Effective Surface Recombination of p+ Layers Doped Using Ion Implantation or Surface Deposited B Sources☆

Abstract Two key factors need to be fulfilled in order to enable high efficiency bifacial p-type PERT cell. High bulk lifetime values retention during production processes, and minimized effective surface recombination, S eff in the p + layer. The influence of boron doped layer parameters on the effective surface recombination in the p + layer of an n + -p-p + bifacial PERT solar cell is evaluated. Back IQE data of n + -p-p + cells with over-doped p + layer were used for evaluation of S eff values in the p + layer. Simulation was made for several doping profiles with the surface doping concentration, B s , in the range 10 18 - 10 20 cm -3 . According to simulation, the dominating parameter controlling the effect of the built-in charge in the passivation layer on the effective surface recombination is the B s level. For B s values above ∼10 19 cm -3 this charge has no significant influence. p + layer doping was made by B ion implantation as well as by thermal diffusion from deposited B source. Measurements were performed on symmetrically B doped n-Si wafers with different passivation. Good agreement between simulation and measurements was found.