Formation and annihilation of oxygen donors in multicrystalline silicon for solar cells

New method of fabricating silicon wafer for the photovoltaic application based on sintering and recrystallization steps

“…The oxygen level is about 3 Â 10 18 and 10 19 at/cm 3 for samples recrystallized by ZMR and FWR. These high oxygen concentrations result in very active precipitates (called thermal donors) [18]. The presence of carbon will also lead to SiC precipitates formation that will end up reducing the material lifetime.…”

Effect of accelerated crucible rotation on the segregation of impurities in vertical Bridgman growth of multi-crystalline silicon

“…Higher carbon concentration in the center of the ingot could promote unwanted SiC precipitation. Otherwise a lower oxygen concentration in the same area could be favorable to reduce oxygen related defects, like thermal and new donors which can reduce the minority carrier lifetime [20]. For low values of the Ekman time scale radial segregation increases further.…”

Impurity segregation in directional solidified multi-crystalline silicon

“…Other oxygen related defects, like thermal and new donors can reduce the minority carrier lifetime [3]. At substitutional sites carbon does not influence carrier recombination.…”

“…At substitutional sites carbon does not influence carrier recombination. Nitrogen is electrically inactive but may form lifetime limiting complexes with oxygen as a major source of low lifetime in bottom and edge regions of the mc-silicon ingot [3]. If the solubility limit of carbon or nitrogen is exceeded, SiC and Si 3 N 4 precipitates can form locally in the melt and in the crystal [4][5][6].…”