Modeling of gettering of precipitated impurities from Si for carrier lifetime improvement in solar cell applications

Physical and numerical modeling of impurity gettering from multicrystalline Si for solar cell production has been carried out using Fe as a model impu rity. Calculated change of nonradiative recombination coefficient of minori ty carriers in the course of gettering is used as a tool for evaluating the gettering efficiency. A derivation of the capture cross section of impurit y precipitates, as compared to single atom recombination centers, is presen ted. Low efficiency of the conventional application of the gettering proces s is explained by the modeling results. The variable temperature gettering process is modeled and predicted to provide high gettering efficiency and s hort needed gettering times. (C) 1999 American Institute of Physics. [S0021 -8979(99)00717-3].