Additivity of phosphorus gettering and hydrogenation in multicrystalline silicon cells

External gettering effect by phosphorus diffusion is used to improve multicrystalline silicon wafers. After diffusion at 900°C to 4 h it was found that the effective diffusion lengths L_n of minority carriers achieve or exceed 200 μ. After diffusion at 850°C for 4 h the improvements are less marked, and hydrogenation is needed to obtain the same increase of L_n. SIMS analysis indicate that the gettered impurities are essentially iron, copper and nickel. LBIC scanning show that grains, grain boundaries and dislocations are partly passivated during the gettering