On the micromechanisms of repeated precipitation on edge dislocations

1978 ◽  
Vol 13 (10) ◽  
pp. 2233-2240 ◽  
Author(s):  
J. K. Solberg ◽  
E. Nes
Keyword(s):  
Edge Dislocations ◽  
Repeated Precipitation

Elimination of emitter edge dislocations in silicon planar n-p-n transistors

1980 ◽  
Vol 16 (22) ◽  
pp. 842 ◽  
Author(s):  
N.D. Stojadinović ◽  
R.S. Popović
Keyword(s):  
Edge Dislocations

scholarly journals Structure and properties of edge dislocations in BiFeO3

2019 ◽  
Vol 3 (3) ◽  
Author(s):  
Piyush Agrawal ◽  
Marco Campanini ◽  
Andrew Rappe ◽  
Shi Liu ◽  
Vincenzo Grillo ◽  
...  
Keyword(s):  
Structure And Properties ◽  
Edge Dislocations

TEM investigation of defect reduction and etch pit formation in GaN

2003 ◽  
Vol 798 ◽  
Author(s):  
Angelika Vennemann ◽  
Jens Dennemarck ◽  
Roland Kröger ◽  
Tim Böttcher ◽  
Detlef Hommel ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Dislocation Density ◽  
Line Tension ◽  
Threading Dislocations ◽  
Dislocation Loops ◽  
Etch Pits ◽  
Defect Reduction ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
Edge Dislocations

ABSTRACTGaN samples of this study were chemically wet etched to gain easier access to the dislocation sturcture. The scanning electron microscopy and transmission electron microscopy investigations revealed four different types of etch pits. After brief etching, several dislocations with screw component showed large etch pits, which may be correlated with the core of the screw dislocation. By means of SiNx micromasking the dislocation density could be reduced by more than one order of magnitude. The reduction of threading dislocations in the SiNx region in GaN grown on 〈0001〉 sapphire is due to bending of the threading dislocations into the {0001} plane, such that they form dislocation loops if they meet dislocations with opposite Burgers vectors. Accordingly, the achievable reduction of the dislocation density is limited by the probability that these dislocations interact. Edge dislocations bend more easily on account of their low line tension. This results in a preferential bending and reduction of dislocations with edge character.

Evolution of Basal Plane Dislocations during 4H-SiC Epitaxial Growth

2008 ◽  
Vol 600-603 ◽  
pp. 317-320 ◽  
Author(s):  
Robert E. Stahlbush ◽  
Brenda L. VanMil ◽  
Kendrick X. Liu ◽  
Kok Keong Lew ◽  
Rachael L. Myers-Ward ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Basal Plane ◽  
Gas Flow ◽  
Epitaxial Layers ◽  
Half Loop ◽  
Edge Dislocations

The evolution of basal plane dislocations (BPDs) in 4H-SiC epitaxy during its growth is investigated by using two types of interrupted growth in conjunction with ultraviolet photoluminescence (UVPL) imaging of the dislocations. For the first, each epitaxial growth was stopped after 10-20 μm and a UVPL map was collected. For the second, changing the gas flow interrupted the growth and the BPDs were imaged at the end. The first sequence made it possible to track the formation of half-loop arrays and show that they arise from BPDs that glide perpendicular to the offcut direction. For both types, each interruption causes between 30 – 50% of the BPDs to be converted to threading edge dislocations (TEDs). This result suggests that using interrupted growth may be an alternate method to producing epitaxial layers with low BPD concentration.

scholarly journals Coincident Electron Channeling and Cathodoluminescence Studies of Threading Dislocations in GaN

2013 ◽  
Vol 20 (1) ◽  
pp. 55-60 ◽  
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.

Dislocation Nucleation and Growth in MOCVD GaN/AlN Films on Stepped and Step-free 4H-SiC Mesa Substrates

2008 ◽  
Vol 1090 ◽  
Author(s):  
Mark E. Twigg ◽  
Yoosuf N. Picard ◽  
Nabil D. Bassim ◽  
Joshua D. Caldwell ◽  
Michael A. Mastro ◽  
...  
Keyword(s):  
Dominant Role ◽  
High Stress ◽  
Chemical Vapor ◽  
Misfit Strain ◽  
Nucleation And Growth ◽  
Dislocation Nucleation ◽  
Threading Dislocations ◽  
Surface Steps ◽  
Half Loop ◽  
Edge Dislocations

AbstractUsing transmission electron microscopy, we have analyzed dislocations in AlN nucleation layers and GaN films grown by metallorganic chemical vapor deposition (MOCVD) on the (0001) surface of epitaxially-grown 4H-SiC mesas with and without steps. For 4H-SiC substrates free of SiC surface steps, half-loop nucleation and glide parallel to the AlN/SiC interfacial plane play the dominant role in strain relief, with no mechanism for generating threading dislocations. In contrast, 4H-SiC mesa surfaces with steps give rise to regions of high stress at the heteroepitaxial interface, thereby providing an environment conducive to the nucleation and growth of threading dislocations, which act to accommodate misfit strain by the tilting of threading edge dislocations.

Effects of edge dislocations on thermal transport in UO2

2013 ◽  
Vol 434 (1-3) ◽  
pp. 203-209 ◽  
Author(s):  
B. Deng ◽  
A. Chernatynskiy ◽  
P. Shukla ◽  
S.B. Sinnott ◽  
S.R. Phillpot
Keyword(s):  
Thermal Transport ◽  
Edge Dislocations

Plastic Ploughing of a Sinusoidal Asperity on a Rough Surface

2015 ◽  
Vol 82 (7) ◽  
Author(s):  
H. Song ◽  
R. J. Dikken ◽  
L. Nicola ◽  
E. Van der Giessen
Keyword(s):  
Friction Stress ◽  
Dislocation Dynamics ◽  
Two Dimensional ◽  
Unit Process ◽  
Contact Models ◽  
Self Similar ◽  
Dynamics Simulations ◽  
Micrometer Scale ◽  
Edge Dislocations ◽  
Flat Contact

Part of the friction between two rough surfaces is due to the interlocking between asperities on opposite surfaces. In order for the surfaces to slide relative to each other, these interlocking asperities have to deform plastically. Here, we study the unit process of plastic ploughing of a single micrometer-scale asperity by means of two-dimensional dislocation dynamics simulations. Plastic deformation is described through the generation, motion, and annihilation of edge dislocations inside the asperity as well as in the subsurface. We find that the force required to plough an asperity at different ploughing depths follows a Gaussian distribution. For self-similar asperities, the friction stress is found to increase with the inverse of size. Comparison of the friction stress is made with other two contact models to show that interlocking asperities that are larger than ∼2 μm are easier to shear off plastically than asperities with a flat contact.

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