DIRECT CORRELATION OF TRANSITION-METAL IMPURITIES AND MINORITY-CARRIER RECOMBINATION IN MULTICRYSTALLINE SILICON

Impurity and minority carrier lifetime distributions were studied in a s-grown multicrystalline silicon used for terrestrial-based solar cell s. Synchrotron-based x-ray fluorescence and the light beam induced cur rent technique were used to measure impurity and lifetime distribution s, respectively. The purpose of this work was to determine the spatial relation between transition metal impurities and minority carrier rec ombination in multicrystalline silicon solar cells. Our results reveal a direct correlation between chromium, iron: and nickel impurity prec ipitates with regions of high minority carrier recombination. The impu rity concentration was typically 5 X 10(16) atoms/cm(2), indicating th e impurity-rich regions possess nanometer-scale precipitates. These re sults provide the first direct evidence that transition metal agglomer ates play a significant role in solar cell performance. (C) 1998 Ameri can Institute of Physics.