been developed. In this method, hydrogen is diffused out of a TiH_x layer which releases atomic hydrogen upon heating. By cyclic heating, the TiH_x film can be replenished with hydrogen. Even thin films can act as near-ideal sources for atomic hydrogen diffusing into the polycrystalline substrate, comparable to the positive effects of hydrogen incorporation during implantation from a Kaufman-type ion source. The passivation depth is larger for this method. Following the hydrogen diffusion, the TiH_x layer may be converted into an antireflection coating