Identifying defect parameters for common recombination centers in multicrystalline silicon by temperature and injection dependent lifetime spectroscopy

Abstract

In this paper we use temperature- and injection dependent lifetime spectroscopy (TIDLS) to identify the energy levels Et and capture cross section ratios k of the main limiting recombination centers in p-type high performance multicrystalline silicon (HPMC-Si) wafers used for solar cell production. To increase the accuracy and applicability of the TIDLS analysis we propose an error map, which can be used to locate the globally best solutions or define a parameter space of solutions with low mean square error (MSE). In HPMC-Si two defect levels are identified using this approach: The first defect level was found to be located at Et = 0.88 ± 0.05eV eV, with a second solution at 0.25 ± 0.05 eV. The best solution for the capture cross section ratio is found at k = 0.8, however, solutions in the range 0.001 < k < 1.7 also give MSE < 1%. Both Et and k correspond well to previously reported values for iron-boron pairs. For the second defect a capture cross section ratio k = 22 with an energy level at Et = 0.32 eV or Et = 0.70 eV has been identified, with a MSE < 1% in the range 0.25 eV < Et < 0.78 eV and 15 < k < 37. This second defect has been attributed the boron-oxygen related defect, due to its similarity to the well-known defect in Cz-Si wafers.