High quality ion implanted boron emitters in an interdigitated back contact solar cell with 20% efficiency

Ion implantation has the potential to simplify the manufacture of interdigiated back contact (IBC) silicon solar cells. In this work we present IBC solar cells where all doped areas have been produced by ion implantation. For the activation of the implanted dopants and the removal of the damage induced by the implantation a single annealing step, was used. A passivating thermal oxide was grown in the same thermal step. To investigate the proper annealing conditions lifetime samples have been investigated by the QSSPC technique, resulting in saturation current densities as low as 20 fA/cm2 for both the boron doped emitter and the phosphorus doped front surface field. IBC solar cells with conversion efficiencies up to 20% were built, demonstrating that ion implantation is consistent with IBC production and that the process simplification of ion implantation may be realized. This result is the highest efficiency ion implanted solar cell that has ever been reported.