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TEM & STEM simulation
In order to quantitatively analyze atomic resolution experimental images from a transmission electron microscope, it is crutial to fully understand and account for the many complex interactions between the beam and the specimen. Therefore, we dedicate considerable effort to simulating electron microscope images from first principles for comparison with experimental data. By matching our experimental work with analogous simulations, we are able to accurately determine specimen thickness, structure, and orientation, observe the effects of bonding between atoms, and determine the positions of individual dopant atoms. Through such work, we are advancing the field of electron microscopy and finding new ways of characterizing material behavior at atomic resolution.
Figure:(a) A model of a [001] oriented 2.5 nm Si nanocrystal showing the positions of five substitutional dopant sites in the central column. (b) Simulated data showing the relationship between crystal tilt away from the [001] zone axis and the visibility of Ge dopant atoms in each position shown in (a). (c) Minimum and maximum visibilities at each dopant position in (b) showing the error in depth determination associated with a 30 mrad tilt uncertainty. Figure reproduced from [1].
Recommended Reading
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"Effects of small-angle mistilts on dopant visibility in ADF-STEM imaging of nanocrystals"
J. T. Held, S. Duncan, K. A. Mkhoyan
- Ultramicroscopy 177, 53 (2017)
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