Simulation of Forescattered Electron Channeling Contrast Imaging of Threading Dislocations Penetrating SiC Surfaces

ABSTRACTThe interpretation of ECCI images in the forescattered geometry presents a more complex diffraction configuration than that encountered in the backscattered geometry. Determining the Kikuchi line that is the primary source of image intensity often requires more than simple inspection of the electron-channeling pattern. This problem can be addressed, however, by comparing recorded ECCI images of threading screw dislocations in 4H-SiC with simulated images. An ECCI image of this dislocation is found to give the orientation of the dominant Kikuchi line, greatly simplifying the determination of the diffraction simulation. In addition, computed images of threading screw dislocations in 4H-SiC were found to exhibit channeling contrast essentially identical to that obtained experimentally by ECCI and allowing determination of the dislocation Burgers vector.

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Burgers Vector Determination of Threading Screw Dislocations in 4H-SiC via Forescattered Electron Channeling Contrast Imaging

Microscopy and Microanalysis ◽

10.1017/s1431927609092319 ◽

2009 ◽

Vol 15 (S2) ◽

pp. 1018-1019

Author(s):

ME Twigg ◽

YN Picard ◽

JD Caldwell ◽

CR Eddy

Keyword(s):

Contrast Imaging ◽

Screw Dislocations ◽

Burgers Vector ◽

Electron Channeling

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

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Using Multiple Contrast Mechanisms via Forescatter Electron Channeling Contrast Imaging to Resolve the Burgers Vector of GaN Threading Dislocations

Microscopy and Microanalysis ◽

10.1017/s1431927609094562 ◽

2009 ◽

Vol 15 (S2) ◽

pp. 674-675

Author(s):

YN Picard ◽

ME Twigg ◽

JD Caldwell ◽

CR Eddy Jr. ◽

MA Mastro ◽

...

Keyword(s):

Threading Dislocations ◽

Contrast Imaging ◽

Burgers Vector ◽

Electron Channeling ◽

Contrast Mechanisms

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

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Coincident Electron Channeling and Cathodoluminescence Studies of Threading Dislocations in GaN

Microscopy and Microanalysis ◽

10.1017/s1431927613013755 ◽

2013 ◽

Vol 20 (1) ◽

pp. 55-60 ◽

Cited By ~ 20

Author(s):

Gunasekar Naresh-Kumar ◽

Jochen Bruckbauer ◽

Paul R. Edwards ◽

Simon Kraeusel ◽

Ben Hourahine ◽

...

Keyword(s):

Structural Damage ◽

Light Emission ◽

Threading Dislocations ◽

Nonradiative Recombination ◽

Contrast Imaging ◽

Force Microscopy ◽

Electron Channeling ◽

Microscopy Techniques ◽

Cathodoluminescence Imaging ◽

Edge Dislocations

AbstractWe combine two scanning electron microscopy techniques to investigate the influence of dislocations on the light emission from nitride semiconductors. Combining electron channeling contrast imaging and cathodoluminescence imaging enables both the structural and luminescence properties of a sample to be investigated without structural damage to the sample. The electron channeling contrast image is very sensitive to distortions of the crystal lattice, resulting in individual threading dislocations appearing as spots with black–white contrast. Dislocations giving rise to nonradiative recombination are observed as black spots in the cathodoluminescence image. Comparison of the images from exactly the same micron-scale region of a sample demonstrates a one-to-one correlation between the presence of single threading dislocations and resolved dark spots in the cathodoluminescence image. In addition, we have also obtained an atomic force microscopy image from the same region of the sample, which confirms that both pure edge dislocations and those with a screw component (i.e., screw and mixed dislocations) act as nonradiative recombination centers for the Si-doped c-plane GaN thin film investigated.

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Determination of the sign of the burgers vector for nearly screw dislocations a direct application of x-ray dynamical theory

Philosophical Magazine A ◽

10.1080/01418618008239313 ◽

1980 ◽

Vol 41 (3) ◽

pp. 291-306 ◽

Cited By ~ 10

Author(s):

E. Dunia ◽

C. Malgrange ◽

J. F. Petroff

Keyword(s):

Dynamical Theory ◽

Direct Application ◽

Screw Dislocations ◽

Burgers Vector ◽

X Ray

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Microcrack Nucleation and Crack Propagation in Equiaxed γ TiAl

MRS Proceedings ◽

10.1557/proc-753-bb3.8 ◽

2002 ◽

Vol 753 ◽

Cited By ~ 1

Author(s):

Martin A. Crimp ◽

Boon-Chi Ng ◽

Benjamin A. Simkin ◽

Thomas R. Bieler

Keyword(s):

Ex Situ ◽

Contrast Imaging ◽

Active Deformation ◽

Electron Channeling ◽

Microcrack Initiation ◽

Grain Orientations ◽

Contrast Analysis ◽

Defect Imaging

ABSTRACTTo gain a better understanding of the ductility limitations in TiAl alloys, the mechanisms involved in deformation strain transfer and/or microcrack initiation at grain boundaries have been examined in an equiaxed near-γ alloy. These studies have been carried out on both in-situ and ex-situ deformed bulk samples using scanning electron microscopy (SEM) techniques for both orientation analysis and deformation defect imaging. Selected area electron channeling patterns (SACPs) have allowed determination of grain orientations, eliminating ambiguity between the a and c axes. Deformation twins and dislocations have been imaged in the bulk samples using electron channeling contrast imaging (ECCI). A combination of ECCI contrast analysis and trace analysis based on orientations determined from SACP has allowed identification of the active deformation systems. Microcracks have been found to initiate at γ-γ boundaries as a result of an inability to adequately transfer twin strain from grain to grain. Once initiated, cracks propagate through cleavage and re-nucleation of grain boundary microcracks in front of the advancing crack. A geometric based predictive factor has been developed that accounts for microcrack initiation at γ-γ boundaries based in deformation twinning and strain accommodation by ordinary dislocations.

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Synchrotron X-Ray Topography Studies of the Propagation and Post-Growth Mutual Interaction of Threading Growth Dislocations with C-Component of Burgers Vector in PVT-Grown 4H-SiC

Materials Science Forum ◽

10.4028/www.scientific.net/msf.717-720.343 ◽

2012 ◽

Vol 717-720 ◽

pp. 343-346 ◽

Cited By ~ 11

Author(s):

Fang Zhen Wu ◽

Huan Huan Wang ◽

Sha Yan Byrapa ◽

Balaji Raghothamachar ◽

Michael Dudley ◽

...

Keyword(s):

Opposite Sign ◽

Equilibrium Concentration ◽

Vapor Transport ◽

Mutual Interaction ◽

Similar Reaction ◽

Threading Dislocations ◽

Screw Dislocations ◽

Burgers Vector ◽

X Ray ◽

Nucleation Sites

Synchrotron White Beam X-ray Topography (SWBXT) imaging of wafers cut parallel to the growth axis from 4H-SiC boules grown using Physical Vapor Transport has enabled visualization of the evolution of the defect microstructure. Here we present observations of the propagation and post-growth mutual interaction of threading growth dislocations with c-component of Burgers vector. Detailed contrast extinction studies reveal the presence of two types of such dislocations: pure c-axis screw dislocations and those with Burgers Vector n1c+n2a, where n1is equal to 1 and n2is equal to 1 or 2. In addition, observations of dislocation propagation show that some of the threading dislocations with c-component of Burgers adopt a curved, slightly helical morphology which can drive the dislocations from adjacent nucleation sites together enabling them to respond to the inter-dislocation forces and react. Since all of the dislocations exhibiting such helical configurations have significant screw component, and in view of the fact that such dislocations are typically not observed to glide, it is believed that such morphologies result in large part from the interaction of a non-equilibrium concentration of vacancies with the originally approximately straight dislocation cores during post-growth cooling. Such interactions can lead to complete or partial Burgers vector annihilation. Among the reactions observed are: (a) the reaction between opposite-sign threading screw dislocations with Burgers vectors c and –c wherein some segments annihilate leaving others in the form of trails of stranded loops comprising closed dislocation dipoles; (b) the reaction between threading dislocations with Burgers vectors of -c+a and c+a wherein the opposite c-components annihilate leaving behind the two a-components; (c) the similar reaction between threading dislocations with Burgers vectors of -c and c+a leaving behind the a-component.

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Diffraction Contrast of Threading Dislocations in GaN and 4H-SiC Epitaxial Layers Using Electron Channeling Contrast Imaging

Journal of Electronic Materials ◽

10.1007/s11664-010-1143-2 ◽

2010 ◽

Vol 39 (6) ◽

pp. 743-746 ◽

Cited By ~ 5

Author(s):

M. E. Twigg ◽

Y. N. Picard ◽

J. D. Caldwell ◽

C. R. Eddy ◽

M. A. Mastro ◽

...

Keyword(s):

Epitaxial Layers ◽

Threading Dislocations ◽

Contrast Imaging ◽

Electron Channeling ◽

Diffraction Contrast

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Towards Non-Destructive Burgers Vector Identification of Dislocations in Electronic Materials via Electron Channeling Contrast Imaging

Microscopy and Microanalysis ◽

10.1017/s1431927610062161 ◽

2010 ◽

Vol 16 (S2) ◽

pp. 1558-1559

Author(s):

RJ Kamaladasa ◽

ME Twigg ◽

M De Graef ◽

YN Picard

Keyword(s):

Electronic Materials ◽

Contrast Imaging ◽

Burgers Vector ◽

Electron Channeling ◽

Non Destructive

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

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Photoluminescence Imaging and Discrimination of Threading Dislocations in 4H-SiC Epilayers

Materials Science Forum ◽

10.4028/www.scientific.net/msf.778-780.313 ◽

2014 ◽

Vol 778-780 ◽

pp. 313-318 ◽

Cited By ~ 7

Author(s):

Masahiro Nagano ◽

Isaho Kamata ◽

Hidekazu Tsuchida

Keyword(s):

High Resolution ◽

Spot Size ◽

Threading Dislocations ◽

Cross Sectional ◽

Screw Dislocations ◽

Burgers Vector ◽

Inclination Angles

This paper demonstrates high-resolution photoluminescence (PL) imaging and discrimination of threading dislocations in 4H-SiC epilayers. Threading screw dislocations (TSDs) and TEDs are distinguished by differences in PL spot size and spectrum. We found that TEDs are further discriminated into six types according to their Burgers vector directions by the appearance of PL imaging. Cross-sectional PL imaging reveals inclination angles of threading dislocations across a thick epilayer.

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