Observation of carrier recombination in single Shockley stacking faults and at partial dislocations in 4H-SiC

2018 ◽  
Vol 124 (9) ◽  
pp. 095702 ◽  
Author(s):  
Masashi Kato ◽  
Shinya Katahira ◽  
Yoshihito Ichikawa ◽  
Shunta Harada ◽  
Tsunenobu Kimoto
Keyword(s):  
Stacking Faults ◽  
Partial Dislocations ◽  
Carrier Recombination

Structure of stacking faults in pyrite using TEM techniques

1992 ◽  
Vol 50 (1) ◽  
pp. 358-359
Author(s):  
Raja Subramanian ◽  
Kenneth S. Vecchio
Keyword(s):  
Lattice Structure ◽  
Stacking Faults ◽  
Covalent Bond ◽  
Group Symmetry ◽  
Iron Pyrite ◽  
Dislocation Glide ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
Contrast Analysis ◽  
Chlorine Ions

The structure of stacking faults and partial dislocations in iron pyrite (FeS2) have been studied using transmission electron microscopy. Pyrite has the NaCl structure in which the sodium ions are replaced by iron and chlorine ions by covalently-bonded pairs of sulfur ions. These sulfur pairs are oriented along the <111> direction. This covalent bond between sulfur atoms is the strongest bond in pyrite with Pa3 space group symmetry. These sulfur pairs are believed to move as a whole during dislocation glide. The lattice structure across these stacking faults is of interest as the presence of these stacking faults has been preliminarily linked to a higher sulfur reactivity in pyrite. Conventional TEM contrast analysis and high resolution lattice imaging of the faulted area in the TEM specimen has been carried out.

Characterization of Defect Structures in 3C-SiC Single Crystals Using Synchrotron White Beam X-ray Topography

1996 ◽  
Vol 423 ◽  
Author(s):  
W. Huang ◽  
M. Dudley ◽  
C. Fazi
Keyword(s):  
Single Crystals ◽  
Stacking Faults ◽  
Interference Microscopy ◽  
Defect Structures ◽  
Growth Sector ◽  
X Ray ◽  
Partial Dislocations ◽  
White Beam ◽  
Transmission And Reflection

AbstractDefect structures in (111) 3C-SiC single crystals, grown using the Baikov technique, have been studied using Synchrotron White Beam X-ray Topography (SWBXT). The major types of defects include complex growth sector boundary structures, double positioning twins, stacking faults on { 111 } planes, inclusions and dislocations (including growth dislocations and partial dislocations bounding stacking faults). Detailed stacking fault and double positioning twin configurations are determined using a combination of Nomarski interference microscopy, SEM and white beam x-ray topography in both transmission and reflection geometries. Possible defect generation phenomena are discussed.

Dislocations and stacking faults in stainless steel

1957 ◽  
Vol 240 (1223) ◽  
pp. 524-538 ◽  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stainless Steel ◽  
Grain Boundaries ◽  
Stacking Faults ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Thin Sections ◽  
Partial Dislocations ◽  
Transmission Electron

Further experiments by transmission electron microscopy on thin sections of stainless steel deformed by small amounts have enabled extended dislocations to be observed directly. The arrangement and motion of whole and partial dislocations have been followed in detail. Many of the dislocations are found to have piled up against grain boundaries. Other observations include the formation of wide stacking faults, the interaction of dislocations with twin boundaries, and the formation of dislocations at thin edges of the foils. An estimate is made of the stacking-fault energy from a consideration of the stresses present, and the properties of the dislocations are found to be in agreement with those expected from a metal of low stacking-fault energy.

scholarly journals Dissociation Behavior of Dislocations in Ice

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 386
Author(s):  
Takeo Hondoh
Keyword(s):  
Basal Plane ◽  
Dislocation Line ◽  
Stacking Faults ◽  
Physical Models ◽  
Time Constants ◽  
Burgers Vector ◽  
Partial Dislocations ◽  
Perfect Dislocation ◽  
Low Energies ◽  
Dissociated State

Dislocations in ice behave very differently from those in other materials due to the very low energies of stacking faults in the ice basal plane. As a result, the dislocations dissociate on the basal plane, from a perfect dislocation into two partial dislocations with equilibrium width we ranging from 20 to 500 nm, but what is the timescale to reach this dissociated state? Using physical models, we estimate this timescale by calculating two time-constants: the dissociation-completing time td and the dissociation-beginning time tb. These time constants are calculated for two Burgers vectors as a function of temperature. For perfect dislocations with Burgers vector <c + a>, td is more than one month even at the melting temperature TM, and it exceeds 103 years below −50 ℃, meaning that the dissociation cannot be completed during deformation over laboratory timescales. However, in this case the beginning time tb is less than one second at TM, and it is within several tens of minutes above −50 ℃. These dislocations can glide on non-basal planes until they turn to the dissociated state during deformation, finally resulting in sessile extended dislocations of various widths approaching to the equilibrium value we. In contrast, for perfect dislocations with Burgers vector <a>, td is less than one second above −50 ℃, resulting in glissile extended dislocations with the equilibrium width we on the basal plane. This width is sensitive to the shear stress τ exerted normal to the dislocation line, leading to extension of the intervening stacking fault across the entire crystal grain under commonly accessible stresses. Also, due to the widely dissociated state, dislocations <a> cannot cross-slip to non-basal planes. Such behavior of extended dislocations in ice are notable when compared to those of other materials.

The mechanisms of plastic deformation of rapidly solidified Al3Ti and Al67Ni8Ti25 intermetallic compounds.

1988 ◽  
Vol 133 ◽  
Author(s):  
Vijay K. Vasudevan ◽  
Robert Wheeler ◽  
Hamish L. Fraser
Keyword(s):  
Room Temperature ◽  
Considerable Increase ◽  
Stacking Faults ◽  
Temperature Deformation ◽  
Deformation Microstructure ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
The Mean ◽  
Rapidly Solidified ◽  
Mechanisms Of Plastic Deformation

ABSTRACTThe dislocation structures in rapidly solidified Al3Ti with the DO22 structure and the ternary Al-25Ti-8Ni (at.%) alloy with the L12 structure deformed in compression in the temperature range of 25 to 800°C have been studied by transmission electron microscopy. The room temperature deformation microstructure of the Al3Ti compound is characterized by the presence of stacking faults/order twins on {111} planes bounded by partial dislocations with Burgers vector b=1/6<112], as reported by others. At intermediate temperatures, besides the stacking faults, slip is also observed as bands on the {001] plane delineated by dislocations with b=1/2<110] which bound APB's. At 600°C, the reported increase in ductility is associated here with additional slip on the {001)<110], {001)[100] and {001)[010] systems. Dislocations with b=<110] exist as pairs of partial dislocations with b=1/2<110] connected by APB's. The mean separation between the partials was measured to be 30 nm, corresponding to an APB energy of ≍32 mJ.m-2 on the (001) plane. Observations also indicate that the APB energy is anisotropic, i.e., is considerably higher on the {111} planes compared to the {001) plane. The deformation microstructure of the Al-25Ti-8Ni L12 alloy is characterized by slip of dislocations with b=<110> gliding on {111} planes, a major fraction of which exist as dipoles. Following deformation at 300°C, there is essentially no evidence of dissociation of these dislocations, although some dissociated dislocations on (001) having b=l/2<110> are also observed. With an increase in temperature, there is a considerable increase in dislocation activity and strong evidence for 1/2<110> dissociated dislocations is present.

Stacking Faults and 3C Quantum Wells in Hexagonal SiC Polytypes

2006 ◽  
Vol 527-529 ◽  
pp. 351-354 ◽  
Author(s):  
M.S. Miao ◽  
Walter R.L. Lambrecht
Keyword(s):  
Band Structure ◽  
Quantum Wells ◽  
First Principles ◽  
Driving Force ◽  
Stacking Faults ◽  
Band Gaps ◽  
Partial Dislocations ◽  
Band Structure Calculations ◽  
Thermodynamic Driving Force ◽  
Structure Calculations

The electronic driving force for growth of stacking faults (SF) in n-type 4H SiC under annealing and in operating devices is discussed. This involves two separate aspects: an overall thermodynamic driving force due to the capture of electrons in interface states and the barriers that need to be overcome to create dislocation kinks which advance the motion of partial dislocations and hence expansion of SF. The second problem studied in this paper is whether 3C SiC quantum wells in 4H SiC can have band gaps lower than 3C SiC. First-principles band structure calculations show that this is not the case due to the intrinsic screening of the spontaneous polarization fields.

Tailoring Microstructures Under Strong Non-Equilibrium Conditions: A Feasible Path Towards High JC in Melt Textured YBa2Cu3O7

2000 ◽  
Vol 659 ◽  
Author(s):  
Felip Sandiumenge ◽  
Jérôme Plain ◽  
Teresa Puig ◽  
Xavier Obradors ◽  
Jacques Rabier ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Partial Dislocation ◽  
Enhancement Factor ◽  
Stacking Faults ◽  
Equilibrium Conditions ◽  
Pinning Centers ◽  
Partial Dislocations ◽  
High Oxygen Pressure ◽  
Density Analysis ◽  
Feasible Path

ABSTRACTMelt textured YBa2Cu3O/Y2BaCuO5 were post processed by high oxygen pressure for different periods and temperatures. This process permits the control of the microstructure, in particular the growth and shape of the stacking faults and thereby the partial dislocation density. Analysis of the Jc(H,T) behavior allow to separate the contribution of Y2BaCuO5 interface from that of dislocations. It is shown that the in-plane partial dislocations act as point-like pinning centers increasing Jc up to 180% but this enhancement factor is counterbalanced by the effect of the stacking faults associated to the partial dislocations.

scholarly journals Structural and electrical studies of partial dislocations and stacking faults in (11-20)-oriented 4H-SiC

2005 ◽  
Vol 2 (6) ◽  
pp. 1763-1763
Author(s):  
L. Ottaviani ◽  
H. Idrissi ◽  
P. Hidalgo ◽  
M. Lancin ◽  
B. Pichaud
Keyword(s):  
Stacking Faults ◽  
Electrical Studies ◽  
Partial Dislocations

The stacking faults and partial dislocations involved in structure transformations of ZnS crystals

1973 ◽  
Vol 27 (1) ◽  
pp. 159-175 ◽  
Author(s):  
I. T. Steinberger ◽  
I. Kiflawi ◽  
Z. H. Kalman ◽  
S. Mardix
Keyword(s):  
Stacking Faults ◽  
Partial Dislocations

Threading Dislocation Density Reduction in GaN/Sapphire Heterostructures.

1999 ◽  
Vol 595 ◽  
Author(s):  
A. Kvit ◽  
A. K. Sharma ◽  
J. Narayan
Keyword(s):  
Basal Plane ◽  
Stacking Faults ◽  
High Density ◽  
Thin Layers ◽  
Interfacial Region ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Plan View ◽  
Partial Dislocations

AbstractLarge lattice mismatch between GaN and α-Al2O3 (15%) leads to the possibility of high threading dislocation densities in the nitride layers grown on sapphire. This investigation focused on defect reduction in GaN epitaxial thin layer was investigated as a function of processing variables. The microstructure changes from threading dislocations normal to the basal plane to stacking faults in the basal plane. The plan-view TEM and the corresponding selected-area diffraction patterns show that the film is single crystal and is aligned with a fixed epitaxial orientation to the substrate. The epitaxial relationship was found to be (0001)GaN∥(0001)Sap and [01-10]GaN∥[-12-10]Sap. This is equivalent to a 30° rotation in the basal (0001) plane. The film is found to contain a high density of stacking faults with average spacing 15 nm terminated by partial dislocations. The density of partial dislocations was estimated from plan-view TEM image to be 7×109 cm−2. The cross-section image of GaN film shows the density of stacking faults is highest in the vicinity of the interface and decreases markedly near the top of the layer. Inverted domain boundaries, which are almost perpendicular to the film surface, are also visible. The concentration of threading dislocation is relatively low (∼;2×108 cm−2), compared to misfit dislocations. The average distance between misfit dislocations was found to be 22 Å. Contrast modulations due to the strain near misfit dislocations are seen in high-resolution cross-sectional TCM micrograph of GaN/α-Al2O3 interface. This interface is sharp and does not contain any transitional layer. The interfacial region has a high density of Shockley and Frank partial dislocations. Mechanism of accommodation of tensile, sequence and tilt disorder through partial dislocation generation is discussed. In order to achieve low concentration of threading dislocations we need to establish favorable conditions for some stacking disorder in thin layers above the film-substrate interface region.

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