Passivation of defects in polycrystalline silicon solar cells by molecular hydrogen annealing

The paper presents a new technique for passivating grain boundaries and intragrain defects in the polycrystalline silicon material of the solar cells. Enhancement in the minority-carrier diffusion length has been achieved by thermal annealing in molecular hydrogen in previously formed n+ p junctions. The annealing temperature dependence of the diffusion length has been studied in the temperature range of 400 to 700° C. The study shows a significant increase in the diffusion length from 21-8/ im to 67-8/ jm by this process. The diffusion length increases with annealing in molecular hydrogen and shows a peak value at 600° C.