Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 60: Poster Session III (Methods: Atomic and electronic structure; Methods: electronic structure theory; Methods: Molecular simulations and statistical mechanics; Methods: Sanning probe techniques; Methods: other (experimental); Methods: other (theory) )

O 60.34: Poster

Wednesday, March 24, 2010, 17:45–20:30, Poster B2

Contrast formation in the SEM at lowest landing energy of the electrons — •Philipp Tonndorf, Steffen Schulze, and Michael Hietschold — Chemnitz University of Technology, Institute of Physics, Solid Surfaces Analysis Group, D-09107 Chemnitz, Germany

The primary electrons initially have normal energies of several keV and are slowed down until just before the sample to a few 100 eV by an electric opposing field. This ensures that the chromatic error in the electron optics remains low.

Electron with reduced energy can't penetrate so far into the sample. So they have a smaller interaction volume, which promises to improve the resolution. For example, you can see the walls of the studied carbon nanotubes, which you can't recognize with higher electron energies.

There is also a change in the secondary electron yield and the backscatter coefficient, which causes other contrasts. For gold on carbon the contrasts reversed under 500eV landing energy.

Even charges of the sample can be reduced. You could represent structures from Al on Si3N4 with opposing field better than without opposing field.

This technique is very surface sensitive and can detect details, which are hidden at higher energies and you can investigate samples that would be destroyed by higher landing energies. Poorly or non-conductive samples can be scanned without the need to evaporate a conductive layer.