Regensburg 2010 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 28: Nanostructured Materials I

MM 28.6: Vortrag

Mittwoch, 24. März 2010, 11:30–11:45, H16

Trouble at the boundary surface: modeling field distortions and atom trajectories in 3D-AP — •Christian Oberdorfer and Guido Schmitz — Institut für Materialphysik, Westfälische Wilhelms-Universität Münster

Within the last years atom probe tomography (3D-AP) has seen an impressive progress. Instruments utilizing femtosecond laser pulses to trigger the fundamental field evaporation process and a wide angle detector alignment are state of the art. The progress in instrumentation draws focus to more sophisticated methods for data analysis and interpretation, since it is now possible to analyse materials of poor conductivity (ceramics, glasses and semiconductors).

Measurements of these materials will reveal strong artefacts which originate from their heterogeneous electronic properties. In order to address this problem, a simulation of the field evaporation of such specimens is carried out. The electric field at the surface of a modeled specimen is computed using finite elements. A single surface atom then gets field evaporated and subsequently the trajectory onto a detector like counter-electrode is computed. The described procedure is repeated atom by atom until a certain termination condition is reached. Afterwards the collected data of all of the detector positions is used to carry out a common 3D-AP volume reconstruction. This way a detailed analysis of apparent artefacts is enabled.

Results of this approach for different geometric setups of heterogeneous dielectric/metallic structures (layers, precipitates) will be presented and allow estimation of possible measurement artefacts.