Dresden 2006 – scientific programme

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MM: Metall- und Materialphysik

MM 25: Poster Session

MM 25.19: Poster

Wednesday, March 29, 2006, 15:30–17:30, P4

Electron Holographic Materials Analysis at Atomic Resolution — •Martin Linck, Hannes Lichte, and Michael Lehmann — Institute for Structure Physics, Technische Universität Dresden, Dresden, Germany

Electron holography is a promising method to contribute also to the question No-dqWhich atoms are where?No-dq: The phase shift phi of the electron wave by an atom is related to the atomic number Z. Therefore, measuring the phase shift from a holographic phase image at atomic resolution in principle allows determining the atomic number. For quantitative evaluation, the atomic phase shift was determined by means of simulations, which are presently refined by means of DFT-calculations [1]. It turns out that - in addition to a coarse increase as phi proportional to Z^0.6 - the phase dependence is also strongly influenced by the electron configuration of the atoms, by thickness effects of the specimen, and by dynamical electron diffraction. Consequently, the inversion as Z(phi) is mostly not straightforward. Nevertheless, we succeeded in distinguishing atomic columns in binary materials, e.g. of Ga(Z=31) and As (Z=33) in (110)-oriented GaAs, showing the high potential of the method.

[1] Axel Rother et al., this conference