Review and Recent Development in Combining Photoluminescence- and Electroluminescence-Imaging with Carrier Lifetime Measurements via Modulated Photoluminescence at Variable Temperatures
In this contribution we give a review on measurement techniques which allow to measure the minority carrier lifetime in silicon solar cell precursors in a spatially resolved manner. The measurement of spatially resolved lifetime using the combination of modulated photoluminescence and photoluminescence imaging (Mod-PL calibrated PLI) is reviewed in detail. Based on our experience we present a canon of recommendations for the features of the experimental setup and the data analysis methods, which we consider to be necessary for Mod-PL calibrated PLI measurements. Using these recommendations the results of selected samples are checked for reproducibility, selfconsistency and cross compared to photoconductance based results. Reproducibility is observed to be better than 1 %. The dependence on critical input parameters like measurement frequency and calibration position is observed to be smaller than 5 %. Comparison to photoconductance decay measurements for a broad variety of specimen throughout our R&D environment reveals deviation of less than 10 % for most samples, which can partly be attributed to potential artifacts in the photoconductance measurements. An overview on some selected applications of temperature controlled Mod-PL calibrated PLI measurements in an R&D environment is given. The overview includes the applications: prediction of efficiency potential of silicon material, process optimization of laser processes, quantitative determination of metal induced recombination, quantitative determination of series resistance, determination of material specific temperature coefficients and classification and localization of material defects via temperature and injection dependent lifetime spectroscopy.