Dresden 2017 – scientific programme

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MA: Fachverband Magnetismus

MA 7: Analytical Electron Microscopy: SEM and TEM-based Material Analysis

MA 7.8: Invited Talk

Monday, March 20, 2017, 12:15–12:45, MER 02

Microstructural characterization of non-metallic precipitates in silicon crystallization processes for photovoltaic applications — •Susanne Richter, Martina Werner, Sina Swatek, and Christian Hagendorf — Fraunhofer Center for Silicon Photovoltaics CSP, Otto-Eißfeldt-Str. 12, D-06120 Halle (Saale)

During the directional crystallization of silicon the formation of non-metallic precipitates may occur due to enrichment and segregation of carbon and nitrogen. Different types of precipitates lead to different defects in the later processed solar cells. Extensive material analyses were performed to obtain micro structural, chemical and electrical properties of all occurring precipitate types including analyses via IR microscopy, ToF-SIMS, FIB target preparation for TEM combined with nanospot-EDS and SAED. As a result in addition to the previous state of knowledge a precipitate classification is deduced. Selective material properties are correlated to individual precipitate types such as morphology, crystal structure (and polytype) or the presence of certain impurities. These properties can be used for precipitate identification and prediction of expected defect behavior. Especially the correlation between the found impurities, its concentrations within the precipitates analyzed by ToF-SIMS, EDS and ICP-MS, and the resulting crystallographic microstructure investigated by TEM and SAED are presented in detail.