Scanning electron microscopy analysis of defect clusters in multicrystalline solar grade silicon solar cells

Solar cells from an identical commercial manufacturing unit have been investigated by electroluminescence to first detect the defect clusters. A further analysis has been done by scanning electron microscopy in secondary electron imaging mode to understand the propagation mechanism of defects. It appears that defect cluster boundaries can be very sharp or spread in the bulk with little apparent effect on the overall cell efficiency. And it is shown that grain boundaries act clearly as arrests to further propagation of these defects.