Dresden 2017 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 8: Topical session: Interface-Controlled Microstructures: Mechanical Properties and Mechano-Chemical Coupling - Segregation and Embrittlement II
MM 8.3: Vortrag
Montag, 20. März 2017, 12:15–12:30, BAR 205
Confined topological impurity segregation at faceted Si grain boundaries — •Christian Liebscher1, Andreas Stoffers1, Oana Cojocaru-Mirédin2, Baptiste Gault1, Christina Scheu1, Gerhard Dehm1, and Dierk Raabe1 — 1Max-Planck-Institut für Eisenforschung GmbH, 40237 Düsseldorf, Germany — 2RWTH Aachen, Institute of Physics (IA), 52056 Aachen, Germany
Coincident site lattice (CSL) boundaries and trace impurities of Carbon (C) and Iron (Fe) are degrading the electrical performance of multicrystalline Silicon (mc-Si) by promoting charge carrier recombination. Our study provides unprecedented insights into the connection of the faceted nature of grain boundaries in mc-Si and confined impurity segregation. The direct correlation of atomic resolution aberration-corrected scanning transmission electron microscopy (STEM) and 3D atom probe tomography (APT), obtained by probing exactly the same specimen position in both instruments establishes segregation of Carbon (C) and Iron (Fe+N) to linear junctions of merging grain boundary facets. Both, the segregation patterns of C and (Fe+N), as observed by APT, form linear segregation tubes that decorate facet junctions of a Σ3 grain boundary with a facet length between 2 and 10 nm. By observing the atomic structure of a Σ9 grain boundary with a facet length of 10 to 50 nm on an APT needle by STEM followed by subsequent 3D chemical analysis directly verifies the confined impurity segregation that is driven by the grain boundary topology.