Correlating Defect Band Luminesce to Elemental Distribution by X-Ray Fluorescence

Photoluminescence (PL) imaging is a widely accepted tool to characterize the quality of multicrystalline and monocrystalline silicon cells. Recently a set of neighboring multicrystalline silicon wafers taken from a cell production line at different stages of processing have shown an unexpected PL trend. Band-to-band PL (BPL) and sub-bandgap PL (subPL), where collected for the entire silicon wafers. Interestingly, a reversal of the subPL intensity in various regions of the wafer is observed right after the deposition of the anti-reflective coating (ARC). Regions with low subPL intensity before ARC exhibit high subPL intensity afterwards, and the opposite holds true for other regions of the wafer. Some authors have performed high-resolution cathodoluminesce spectroscopy, EBIC and dark lock-in-thermography to elucidate the origin of this phenomenon, In this work we present the results of the nanoscale X-ray fluorescence imaging at the points of subPL reversal to evaluate the role of metal decoration on this uncommon behavior and we complement it with our previous findings on the distribution of impurities during cell processing.