Berlin 2015 – wissenschaftliches Programm

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MI: Fachverband Mikrosonden

MI 3: Analytical Scanning Electron Microscopy

MI 3.5: Vortrag

Montag, 16. März 2015, 16:30–16:45, EMH 225

Quantitative EDS with focus on the nanometer scale for combinations of light and heavy elements. — •Meiken Falke, Igor Nemeth, Andi Kaeppel, and Ralf Terborg — Bruker nano GmbH, Am Studio 2D, 12489 Berlin, Germany

Quantitative spatially resolved chemical characterization of mixtures of light and heavy elements in the electron microscope is a challenge. Complicating factors are e.g. preparation artefacts, radiation damage and signal absorption. Energy dispersive X-ray spectroscopy (EDS) is one technique for composition analysis of bulk and electron transparent samples. For bulk analysis sophisticated absolute EDS quantification methods have been developed. Multiple detector arrangements at high solid and take-off angles speed up and simplify the analysis in case of complex topography or beam sensitivity and limit the need for sample preparation. For quantitative analysis of electron transparent objects the Cliff-Lorimer method is widely used and can provide data on the accuracy level of a few at%. Using large solid and take-off angles, even the ppm level can be accessed. The results are valid only relative to a suitable standard of similar thickness and composition though. An alternative is the Zeta-factor method, Ref 1. It additionally includes information on the beam current and accommodates the use of any standard with known composition, thickness and density. This method can deliver absolute quantification while accounting e.g. for absorption effects. Examples for all techniques mentioned above will be shown. Ref.1 Watanabe M. & Williams D.B, J. of Micr. Vol. 221, 2006, 89.