scholarly journals Bright mid-infrared photoluminescence from high dislocation density epitaxial PbSe films on GaAs

APL Materials ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 111112
Author(s):  
Jarod Meyer ◽  
Aaron J. Muhowski ◽  
Leland Nordin ◽  
Eamonn Hughes ◽  
Brian Haidet ◽  
...  
Keyword(s):  
Dislocation Density ◽  
High Dislocation Density ◽  
Mid Infrared

Observations of dislocation interactions with recrystallized grain boundaries

1988 ◽  
Vol 46 ◽  
pp. 628-629
Author(s):  
C. W. Price
Keyword(s):  
Dislocation Density ◽  
Grain Boundary ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Dislocation Structure ◽  
Hot Deformation ◽  
Static Recrystallization ◽  
High Dislocation Density ◽  
High Angle ◽  
Dislocation Interactions

Little evidence exists on the interaction of individual dislocations with recrystallized grain boundaries, primarily because of the severely overlapping contrast of the high dislocation density usually present during recrystallization. Interesting evidence of such interaction, Fig. 1, was discovered during examination of some old work on the hot deformation of Al-4.64 Cu. The specimen was deformed in a programmable thermomechanical instrument at 527 C and a strain rate of 25 cm/cm/s to a strain of 0.7. Static recrystallization occurred during a post anneal of 23 s also at 527 C. The figure shows evidence of dissociation of a subboundary at an intersection with a recrystallized high-angle grain boundary. At least one set of dislocations appears to be out of contrast in Fig. 1, and a grainboundary precipitate also is visible. Unfortunately, only subgrain sizes were of interest at the time the micrograph was recorded, and no attempt was made to analyze the dislocation structure.

Anisotropic Lattice Relaxation and its Mechanism of ZnSe Epilayer Grown on (001) GaAs Substrate by Molecular Beam Epitaxy

1995 ◽  
Vol 399 ◽  
Author(s):  
C.S. Kim ◽  
S.K. Noh ◽  
H.J. Lee ◽  
Y.K. Cho ◽  
Y.I. Kim ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Gaas Substrate ◽  
Molecular Beam ◽  
Rotation Angle ◽  
Lattice Relaxation ◽  
High Dislocation Density ◽  
Sinusoidal Oscillation ◽  
Double Crystal ◽  
X Ray ◽  
Anisotropic Lattice

ABSTRACTWe have investigated anisotropic lattice relaxation and its mechanism of ZnSe epitaxial layer grown on (001) GaAs substrate by MBE. Double-crystal X-ray rocking curves for (004), {115} and {404} reflections were measured as a function of the azimuthal rotation angle of the sample. We observed the sinusoidal oscillation of the FWHM of the epilayer peak for (004) reflections due to the asymmetric dislocation density along two orthogonal <110> directions, and the direction of the maximum FWHM corresponding to high dislocation density is along [110]. In addition, the strain along [110] is smaller than that along [1-10], indicating that the layer suffered anisotropic lattice relaxation. The direction of larger relaxation([l-10]) is not consistent with that of high dislocation density([110]). The results suggest that the asymmetry in dislocation density is not responsible for the anisotropic relaxation of the ZnSe epilayer.

High dislocation density–induced large ductility in deformed and partitioned steels

Science ◽  
2017 ◽  
Vol 357 (6355) ◽  
pp. 1029-1032 ◽  
Author(s):  
B. B. He ◽  
B. Hu ◽  
H. W. Yen ◽  
G. J. Cheng ◽  
Z. K. Wang ◽  
...  
Keyword(s):  
Dislocation Density ◽  
High Dislocation Density

Strong and ductile steel via high dislocation density and heterogeneous nano/ultrafine grains

2019 ◽  
Vol 759 ◽  
pp. 1-10 ◽  
Author(s):  
Gang Niu ◽  
Qibo Tang ◽  
Hatem S. Zurob ◽  
Huibin Wu ◽  
Lixiong Xu ◽  
...  
Keyword(s):  
Dislocation Density ◽  
High Dislocation Density ◽  
Ultrafine Grains ◽  
Ductile Steel

Unusual Plastic Deformation Behavior in Lath Martensitic Steel Containing High Dislocation Density

2017 ◽  
Vol 905 ◽  
pp. 46-51
Author(s):  
Stefanus Harjo ◽  
Takuro Kawasaki ◽  
Yo Tomota ◽  
Wu Gong
Keyword(s):  
Plastic Deformation ◽  
Dislocation Density ◽  
Deformation Behavior ◽  
Tensile Deformation ◽  
Lath Martensite ◽  
Strengthening Mechanism ◽  
High Dislocation Density ◽  
Random Arrangement ◽  
Plastic Deformation Behavior ◽  
In Situ Neutron Diffraction

To understand the strengthening mechanism of a metallic material with high dislocation density, the plastic deformation behavior of lath martensite was studied by means of in situ neutron diffraction measurements during tensile deformations using a 22SiMn2TiB steel and a Fe-18Ni alloy. The characteristics of dislocation were analyzed and were discussed with the relation of stress-strain curves. The dislocation densities (ρ) induced by martensitic transformation during heat-treatment in both materials were found to be originally as high as 1015 m-2 order, and subsequently to increase slightly by the tensile deformation. The parameter M value which displays the dislocation arrangement dropped drastically at the beginning of plastic deformation in both materials, indicating that the random arrangement became more like a dipole arrangement.

scholarly journals Improvement of GaN crystalline quality by SiNx layer grown by MOVPE

2020 ◽  
Vol 59 (4) ◽  
Author(s):  
Alice Hospodková ◽  
Markéta Slavická Zíková ◽  
Tomáš Hubáček ◽  
Jiří Pangrác ◽  
Karla Kuldová ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Probable Mechanism ◽  
The Other ◽  
High Dislocation Density ◽  
Nonradiative Recombination ◽  
Reduction Mechanism ◽  
Lateral Overgrowth ◽  
Dislocation Reduction ◽  
Original Dislocation ◽  
Sinx Layer

In this work the mechanism which helps to reduce the dislocation density by deposition of a SiNx interlayer is discussed. It is shown that the dislocation reduction by SiNx interlayer deposition is influenced by dislocation density in the underlying GaN layers. The SiNx interlayer is very effective when the original dislocation density is high, while in the case of lower dislocation density the deposition of SiNx is not effective for crystal quality improvement. Although it is widely accepted that SiNx serves as a barrier for dislocation propagation, similarly to the enhanced lateral overgrowth method, it is shown that after masking the SiNx deposition cannot be the dominant dislocation reduction mechanism. The most probable mechanism is the annihilation of bended neighbouring dislocations during the coalescence of 3D islands. The SiNx layer cannot serve as a barrier for dislocations, since it is probably dissolved during the following GaN growth and dissolved Si atoms are incorporated into the above-grown GaN layer which stimulates the 3D island formation. Then the use of the SiNx interlayer for dislocation reduction is recommended only for the improvement of layers with a high dislocation density. On the other hand, the PL signal was strongly enhanced for both low and high dislocation density structures with the SiNx interlayer, suggesting that the interlayer might help to suppress the nonradiative recombination in subsequent GaN that is not related to the dislocation density, which remained the same. But its origin has to be studied further.

Extremely high dislocation density and deformation pathway of CrMnFeCoNi high entropy alloy at ultralow temperature

2020 ◽  
Vol 188 ◽  
pp. 21-25 ◽  
Author(s):  
Muhammad Naeem ◽  
Haiyan He ◽  
Stefanus Harjo ◽  
Takuro Kawasaki ◽  
Fan Zhang ◽  
...  
Keyword(s):  
Dislocation Density ◽  
High Dislocation Density ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Ultralow Temperature
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