Determination of the Core-structure of Shockley Partial Dislocations in 4H-SiC

ABSTRACTSynchrotron x-ray topographs taken using basal plane reflections indicate that the electron-hole recombination activated Shockley partial dislocations in 4H silicon carbide bipolar devices appear as either white stripes with dark contrast bands at both edges or dark lines. In situ electroluminescence observations indicated that the mobile partial dislocations correspond to the white stripes in synchrotron x-ray topographs, while immobile partial dislocations correspond to the dark lines. Computer simulation based on ray-tracing principle indicates that the contrast variation of the partial dislocations in x-ray topography is determined by the position of the extra atomic half planes associated with the partial dislocations lying along their Peierls valley directions. The chemical structure of the Shockley partial dislocations can be subsequently determined unambiguously and non-destructively.

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Synchrotron X-Ray Topographic Studies of Recombination Activated Shockley Partial Dislocations in 4H-Silicon Carbide Epitaxial Layers

Materials Science Forum ◽

10.4028/www.scientific.net/msf.600-603.357 ◽

2008 ◽

Vol 600-603 ◽

pp. 357-360 ◽

Cited By ~ 1

Author(s):

Yi Chen ◽

Xian Rong Huang ◽

Ning Zhang ◽

Michael Dudley ◽

Joshua D. Caldwell ◽

...

Keyword(s):

Stacking Faults ◽

Epitaxial Layers ◽

Threading Dislocations ◽

X Rays ◽

Electron Hole ◽

X Ray ◽

Shockley Partial ◽

Partial Dislocations ◽

Edge Component ◽

Hole Recombination

Electron-hole recombination activated Shockley partial dislocations bounding expanding stacking faults and their interactions with threading dislocations have been studied in 4H-SiC epitaxial layers using synchrotron x-ray topography. The bounding partials appear as white stripes or narrow dark lines in back-reflection X-ray topographs recorded using the basal plane reflections. Such contrast variations are attributable to the defocusing/focusing of the diffracted X-rays due to the edge component of the partial dislocations, which creates a convex/concave distortion of the basal planes. Simulation results based on the ray-tracing principle confirm our argument. The sign of the partial dislocations can be subsequently determined.

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Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

10.26434/chemrxiv.11345063.v2 ◽

2020 ◽

Author(s):

Keishiro Yamashita ◽

Kazuki Komatsu ◽

Hiroyuki Kagi

Keyword(s):

Crystal Structure ◽

High Pressure ◽

Crystal Growth ◽

Single Crystal ◽

Room Temperature ◽

Growth Technique ◽

Salt Hydrate ◽

X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

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A Mechanical Loading/Synchrotron X-Ray Diffraction System for In-Situ Determination of Lattice Strains

10.21236/ada430973 ◽

2005 ◽

Author(s):

Matthew Miller ◽

Paul Dawson

Keyword(s):

Mechanical Loading ◽

X Ray Diffraction ◽

X Ray ◽

Lattice Strains

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Enhanced visible-active photocatalytic behaviors observed in Mn-doped BiFeO3

Modern Physics Letters B ◽

10.1142/s0217984918501853 ◽

2018 ◽

Vol 32 (17) ◽

pp. 1850185 ◽

Cited By ~ 5

Author(s):

Yun-Hui Si ◽

Yu Xia ◽

Ya-Yun Li ◽

Shao-Ke Shang ◽

Xin-Bo Xiong ◽

...

Keyword(s):

Photocatalytic Activity ◽

Visible Light ◽

Band Gap ◽

Diffuse Reflectance Spectroscopy ◽

X Ray Diffraction ◽

Electron Hole ◽

X Ray ◽

Mn Doped ◽

Hole Recombination ◽

Narrow Band Gap Semiconductors

A series of BiFeO3 and BiFe[Formula: see text]Mn[Formula: see text]O3 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized by a hydrothermal method. The samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy (EDS) and UV–Vis diffuse reflectance spectroscopy, and their photocatalytic activity was studied by photocatalytic degradation of methylene blue in aqueous solution under visible light irradiation. The band gap of BiFeO3 was significantly decreased from 2.26 eV to 1.90 eV with the doping of Mn. Furthermore, the 6% Mn-doped BiFeO3 photocatalyst exhibited the best activity with a degradation rate of 94% after irradiation for 100 min. The enhanced photocatalytic activity with Mn doping could be attributed to the enhanced optical absorption, increment of surface reactive sites and reduction of electron–hole recombination. Our results may be conducive to design more efficient photocatalysts responsive to visible light among narrow band gap semiconductors.

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CeO2/TiO2 Nanotubes Composites: Synthesis, Characterization, and Photocatalytic Properties

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.583.86 ◽

2012 ◽

Vol 583 ◽

pp. 86-90 ◽

Cited By ~ 3

Author(s):

Hai Bin Li ◽

Xin Yong Li ◽

Yan De Song ◽

Shu Guang Chen ◽

Ying Wang ◽

...

Keyword(s):

Diffuse Reflectance Spectroscopy ◽

Atomic Ratio ◽

X Ray Diffraction ◽

Hydrothermal Route ◽

Electron Hole ◽

Calcination Process ◽

X Ray ◽

Transmission Electron ◽

Hole Recombination

TiO2nanotubes were prepared via a hydrothermal route. CeO2nanoparticles with diameters around 5nm were loaded onto the surface of TiO2nanotubes via a deposition approach followed by a calcination process. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectroscopy (UV-vis) were applied for the characterization of the as-prepared CeO2/TiO2nanotubes composites. The results show that CeO2particles are highly dispersed on the surface of TiO2nanotubes. The TiO2 nanotubes are modified to response to the visible light due to the combination with CeO2. The CeO2/TiO2nanotubes composites with a CeO2/TiO2atomic ratio of 2.5% show a further improvement on the photocatalytic activity for degradation of Rhodamine B in water. The presence of CeO2improves the light absorption of TiO2nanotubes and inhibits the electron-hole recombination.

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High Pressure Earth Science. Determination of the Phase Boundaries of Mantle Minerals using in situ X-ray Diffraction Technique.

The Review of High Pressure Science and Technology ◽

10.4131/jshpreview.9.34 ◽

1999 ◽

Vol 9 (1) ◽

pp. 34-42

Author(s):

Norimasa NISHIYAMA ◽

Tetsuo IRIFUNE

Keyword(s):

High Pressure ◽

Earth Science ◽

X Ray Diffraction ◽

Phase Boundaries ◽

Mantle Minerals ◽

X Ray

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Determination of the crystal structure of magnesium perchlorate hydrates by X-ray powder diffraction and the charge-flipping method

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768110039686 ◽

2010 ◽

Vol 66 (6) ◽

pp. 579-584 ◽

Cited By ~ 12

Author(s):

Kevin Robertson ◽

David Bish

Keyword(s):

Crystal Structures ◽

Powder Diffraction ◽

Fundamental Parameter ◽

Magnesium Perchlorate ◽

Space Group ◽

X Ray ◽

Partial Pressures ◽

Dehydration Reactions

X-ray powder diffraction (XRD) data were used to solve the crystal structures of phases in the magnesium perchlorate hydrate system, Mg(ClO4)2·nH2O (n = 4, 2). A heating stage and humidity generator interfaced to an environmental cell enabled in-situ XRD analyses of dehydration reactions under controlled temperatures and partial pressures of H2O (P_{{\rm H}_2{\rm O}}). The crystal structures were determined using an ab initio charge-flipping method and were refined using fundamental-parameter Rietveld methods. Dehydration of magnesium perchlorate hexahydrate to tetrahydrate (348 K) results in a decrease in symmetry (space group = C2), where isolated Mg2+ cations are equatorially coordinated by four H2O molecules with two [ClO4]− tetrahedra at the apices. Further dehydration to the dihydrate (423 K) leads to bridging of the isolated packets to form double corner-sharing chains of octahedra and polyhedra (space group = C2/m).

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In-situ X-ray diffraction investigations of thin films: Determination of thermoelastic constants

Fifth Size Strain Conference. Diffraction Analysis of the Microstructure of Materials ◽

10.1524/9783486992564-032 ◽

2008 ◽

pp. 253-260

Keyword(s):

Thin Films ◽

X Ray Diffraction ◽

X Ray

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Residual Stresses and Differential Deformation of Electroplated Structures

Advances in X-ray Analysis ◽

10.1154/s0376030800019558 ◽

1989 ◽

Vol 33 ◽

pp. 161-169

Author(s):

G. Sheikh ◽

I. C. Noyan

Keyword(s):

Residual Stresses ◽

Lattice Parameter ◽

Stress Profile ◽

X Ray ◽

Residual Stress Profile ◽

Cyclic Loading And Unloading ◽

Nickel Substrates ◽

Loading And Unloading

AbstractWe report the results of a recent study where nickel substrates electroplated with chromium were loaded in-situ on an x-ray diffractometer. This technique allows determination of lattice spacings in the vicinity of the interface for both the film and the substrate as a function of the applied load. We used such lattice parameter data, SEM observations of the surface and x-ray peak breadth data to study the partitioning of deformation between the film and the substrate. The data indicates progressive loss of adhesion between the film and the substrate with increasing deformation. We observe significant effect of electroplating residual stresses on the mechanical behavior of the system. The loss of adhesion between the film and the substrate coupled with the initial residual stress profile causes an apparent 'negative Poisson's ratio' for the film during initial stages of the loading. This effect disappears with cyclic loading and unloading.

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