Recombination Activity of 2D Extended Defects in Monolike Silicon

Monolike silicon wafers can achieve solar cells efficiencies close to those of CZ silicon. However, this performance is affected by the presence of 2D structural defects, especially sub-grain boundaries zones that expand in the upper part of the ingots. In the present work, the relations between the structure of different types of 2D defects, previously characterized by EBSD and synchrotron based X-ray topography, and their electrical activities are analyzed. The defects are generated independently by misorienting the seeds by various tilt angles Δθ relative to the growth direction <100>. LBIC and PL imaging are used to quantify the surface recombination velocity (SRV) of isolated defects at different heights of the ingot. The relative effects of the differences in structure of these defects, position in ingot, and cell processing treatment are exemplified and discussed.