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Comparison of line-wise pl-imaging and area-wise pl-imaging

: Höffler, H.; Dost, G.; Brand, A.; Haunschild, J.; Schremmer, H.; Bergmann, A.

Volltext ()

Energy Procedia 124 (2017), S.66-75
ISSN: 1876-6102
International Conference on Crystalline Silicon Photovoltaics (SiliconPV) <7, 2017, Freiburg>
Zeitschriftenaufsatz, Konferenzbeitrag, Elektronische Publikation
Fraunhofer ISE ()

In this contribution we compare the results of a line-scanning camera and line-wise illumination based PL-imaging system (Line-PLI) to the results of a "classic" PL-imaging system featuring a matrix camera and a full area illumination of the wafer. We investigate the impact of the different injection conditions which result from the significantly higher irradiance user in the Line-PLI system. We derive a formula which can easily be used to predict how high the irradiance may be without causing the lifetime to be limited by intrinsic silicon recombination. We compare the image contrasts caused by regions of different recombination activity and we compare the robustness of the method, which calibrates the PL-images to local effective lifetime using photoconductance (QSSPC) measurements. As a result it can be said that contrasts between regions of high and low recombination activity are more pronounced using the investigated Line-PLI setup, which qualifies it excellently f or the visualization of process inhomogeneities causing defects on solar cell precursor. We calculate that the irradiance of the investigated setup is still low enough to differentiate between regions of different Shockley-Read-Hall recombination if the effective sample lifetimes are roughly below 250 mu s. Moreover we derive an uncertainty of 24 % on the absolute values of effective lifetime using the Area-PLI setup while we derive an uncertainty of only 8 % on the absolute values of effective lifetime using the Line-PLI setup for the investigated samples.