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** plus minus p junctions. The annealing temperature dependence of the diffusion length has been studied in the temperature range of 400 to 700 degree C. The study shows a significant increase in the diffusion length from 21. 8 mu m to 67. 8 mu m by this process. The diffusion length increases with annealing in molecular hydrogen and shows a peak value at 600 degree C.