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

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

MRS Proceedings ◽

10.1557/proc-1069-d03-03 ◽

2008 ◽

Vol 1069 ◽

Author(s):

Yi Chen ◽

Ning Zhang ◽

Xianrong Huang ◽

Joshua D Caldwell ◽

Kendrick X Liu ◽

...

Keyword(s):

Contrast Variation ◽

Electron Hole ◽

X Ray ◽

Shockley Partial ◽

Partial Dislocations ◽

Bipolar Devices ◽

Simulation Based ◽

Hole Recombination

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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Interaction between Recombination Enhanced Dislocation Glide Process Activated Basal Stacking Faults and Threading Dislocations in 4H-Silicon Carbide Epitaxial Layers

MRS Proceedings ◽

10.1557/proc-0994-f12-03 ◽

2007 ◽

Vol 994 ◽

Author(s):

Yi Chen ◽

Michael Dudley ◽

Kendrick X Liu ◽

Robert E Stahlbush

Keyword(s):

Silicon Carbide ◽

Partial Dislocation ◽

Displacement Vector ◽

Stacking Faults ◽

Epitaxial Layers ◽

Threading Dislocations ◽

Screw Dislocations ◽

Dislocation Glide ◽

Shockley Partial ◽

Partial Dislocations

AbstractElectron-hole recombination enhanced glide of Shockley partial dislocations bounding expanding stacking faults and their interactions with threading dislocations in 4H silicon carbide epitaxial layers have been studied using synchrotron white beam X-ray topography and in situ electroluminescence. The mobile silicon-core Shockley partial dislocations bounding the stacking faults are able to cut through threading edge dislocations leaving no trailing dislocation segments in their wake. However, when the Shockley partial dislocations interact with threading screw dislocations, trailing 30o partial dislocation dipoles are initially deposited in their wake due to the pinning effect of the threading screw dislocations. These dipoles spontaneously snap into their screw orientation, regardless the normally immobile carbon-core Shockley partial dislocation components in the dipoles. They subsequently cross slip and annihilate, leaving a prismatic stacking fault in (2-1-10) plane with the displacement vector 1/3[01-10].

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Misfit Dislocations in Epitaxial Layers of SI on Gap (001) Substrates

MRS Proceedings ◽

10.1557/proc-37-331 ◽

1984 ◽

Vol 37 ◽

Cited By ~ 7

Author(s):

M. P. A. Viegers ◽

C. W. T. Bulle Lieuwma ◽

P. C. Zalm ◽

P. M. J. Maree

Keyword(s):

Strain Field ◽

Stacking Faults ◽

Misfit Strain ◽

Epitaxial Layers ◽

Misfit Dislocations ◽

Biaxial Strain ◽

Burgers Vector ◽

Shockley Partial ◽

Partial Dislocations ◽

Geometrical Effect

AbstractMisfit dislocations in epitaxial layers of Si grown by MBE at 570°C on GaP(001) substrates have been studied by TEM. It is found that layers as thick as 500 Å at least reside coherently on the substrate without misfit dislocations. In 1000 Å layers of Si the misfit strain is accommodated in part by 60-degree type dislocations with their Burgers vector inclined with respect to the interface, and by stacking faults intersecting the Si layer. The dislocations are dissociated into 30- and 90-degree Shockley partial dislocations. It is shown that in the case of a biaxial strain field, which is tensile in a (001)-plane, the 90-degree partial must be nucleated first. Only then can the 30-degree partial follow on the same glide plane. This geometrical effect explains the presence of dislocations as well as stacking faults in the Si layer.

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Effect of Bipolar Gate-to-Drain Current on the Electrical Properties of Vertical Junction Field Effect Transistors

Materials Science Forum ◽

10.4028/www.scientific.net/msf.615-617.719 ◽

2009 ◽

Vol 615-617 ◽

pp. 719-722 ◽

Cited By ~ 7

Author(s):

Victor Veliadis ◽

Harold Hearne ◽

Eric J. Stewart ◽

Joshua D. Caldwell ◽

Megan Snook ◽

...

Keyword(s):

Field Effect ◽

Field Effect Transistors ◽

Stacking Faults ◽

Vertical Channel ◽

Drain Current ◽

Epitaxial Layers ◽

Electron Hole ◽

Blocking Voltage ◽

Hole Recombination ◽

Post Stress

Electron-hole recombination-induced stacking faults have been shown to degrade the I-V characteristics of SiC power p-n diodes and DMOSFETs with thick drift epitaxial layers. In this paper, we investigate the effect of bipolar gate-to-drain current on vertical-channel JFETs. The devices have n- drift epitaxial layers of 12-μm and 100-μm thicknesses, and were stressed at a fixed gate-to-drain current density of 100 A/cm2 for 500 hrs and 5 hrs, respectively. Significant gate-to-drain and on-state conduction current degradations were observed after stressing the 100-μm drift VJFET. Annealing at 350°C reverses the stress induced degradations. After 500 hours of stressing, the gate-to-source, gate-to-drain, and blocking voltage characteristics of the 12-μm VJFET remain unaffected. However, the on-state drain current was 79% of its pre-stress value. Annealing at 350°C has no impact on the post-stress on-state drain current of the 12-μm VJFET. This leads us to attribute the degradation to a “burn-in” effect.

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Investigation of Electron–Hole Recombination-Activated Partial Dislocations and Their Behavior in 4H-SiC Epitaxial Layers

Journal of Electronic Materials ◽

10.1007/s11664-007-0328-9 ◽

2007 ◽

Vol 37 (5) ◽

pp. 706-712

Author(s):

Yi Chen ◽

Ning Zhang ◽

Michael Dudley ◽

Joshua D. Caldwell ◽

Kendrick X. Liu ◽

...

Keyword(s):

Epitaxial Layers ◽

Electron Hole ◽

Partial Dislocations ◽

Hole Recombination

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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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Stacking faults in β-Ga2O3 crystals observed by X-ray topography

Journal of Applied Crystallography ◽

10.1107/s1600576718011093 ◽

2018 ◽

Vol 51 (5) ◽

pp. 1372-1377 ◽

Cited By ~ 11

Author(s):

Hirotaka Yamaguchi ◽

Akito Kuramata

Keyword(s):

Crystal Growth ◽

Partial Dislocation ◽

Structural Model ◽

Stacking Faults ◽

Elastic Instability ◽

Planar Defects ◽

X Ray ◽

Self Energy ◽

Unique Structural Feature ◽

Edge Component

Planar defects in (\overline{2}01)-oriented β-Ga2O3 wafers were studied using X-ray topography. These planar defects were rectangular with dimensions of 50–150 µm, and the X-ray topography analysis revealed that they were stacking faults (SFs) enclosed by a single partial dislocation loop on the (\overline{2}01) plane. The SF formation was found to be supported by a unique structural feature of the (\overline{2}01) plane as a slip plane; the (\overline{2}01) plane consists of close-packed octahedral Ga and O layers, allowing slips to form SFs. Vacancy arrays along the b axis in the octahedral Ga layer reduce the self-energy of the edge component in the partial dislocation extending along the b axis. It is speculated that the SFs occur during the crystal growth process for unknown reasons and then recover owing to elastic instability after initially increasing in size as crystal growth proceeds. Based on this analysis, a structural model for the SFs is proposed.

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Characterization of Defect Structures in 3C-SiC Single Crystals Using Synchrotron White Beam X-ray Topography

MRS Proceedings ◽

10.1557/proc-423-545 ◽

1996 ◽

Vol 423 ◽

Cited By ~ 1

Author(s):

W. Huang ◽

M. Dudley ◽

C. Fazi

Keyword(s):

Single Crystals ◽

Stacking Faults ◽

Interference Microscopy ◽

Defect Structures ◽

Growth Sector ◽

X Ray ◽

Partial Dislocations ◽

White Beam ◽

Transmission And Reflection

AbstractDefect structures in (111) 3C-SiC single crystals, grown using the Baikov technique, have been studied using Synchrotron White Beam X-ray Topography (SWBXT). The major types of defects include complex growth sector boundary structures, double positioning twins, stacking faults on { 111 } planes, inclusions and dislocations (including growth dislocations and partial dislocations bounding stacking faults). Detailed stacking fault and double positioning twin configurations are determined using a combination of Nomarski interference microscopy, SEM and white beam x-ray topography in both transmission and reflection geometries. Possible defect generation phenomena are discussed.

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