Hydrogen Passivation of Electrically Active Defects in Polycrystalline Silicon Solar Cells

We have observed significant improvements in the efficiencies of dendritic web and edge-supported-pulling (ESP) silicon sheet solar cells after hydrogen ion beam passivation for a period of ten minutes or less. We have studied the effects of the hydrogen ion beam treatment with respect to silicon material damage, silicon sputter rate, introduction of impurities, and changes in reflectance. Wehave determined that the silicon sputter rate for a constant ion beam flux of 0.60+/- 0.05 mA/cm exhibits a maximum at approximately 1400 eV ion beam energy. We have observed that hydrogen ion beam treatment can result in a reduced fill factor, which is caused by damage to the front metallization of the cell rather than by damage to the p-n junction.