BSF Islands For Reduced Recombination In IBC Cells

We present a back junction back contact cell with small isolated BSF “island” areas, surrounded by emitter area. This is an alternative for the more common IBC cell with interdigitated fingers. The optimal cell lay-out was determined by device simulations. We used discontinuous emitter and BSF contacts, which we connected through floating metal fingers. Additionally, we applied a lighter front floating emitter diffusion. The performance increase predicted by the simulations was experimentally confirmed. The investigated design leads to a strong recombination reduction in our industrial IBC Mercury cell, leading to a 0.6% absolute gain in efficiency.