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 limits the yield ultimately. Therefore, a new method employing the titanium-hydrogen system has been developed, which does not increase the surface recombination at the emitter. In this method hydrogen is diffused out a TiHx layer which upon heating releases atomic hydrogen. By cyclic heating the TiHx film can be replenished with hydrogen. Thus even thin films can act as near 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 new method. Following the hydrogen diffusion, the TiHx layer may be converted into an antireflection coating.