scholarly journals Quantitative Evaluation of Dislocation Density in Epitaxial GaAs Layer on Si Using Transmission Electron Microscopy

2014 ◽  
Vol 44 (2) ◽  
pp. 74-78 ◽  
Author(s):  
Kangsik Kim ◽  
Jongyoung Lee ◽  
Hyojin Kim ◽  
Zonghoon Lee
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Density ◽  
Quantitative Evaluation ◽  
Gaas Layer ◽  
Epitaxial Gaas ◽  
Transmission Electron

Defect-Engineered Graded GexSi1-x Buffers on Si (001) with Extreme Low Threading Dislocation Density

1995 ◽  
Vol 378 ◽  
Author(s):  
G. Kissinger ◽  
T. Morgenstern ◽  
G. Morgenstern ◽  
H. B. Erzgräber ◽  
H. Richter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Dislocation Density ◽  
Threading Dislocation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Threading Dislocation Density

AbstractStepwise equilibrated graded GexSii-x (x≤0.2) buffers with threading dislocation densities between 102 and 103 cm−2 on the whole area of 4 inch silicon wafers were grown and studied by transmission electron microscopy, defect etching, atomic force microscopy and photoluminescence spectroscopy.

Microstructure Evolution of Hydrogenated Ti6Al4V Alloy during Compression

2012 ◽  
Vol 190-191 ◽  
pp. 517-521
Author(s):  
Bao Guo Yuan ◽  
Qiang Chen ◽  
Hai Ping Yu ◽  
Ping Li ◽  
Ke Min Xue ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Density ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
True Strain ◽  
True Stress ◽  
Compression Tests ◽  
Transmission Electron ◽  
Good Repeatability

Compression tests of the hydrogenated Ti6Al4V0.2H alloy were carried out using an Instron 5569 machine at room temperature. True stress-strain curves of the hydrogenated Ti6Al4V0.2H alloy under different compressive strains were obtained. Microstructure evolution of the hydrogenated Ti6Al4V0.2H alloy during the process of compression was investigated by optical microscopy and transmission electron microscopy. Results show that true stress-true strain curves of Ti6Al4V0.2H alloy have good repeatability. The deformation of grains, the dislocation density and slipping evolution during the process of compression are discussed.

Hacroscopic Defects in Epitaxial Silicon on Simox and in Annealed SIMOX

1987 ◽  
Vol 107 ◽  
Author(s):  
A. Mogro-Campero ◽  
N. Lewis ◽  
S.A. Al-Marayati
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Dislocation Density ◽  
Silicon Surface ◽  
Epitaxial Silicon ◽  
Buried Oxide ◽  
Transmission Electron ◽  
Annealing Step ◽  
Order Of Magnitude

AbstractEpitaxial silicon layers of 5¼m were grown on SIMOX wafers. The dislocation density decreases by more than an order of magnitude as a function of distance away from the buried oxide. Shallow pits (about 0.5 urn deep and several um wide) are observed on the epitaxial layer with a density of 1-2 mm2. Their density did not change with various processing variations. A search for the origin of the pits by transmission electron microscopy reveals that they may be associated with regions of irregularly thin and sometimes missing buried oxide, which appear after the usual high temperature SIMOX annealing step. These defective regions in the buried oxide appear to initiate twinned growth in the epitaxial silicon, and are associated with pits at the top epitaxial silicon surface.

scholarly journals Microstructure and dislocation hardening mechanism of VT8 alloy

2021 ◽  
Vol 99 (3) ◽  
pp. 22-31
Author(s):  
Z.A. Duriagina ◽  
◽  
I.A. Lemishka ◽  
O.S. Filimonov ◽  
A.M. Trostianchyn ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Titanium Alloy ◽  
Dislocation Density ◽  
Internal Stresses ◽  
Structural Components ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Local Internal Stresses ◽  
Scalar Dislocation Density

Specimens of titanium alloy VT8, which is used for the manufacture of gas turbine engine elements, were investigated in the initial state and after fracture toughness testing by methods of transmission electron microscopy and diffraction analysis. The features of the microstructure, structure morphology, the nature of phase distribution and structural components were established. Defects in the crystal structure, the formations of dislocation inhomogeneities and local concentrators of internal stresses were identified using JEM-200CX transmission electron microscope. The scalar dislocation density is determined by the secant method. The study of VT8 titanium alloy samples before and after destruction, which is used for the manufacture of GTE elements, using the methods of transmission electron microscopy and diffraction analysis was made. Microstructural investigations for a detailed analysis of the structure features, morphology and phase formations distribution, as well as their components establishment, the nature of crystal lattice defects, the formation of dislocation inhomogeneities and local concentrators of internal stresses were performed on a JEM-200CX transmission electron microscope. The scalar dislocation density was measured by the secant method. It is shown that the studied samples of VT8 titanium alloy are characterized by a two-phase (α + β) microstructure in the form of large -phase plates, 0.15 ... 0.76 μm in size, interspersed with an insignificant amount of thin-plate β-phase, with a size of 0.04 ... 0.21 μm. Based on scalar dislocation densities, the level of local internal stresses in the places of dislocation accumulations, which are sources of crack formation, was analytically estimated. Dispersed particles of secondary phases characterized by different sizes and different structure morphologies were identified. The calculated dislocation densities and an estimate of the average distance over which they move in the process of deformation are used as the basis for creating a statistical map of localized deformation level indicators in the alloy structural components and on the fracture surface. It is shown that as a result of fracture after testing for low-cycle fatigue, the dislocation density increases, the level of local internal stresses increases, and the formation of a cellular structure in the α- and β-phases and deformation grain-boundary defects occurs. Keywords: VT8 alloy, dislocation structure, microstructure, transmission electron microscopy, local internal stresses.

Cantilever Epitaxy of GaN on Sapphire: Further Reductions in Dislocation Density

2002 ◽  
Vol 743 ◽  
Author(s):  
D. M. Follstaedt ◽  
P. P. Provencio ◽  
D. D. Koleske ◽  
C. C. Mitchell ◽  
A. A. Allerman ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Density ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Processing Conditions ◽  
Optimum Growth ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Threading Dislocation Density

ABSTRACTThe density of vertical threading dislocations at the surface of GaN grown on sapphire by cantilever epitaxy has been reduced with two new approaches. First, narrow mesas (<1 μm wide) were used and {11–22} facets formed over them early in growth to redirect dislocations from vertical to horizontal. Cross-sectional transmission electron microscopy was used to demonstrate this redirection and to identify optimum growth and processing conditions. Second, a GaN nuc-leation layer with delayed 3D → 2D growth transition and inherently lower threading dislocation density was adapted to cantilever epitaxy. Several techniques show that a dislocation density of only 2–3×107/cm2 was achieved by combining these two approaches. We also suggest other developments of cantilever epitaxy for reducing dislocations in heteroepitaxial systems.

Defects in Mbe-Grown GaAs/ScxEr1–xAs/GaAs Layers

1990 ◽  
Vol 198 ◽  
Author(s):  
Jane G. Zhu ◽  
Chris J. Palmstrdøm ◽  
C. Barry Carter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam Epitaxy ◽  
Growth Stage ◽  
Molecular Beam ◽  
Gaas Layer ◽  
Stacking Fault ◽  
Initial Growth ◽  
Gaas Substrates ◽  
Transmission Electron

ABSTRACTThe microstructure and the structure of defects in GaAs/ScxEr1–xAs/GaAs (x=0 and 0.3) heterostructures grown on (100) GaAs substrates by molecular beam epitaxy have been characterized using transmission electron microscopy. The top GaAs layer forms islands on ScxEr1–xAs at the initial growth stage, and the area covered by GaAs varies with the growth temperature. In addition to regions of epitactic (100) GaAs, regions of {122}- and (111)-oriented GaAs are observed on (100)-oriented ScxEr1–xAs. A high density of stacking-fault pyramids is found in epilayers of GaAs grown on a thin epilayer of ErAs, where the ErAs layers are only one or two monolayers thick. The apex of each stacking-fault pyramid is located at the ScxEr1–xAs/GaAs interface.

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