Stöger-Pollach, M., & Schattschneider, P. (2007). The influence of relativistic energy losses on bandgap determination using valence EELS. Ultramicroscopy, 107(12), 1178–1185. https://doi.org/10.1016/j.ultramic.2007.01.015
E057-02 - Fachbereich Universitäre Serviceeinrichtung für Transmissions- Elektronenmikroskopie E138-03 - Forschungsbereich Functional and Magnetic Materials
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Zeitschrift:
Ultramicroscopy
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ISSN:
0304-3991
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Datum (veröffentlicht):
Nov-2007
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Umfang:
8
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Verlag:
ELSEVIER
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Peer Reviewed:
Ja
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Keywords:
Electronic, Optical and Magnetic Materials; Atomic and Molecular Physics, and Optics; Semiconductors; Instrumentation; EELS; Bandgap; Kramers-Kronig
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Abstract:
The influence of relativistic energy losses on bandgap determination using valence EELS
M. Stöger-Pollach a and P. Schattschneider a
a University Service Center for Transmission Electron Microscopy, Technische Universität Wien, Wiedner Hauptstraße 8-10, A-1040 Wien, Austria
Abstract
Since monochromated transmission electron microscopes have become available, the determination of bandgaps and optical properties using electron energy loss spectrometry (EELS) has again attracted interest. The underlying idea is very simple: below the bandgap energy no transitions can contribute to the valence EELS signal. However, the bandgap cannot be directly read out from the recorded data. Therefore the optical properties cannot be determined correctly from the low loss using the Kramers-Kronig relations. We will discuss under which conditions relativistic effects may be surpressed. It is demonstrated that scanning TEM (STEM) geometry is not applicable for most bandgap measurements.
