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.

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.

Investigation of Dislocation Behavior at the Early Stage of PVT-Grown 4H-SiC Crystals

2020 ◽  
Vol 1004 ◽  
pp. 44-50
Author(s):  
Tuerxun Ailihumaer ◽  
Balaji Raghothamachar ◽  
Michael Dudley ◽  
Gilyong Chung ◽  
Ian Manning ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Basal Plane ◽  
Opposite Sign ◽  
Early Stage ◽  
Vapor Transport ◽  
Grown Layer ◽  
Growth Interface ◽  
X Ray ◽  
Dislocation Behavior ◽  
Simulated Images

Dislocation behavior during the early stages of physical vapor transport (PVT) growth of 6-inch diameter 4H-SiC crystals has been investigated by synchrotron monochromatic beam X-ray topography (SMBXT) in conjunction with ray tracing simulations of dislocation images. Our studies reveal that most of the TSDs/TMDs are replicated into the newly grown layer while most TEDs are generated by either nucleation in pairs at the growth interface or by redirection of BPDs in the seed crystal. Most BPDs in the newly grown layer are of screw type with and this has been verified by comparison with ray tracing simulated images. TEDs with same and opposite sign of Burgers vector are found to be deflected on to the same basal plane by the overgrowth of macro-steps and they glide in the same and opposite directions respectively. TMDs deflected on to the basal plane by macro-steps get dissociated into c and a components, with the a segment undergoing glide to form V-shaped configurations.

Evaluation of Basal Plane Dislocation Behavior in the Epitaxial Layer on a 4H-SiС Wafer Fabricated by the Solution Growth Method

2019 ◽  
Vol 963 ◽  
pp. 80-84 ◽  
Author(s):  
Kazuaki Seki ◽  
Kazuhiko Kusunoki ◽  
Shinsuke Harada ◽  
Toru Ujihara
Keyword(s):  
Epitaxial Layer ◽  
Basal Plane ◽  
Solution Method ◽  
Chemical Vapor ◽  
Bulk Crystals ◽  
Bipolar Devices ◽  
Basal Plane Dislocation ◽  
Growth Method ◽  
Dislocation Behavior ◽  
Koh Etching

A 4H-SiC 4° off-wafer fabricated from a bulk crystal grown using the solution method has high quality with extremely low-density threading screw (TSD) and basal plane (BPD) dislocations. For application to electronic devices, we formed an epitaxial layer on the solution-method-prepared wafer via chemical vapor deposition and evaluated the BPD in the epitaxial layer using synchrotron X-ray topography and molten KOH etching. The BPD density of the epitaxial layer formed on the solution-grown crystals was extremely low. Bulk crystals fabricated as wafers by the solution method are expected to be applied to high-voltage bipolar devices that do not suffer from degradation of forward characteristics.

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.

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.

Analysis of Dislocation Behavior in Low Dislocation Density, PVT-Grown, Four-Inch Silicon Carbide Single Crystals

2010 ◽  
Vol 1246 ◽  
Author(s):  
Michael Dudley ◽  
Shayan Byrappa ◽  
Huanhuan Wang ◽  
Fangzhen Wu ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Basal Plane ◽  
Growth Conditions ◽  
Formation Mechanisms ◽  
Stress Growth ◽  
Low Dislocation Density ◽  
Basal Plane Dislocation ◽  
Dislocation Behavior ◽  
New Generation ◽  
Insight Into

AbstractSynchrotron White Beam X-ray Topography studies are presented of dislocation behavior and interactions in a new generation of one hundred millimeter diameter, 4H-SiC wafers grown using Physical Vapor Transport (PVT) under specially designed low stress conditions. Such low stress growth conditions have, for example enabled reductions of basal plane dislocation (BPD) densities by two or three orders of magnitude compared to previous levels down to just a few hundred per square centimeter. This provides a unique opportunity to discern details of dislocation behavior which were previously precluded due to complications of image overlap at higher densities. Among the phenomena observed in these studies is the deflection of threading dislocations onto the basal plane producing various stacking fault configurations. Analysis of the contrast from these faults enables determination of their fault vectors which, in turn, provides insight into their possible formation mechanisms.

scholarly journals Analysis of the Basal Plane Dislocation Density and Thermomechanical Stress during 100 mm PVT Growth of 4H-SiC

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2207 ◽  
Author(s):  
Johannes Steiner ◽  
Melissa Roder ◽  
Binh Duong Nguyen ◽  
Stefan Sandfeld ◽  
Andreas Danilewsky ◽  
...  
Keyword(s):  
Basal Plane ◽  
Growth Parameters ◽  
Electronic Devices ◽  
Defect Distribution ◽  
Thermomechanical Stress ◽  
X Ray ◽  
Basal Plane Dislocation ◽  
The Impact ◽  
Koh Etching

Basal plane dislocations (BPDs) in 4H silicon carbide (SiC) crystals grown using the physical vapor transport (PVT) method are diminishing the performance of SiC-based power electronic devices such as pn-junction diodes or MOSFETs. Therefore, understanding the generation and movement of BPDs is crucial to grow SiC suitable for device manufacturing. In this paper, the impact of the cooldown step in PVT-growth on the defect distribution is investigated utilizing two similar SiC seeds and identical growth parameters except for a cooldown duration of 40 h and 70 h, respectively. The two resulting crystals were cut into wafers, which were characterized by birefringence imaging and KOH etching. The initial defect distribution of the seed wafer was characterized by synchrotron white beam X-ray topography (SWXRT) mapping. It was found that the BPD density increases with a prolonged cooldown time. Furthermore, small angle grain boundaries based on threading edge dislocation (TED) arrays, which are normally only inherited by the seed, were also generated in the case of the crystal cooled down in 70 h. The role of temperature gradients inside the crystal during growth and post-growth concerning the generation of shear stress is discussed and supported by numerical calculations.

Nucleation of c-Axis Screw Dislocations at Substrate Surface Damage during 4H-Silicon Carbide Homo-Epitaxy

2010 ◽  
Vol 645-648 ◽  
pp. 295-298 ◽  
Author(s):  
Michael Dudley ◽  
Ning Zhang ◽  
Yu Zhang ◽  
Balaji Raghothamachar ◽  
Edward K. Sanchez
Keyword(s):  
Basal Plane ◽  
Opposite Sign ◽  
Substrate Surface ◽  
Surface Damage ◽  
Dislocation Nucleation ◽  
Screw Dislocations ◽  
Basal Plane Dislocation ◽  
Residual Damage ◽  
Step Flow Growth ◽  
Edge Dislocations

Observations of dislocation nucleation occurring at substrate surface scratches during 4H-SiC CVD homoepitaxial growth are reported. Sub-surface residual damage associated with the scratches is observed to act as nucleation sites for basal plane dislocations (BPDs), threading edge dislocations (TEDs) and threading screw dislocations (TSDs) in the epilayer. TEDs and BPDs replicate from the surface intersections of basal plane dislocation half-loops injected into the substrate surface. A model for the nucleation mechanism of TSDs, which nucleate in opposite sign pairs, is presented which involves overgrowth of surface indentations associated with the scratch during step flow growth. Atomic steps which approach these local surface indentations can collapse creating pairs of opposite sign screw dislocations which have Burgers vector magnitude equal to the magnitude of the step disregistry created during the collapse.

Investigation of Basal Plane Dislocation Reduction/Elimination by Molten KOH-NaOH Eutectic Etching Method

2012 ◽  
Vol 717-720 ◽  
pp. 125-128 ◽  
Author(s):  
Hai Zheng Song ◽  
Tangali S. Sudarshan
Keyword(s):  
Epitaxial Growth ◽  
Basal Plane ◽  
Etch Pits ◽  
Etch Pit ◽  
Etching Method ◽  
Dislocation Reduction ◽  
Short Period ◽  
Basal Plane Dislocation ◽  
Non Destructive ◽  
Koh Etching

An optimized molten KOH-NaOH eutectic etching method is developed to reveal defects in highly n-doped SiC substrates and to pre-treat the substrate prior to epitaxial growth. Different from the conventional KOH etching method, by way of eutectic method, the basal plane dislocation (BPD) conversion in the subsequent epitaxial growth is independent of the etch pit size pre-generated on the substrate. Even with a short period (~3 minutes) of pretreatment which does not generate any visible etch pits or degradation of surface morphology on the substrate, an epilayer with low BPD density -2 is still achieved. This simple and non-destructive method shows high potential to be practically employed as one of the basic pretreatment steps to the substrates in SiC epitaxial growth in order to achieve very low or free BPD density.

Starting Point of Step-Bunching Defects on 4H-SiC Si-Face Substrates

2015 ◽  
Vol 821-823 ◽  
pp. 367-370 ◽  
Author(s):  
Kentaro Tamura ◽  
Masayuki Sasaki ◽  
Chiaki Kudou ◽  
Tamotsu Yamashita ◽  
Hideki Sako ◽  
...  
Keyword(s):  
Oxide Layer ◽  
Epitaxial Layer ◽  
Basal Plane ◽  
X Ray ◽  
Step Bunching ◽  
Line Feature ◽  
Starting Point ◽  
Basal Plane Dislocation ◽  
Koh Etching

On 4H-SiC Si-face substrates after H2etching, the defect with “line” feature parallel to a step as “bunched-step line” was observed. Using X-ray topography and KOH etching, we confirmed that the bunched-step line originated from basal plane dislocation (BPD). Use of the substrate with the lowest BPD density will be effective to reduce bunched-step line that would affect oxide layer reliability on an epitaxial layer. However, more detail investigation needs to classify the BPD that would become a starting point of bunched-step line.

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