scholarly journals Rocking Curve Imaging Investigation of the Long-Range Distortion Field between Parallel Dislocations with Opposite Burgers Vectors

2021 ◽  
Vol 11 (19) ◽  
pp. 9054
Author(s):  
Thu Nhi Tran Caliste ◽  
Alexis Drouin ◽  
Damien Caliste ◽  
Carsten Detlefs ◽  
José Baruchel
Keyword(s):  
Long Range ◽  
Peak Position ◽  
Bragg Diffraction ◽  
Rocking Curve ◽  
Low Dislocation Density ◽  
Highly Sensitive ◽  
Local Lattice ◽  
Diffraction Imaging ◽  
Matrix Orientation ◽  
Monochromatic Synchrotron

We observe a long-range distortion field between parallel dislocations with opposite Burgers vectors in a platelet-shaped single crystal of 4H-SiC with a low dislocation density (~103 cm/cm3). This distortion field is in the µradian range when the distance D between dislocations is in the ~50–250 µm range. We were able to characterise this weak distortion field through Rocking Curve Imaging (RCI), a highly sensitive Bragg diffraction imaging technique using monochromatic synchrotron radiation. From the experimental images, we generate maps of the angle of maximum reflectance (“peak position”) that provide a measurement of the local lattice orientation. Deviations from the crystal matrix orientation are associated with the long-range distortion field around dislocations. Between parallel dislocations with opposite Burgers vectors, this distortion does not decay to zero but towards a constant value α. We propose a simple model considering the angular parameter α characterising the distortion. This model indicates that α should roughly vary as 1/D. This appears to be in fair agreement with our experimental data.

scholarly journals Synchrotron Bragg diffraction imaging characterization of synthetic diamond crystals for optical and electronic power device applications

2017 ◽  
Vol 50 (2) ◽  
pp. 561-569 ◽  
Author(s):  
Thu Nhi Tran Thi ◽  
J. Morse ◽  
D. Caliste ◽  
B. Fernandez ◽  
D. Eon ◽  
...  
Keyword(s):  
Surface Damage ◽  
Lattice Parameter ◽  
Bragg Diffraction ◽  
Fast Method ◽  
Extended Defects ◽  
X Ray ◽  
Single Crystal Diamond ◽  
Local Lattice ◽  
Diffraction Imaging

Bragg diffraction imaging enables the quality of synthetic single-crystal diamond substrates and their overgrown, mostly doped, diamond layers to be characterized. This is very important for improving diamond-based devices produced for X-ray optics and power electronics applications. The usual first step for this characterization is white-beam X-ray diffraction topography, which is a simple and fast method to identify the extended defects (dislocations, growth sectors, boundaries, stacking faults, overall curvature etc.) within the crystal. This allows easy and quick comparison of the crystal quality of diamond plates available from various commercial suppliers. When needed, rocking curve imaging (RCI) is also employed, which is the quantitative counterpart of monochromatic Bragg diffraction imaging. RCI enables the local determination of both the effective misorientation, which results from lattice parameter variation and the local lattice tilt, and the local Bragg position. Maps derived from these parameters are used to measure the magnitude of the distortions associated with polishing damage and the depth of this damage within the volume of the crystal. For overgrown layers, these maps also reveal the distortion induced by the incorporation of impurities such as boron, or the lattice parameter variations associated with the presence of growth-incorporated nitrogen. These techniques are described, and their capabilities for studying the quality of diamond substrates and overgrown layers, and the surface damage caused by mechanical polishing, are illustrated by examples.

scholarly journals Three-dimensional rocking curve imaging to measure the effective distortion in the neighbourhood of a defect within a crystal: an ice example

2013 ◽  
Vol 46 (4) ◽  
pp. 842-848 ◽  
Author(s):  
Armelle Philip ◽  
Jacques Meyssonnier ◽  
Rafael T. Kluender ◽  
José Baruchel
Keyword(s):  
Subsurface Layer ◽  
Angular Position ◽  
Three Dimensional ◽  
Bragg Diffraction ◽  
Rocking Curve ◽  
Transmission Case ◽  
Integrated Intensity ◽  
Diffraction Imaging ◽  
Beam Diffraction ◽  
Crystal Bulk

Rocking curve imaging (RCI) is a quantitative version of monochromatic beam diffraction topography that involves using a two-dimensional detector, each pixel of which records its own `local' rocking curve. From these local rocking curves one can reconstruct maps of particularly relevant quantities (e.g. integrated intensity, angular position of the centre of gravity, FWHM). Up to now RCI images have been exploited in the reflection case, giving a quantitative picture of the features present in a several-micrometre-thick subsurface layer. Recently, a three-dimensional Bragg diffraction imaging technique, which combines RCI with `pinhole' and `section' diffraction topography in the transmission case, was implemented. It allows three-dimensional images of defects to be obtained and measurement of three-dimensional distortions within a 50 × 50 × 50 µm elementary volume inside the crystal with angular misorientations down to 10−5–10−6 rad. In the present paper, this three-dimensional-RCI (3D-RCI) technique is used to study one of the grains of a three-grained ice polycrystal. The inception of the deformation process is followed by reconstructing virtual slices in the crystal bulk. 3D-RCI capabilities allow the effective distortion in the bulk of the crystal to be investigated, and the predictions of diffraction theories to be checked, well beyond what has been possible up to now.

X-ray rocking curve imaging on large arrays of extremely tall SiGe microcrystals epitaxial on Si

2021 ◽  
Vol 54 (4) ◽  
Author(s):  
Mojmír Meduňa ◽  
Ondřej Caha ◽  
Emanuil Choumas ◽  
Franco Bressan ◽  
Hans von Känel
Keyword(s):  
Imaging Technique ◽  
Sample Surface ◽  
Real Space ◽  
Peak Position ◽  
Pixel Detector ◽  
Laboratory Equipment ◽  
Rocking Curve ◽  
X Ray ◽  
Local Lattice ◽  
The Individual

This work investigates layers of densely spaced SiGe microcrystals epitaxially formed on patterned Si and grown up to extreme heights of 40 and 100 µm using the rocking curve imaging technique with standard laboratory equipment and a 2D X-ray pixel detector. As the crystalline tilt varied both within the epitaxial SiGe layers and inside the individual microcrystals, it was possible to obtain real-space 2D maps of the local lattice bending and distortion across the complete SiGe surface. These X-ray maps, showing the variation of crystalline quality along the sample surface, were compared with optical and scanning electron microscopy images. Knowing the distribution of the X-ray diffraction peak intensity, peak position and peak width immediately yields the crystal lattice bending locally present in the samples as a result of the thermal processes arising during the growth. The results found here by a macroscopic-scale imaging technique reveal that the array of large microcrystals, which tend to fuse at a certain height, forms domains limited by cracks during cooling after the growth. The domains are characterized by uniform lattice bending and their boundaries are observed as higher distortion of the crystal structure. The effect of concave thermal lattice bending inside the microcrystal array is in excellent agreement with the results previously presented on a microscopic scale using scanning nanodiffraction.

scholarly journals Characterization of defects in mono-like silicon for photovoltaic applications using X-ray Bragg diffraction imaging

2015 ◽  
Vol 48 (3) ◽  
pp. 645-654 ◽  
Author(s):  
M. G. Tsoutsouva ◽  
V. A. Oliveira ◽  
J. Baruchel ◽  
D. Camel ◽  
B. Marie ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Quantitative Information ◽  
Peak Position ◽  
Bragg Diffraction ◽  
Large Field ◽  
High Angular Resolution ◽  
Solar Cell Efficiency ◽  
X Ray ◽  
Cell Efficiency ◽  
Diffraction Imaging

Rocking curve imaging (projection and section X-ray topography) has been used to study the generation and propagation of defects at the junctions between and above the seed crystals in mono-like silicon ingots. The images of different kinds of defects such as precipitates, dislocations and twins in the integrated intensity, full width at half-maximum and peak position maps resulting from the experiment have been studied. The qualitative and quantitative information that can be extracted from these maps, in particular the contrast of the images of the various defects, is discussed. These defects have a detrimental effect on solar cell efficiency and their detailed investigation allows clues to be obtained in order to improve the growth process. This work shows that synchrotron X-ray diffraction imaging techniques, because of their high angular resolution (<10−4°) and large field of view (several mm2), constitute a powerful tool for investigating the initial stages of growth of directionally solidified mono-like silicon.

scholarly journals Lattice Distortion and Phase Stability of Pd-Doped NiCoFeCr Solid-Solution Alloys

Entropy ◽  
2018 ◽  
Vol 20 (12) ◽  
pp. 900 ◽  
Author(s):  
Fuxiang Zhang ◽  
Yang Tong ◽  
Ke Jin ◽  
Hongbin Bei ◽  
William Weber ◽  
...  
Keyword(s):  
Long Range ◽  
Lattice Distortion ◽  
Maximum Pressure ◽  
Local Lattice Distortion ◽  
X Ray ◽  
High Entropy ◽  
Local Lattice ◽  
Pd Doping ◽  
Fcc Phase ◽  
The Stability

In the present study, we have revealed that (NiCoFeCr)100−xPdx (x= 1, 3, 5, 20 atom%) high-entropy alloys (HEAs) have both local- and long-range lattice distortions by utilizing X-ray total scattering, X-ray diffraction, and extended X-ray absorption fine structure methods. The local lattice distortion determined by the lattice constant difference between the local and average structures was found to be proportional to the Pd content. A small amount of Pd-doping (1 atom%) yields long-range lattice distortion, which is demonstrated by a larger (200) lattice plane spacing than the expected value from an average structure, however, the degree of long-range lattice distortion is not sensitive to the Pd concentration. The structural stability of these distorted HEAs under high-pressure was also examined. The experimental results indicate that doping with a small amount of Pd significantly enhances the stability of the fcc phase by increasing the fcc-to-hcp transformation pressure from ~13.0 GPa in NiCoFeCr to 20–26 GPa in the Pd-doped HEAs and NiCoFeCrPd maintains its fcc lattice up to 74 GPa, the maximum pressure that the current experiments have reached.

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