Misfit dislocations generated during non-ideal boron and phosphorus diffusion and their effect on high-efficiency silicon solar cells

Boron and phosphorus diffusions are used in many high-efficiency mono-crystalline silicon solar cell designs to form collecting junctions, localized contact diffusions, and back surface fields. The diffusion of boron or phosphorus generates stress on the silicon lattice as a result of their atomic mismatch with silicon. If this stress exceeds the fracture stress of silicon, a misfit dislocation network is generated. This paper uses photo-conductance lifetime measurements and Yang defect etching to demonstrate that boron and phosphorus misfit dislocation networks result in bulk asymmetric Shockley-Read-Hall (SRH) recombination. Finally, the presence of diffusion-induced misfit dislocations in high-efficiency silicon solar cells is demonstrated to result in bulk asymmetric-SRH, and reduced fill factor.