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Spatial Resolution and Information Transfer in Scanning Transmission Electron Microscopy

Published online by Cambridge University Press:  03 January 2008

Yiping Peng ,
Mark P. Oxley ,
Andrew R. Lupini ,
Matthew F. Chisholm  and
Stephen J. Pennycook
Yiping Peng
Affiliation:
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6031, USA
Mark P. Oxley
Affiliation:
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6031, USA
Andrew R. Lupini
Affiliation:
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6031, USA
Matthew F. Chisholm
Affiliation:
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6031, USA
Stephen J. Pennycook
Affiliation:
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6031, USA
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Abstract

The relation between image resolution and information transfer is explored. It is shown that the existence of higher frequency transfer in the image is just a necessary but not sufficient condition for the achievement of higher resolution. Adopting a two-point resolution criterion, we suggest that a 10% contrast level between two features in an image should be used as a practical definition of resolution. In the context of scanning transmission electron microscopy, it is shown that the channeling effect does not have a direct connection with image resolution because sharp channeling peaks do not move with the scanning probe. Through a quantitative comparison between experimental image and simulation, a Fourier-space approach is proposed to estimate defocus and sample thickness. The effective atom size in Z-contrast imaging depends on the annular detector's inner angle. Therefore, an optimum angle exists for the highest resolution as a trade-off between reduced atom size and reduced signal with limited information transfer due to noise.

Keywords

ADFSTEMresolutioninformation transfernoisedefocusthicknessdetector inner angle
Type
Research Article
Information
Microscopy and Microanalysis , Volume 14 , Issue 1: Special Issue: Materials Research in an Aberration-Free Environment , February 2008 , pp. 36 - 47
Copyright
© 2008 Microscopy Society of America

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