Dresden 2020 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 17: Microstructure, Real Structure and Crystal Defects

KFM 17.6: Talk

Friday, March 20, 2020, 11:30–11:50, TOE 317

Structural defects in silicon observed in situ by X-ray diffraction imaging during heating and solidification — •Maike Becker, Gabrielle Regula, Serge W. Neves Dias, Hadjer Ouaddah, Guillaume Reinhart, and Nathalie Mangelinck-Noël — Marseille Univ, Université de Toulon, CNRS, IM2NP, Marseille, France

Dislocations affect decisively the crystal quality and thus, the minority carrier lifetime, which is problematic for the efficiency of silicon in photovoltaic applications. The understanding of the formation of the dislocation arrangement is of particular importance whenever seeds are part of the Si ingot manufacturing process. To explore the role of seed crystals, this work focuses on dislocation nucleation and mobility in a seed during heating up to the melting point and during the start of solidification. Synchrotron in situ X-ray diffraction imaging (topography) is used to observe extended crystallographic defects in a silicon wafer. During heating, dislocations are generated at the sample edges and propagate in the sample. We measure their motion which intensifies with increasing temperature and observe their interactions. When solidification is triggered, some dislocations initially present in the seed propagate in the regrown crystal with the solid-liquid interface. The density of these growth dislocations decreases in the up-grown crystal when interacting with Σ3 grain boundaries. Besides, the formation of new dislocation sources can be observed during the experiment nearby higher-order grain boundaries.