Effect of metal impurities concentration on electrical properties in N-type Recharged-Czochralski silicon

The electrical properties of N-type Recharged-Czochralski (RCz) silicon solar cells are significantly affected by the concentration of metal impurities in the silicon materials. In this work, several N-type RCz silicon ingots were grown using feedstock with different impurities concentration, and the distribution of minority carrier lifetime was tested. It was discovered that a broader range of feedstock impurity concentrations resulted in high and stable minority carrier lifetime of the ingots. Solar cells made from these ingots had an average efficiency of over 24.57%. Meanwhile, the results of impurities segregation calculation and solar cells electroluminescence(EL) test were given. The results indicated that ring defects were the primary cause of differences in electrical properties among silicon ingots produced from feedstock with varying impurity concentrations. Further, the process window to produce high efficiency N-type Czochralski(Cz) silicon solar cells was broadened, and the production cost could be reduced.