Influence of Surface Relaxation and Multi-Dislocation Strain Field Interactions on X-ray Topographic Images of Dislocations in Semiconductor Materials

1992 ◽  
Vol 262 ◽  
Author(s):  
Jun Wu ◽  
Thomas Fannin ◽  
Michael Dudley ◽  
Vijay Shastry ◽  
Peter Anderson
Keyword(s):  
Local Stress ◽  
Surface Relaxation ◽  
Contour Analysis ◽  
Displacement Fields ◽  
X Ray ◽  
Relaxation Effects ◽  
Slip Bands ◽  
Sensitive Function ◽  
Local Slip ◽  
Surface Intersections

ABSTRACTAnalysis of the white beam synchrotron x-ray topographic contrast behavior of screw dislocations comprising slip bands in silicon, observed under low absorption conditions, is presented. For both individual and groups of dislocations, observed “Direct Image” contrast at the surface intersections of dislocation lines, on reflections for which g·b=0, could be accounted for using equi-misorientation contour analysis using displacement fields which take surface relaxation effects into account. This contrast is shown to be a sensitive function of the local stress environment. In addition, diffuse area contrast observed within and in the vicinity of slip bands on such reflections is also observed to be very sensitive to long range strain fields associated with adjacent slip bands and other defects in the local slip band environment.

Influence of surface relaxation on the contrast of threading edge dislocations in synchrotron X-ray topographs under the condition of g · b = 0 and g · b × l = 0

2021 ◽  
Vol 54 (2) ◽  
Author(s):  
Hongyu Peng ◽  
Tuerxun Ailihumaer ◽  
Fumihiro Fujie ◽  
Zeyu Chen ◽  
Balaji Raghothamachar ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Depth Profiling ◽  
Simulation Method ◽  
Surface Relaxation ◽  
X Ray ◽  
Relaxation Effects ◽  
Orientation Contrast ◽  
Relaxation Depth ◽  
Edge Dislocations ◽  
Ray Tracing Simulation

Residual contrast of threading edge dislocations is observed in synchrotron back-reflection X-ray topographs of 4H-SiC epitaxial wafers recorded using basal plane reflections where both g · b = 0 and g · b × l = 0. The ray-tracing simulation method based on the orientation contrast formation mechanism is applied to simulate images of such dislocations by applying surface relaxation effects. The simulated contrast features match the observed features on X-ray topographs, clearly demonstrating that the contrast is dominated by surface relaxation. Depth profiling indicates that the surface relaxation primarily takes place within a depth of 5 µm below the surface.

Determination of Strain Distributions in Aluminum Thin Films as a Function of Temperature by the use of Synchrotron Grazing Incidence X-Ray Scattering

1991 ◽  
Vol 239 ◽  
Author(s):  
Ramnath Venkatraman ◽  
Paul R. Besser ◽  
Sean Brennan ◽  
John C. Bravman
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Grazing Incidence ◽  
Surface Relaxation ◽  
Line Broadening ◽  
X Ray ◽  
Relaxation Effects ◽  
X Ray Scattering ◽  
Ray Scattering

ABSTRACTWe have measured elastic strain distributions with depth as a function of temperature in Al thin films of various thicknesses on oxidized silicon using synchrotron grazing incidence X-ray scattering (GIXS). Disregarding minor surface relaxation effects that depend on the film thickness, it is shown that there are no gross strain gradients in these films in the range of temperatures (between room temperature and 400°C) considered. We also observe X-ray line broadening effects, suggesting an accumulation of dislocations on cooling the films, and their annealing out as the films are reheated.

Influence of Surface Relaxation on X-Ray Topographic Imaging of Interfacial Dislocations in Heterosystems.

1990 ◽  
Vol 209 ◽  
Author(s):  
Gong-Da Yao ◽  
Jun Wu ◽  
Michael Dudley ◽  
Vijay Shastry ◽  
Peter Anderson
Keyword(s):  
Surface Relaxation ◽  
X Ray ◽  
Relaxation Effects ◽  
Single Crystal Films ◽  
Crystal Films ◽  
Interfacial Dislocations ◽  
Depth Sensitivity ◽  
Edge Dislocations ◽  
Topographic Imaging ◽  
Laue Geometry

ABSTRACTThe influence of surface relaxation on the imaging of dislocations in thin single crystal films, using white beam synchrotron radiation topography in grazing Bragg-Laue geometry, has been assessed. The predicted visibility of dislocation images on grazing Bragg- Laue topographs, for the particular case of interfacial edge dislocations in a GaAs/Si heterostructure, is shown to be strongly influenced. Agreement between predicted and observed visibility could only be obtained by incorporating the surface relaxation effects, which thus strongly influence the depth sensitivity of the technique, i.e. the ability to pinpoint the depth of a dislocation. Dislocation image widths are also influenced by these effects.

Role of water in the surface relaxation of the fluorapatite (100) surface by grazing incidence x-ray diffraction

2007 ◽  
Vol 75 (3) ◽  
Author(s):  
Aparna Pareek ◽  
Xavier Torrelles ◽  
Jordi Rius ◽  
Uta Magdans ◽  
Hermann Gies
Keyword(s):  
Grazing Incidence ◽  
Surface Relaxation ◽  
X Ray Diffraction ◽  
X Ray

Surface relaxation effects on the properties of porous silicon

2002 ◽  
Vol 91 (5) ◽  
pp. 3085-3089 ◽  
Author(s):  
E. Vázquez ◽  
J. Tagüeña-Martı́nez ◽  
L. E. Sansores ◽  
C. Wang
Keyword(s):  
Porous Silicon ◽  
Surface Relaxation ◽  
Relaxation Effects

scholarly journals Investigation by Digital Image Correlation of Mixed Mode I and II Fracture Behavior of Metallic IASCB Specimens with Additive Manufactured Crack-Like Notch

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 400 ◽  
Author(s):  
Ivo Campione ◽  
Tommaso Maria Brugo ◽  
Giangiacomo Minak ◽  
Jelena Janković Tomić ◽  
Nebojša Bogojević ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Mixed Mode ◽  
Fracture Behavior ◽  
Selective Laser Sintering ◽  
Local Stress ◽  
Fatigue Loading ◽  
Image Correlation ◽  
Mode I ◽  
Displacement Fields

This work investigates the fracture behavior of maraging steel specimens manufactured by the selective laser sintering (SLS) technology, in which a crack-like notch (sharp notch) was directly produced during the additive manufacturing (AM) process. For the evaluation of the fracture toughness, the inclined asymmetrical semi-circular specimen subjected to three points loading (IASCB) was used, allowing to cover a wide variety of Mode I and II combinations. The effectiveness of manufacturing crack-like notches via the SLS technique in metals was evaluated by comparing the obtained experimental results with the ones obtained with pre-cracks induced by fatigue loading. The investigation was carried out by using the digital image correlation (DIC) technique, that allowed the evaluation of the full displacement fields around the crack tip. The displacement field was then used to compute the stress intensity factors (SIFs) for various combinations of Mode I and II, via a fitting technique which relies on the Williams’ model for the displacement. The SIFs obtained in this way were compared to the results obtained with the conventional critical load method. The results showed that the discrepancy between the two methods reduces by ranging from Mode I to Mode II loading condition. Finally, the experimental SIFs obtained by the two methods were described by the mixed mode local stress criterium.

Structure refinement and crystal chemistry of tokkoite and tinaksite from the Murun massif (Russia)

2017 ◽  
Vol 81 (2) ◽  
pp. 251-272 ◽  
Author(s):  
M. Lacalamita ◽  
E. Mesto ◽  
E. Kaneva ◽  
F. Scordari ◽  
G. Pedrazzi ◽  
...  
Keyword(s):  
Exchange Reaction ◽  
Diffraction Data ◽  
Structure Refinement ◽  
Local Stress ◽  
Geometrical Parameters ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
Lattice Constants ◽  
Mössbauer Analysis

AbstractThe structures of tokkoite, K2Ca4[Si7O18OH](OH,F) and tinaksite, K2Ca2NaTi[Si7O18OH]O from the Murun massif (Russia) were refined from single-crystal X-ray diffraction data in the triclinic space group P1̄. Average crystallographic data are a ≈ 10.423, b ≈ 12.477, c ≈ 7.112 Å, α ≈ 89.92°, β ≈ 99.68°, γ ≈ 92.97°, V ≈ 910.5 Å3 for tokkoite; a ≈ 10.373, b ≈ 12.176, c ≈ 7.057 Å, α ≈ 90.82°, β ≈ 99.22°, γ ≈ 92.80°, V ≈ 878.5 Å3 for tinaksite. The substantial similarities between the geometrical parameters of the tokkoite and tinaksite structures led us to conclude that the two minerals are isostructural. However, major differences of tokkoite with respect to tinaksite are larger lattice constants, especially concerning the b parameter, longer <M–O> distances, especially <M1–O>; larger values of the M1–M3 and O20–O2 bond lengths, and a stronger distortion of the M1 polyhedron. Mössbauer analysis showed that significant trivalent iron is present, VIFe3+ 40.0(7)% in tokkoite and 12.8(3)% in tinaksite. It is confirmed that 2Ca(M1+M2)2+ + (F,OH)(O20)–↔ Ti(M1)4+ + Na(M2)+ + O(O20)– is the exchange reaction that describes the relation between tokkoite and tinaksite. In addition, this exchange reaction causes local stress involving mainly the M1 site and its interaction with the M2 and M3 sites.

Comparison between Pile-Up Singularities and Stress Fields Induced by Thin Slip Bands. Application to the Prediction of Grain Boundary Microcrack Nucleation

2013 ◽  
Vol 592-593 ◽  
pp. 61-66
Author(s):  
Maxime Sauzay ◽  
Mohamed Ould Moussa
Keyword(s):  
Slip Band ◽  
Tensile Deformation ◽  
Finite Thickness ◽  
Local Stress ◽  
Stress Fields ◽  
Stress Concentrations ◽  
Griffith Criterion ◽  
Slip Bands ◽  
Pile Up ◽  
Microcrack Initiation

Slip localization is widely observed in metallic polycrystals after tensile deformation, cyclic deformation or pre-irradiation followed by tensile deformation. Such strong deformation localized in thin slip bands induces local stress concentrations in the quasi-elastic matrix around, at the intersections between slip bands (SBs) and grain boundaries (GBs) where microcrack initiation is often observed. Since the work of Stroh, such stress fields have been mostly modeled using the dislocation pile-up theory which leads to stress singularities similar to the LEFM ones. The Griffith criterion has then been widely applied, leading usually to strong underestimations of the macroscopic stress to GB crack initiation. In fact, slip band thickness is finite: 20nm-1000nm depending on material, temperature and loading conditions. Then, many slip planes are plastically activated through the thickness, and not only one single atomic plane. To evaluate more realistic stress fields, numerous crystalline finite element (FE) computations have been carried out using microstructure inputs (slip band aspect ratio, crystal and GB orientation...). A strong influence of slip band thickness close to the slip band corner has been highlighted, which is not accounted for by the pile-up theory. But far away, the thickness has a negligible effect and the predicted stress fields are close to the one predicted by the pile-up theory. Closed-form expressions are deduced from the numerous FE computation results allowing a straightforward prediction of GB stress fields. Slip band plasticity parameters, such as length and thickness, as well as crystal orientation, GB plane and remote stress are taken into account. The dependence with respect to the various parameters can be understood in the framework of matching expansions usually applied to cracks with V notches of finite thickness. As the exponent of the GB stress close-field is only about one-half of the pile-up or LEFM crack one, the Griffith criterion may not be used for GB microcrack prediction in case of finite thickness. That is why finite crack fracture mechanics is used together with both energy and stress criteria. Taking into account SB finite thickness, t>0, leads to predicted remote stresses to GB microcrack initiation three to six times lower than the ones predicted using the to pile-up theory, in agreement with experimental data.

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