Position dependence of the visibility of a single gold atom in silicon crystals in HAADF-STEM image simulation

In a STEM an electron beam is focused into a small probe on the specimen. This probe is raster scanned across the specimen to form an image from the electrons transmitted through the specimen. The objective lens is positioned before the specimen instead of after the specimen as in a CTEM. Because the probe is focused and scanned before the specimen, accurate annular dark field (ADF) STEM image simulation is more difficult than CTEM simulation. Instead of an incident uniform plane wave, ADF-STEM simulation starts with a probe wavefunction focused at a specified position on the specimen. The wavefunction is then propagated through the specimen one atomic layer (or slice) at a time with Fresnel diffraction between slices using the multislice method. After passing through the specimen the wavefunction is diffracted onto the detector. The ADF signal for one position of the probe is formed by integrating all electrons scattered outside of an inner angle large compared with the objective aperture.

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Including Thermal Vibrations and Bonding in HAADF-STEM Image Simulation

Microscopy and Microanalysis ◽

10.1017/s1431927614002499 ◽

2014 ◽

Vol 20 (S3) ◽

pp. 154-155 ◽

Cited By ~ 1

Author(s):

Michael Odlyzko ◽

K. Andre Mkhoyan

Keyword(s):

Image Simulation ◽

Stem Image ◽

Thermal Vibrations

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Kinematic HAADF-STEM image simulation of small nanoparticles

Micron ◽

10.1016/j.micron.2015.04.005 ◽

2015 ◽

Vol 74 ◽

pp. 47-53 ◽

Cited By ~ 10

Author(s):

D.S. He ◽

Z.Y. Li ◽

J. Yuan

Keyword(s):

Image Simulation ◽

Stem Image ◽

Small Nanoparticles

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Multislice HAADF STEM Image Simulation of Complex Oxidation Catalyst "Ml"

Microscopy and Microanalysis ◽

10.1017/s1431927615009459 ◽

2015 ◽

Vol 21 (S3) ◽

pp. 1735-1736

Author(s):

Douglas A. Blom

Keyword(s):

Oxidation Catalyst ◽

Image Simulation ◽

Stem Image ◽

Complex Oxidation

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Bloch-wave-based STEM image simulation with layer-by-layer representation

Ultramicroscopy ◽

10.1016/j.ultramic.2009.05.007 ◽

2009 ◽

Vol 109 (9) ◽

pp. 1203-1209 ◽

Cited By ~ 3

Author(s):

Takao Morimura ◽

Masayuki Hasaka

Keyword(s):

Bloch Wave ◽

Layer By Layer ◽

Image Simulation ◽

Stem Image

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Single atom visibility on (111) silicon in simulated ADF STEM images

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106168 ◽

1988 ◽

Vol 46 ◽

pp. 820-821

Author(s):

R. F. Loane

Keyword(s):

Silicon Crystal ◽

Gold Atom ◽

Scanning Transmission Electron Microscope ◽

Dark Field ◽

Single Atom ◽

Transmission Electron ◽

Scanning Transmission ◽

Crystal Substrate ◽

Annular Dark Field ◽

Stem Image

The multislice method has been adapted to simulate annular dark field (ADF) scanning transmission electron microscope (STEM) images. In the STEM image simulation, a highly focused electron probe is scanned across a specimen and the scattered intensity, accumulated over an annular detector, is recorded as a function of probe position. Each pixel in the STEM image is determined by an entire multislice calculation for a particular position of the incident probe. This N4 process is very computationally expensive and currently requires the use of a supercomputer to achieve runtimes of less than a day.The simulated specimen consisted of a (111) silicon crystal substrate, which was a multiple of 94 Å (30 slices) thick, followed by an additional slice containing a single gold atom. Slice potentials were 38.4 Å x 39.9 Å (256 x 256 pixels) in size, which set the maximum included scattering angle to 79 mrad.

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