Efficiency improvement of crystalline silicon solar cells with a back-surface field produced by boron and aluminum co-doping

By combining the doping process of Al alloying with the higher solubility of B in Si, a B/Al co-doped shallow back-surface field (B/Al-BSF) layer was created for fabrication of Si solar cells. The increased carrier concentration in the B/Al-BSF facilitates the modulation of BSF strength. The back-surface recombination velocity exhibits a U-shape function of carrier concentration, and reaches a minimum at a carrier concentration of 1019 cm−3. As a result, the solar cell efficiency can be improved by 0.5%.