X-ray microbeam three-dimensional topography for dislocation strain-field analysis of 4H-SiC

2013 ◽  
Vol 114 (2) ◽  
pp. 023511 ◽  
Author(s):  
R. Tanuma ◽  
D. Mori ◽  
I. Kamata ◽  
H. Tsuchida
Keyword(s):  
Strain Field ◽  
Three Dimensional ◽  
Field Analysis ◽  
X Ray

Strain field analysis with the X-ray integration method

Strain ◽  
1983 ◽  
Vol 19 (2) ◽  
pp. 69-75 ◽  
Author(s):  
A. Peiter ◽  
W. Lode
Keyword(s):  
Strain Field ◽  
Integration Method ◽  
Field Analysis ◽  
X Ray

scholarly journals Characterization of Screw Dislocations in a 4H-Silicon Carbide Diode Using X-Ray Microbeam Three-Dimensional Topography

2009 ◽  
Vol 615-617 ◽  
pp. 251-254 ◽  
Author(s):  
Ryohei Tanuma ◽  
Tae Tamori ◽  
Yoshiyuki Yonezawa ◽  
Hirotaka Yamaguchi ◽  
Hirofumi Matsuhata ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Strain Field ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Hollow Core ◽  
Screw Dislocations ◽  
X Ray ◽  
Microplasma Breakdown ◽  
Symmetry Break

This paper describes the study of non-hollow-core elementary screw dislocations (SDs) in silicon carbide (SiC) diodes using X-ray microbeam three-dimensional topography. Strain analysis shows that typical screw dislocations having a symmetric strain field tend to cause microplasma breakdown, whereas deformed SDs do not. The symmetry break in SDs will relax the focussing of strain and lessen the formation of defects, thereby leading to the desirable non-leak property.

scholarly journals Intragranular strain estimation in far-field scanning X-ray diffraction using a Gaussian process

2021 ◽  
Vol 54 (4) ◽  
Author(s):  
Axel Henningsson ◽  
Johannes Hendriks
Keyword(s):  
Gaussian Process ◽  
Strain Field ◽  
A Priori ◽  
Three Dimensional ◽  
Polycrystalline Materials ◽  
X Ray Diffraction ◽  
Polycrystalline Specimen ◽  
X Ray ◽  
Reconstruction Methods ◽  
Mean Square Errors

A new method for estimation of intragranular strain fields in polycrystalline materials based on scanning three-dimensional X-ray diffraction (scanning 3DXRD) data is presented and evaluated. Given an a priori known anisotropic compliance, the regression method enforces the balance of linear and angular momentum in the linear elastic strain field reconstruction. By using a Gaussian process (GP), the presented method can yield a spatial estimate of the uncertainty of the reconstructed strain field. Furthermore, constraints on spatial smoothness can be optimized with respect to measurements through hyperparameter estimation. These three features address weaknesses discussed for previously existing scanning 3DXRD reconstruction methods and, thus, offer a more robust strain field estimation. The method is twofold validated: firstly by reconstruction from synthetic diffraction data, and secondly by reconstruction of a previously studied tin (Sn) grain embedded in a polycrystalline specimen. Comparison against reconstructions achieved by a recently proposed algebraic inversion technique is also presented. It is found that the GP regression consistently produces reconstructions with lower root-mean-square errors, mean absolute errors and maximum absolute errors across all six components of strain.

scholarly journals X-ray asterism and the structure of cracks from indentations in silicon

2016 ◽  
Vol 49 (1) ◽  
pp. 250-259 ◽  
Author(s):  
B. K. Tanner ◽  
J. Garagorri ◽  
E. Gorostegui-Colinas ◽  
M. R. Elizalde ◽  
D. Allen ◽  
...  
Keyword(s):  
Long Range ◽  
Strain Field ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Three Dimensional ◽  
Mechanical Damage ◽  
X Ray Diffraction ◽  
Microscopy Imaging ◽  
X Ray ◽  
Crack Morphology

The asterism observed in white radiation X-ray diffraction images (topographs) of extended cracks in silicon is investigated and found to be associated with material that is close to breakout and surrounded by extensive cracking. It is a measure of the mechanical damage occurring when the fracture planes do not follow the low-index cleavage planes associated with the crystal structure. It is not related to a propensity for some cracked wafers to shatter during subsequent high-temperature processing. There is no correlation between crack morphology and alignment of an indenter with respect to the orientation of a silicon wafer, the cracks being generated from the apices of the indenter and having threefold symmetry for Berkovich indents and fourfold symmetry for Vickers indents. X-ray diffraction imaging (XRDI) of indents does not reveal this underlying symmetry and the images exhibit a very substantial degree of variation in their extent. This arises because the XRDI contrast is sensitive to the long-range strain field around the indent and breakout reduces the extent of this long-range strain field. Breakout is also detected in the loss of symmetry in the short-range strain field imaged by scanning micro-Raman spectroscopy. Weak fourfold symmetric features at the extremes of the images, and lying along 〈110〉 directions, are discussed in the context of slip generated below the room-temperature indents. Scanning electron microscopy imaging of the region around an indent during focused ion beam milling has permitted the three-dimensional reconstruction of the crack morphology. The surface-breaking Palmqvist cracks are found to be directly connected to the median subsurface cracks, and the presence of extensive lateral cracks is a prerequisite for material breakout at indenter loads above 200 mN. The overall crack shape agrees with that predicted from simulation.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

3-D reconstruction of molecular shape from microcrystal thin sections

1983 ◽  
Vol 41 ◽  
pp. 748-749
Author(s):  
S. Cusack ◽  
J.-C. Jésior
Keyword(s):  
Three Dimensional ◽  
Molecular Shape ◽  
Biological Molecules ◽  
Fourier Space ◽  
Single Particles ◽  
Thin Sections ◽  
Standard Methods ◽  
X Ray ◽  
X Ray Crystallography ◽  
Dimensional Reconstruction

Three-dimensional reconstruction techniques using electron microscopy have been principally developed for application to 2-D arrays (i.e. monolayers) of biological molecules and symmetrical single particles (e.g. helical viruses). However many biological molecules that crystallise form multilayered microcrystals which are unsuitable for study by either the standard methods of 3-D reconstruction or, because of their size, by X-ray crystallography. The grid sectioning technique enables a number of different projections of such microcrystals to be obtained in well defined directions (e.g. parallel to crystal axes) and poses the problem of how best these projections can be used to reconstruct the packing and shape of the molecules forming the microcrystal.Given sufficient projections there may be enough information to do a crystallographic reconstruction in Fourier space. We however have considered the situation where only a limited number of projections are available, as for example in the case of catalase platelets where three orthogonal and two diagonal projections have been obtained (Fig. 1).

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