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DS: Dünne Schichten

DS 4: Thin film analysis II

DS 4.3: Talk

Monday, March 27, 2006, 11:45–12:00, GER 38

Aberration correction used for interface characterisation with atomic resolution — •Meiken Falke¹, Andrew Bleloch², Uwe Falke², Gunter Beddies¹, and Steffen Teichert¹ — ¹Institut f. Physik, TU-Chemnitz, 09107 Chemnitz, Germany — ²superSTEM, Daresbury Laboratory, Daresbury, WA44AD, UK

Recently aberration corrected dedicated scanning transmission electron microscopy with a probe size of 0.1 nm became available . The high angle annular darkfield signal acquired with this spatial resolution allows to distinguish between atomic columns of different composition in a crystal. Thus C_s-corrected dedicated STEM provides a powerful tool for studying metal silicon compounds (silicides) and their interfaces to the silicon substrate. Epitaxial cobalt- and nickel-disilicide silicon (001) junctions of buried thin films were studied by dedicated aberration-corrected STEM. Two different interface structures were unequivocally identified, one of which represents a (2×1) reconstruction found experimentally for the first time. The results are consistent with predictions from total energy calculations. Due to the cubic crystal symmetry of both, the silicide and the Si substrate, the interface consists of a patchwork of different domains. In addition to the usual misfit dislocations at a relaxed commensurate interface, here dislocations are required at the boundaries of those domains. A complex defect structure, was found to solve both crystallographic constraints. The Burgers vector for each type of interface domain junction could be derived from the identified atomic arrangement in the two interface structures and from crystallographic considerations.