Dislocation Contrast of 4H-SiC in X-Ray Topography under Weak-Beam Condition

2008 ◽  
Vol 600-603 ◽  
pp. 313-316 ◽  
Author(s):  
Hirotaka Yamaguchi ◽  
Hirofumi Matsuhata ◽  
Ichiro Nagai
Keyword(s):  
Basal Plane ◽  
Dislocation Core ◽  
Grazing Incidence ◽  
Diffraction Peak ◽  
Rocking Curve ◽  
Screw Dislocations ◽  
X Ray ◽  
Weak Beam ◽  
Diffraction Geometry ◽  
Basal Plane Dislocation

We have investigated dislocation image of 4H-SiC wafers projected on synchrotron X-ray topographs taken under different positions in the rocking curve of a diffraction peak. The diffraction geometry was grazing-incidence extremely asymmetric and the diffraction vectors were g = 1 1 2 8 and 112 8. The weak-beam images were demonstrated for basal-plane dislocations and threading-screw dislocations. The basal-plane dislocation images became narrower in width at the off-Bragg conditions, and they were decomposed to separate lines under the weak-beam condition. The threading-screw dislocations showed changes in their shape and contrast as the crystal set was tilted from the rocking-curve peak, and finally the characteristic images near the dislocation core were observed under the weak-beam condition. The origin of these weak-beam images is unclear, but it will offer detailed analysis of the dislocations.

Dislocation contrast on X-ray topographs under weak diffraction conditions

2021 ◽  
Vol 54 (4) ◽  
Author(s):  
Hongyu Peng ◽  
Tuerxun Ailihumaer ◽  
Yafei Liu ◽  
Balaji Raghotharmachar ◽  
Xianrong Huang ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Grazing Incidence ◽  
Local Lattice Distortion ◽  
Rocking Curve ◽  
Distinctive Features ◽  
X Ray ◽  
Orientation Contrast ◽  
Weak Beam ◽  
Local Lattice ◽  
Contrast Analysis

The contrast of dislocations in 4H-SiC crystals shows distinctive features on grazing-incidence X-ray topographs for diffraction at different positions on the operative rocking curve. Ray-tracing simulations have previously been successfully applied to describe the dislocation contrast at the peak of a rocking curve.The present work shows that the dislocation images observed under weak diffraction conditions can also be simulated using the ray-tracing method. These simulations indicate that the contrast of the dislocations is dominated by orientation contrast. Analysis of the effective misorientation reveals that the dislocation contrast in weak-beam topography is more sensitive to the local lattice distortion, consequently enabling information to be obtained on the dislocation sense which cannot be obtained from the peak.

Defect Evaluation of SiC Crystal Grown by Solution Method: The Study by Synchrotron X-Ray Topography and Etching Method

2011 ◽  
Vol 679-680 ◽  
pp. 28-31 ◽  
Author(s):  
Shigeta Kozawa ◽  
Kazuaki Seki ◽  
Alexander ◽  
Yuji Yamamoto ◽  
Toru Ujihara ◽  
...  
Keyword(s):  
Basal Plane ◽  
Solution Method ◽  
Grown Layer ◽  
Screw Dislocations ◽  
X Ray ◽  
Etching Method ◽  
Basal Plane Dislocation ◽  
Dislocation Behavior

We investigated dislocation behavior in the crystal grown on 6H-SiC (0001) by solution method using synchrotron X-ray topography and thermal chlorine etching. It was confirmed that basal plane dislocation was not newly formed in the grown layer. In addition, the positions of threading screw dislocations (TSDs) were displaced and some of them disappeared in the grown layer. This displacement was caused by the bending of the TSDs during growth.

Simulation of threading dislocation images in X-ray topographs of silicon carbide homo-epilayers

2005 ◽  
Vol 38 (3) ◽  
pp. 442-447 ◽  
Author(s):  
W. M. Vetter ◽  
H. Tsuchida ◽  
I. Kamata ◽  
M. Dudley
Keyword(s):  
Basal Plane ◽  
Grazing Incidence ◽  
Threading Dislocation ◽  
Screw Dislocations ◽  
X Ray ◽  
Maximum Resolution ◽  
Reflection Geometry ◽  
Reflection Equations ◽  
Experimental Geometry ◽  
Edge Dislocations

Three types of dislocation are seen in homo-epilayers of SiC grown on 4H-SiC wafers with an 8° surface offcut: axial screw dislocations, basal plane dislocations propagated into the epilayer at an 8° inclination and threading edge dislocations. These types may be imaged by monochromatic synchrotron X-ray topography in the grazing-incidence reflection geometry using the 11\overline 28 reflection. Equations needed to apply the ray-tracing method of computer simulating X-ray topographic defect images in this experimental geometry were derived and used to simulate images of all three. Simulations for axial screw dislocations appear as white circles surrounded by narrow dark rings, and those for basal plane dislocations as linear white streaks, both consistent with experimental topographs. Simulations of the threading edge dislocations showed 4 µm wide white ovals with narrow arcs of dark contrast at their ends, inclined relative to the g vector of the topograph according to the sign of their Burgers vector. These images resembled the experimental topographs inasmuch as was possible at the maximum resolution of X-ray topographs.

X-ray diffraction properties of curved crystal diffractors

1992 ◽  
Vol 50 (2) ◽  
pp. 1734-1735
Author(s):  
W. Z. Chang ◽  
D. B. Wittry
Keyword(s):  
Diffraction Theory ◽  
X Rays ◽  
Diffraction Image ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray ◽  
Bent Crystal ◽  
Diffraction Geometry ◽  
Crystal Parameter ◽  
Quantitative Procedure

Since Du Mond and Kirkpatrick first discussed the principle of a bent crystal spectrograph in 1930, curved single crystals have been widely utilized as spectrometric monochromators as well as diffractors for focusing x rays diverging from a point. Curved crystal diffraction theory predicts that the diffraction parameters - the rocking curve width w, and the peak reflection coefficient r of curved crystals will certainly deviate from those of their flat form. Due to a lack of curved crystal parameter data in current literature and the need for optimizing the choice of diffraction geometry and crystal materials for various applications, we have continued the investigation of our technique presented at the last conference. In the present abstract, we describe a more rigorous and quantitative procedure for measuring the parameters of curved crystals.The diffraction image of a singly bent crystal under study can be obtained by using the Johann geometry with an x-ray point source.

Synchrotron X-Ray Topography Study on the Relationship between Local Basal Plane Bending and Basal Plane Dislocations in PVT-Grown 4H-SiC Substrate Wafers

2020 ◽  
Vol 1004 ◽  
pp. 393-400
Author(s):  
Tuerxun Ailihumaer ◽  
Hongyu Peng ◽  
Balaji Raghothamachar ◽  
Michael Dudley ◽  
Gilyong Chung ◽  
...  
Keyword(s):  
Basal Plane ◽  
Local Strain ◽  
Grazing Incidence ◽  
Peak Shift ◽  
Linear Mapping ◽  
Incidence Geometry ◽  
Convex Shape ◽  
X Ray ◽  
Black And White ◽  
Plane Bending

Synchrotron monochromatic beam X-ray topography (SMBXT) in grazing incidence geometry shows black and white contrast for basal plane dislocations (BPDs) with Burgers vectors of opposite signs as demonstrated using ray tracing simulations. The inhomogeneous distribution of these dislocations is associated with the concave/convex shape of the basal plane. Therefore, the distribution of these two BPD types were examined for several 6-inch diameter 4H-SiC substrates and the net BPD density distribution was used for evaluating the nature and magnitude of basal plane bending in these wafers. Results show different bending behaviors along the two radial directions - [110] and [100] directions, indicating the existence of non-isotropic bending. Linear mapping of the peak shift of the 0008 reflection along the two directions was carried out using HRXRD to correlate with the results from the SMBXT measurements. Basal-plane-tilt angle calculated using the net BPD density derived from SMBXT shows a good correlation with those obtained from HRXRD measurements, which further confirmed that bending in basal plane is caused by the non-uniform distribution of BPDs. Regions of severe bending were found to be associated with both large tilt angles (95% black contrast BPDs to 5% white contrast BPDs) and abrupt changes in a and c lattice parameters i.e. local strain.

Reconstructed Structure of SiO2/Si(111) Interface

1990 ◽  
Vol 208 ◽  
Author(s):  
Ichiro Hirosawa ◽  
Jun'ichiro Nizuki ◽  
Toru Tatsumi ◽  
Koichi Akimoto ◽  
Junji Matsui
Keyword(s):  
Molecular Beam ◽  
Structural Model ◽  
Oxidation Process ◽  
Grazing Incidence ◽  
Interface Structure ◽  
X Ray Diffraction ◽  
Initial Oxidation ◽  
X Ray ◽  
Diffraction Geometry ◽  
Symmetry Structure

ABSTRACTIn order to investigate the initial oxidation process Qf the Si (111) surface, we have studied the molecular beam deposited Si0 2/Si(111)-7×7 interface structure using grazing incidence X-ray diffraction geometry. We suggest a three-fold symmetry structural model composed of stacking fault layer, dimer layer and additional ordered atoms. The three-fold symmetry structure comes from the preference for oxidation in the faulted half of the 7×7 structure.

The Performance of Channel Cut Collimators for Precision X-Ray Diffraction Studies of Epitaxial Layers

1990 ◽  
Vol 208 ◽  
Author(s):  
Neil Loxley ◽  
D. Keith Bowen ◽  
Brian K. Tanner
Keyword(s):  
Grazing Incidence ◽  
Curve Analysis ◽  
Epitaxial Layers ◽  
Angular Divergence ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
Experimental Performance ◽  
Low Background ◽  
X Ray ◽  
Angle Scattering

ABSTRACTReplacement of the pinhole collimator on a double axis X-ray diffractometer with a device incorporating a channel-cut crystal permits the beam to be pre-conditioned in angular divergence. We examine the merits of such devices, known as channel-cut collimators (CCC's), of different materials and reflections. The experimental performance of InP 004 and Si 022 CCC's is presented.With a reference crystal on the first axis, set in the dispersive peometry with respect to the CCC, conditioning in wavelength spread is achieved. Dispersion broadening is effectively eliminated and no resetting of the reference crystal is required when changing specimen materials or reflections. The devices have extremely low background and reduced Bragg tails. Application of the 4-reflection CCC to rocking curve analysis of thin epitaxial layers, ultra-low angle scattering from biological systems, grazing incidence reflectometry and triple axis diffraction of semi-conductors is discussed.

Characterization of Defect Structures in SiC Single Crystals Using Synchrotron X-Ray Topography

1993 ◽  
Vol 307 ◽  
Author(s):  
S. Wang ◽  
M. Dudley ◽  
C. Carter ◽  
D. Asbury ◽  
C. Fazit
Keyword(s):  
Detailed Analysis ◽  
Single Crystals ◽  
Basal Plane ◽  
Defect Structures ◽  
Dislocation Generation ◽  
Screw Dislocations ◽  
X Ray ◽  
White Beam

ABSTRACTSynchrotron white beam X-ray topography has been used to characterize defect structures in 6H-SiC wafers grown on (0001) seeds. Two major types of defects are observed: super screw dislocations approximately perpendicular to the basal plane and dislocation networks lying in the basal plane. The super screw dislocations, which have open cores, are growth dislocations. These dislocations act as sources and/or sinks for the glide dislocation networks. Detailed analysis and discussion of dislocation generation phenomena and Burgers vectors will be presented.

Microbeam X-ray diffraction from twisted lamellar crystals: theory and computer simulation

2009 ◽  
Vol 42 (4) ◽  
pp. 673-680 ◽  
Author(s):  
Valeriy A. Luchnikov ◽  
Dimitri A. Ivanov
Keyword(s):  
Basal Plane ◽  
Peak Position ◽  
Diffraction Peak ◽  
Reciprocal Space ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Broadening ◽  
Asymmetric Shape ◽  
Diffraction Peaks ◽  
Lamellar Crystals

The diffraction peak position, width and intensity distribution are calculated for the case of a helicoidally twisted crystalline lamella, both analytically and numerically. It is shown that the diffraction peak broadening depends on the orientation of the corresponding reciprocal-space vector with respect to the helicoid axis and the normal to the lamellar basal plane. The equatorial peaks, which are close to the normal direction to the lamellar basal plane, are characterized by the highest azimuthal width. By contrast, the reflections positioned close to the lamellar surface have the smallest azimuthal width. For non-equatorial peaks in the proximity of the twisting axis the intensity has an unusual asymmetric shape. The shape of the microbeam, as well as its position and direction with respect to the lamella, influences the shape of the diffraction peaks in reciprocal space and their appearance in two-dimensional diffractograms. The proposed approach can be useful, for example, for the interpretation of microbeam diffractograms of banded polymer spherulites.

X-ray topographic dislocation contrast visible in reflections orthogonal to the Burgers vectors of axial screw dislocations in hexagonal silicon carbide

2001 ◽  
Vol 34 (1) ◽  
pp. 20-26 ◽  
Author(s):  
W. M. Vetter ◽  
M. Dudley
Keyword(s):  
Silicon Carbide ◽  
Electron Microscope ◽  
Basal Plane ◽  
High Density ◽  
Screw Dislocations ◽  
X Ray ◽  
Apparent Violation ◽  
Light Contrast

Contrast is associated with micropipes in X-ray topographs of SiC crystals obtained with prismatic reflections, representing an apparent violation of theg·b= 0 invisibility criterion. This is explained as a population of basal-plane dislocations with Burgers vectors of the setb= {\textstyle{1 \over 3}}〈11{\bar{2}}0〉 that occur in a high density within a few micrometers of the micropipes, below the resolution of X-ray topography. These basal-plane dislocations could be observed under an electron microscope. The presence of the surfaces of the micropipes influences the dislocation images in the topographs taken with prismatic reflections, often resulting in a band of light contrast along the axes of the micropipes.

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