Microscale Characterization of Surface Recombination at the Vicinity of Laser-Processed Regions in c-Si Solar Cells

Laser firing processes have emerged as a technologically feasible approach for the fabrication of local point contacts or local doped regions in advanced high-efficiency crystalline-Si (c-Si) solar cells. In this work, we analyze the local impact induced by the laser pulse on the passivation layers, which are commonly present in advanced c-Si solar cell architectures to reduce surface recombination. We use microphotoluminescence (PL) measurements with a spatial resolution of 7 μm to evaluate the passivation performance at the surroundings of laser-processed regions (LPRs). In particular, we have studied LPRs performed on SiC_x/Al₂O₃-and Al₂O₃-passivated c-Si wafers by an infrared (1064 nm) laser. Micro-PL results show that passivation quality of c-Si surface is affected up to about 100 μm away from the LPR border and that the extension of this damaged zone is correlated with the laser power and to the presence of capping layers. In the final part of the work, the observed decrease in passivation quality is included in an improved 3-D simulation model that gives accurate information about the recombination velocities associated with the studied LPRs.