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

Abstract

Physical and numerical modeling of impurity gettering from multicrystalline Si for solar cell production has been carried out using Fe as a model impurity. Calculated change of nonradiative recombination coefficient of minority carriers in the course of gettering is used as a tool for evaluating the gettering efficiency. A derivation of the capture cross section of impurity precipitates, as compared to single atom recombination centers, is presented. Low efficiency of the conventional application of the gettering process is explained by the modeling results. The variable temperature gettering process is modeled and predicted to provide high gettering efficiency and short needed gettering times.