Multiplication of Basal Plane Dislocations via Interaction with c-Axis Threading Dislocations in 4H-SiC

2006 ◽  
Vol 911 ◽  
Author(s):  
Yi Chen ◽  
Govindhan Dhanaraj ◽  
Michael Dudley ◽  
Hui Zhang ◽  
Ronghui Ma ◽  
...  
Keyword(s):  
Vapor Deposition ◽  
Basal Plane ◽  
Opposite Sign ◽  
Chemical Vapor ◽  
Threading Dislocations ◽  
Dislocation Loops ◽  
X Ray ◽  
Large Numbers ◽  
Basal Plane Dislocation ◽  
Edge Dislocations

AbstractSilicon carbide (SiC) substrates with chemical vapor deposition (CVD) grown epilayers have been characterized by synchrotron white beam X-ray topography (SWBXT). Large numbers of circular basal plane dislocation loops (BPDs) were observed in the substrate which were anchored by threading screw dislocations (SDs). Threading edge dislocations (TEDs) are not observed to play an important role in the multiplication of BPDs. A SD-assisted “conservative climb” model is proposed to explain the multiplication of BPDs during growth and/or post-growth processes. BPDs are shown to multiply on adjacent parallel basal planes via single SD-assisted as well as opposite sign SD-pair-assisted “conservative climb”.

Turning of Basal Plane Dislocations during Epitaxial Growth on 4° Off-Axis 4H-SiC

2009 ◽  
Vol 615-617 ◽  
pp. 105-108 ◽  
Author(s):  
Rachael L. Myers-Ward ◽  
Brenda L. VanMil ◽  
Robert E. Stahlbush ◽  
S.L. Katz ◽  
J.M. McCrate ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Epitaxial Growth ◽  
Conversion Efficiency ◽  
Vapor Deposition ◽  
Basal Plane ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Epitaxial Layers ◽  
Basal Plane Dislocation ◽  
Edge Dislocations

Epitaxial layers were grown on 4° off-axis 4H-SiC substrates by hot-wall chemical vapor deposition. The reduced off-cut angle resulted in lower basal plane dislocation (BPD) densities. The dependence of BPD reduction on growth conditions was investigated using ultraviolet photoluminescence (UVPL) imaging. With this method, it was found that the dislocations were converting to threading edge dislocations throughout the thickness of the film. A high (≥ 97%) conversion efficiency was found for all films grown with this orientation. A conversion of 100% was achieved for several films without pre-growth treatments or growth interrupts.

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.

The Nucleation and Propagation of Threading Dislocations with C-Component of Burgers Vector in PVT-Grown 4H-SiC

2013 ◽  
Vol 740-742 ◽  
pp. 217-220 ◽  
Author(s):  
Fang Zhen Wu ◽  
Michael Dudley ◽  
Huan Huan Wang ◽  
Sha Yan Byrapa ◽  
Shun Sun ◽  
...  
Keyword(s):  
Basal Plane ◽  
Opposite Sign ◽  
Growth Direction ◽  
Threading Dislocations ◽  
Burgers Vector ◽  
X Ray ◽  
White Beam

Studies of threading dislocations with Burgers vector of c+a have been carried out using synchrotron white beam X-ray topography. The nucleation and propagation of pairs of opposite sign threading c+a dislocations is observed. Overgrowth of inclusions by growth steps leads to lattice closure failure and the stresses associated with this can be relaxed by the nucleation of opposite sign pairs of dislocations with Burgers vector c+a. Once these dislocations are nucleated they propagate along the c-axis growth direction, or can be deflected onto the basal plane by overgrowth of macrosteps. For the c+a dislocations, partial deflection can occasionally occur, e.g. the a-component deflects onto basal plane while the c-component continuously propagates along the growth direction. One factor controlling the details of these deflection processes is suggested to be related to the ratio between the height of the overgrowing macrostep and that of the surface spiral hillock associated with the threading growth dislocations with c-component of Burgers vector.

Behavior of Basal Plane Dislocations and Low Angle Grain Boundary Formation in Hexagonal Silicon Carbide

2007 ◽  
Vol 556-557 ◽  
pp. 231-234 ◽  
Author(s):  
Yi Chen ◽  
Govindhan Dhanaraj ◽  
William M. Vetter ◽  
Rong Hui Ma ◽  
Michael Dudley
Keyword(s):  
Silicon Carbide ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Basal Plane ◽  
Opposite Sign ◽  
Three Dimensional ◽  
Cross Slip ◽  
X Ray ◽  
Tilt Boundaries ◽  
Edge Dislocations

The interactions between basal plane dislocations (BPDs) and threading screw and edge dislocations (TSDs and TEDs) in hexagonal SiC have been studied using synchrotron white beam x-ray topography (SWBXT). TSDs are shown to strongly interact with advancing basal plane dislocations (BPDs) while TEDs do not. A BPD can cut through an individual TED without the formation of jogs or kinks. The BPDs were observed to be pinned by TSDs creating trailing dislocation dipoles. If these dipoles are in screw orientation segments can cross-slip and annihilate also potentially leaving isolated trailing loops. The three-dimensional (3D) distribution of BPDs can lead to aggregation of opposite sign edge segments leading to the creation of low angle grain boundaries (LAGBs) characterized by pure basal plane tilt of magnitude determined by the net difference in densities of the opposite sign dislocations. Similar aggregation can also occur against pre-existing prismatic tilt boundaries made up of TED walls with the net difference in densities of the opposite sign dislocations contributing some basal plane tilt character to the LAGB.

Characterization and Reduction of Defects in 4H-SiC Substrate and Homo-Epitaxial Wafer

2020 ◽  
Vol 1004 ◽  
pp. 387-392 ◽  
Author(s):  
Long Yang ◽  
Li Xia Zhao ◽  
Hui Wang Wu ◽  
Yafei Liu ◽  
Tuerxun Ailihumaer ◽  
...  
Keyword(s):  
Basal Plane ◽  
Chemical Vapor ◽  
Vapor Transport ◽  
Etching Time ◽  
X Ray ◽  
Half Loop ◽  
Dislocation Behavior ◽  
Edge Dislocations ◽  
Defect Morphology ◽  
Koh Etching

4H-SiC substrates and homo-epitaxial layers were obtained using the traditional methods of physical vapor transport and chemical vapor deposition. Defect morphology has been studied using both Synchrotron White Beam X-ray Topography and Monochromatic Beam X-ray Topography. Molten KOH etching method was adopted to further investigate the dislocation behavior mechanisms. Deflected dislocations were observed at the periphery regions in both substrate and epitaxial wafers. 3C polytypes and half loop arrays were observed in the 4H-SiC epitaxial wafer. It is also found that the majority of basal plane dislocations are converted to threading edge dislocations in the epitaxial wafer samples. The proportion of BPD to TED conversion depends on the surface step morphology and growth mode in epitaxial growth which in turn depends on the C/Si ratio. By the optimization of etching time prior to epitaxy and C/Si ratio, high-quality epitaxial wafers with extremely low basal plane dislocations densities (＜0.1 cm-2) was obtained.

Characterization of 100 mm Diameter 4H-Silicon Carbide Crystals with Extremely Low Basal Plane Dislocation Density

2010 ◽  
Vol 645-648 ◽  
pp. 291-294 ◽  
Author(s):  
Michael Dudley ◽  
Ning Zhang ◽  
Yu Zhang ◽  
Balaji Raghothamachar ◽  
Sha Yan Byrapa ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Dislocation Density ◽  
Basal Plane ◽  
X Ray ◽  
Repetitive Process ◽  
Basal Plane Dislocation ◽  
And Behavior ◽  
New Generation ◽  
Edge Dislocations

Synchrotron White Beam X-ray Topography (SWBXT) studies are presented of basal plane dislocation (BPD) configurations and behavior in a new generation of 100mm diameter, 4H-SiC wafers with extremely low BPD densities (3-4 x 102 cm-2). The conversion of non-screw oriented, glissile BPDs into sessile threading edge dislocations (TEDs) is observed to provide pinning points for the operation of single ended Frank-Read sources. In some regions, once converted TEDs are observed to re-convert back into BPDs in a repetitive process which provides multiple BPD pinning points.

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.

Conversion of Basal Plane Dislocations to Threading Edge Dislocations in Growth of Epitaxial Layers on 4H-SiC Substrates with a Vicinal Off-Angle

2014 ◽  
Vol 778-780 ◽  
pp. 99-102 ◽  
Author(s):  
Keiko Masumoto ◽  
Sachiko Ito ◽  
Hideto Goto ◽  
Hirotaka Yamaguchi ◽  
Kentaro Tamura ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Edge Dislocation ◽  
Basal Plane ◽  
Conversion Ratio ◽  
Epitaxial Layers ◽  
Etch Pits ◽  
X Ray ◽  
Basal Plane Dislocation ◽  
Edge Dislocations ◽  
Koh Etching

We have investigated a conversion of basal plane dislocation (BPD) to threading edge dislocation (TED) in growth of epitaxial layers (epi-layers) on 4H-SiC vicinal substrates with an off-angle of 0.85° at low C/Si ratio of 0.7 by using deep KOH etching and X-ray topography observations. Deep KOH etching indicated that BPDs in the substrates converted to TEDs in the epi-layers. X-ray topography observations suggested that the conversion occurred during epitaxial growth when the thickness of epi-layers was less than 1.5 μm. We found that the conversion ratio obtained from counting deep KOH etch pits was over 99%.

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.

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