Long-period ordered structure in a high-strength nanocrystalline Mg-1 at% Zn-2 at% Y alloy studied by atomic-resolution Z-contrast STEM

Dynamics of Annular Bright Field Imaging in Scanning Transmission Electron Microscopy

http://xrm.phys.northwestern.edu/research/pdf_papers/2002/ishizuka_ultramic_2002.pdf

A practical approach for STEM image simulation based on the FFT multislice method.

The scanning transmission electron microscope () has become one of the preeminent instruments for high spatial resolution imaging and spectroscopy of materials, most notably at atomic resolution. The principle of STEM is quite straightforward. A beam of electrons is focused by electron optics to form a small illuminating probe that is raster-scanned across a sample. The sample is thinned such that the vast majority of electrons are transmitted, and the scattered electrons detected using some geometry of detector. The intensity as a function of probe position forms an image. It is the wide variety of possible detectors, and therefore imaging and spectroscopy modes, that gives STEM its strength. The purpose of this chapter is to describe what the STEM is, to highlight some of the types of experiment that can be performed using a STEM, to explain the principles behind the common modes of operation, to illustrate the features of typical STEM instrumentation, and to discuss some of the limiting factors in its performance.

https://www.springer.com/cda/content/document/cda_downloaddocument/9780387252964-c2.pdf?SGWID=0-0-45-465523-p55007576

Scanning Transmission Electron Microscopy

We report a general synthetic approach to tetrapod-shaped colloidal nanocrystals made of various combinations of II-VI semiconductors. Uniform tetrapods were prepared using preformed seeds in the sphalerite structure, onto which arms were grown by coinjection of the seeds and chemical precursors into a hot mixture of surfactants. By this approach, a wide variety of core materials could be chosen (in practice, most of the II-VI semiconductors that could be prepared in the sphalerite phase, namely, CdSe, ZnTe, CdTe); in contrast, the best materials for arm growth were CdS and CdTe. The samples were extensively characterized with the aid of several techniques.

Tetrapod-shaped colloidal nanocrystals of II-VI semiconductors prepared by seeded growth.

Effect of small crystal tilt on atomic-resolution high-angle annular dark field STEM imaging.

Atomic-resolution incoherent high-angle annular dark field STEM images of Si(011)

Observation of arsenic doped silicon has been made by using Z-contrast images of high-angle annular dark field scanning transmission electron microscopy with a tightly focused electron probe. The images show characteristic excess brightness depending on the number of arsenic atoms per atomic column. Through a simple analysis capable of identifying the number of arsenic atoms in an atomic column by using the above characteristic brightness, the quantitative two-dimensional distribution of arsenic atoms can be successfully obtained at atomic resolution, being consistent with the secondary ion mass spectroscopy and Rutherford backscattering spectroscopy measurements. This method is the only capable technique for detecting impurity atoms in every atomic column.

Kazuto Watanabe

Papers

Effect of small crystal tilt on atomic-resolution high-angle annular dark field STEM imaging.

Atomic-resolution incoherent high-angle annular dark field STEM images of Si(011)

Two-dimensional distribution of As atoms doped in a Si crystal by atomic-resolution high-angle annular dark field STEM

Deconvolution processing of HAADF STEM images.

Effect of chromatic aberration on atomic-resolved spherical aberration corrected STEM images.