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Spatially resolved impurity identification via temperature- and injection-dependent photoluminescence imaging

: Mundt, L.; Schubert, M.C.; Schön, J.; Michl, B.; Niewelt, T.; Schindler, F.; Warta, W.


IEEE Journal of Photovoltaics 5 (2015), No.5, pp.1503-1509
ISSN: 2156-3381
Journal Article
Fraunhofer ISE ()
Solarzellen - Entwicklung und Charakterisierung; Silicium-Photovoltaik; Charakterisierung von Prozess- und Silicium-Materialien

Photoluminescence-based impurity imaging methods have been shown to be able to quantify impurities with excellent detection limits of approximately 1010 cm-3. They are, however, limited to metastable defects in p-type silicon only. In this paper, we present an approach that overcomes this limitation by evaluating temperature- and injection-dependent photoluminescence imaging. In contrast with temperature- and injection-dependent lifetime spectroscopy, we are not aiming for determining precise impurity parameters of known contaminants, but rather for identifying lifetime-limiting metal impurities using established impurity parameters from the literature. Our approach is to measure spatially resolved injection-dependent lifetimes by photoluminescence imaging and fit them with respect to established defect parameters. Additional measurements at higher temperature enhance the information content of the analysis. The two-defect approach first identifies the two lifetime-limiting defects and derives a candidate for a third defect. Subsequently, we can determine their concentrations. The presented method is not limited to doping type nor metastable defects and is, therefore, a promising method to characterize the spatially resolved distribution of a large variety of impurities.