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.

Simulation of Threading Edge Dislocation Images in X-Ray Topographs of Silicon Carbide Homo-Epilayers

2006 ◽  
Vol 527-529 ◽  
pp. 411-414
Author(s):  
William M. Vetter ◽  
Hidekazu Tsuchida ◽  
Isaho Kamata ◽  
Michael Dudley
Keyword(s):  
Grazing Incidence ◽  
X Ray ◽  
Maximum Resolution ◽  
Reflection Geometry ◽  
Reflection Equations ◽  
Experimental Geometry ◽  
Edge Dislocations ◽  
Monochromatic Synchrotron ◽  
Tracing Method ◽  
Dark Contrast

Among the types of dislocation seen in homo-epilayers of SiC grown upon 4H-SiC wafers with an 8° surface offcut are 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 2 8 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 the threading edge dislocations. 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 resembled the experimental topographs, inasmuch as was possible at the maximum resolution of x-ray topographs.

Grazing Incidence X-ray Topographic Studies of Threading Dislocations in Hydrothermal Grown ZnO Single Crystal Substrates

2013 ◽  
Vol 1494 ◽  
pp. 121-126 ◽  
Author(s):  
Tianyi Zhou ◽  
Balaji Raghothamachar ◽  
Fangzhen Wu ◽  
Michael Dudley
Keyword(s):  
Single Crystal ◽  
Grazing Incidence ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Screw Dislocations ◽  
X Ray ◽  
Dislocation Defects ◽  
Image Position ◽  
Threading Defects ◽  
Zno Single Crystal

ABSTRACTZnO single crystal substrates grown by the hydrothermal method have been characterized by grazing incidence X-ray topography using both monochromaticand whitesynchrotron X ray beams.11$\bar 2$4 reflection wasrecorded from the (0001) wafers and the different contrast patterns produced by different threading defects were noted. To uniquely identify the Burgers vectors of these threading dislocation defects, we use raytracingsimulation to compare with observed defect contrast. Our studies showed that threading screw dislocations are not commonly observed.Most threading edge dislocationshavetheBurgers vector of1⁄3[2$\bar 1$$\bar 1$0] or1⁄3[12$\bar 2$10]and a density of 2.88×104/cm2.

Conversion of Basal Plane Dislocations to Threading Edge Dislocations by High Temperature Annealing of 4H-SiC Epilayers

2012 ◽  
Vol 1433 ◽  
Author(s):  
Xuan Zhang ◽  
Hidekazu Tsuchida
Keyword(s):  
High Temperature ◽  
Basal Plane ◽  
Image Force ◽  
Line Tension ◽  
Grazing Incidence ◽  
High Temperature Annealing ◽  
X Ray ◽  
Before And After ◽  
Edge Dislocations ◽  
Epilayer Surface

ABSTRACTConversion of basal plane dislocations (BPDs) to threading edge dislocations (TEDs) has been observed in 4H-SiC epilayers by simple high temperature annealing. Grazing incidence reflection synchrotron X-ray topography was used to image the dislocations in the epilayers. By comparing the X-ray topographs before and after annealing, some of the BPDs were confirmed to convert to TEDs from the epilayer surface. The dislocation behaviors during annealing are explained and the mechanism of BPD conversion is discussed. It is argued that the conversion process is realized by constricted BPD segments cross-slipping to the prismatic plane driven by the image force and TED glide on its slip plane driven by the line tension. Certain kinetic processes may assist the formation of constrictions on the BPDs.

Origin Analyses of Trapezoid-Shape Defects in 4-Deg.-off 4H-SiC Epitaxial Wafers by Synchrotron X-Ray Topography

2014 ◽  
Vol 778-780 ◽  
pp. 374-377 ◽  
Author(s):  
Tamotsu Yamashita ◽  
Hirofumi Matsuhata ◽  
Yoshihiko Miyasaka ◽  
Kenji Momose ◽  
Takayuki Sato ◽  
...  
Keyword(s):  
Basal Plane ◽  
Surface Defects ◽  
Epitaxial Film ◽  
Negative Impact ◽  
Film Surface ◽  
Dislocation Loops ◽  
Screw Dislocations ◽  
X Ray ◽  
Mos Devices ◽  
Edge Dislocations

The trapezoid-shape defects are one of the most common surface defects on current 4H-SiC epitaxial film surface since they give rise negative impact for MOS-devices. We have investigated structures and origins of the defects. It is discovered that the possible origins of the trapezoid-shape defects are basal plane dislocations (BPDs), threading edge dislocations (TEDs), threading screw dislocations (TSDs),and the short dislocation loops introduced under scratches.

Observation of Misfit Dislocations Introduced by Epi-Layer Growth on 4H-SiC

2008 ◽  
Vol 600-603 ◽  
pp. 309-312 ◽  
Author(s):  
Hirofumi Matsuhata ◽  
Hirotaka Yamaguchi ◽  
Ichiro Nagai ◽  
Toshiyuki Ohno ◽  
Ryouji Kosugi ◽  
...  
Keyword(s):  
Basal Plane ◽  
Grazing Incidence ◽  
Lattice Parameter ◽  
Layer Growth ◽  
Misfit Dislocations ◽  
Screw Dislocations ◽  
Incidence Geometries ◽  
The Difference ◽  
Edge Dislocations ◽  
Monochromatic Synchrotron

4H-SiC substrate wafers with epi-layers were observed using monochromatic synchrotron X-ray topography in grazing incidence geometries, to investigate the defects in the epi-layer. Misfit dislocations with b=+1/3[11 2 0] caused by the difference in lattice parameter between the epi-layer and the substrate were observed. The misfit dislocations are located near the interface as edge dislocations, and appear at the top surface as screw dislocations on basal planes. It was observed that more than half of them were introduced from the growing epi-layer surface. The misfit dislocations and some screw dislocations with b=+1/3[11 2 0] are observed to remain as basal plane dislocations at the surface, while other basal plane dislocations were converted to threading edge dislocations in the epi-layer.

Investigation of Low Angle Grain Boundaries in Hexagonal Silicon Carbide

2006 ◽  
Vol 955 ◽  
Author(s):  
Yi Chen ◽  
Hui Chen ◽  
Ning Zhang ◽  
Michael Dudley ◽  
Ronghui Ma
Keyword(s):  
Silicon Carbide ◽  
Grain Boundaries ◽  
Basal Plane ◽  
Vapor Transport ◽  
Threading Dislocations ◽  
Prismatic Plane ◽  
Screw Dislocations ◽  
X Ray ◽  
Edge Dislocations ◽  
Dislocation Walls

ABSTRACTInteraction between basal plane dislocations and single or well-spaced threading dislocations is discussed based on synchrotron white beam X-ray topographic studies carried out on physical vapor transport grown hexagonal silicon carbide single crystals. The basal plane dislocations are able to cut through single or well-spaced threading edge dislocations even if the formation of kinks/jogs is energetically unfavorable while threading screw dislocations were mostly observed to act as effective pinning points. However, basal plane dislocations can sometimes cut through a threading screw dislocation, forming a superjog and which subsequently migrates on the prismatic plane via a cross-slip process. Threading edge dislocation walls act as obstacles for the glide of basal plane dislocations and the mechanism by which this occurs is discussed. The character of low angle grain boundaries and their dislocation content are discussed.

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.

Conversion of Basal Plane Dislocations to Threading Edge Dislocations by Annealing 4H-SiC Epilayers at High Temperatures

2013 ◽  
Vol 740-742 ◽  
pp. 601-604
Author(s):  
Xuan Zhang ◽  
Masahiro Nagano ◽  
Hidekazu Tsuchida
Keyword(s):  
Surface Morphology ◽  
Ion Implantation ◽  
Epitaxial Growth ◽  
High Temperatures ◽  
Basal Plane ◽  
Grazing Incidence ◽  
Conversion Ratio ◽  
Prismatic Plane ◽  
X Ray ◽  
Edge Dislocations

Basal plane dislocations (BPDs) converting to threading edge dislocations (TEDs) has been observed in 4H-SiC epilayers after thermal annealing at high temperatures. Grazing incidence reflection synchrotron X-ray topography was used to investigate the dislocation behaviors. It is argued that the conversion is achieved by constricted BPD segments cross-slipping to the prismatic plane and TED glide on its slip plane. Higher conversion ratio and better surface morphology were achieved by performing ion implantation and annealing before epitaxial growth.

Contrast of Basal Plane and Threading Edge Dislocations in 4H-SiC by X-Ray Topography in Grazing Incidence Geometry

2008 ◽  
Vol 600-603 ◽  
pp. 321-324 ◽  
Author(s):  
Hirofumi Matsuhata ◽  
Hirotaka Yamaguchi ◽  
Ichiro Nagai ◽  
Toshiyuki Ohno ◽  
Ryouji Kosugi ◽  
...  
Keyword(s):  
Basal Plane ◽  
Grazing Incidence ◽  
Incidence Geometry ◽  
Burgers Vector ◽  
X Ray ◽  
Substrate Wafer ◽  
G 11 ◽  
Edge Dislocations ◽  
Grazing Incidence Geometry ◽  
Monochromatic Synchrotron

Dislocations in a substrate wafer of 4H-SiC with an epi-layer were observed using technique of monochromatic synchrotron X-ray topography in a grazing incidence geometry. Six different Burgers vectors of basal plane dislocations and threading edge dislocations were identified by changing the Bragg reflections, and by analysis of images of dislocation. We identify some relations of the Burgers vector and the dislocation contrast observed for g=11 2 8. Some of these relationships are discussed in this report.

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