Precipitation and dislocation decoration via extrinsic gettering of Co, Au and Pt by misfit dislocations in Si/Si-2%Ge epitaxy

1989 ◽  
Vol 47 ◽  
pp. 578-579
Author(s):  
D. M. Lee
Keyword(s):  
Imaging Techniques ◽  
Preceding Paper ◽  
Dark Field ◽  
Misfit Dislocations ◽  
Temperature Dependent ◽  
Bright Field ◽  
Dark Field Imaging ◽  
Weak Beam ◽  
Sample Structure ◽  
Field Imaging

Previous work on the gettering activity of a well defined array of buried interfacial misfit dislocations (MDs) showed that the amount of nickel gettered by MD is dominated by the strong temperature-dependent solubility. Precipitation occurs on or in the immediate vicinity of MDs due to nucleation enhancement by strain effects. High temperature 〈1000°C〉 diffusion of gold resulted in the planar colony precipitates on two {111} planes associated with stacking fault formation. In this contribution, we discuss our continuing research pertaining to cobalt, gold (at low temperature), and platinum gettering by MDs which involves studying the nature of dislocation decoration and impurity precipitation in the Si/Si-2%Ge epitaxial system.All the samples used in this study have a buried Si-2%Ge epitaxial layer of ∼ 2 μm thickness.Co, Au and Pt were deliberately diffused into the wafer. The details of the sample structure and preparation are described in a preceding paper. Two-beam bright field and weak-beam dark field imaging techniques were performed on cross-section TEM specimens.

Growth of hematite on (0001) and {1102} sapphire substrates

1990 ◽  
Vol 48 (4) ◽  
pp. 376-377
Author(s):  
Lisa A. Tietz ◽  
Scott R. Summerfelt ◽  
C. Barry Carter
Keyword(s):  
Imaging Techniques ◽  
Chemical Vapor ◽  
Interface Energy ◽  
Dark Field ◽  
Cation Sublattice ◽  
Sapphire Substrates ◽  
Dark Field Imaging ◽  
Weak Beam ◽  
Pressure Chemical ◽  
Interface Structures

Defects in thin films are often introduced at the substrate-film interface during the early stages of growth. The interface structures of semiconductor heterojunctions have been extensively studied because of the electrical activity of defects in these materials. Much less attention has been paid to the structure of oxide-oxide heterojunctions. In this study, the structures of the interfaces formed between hematite (α-Fe2O3) and two orientations of sapphire (α-Al2O3) are examined in relationship to the defects introduced into the hematite film. In such heterojunctions, the oxygen sublattice is expected to have a strong influence on the epitaxy; however, defects which involve only the cation sublattice may be introduced at the interface with little increase in interface energy.Oxide heterojunctions were produced by depositing small quantities of hematite directly onto electrontransparent sapphire substrates using low-pressure chemical vapor deposition. Prior to deposition, the ionthinned substrates were chemically cleaned and annealed at 1400°C to give “clean”, crystalline surfaces. Hematite was formed by the reaction of FeCl3 vapor with water vapor at 1150°C and 1-2 Torr. The growth of the hematite and the interface structures formed on (0001) and {102} substrates have been studied by bright-field, strong- and weak-beam dark-field imaging techniques.

The Dependence of Sample Thickness on Annular Bright Field Microscopy

2011 ◽  
Vol 5 (1) ◽  
Author(s):  
M.M.G. Latting ◽  
W. Walkosz ◽  
R.F. Klie
Keyword(s):  
Image Quality ◽  
Visual Information ◽  
Specific Property ◽  
Dark Field ◽  
Sample Thickness ◽  
Atomic Resolution ◽  
Imaging Method ◽  
Bright Field ◽  
Dark Field Imaging ◽  
Field Imaging

Annular Bright Field (ABF) is a relatively new method of Scanning Transmission Electron Microscopy (STEM) imaging that is desirable because of its ability to provide additional visual information in terms of showing lightweight atoms, whereas standard dark field imaging does not. In order to better understand the parameters necessary to perfect this method, this research article aimed to study a specific property of this imaging method: the dependence of sample thickness on image quality and atomic resolution. Multislice calculations were utilized to generate atomic potentials that were used to simulate different thicknesses of β-Si3N4. The resulting images were then examined to measure atomic full width at half-maximum (FWHM) in order to have a quantifiable value to support visual selection of the best ABF output image. Comparison of image quality/atomic resolution and FWHM values suggested that as a general trend, as sample thickness increases, atomic resolution and image quality deteriorate, citing Huygens' Principle of Classical Optics via the propagation of spherical electron waves through a vacuum. This study will bring a new awareness to the necessary precision required by researchers' sample preparation during Annular Bright Field imaging to yield the best image of their respective samples.

scholarly journals Quantitative analysis of speckle-based X-ray dark-field imaging using numerical wave-optics simulations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sebastian Meyer ◽  
Serena Z. Shi ◽  
Nadav Shapira ◽  
Andrew D. A. Maidment ◽  
Peter B. Noël
Keyword(s):  
Small Angle ◽  
Speckle Pattern ◽  
Random Phase ◽  
Dark Field ◽  
Wave Optics ◽  
X Ray ◽  
Dark Field Imaging ◽  
X Ray Imaging ◽  
Sample Structure ◽  
Field Imaging

AbstractThe dark-field signal measures the small-angle scattering strength and provides complementary diagnostic information. This is of particular interest for lung imaging due to the pronounced small-angle scatter from the alveolar microstructure. However, most dark-field imaging techniques are relatively complex, dose-inefficient, and require sophisticated optics and highly coherent X-ray sources. Speckle-based imaging promises to overcome these limitations due to its simple and versatile setup, only requiring the addition of a random phase modulator to conventional X-ray equipment. We investigated quantitatively the influence of sample structure, setup geometry, and source energy on the dark-field signal in speckle-based X-ray imaging with wave-optics simulations for ensembles of micro-spheres. We show that the dark-field signal is accurately predicted via a model originally derived for grating interferometry when using the mean frequency of the speckle pattern power spectral density as the characteristic speckle size. The size directly reflects the correlation length of the diffuser surface and did not change with energy or propagation distance within the near-field. The dark-field signal had a distinct dependence on sample structure and setup geometry but was also affected by beam hardening-induced modifications of the visibility spectrum. This study quantitatively demonstrates the behavior of the dark-field signal in speckle-based X-ray imaging.

New imaging modes in STEM

1988 ◽  
Vol 46 ◽  
pp. 648-649
Author(s):  
A.V. Jones
Keyword(s):  
Energy Loss ◽  
Dark Field ◽  
Detector System ◽  
Objective Lens ◽  
Acceptance Angle ◽  
Bright Field ◽  
Dark Field Imaging ◽  
Annular Dark Field ◽  
Complex Forms ◽  
Field Imaging

The most often quoted advantage of STEM over conventional TEM is the ability to produce multiple simultaneous images by the use of multiple detector systems. In practice, this postulated advantage has seldom been fully utilised, mainly because of the practical difficulties in designing such detector systems.Most STEMs to date have been constructed as two-channel instruments combining annular dark-field imaging with either filtered bright-freld or inelastic imaging. More complex forms of bright-field detector have been employed1, as have parallel-readout systems for energy-loss spectra but the ability of the spectrometer to produce multiple simultaneous images has not been fully utilised.The basis of the problem lies in the fact that the objective lens and the detector system(s) have in most cases been designed by the manufacturers as separate entities in order to simplify the later addition of user-specific detectors. Since the acceptance angle of even the best spectrometers is relatively small, additional post-specimen lenses [with their attendant aberrations] had to be added in order to make full use of the spectrometer.

scholarly journals Symmetric Talbot-Lau neutron grating interferometry and incoherent scattering correction for quantitative dark-field imaging

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Youngju Kim ◽  
Jacopo Valsecchi ◽  
Jongyul Kim ◽  
Seung Wook Lee ◽  
Markus Strobl
Keyword(s):  
Imaging Techniques ◽  
Reference Sample ◽  
Dark Field ◽  
Incoherent Scattering ◽  
The Novel ◽  
Contrast Imaging ◽  
Dark Field Imaging ◽  
Novel Approach ◽  
Set Up ◽  
Field Imaging

AbstractWe introduce the application of a symmetric Talbot-Lau neutron grating interferometer which provides a significantly extended autocorrelation length range essential for quantitative dark-field contrast imaging. The highly efficient set-up overcomes the limitation of the conventional Talbot-Lau technique to a severely limited micrometer range as well as the limitation of the other advanced dark-field imaging techniques in the nanometer regime. The novel set-up enables efficient and continuous dark-field contrast imaging providing quantitative small-angle neutron scattering information for structures in a regime from some tens of nanometers to several tens of micrometers. The quantitative analysis enabled in and by such an extended range is demonstrated through application to reference sample systems of the diluted polystyrene particle in aqueous solutions. Here we additionally demonstrate and successfully discuss the correction for incoherent scattering. This correction results to be necessary to achieve meaningful quantitative structural results. Furthermore, we present the measurements, data modelling and analysis of the two distinct kinds of cohesive powders enabled by the novel approach, revealing the significant structural differences of their fractal nature.

Dreidimensional abbildende Elektronenmikroskope I. Prinzip der Geräte / Threedimensionally Imaging Electron Microscopes

1972 ◽  
Vol 27 (6) ◽  
pp. 919-929 ◽  
Author(s):  
W. Hoppe
Keyword(s):  
Dark Field ◽  
Imaging Systems ◽  
Atomic Resolution ◽  
Small Object ◽  
Fourier Space ◽  
Bright Field ◽  
Image Construction ◽  
Dark Field Imaging ◽  
Electron Microscopes ◽  
Field Imaging

Abstract Threedimensionally Imaging Electron Microscopes The principles of new electron optical imaging systems will be described which make possible the threedimensional image construction of a small object. Data of threedimensional Fourier space are collected by the registration of several images using primary beams with different tilting angles. The simplest device of such a type - a magnetic fly's eye system - will lead to spherical aberrrations larger than about 20 mm. It will be shown, that there is a good chance to correct “ring zone segment”-systems to reach atomic resolution with or without image-reconstruction-calculations. Not only microscopes with conventional bright field and dark field imaging but also transmission scanning microscopes can be constructed usind these principles.

scholarly journals High Resolution Imaging in Bright and Dark Field at High Voltages

1974 ◽  
Vol 32 ◽  
pp. 356-357
Author(s):  
L. J. Chen ◽  
K. Seshan
Keyword(s):  
Dark Field ◽  
High Resolution Imaging ◽  
Interband Transitions ◽  
Bragg Condition ◽  
Bright Field ◽  
Weak Beam ◽  
Powerful Means ◽  
Resolution Imaging ◽  
Field Imaging ◽  
Order Reflection

The weak beam dark field and high order bright field imaging(2) methods are powerful means for improving the resolution of images detected by diffraction contrast. However, at high voltages, many beam interactions become important as more interband transitions occur between different Bloch waves. At the exact Bragg condition, for any order reflection, usually more than two interband transitions are important for both weak beam and bright field images, and complicated images result.

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