Regensburg 2013 – scientific programme
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KR: Fachgruppe Kristallographie
KR 5: Poster - Crystallography
KR 5.1: Poster
Wednesday, March 13, 2013, 15:00–17:30, Poster B2
Determination and correction of distortions and systematic errors in low-energy electron diffraction — •Falko Sojka1, Matthias Meissner1, Christian Zwick1, Roman Forker1, Claudius Klein2, Michael Horn-von Hoegen2, and Torsten Fritz1 — 1University of Jena, Institute of Solid State Physics, Max-Wien-Platz 1, 07743 Jena, Germany — 2University of Duisburg-Essen, AG Horn-von Hoegen, Lotharstr. 1-21, 47048 Duisburg, Germany
LEED on epitaxial layers is a powerful tool to examine long-range ordering at the interface. However, due to limitations like distortions of the LEED images, additional efforts have to be made in order to derive precise epitaxial relations from the measured LEED patterns.
We developed and implemented an algorithm to determine and correct systematic distortions in LEED images. The procedure is independent of the design of the device (conventional LEED, MCP-LEED, SPA-LEED). Therefore, only a calibration sample with a well-known structure and a suitably high number of diffraction spots is required. The algorithm provides a correction matrix which can be used to rectify all further measurements generated with the same device. Additionally, we found an axial distortion which occurs due to a tilted sample surface. This axial distortion can be described theoretically, and thus it is possible to correct those measurements, too.
Only corrected LEED images represent an unaffected view of the reciprocal space. So we can use them for the determination of the lattice parameters or epitaxial relations by numerical optimization achieving a very high accuracy.