Electrical Activity of Crystal Defects in Multicrystalline Si

Abstract

Upgraded metallurgical-grade silicon (UMG Si) solar cells with different ranges of efficiencies are characterized by light-beam induced current (LBIC) measurements. The interaction between grain boundaries (GBs) and metallic impurities is studied for cells fabricated on wafers at different solidification heights of the ingot. One observes a tight relation between the electrical activity of the grain boundaries and the position of the wafer in the ingot, which is related to the impurity contamination. The presence of a high amount of metallic impurities activates the electrical activity of the grain boundaries. The main features of the LBIC images are discussed in relation to the presence of the metallic impurities.