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Interferometric Diffraction from Amorphous Double Films

Published online by Cambridge University Press:  02 October 2015

Aram Rezikyan ,
James A. Belcourt  and
Michael M. J. Treacy
Aram Rezikyan*
Affiliation:
Department of Physics, Arizona State University, Tempe, Arizona 85287, USA
James A. Belcourt
Affiliation:
Department of Physics, Arizona State University, Tempe, Arizona 85287, USA
Michael M. J. Treacy
Affiliation:
Department of Physics, Arizona State University, Tempe, Arizona 85287, USA
*
*Corresponding author. [email protected]
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Abstract

We explore the interference fringes that arise in diffraction patterns from double-layer amorphous samples where there is a substantial separation, up to about a micron, between two overlapping thin films. This interferometric diffraction geometry, where both waves have interacted with the specimen, reveals phase gradients within microdiffraction patterns. The rapid fading of the observed fringes as the magnitude of the diffraction vector increases confirms that displacement decoherence is strong in high-energy electron scattering from amorphous samples. The fading of fringes with increasing layer separation indicates an effective illumination coherence length of about 225 nm, which is consistent with the value of 270 nm expected for the heated Schottky field emitter source. A small reduction in measured coherence length is expected because of the additional energy spread induced in the beam after it passes through the first layer.

Keywords

interferometric diffractionamorphous double layerinterference fringes
Type
Materials Applications
Information
Microscopy and Microanalysis , Volume 21 , Issue 5 , October 2015 , pp. 1348 - 1360
Copyright
© Microscopy Society of America 2015 

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