Origin of recombination activity of non-coherent ?3{111} grain boundaries with a positive deviation in the tilt angle in cast-grown silicon ingots

Non-coherent ?3{111} grain boundaries (GBs) with a positive deviation in the tilt angle (??110?> 70.5°) exhibit a high recombination activity in high-performance multicrystalline silicon ingots. Most of the GB segments are composed of edge-type dislocations with the Burgers vector bof a/3?111?, unlike Lomer dislocations with b= a/2?110? observed for negative deviations, arranged on coherent ?3{111} GB segments. Stretched ?110? reconstructed bonds along the tilt axis are introduced so as not to form dangling bonds, and large strains are generated around the dislocation cores. Oxygen and carbon atoms segregating due to the strains would induce the recombination activity.