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Updated: Jun 26, 2026

Picometer-Precision Atomic Position Tracking through Electron Microscopy

Picometer-Precision Atomic Position Tracking through Electron Microscopy

Published on: July 3, 2021

Contrast reversal in atomic-resolution chemical mapping.

P Wang¹, A J D'Alfonso, S D Findlay

¹UK SuperSTEM Laboratory, Daresbury Laboratory, Cheshire WA4 4AD, United Kingdom.

Physical Review Letters

|December 31, 2008

Summary

Chemical mapping on silicon using aberration-corrected STEM revealed a contrast reversal. This unexpected effect causes an apparent shift in atomic column positions, explained by imaging simulations.

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Area of Science:

Materials Science
Electron Microscopy
Solid-State Physics

Background:

Aberration-corrected scanning transmission electron microscopy (STEM) offers high spatial resolution for materials analysis.
Chemical mapping techniques are crucial for understanding elemental distribution at the atomic scale.
Silicon is a fundamental material in semiconductor technology, requiring precise characterization.

Purpose of the Study:

To investigate unexpected contrast phenomena during chemical mapping of silicon.
To analyze the positional accuracy of atomic columns mapped using energy-filtered STEM.
To elucidate the physical mechanisms behind observed imaging artifacts.

Main Methods:

Utilizing the Nion UltraSTEM, an aberration-corrected scanning transmission electron microscope.
Performing energy-filtered chemical mapping by selecting specific energy windows above the Si L2,3 edge.
Conducting detailed simulations of the electron imaging process to interpret experimental results.

Main Results:

An unexpected contrast reversal was observed when mapping silicon atomic columns.
The contrast reversal led to an apparent and misleading translation of the silicon atomic column positions.
Simulations confirmed that specific energy window selections can induce this artifact.

Conclusions:

The study highlights a critical artifact in energy-filtered STEM chemical mapping of silicon.
Understanding these imaging mechanisms is essential for accurate atomic-scale analysis.
Aberration-corrected STEM requires careful interpretation of chemical mapping data to avoid misinterpretations of atomic positions.