X-ray characterisation of the basal stacking fault densities of (11-22) GaN

CrystEngComm ◽  
2021 ◽  
Author(s):  
Markus Pristovsek ◽  
Martin Fentrup ◽  
Tongtong Zhu ◽  
Gunnar Kusch ◽  
Colin Humphreys
Keyword(s):  
Basal Plane ◽  
Stacking Faults ◽  
Stacking Fault ◽  
X Ray Diffraction ◽  
X Ray

Basal plane stacking faults (BSF) in GaN (11-22) layers were observed by a laboratory X-ray diffraction (XRD) system. For this, the (11-22) GaN was oriented in the [-12-10] zone for...

X-ray diffraction characterization of the microstructure of close-packed hexagonal nanomaterials

2008 ◽  
Vol 23 (3) ◽  
pp. 213-223 ◽  
Author(s):  
Zhao-hui Pu ◽  
Chuan-zheng Yang ◽  
Pei Qin ◽  
Yu-wan Lou ◽  
Li-fang Cheng
Keyword(s):  
Stacking Faults ◽  
Triple Line ◽  
Stacking Fault ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Nano Zno ◽  
X Ray ◽  
Crystallite Sizes ◽  
Small Crystallite ◽  
Charge Discharge

A general least-squares technique for X-ray diffraction line broadening analysis has been developed. The technique can be used to determine single, double, and triple line broadening effects caused by small particle sizes, microstrain, stacking faults, or all three presented in a closed-packed hexagonal nanomaterial. The technique was applied to characterize the microstructure of β-Ni(OH)2, a negative electrode material in nickel-metal hydride (NiMH) batteries. Double line broadening effects caused by both small crystallite sizes and stacking faults in β-Ni(OH)2 were detected and analyzed. Triple line broadening effects caused simultaneously by small crystallite sizes, microstrain, and stacking faults were detected in β-Ni(OH)2 after activation and charge-discharge cycle tests. The triple line broadening effects were found to be selective and most pronounced for diffraction lines with h−k=3n±1. The broadening effects were larger when l=even, but smaller when l=odd. The shape and the average size of the crystallites, microstrain, and stacking fault probability in β-Ni(OH)2 changed dramatically after activation and charge-discharge cycles. The method was also applied to characterize and investigate the microstructure of nano ZnO materials. Results indicate that no selective broadening appears in the XRD patterns of the nano ZnO materials. The average crystallite sizes were different slightly, and the stacking fault probabilities differed significantly with different dopants.

Stacking Fault Analysis of Epitaxial 3C-SiC on Si(001) Ridges

2016 ◽  
Vol 858 ◽  
pp. 147-150 ◽  
Author(s):  
Mojmír Meduňa ◽  
Thomas Kreiliger ◽  
Ivan Prieto ◽  
Marco Mauceri ◽  
Marco Puglisi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Backscatter Diffraction ◽  
Stacking Faults ◽  
Stacking Fault ◽  
Fault Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Backscatter ◽  
Backscatter Diffraction

The stacking faults (SFs) in 3C-SiC epitaxially grown on ridges deeply etched into Si (001) substrates offcut towards [110] were quantitatively analyzed by electron microscopy and X-ray diffraction. A significant reduction of SF density with respect to planar material was observed for the {111} planes parallel to the ridges. The highest SF density was found in the (-1-11) plane. A previously observed defect was identified as twins by electron backscatter diffraction.

Direct Observation of Stacking Fault Nucleation from Deflected Threading Dislocations with Burgers Vector c+a in PVT Grown 4H-SiC

2014 ◽  
Vol 1693 ◽  
Author(s):  
Fangzhen Wu ◽  
Huanhuan Wang ◽  
Balaji Raghothamachar ◽  
Michael Dudley ◽  
Stephan G. Mueller ◽  
...  
Keyword(s):  
Direct Observation ◽  
Basal Plane ◽  
Stacking Faults ◽  
Stacking Fault ◽  
Formation Mechanisms ◽  
Threading Dislocations ◽  
Burgers Vector ◽  
X Ray ◽  
Transmission Geometry ◽  
Made In

ABSTRACTIn our previous studies [1-3], four kinds of stacking faults in 4H-SiC bulk crystal have been distinguished based on their contrast behavior differences in synchrotron white beam x-ray topography images. These faults are Shockley faults, Frank faults, Shockley plus c/2 Frank faults, and Shockley plus c/4 Frank faults. Our proposed formation mechanisms for these stacking faults involve the overgrowth of the surface outcrop associated with threading screw dislocations (TSDs) or threading mixed dislocations (TMDs) with Burgers vector of c+a by macrosteps and the consequent deflection of TSDs or TMDs onto the basal plane. Previous synchrotron x-ray topography observations were made in offcut basal wafers using transmission geometry. In this paper, further evidence is reported to confirm the proposed stacking fault formation mechanism. Observations are made in axially cut slices with surface plane {11-20}. Several kinds of stacking faults are recognized and their contrast behavior agrees with the four kinds previously reported. Direct observation is obtained of a Shockley plus c/4 Frank stacking fault nucleating from a TMD deflected onto the basal plane. The contrast from stacking faults on the basal plane in the axial slices is enhanced by recording images after rotating the crystal about the active -1010 reflection vector enabling a broader projection of the basal plane.

Diffraction analysis of perovskite-like oxides containing irregular intergrowths

2008 ◽  
Vol 42 (1) ◽  
pp. 1-9 ◽  
Author(s):  
L. Olikhovska ◽  
A. Ustinov
Keyword(s):  
Stacking Faults ◽  
Lattice Parameter ◽  
Stacking Fault ◽  
Layered Perovskite ◽  
Structural Fragment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fault Properties ◽  
Diffraction Peaks ◽  
Position Profile

Features of the X-ray intensity distributions caused by the presence of random and nonrandom stacking faults (irregular intergrowths) in layered perovskite-like oxides are studied by a computer simulation technique. It is shown that, apart from the stacking fault properties, the position, profile and intensity of a diffraction peak are dependent on the ratio between theclattice parameter of the crystal and the thickness of the new structural fragment formed as a result of the stacking fault. A means of characterizing the stacking faults on the basis of the relative positions of pairs of diffraction peaks is presented. The approach is exemplified by the X-ray diffraction study of a disordered single crystal of the system Bi–Sr–Ca–Cu–O.

scholarly journals Effect of multiple laser shock processing on nano-scale microstructure of an aluminum alloy

2018 ◽  
Author(s):  
Simge GencalpIrizalp ◽  
Nursen Saklakoglu
Keyword(s):  
Stacking Faults ◽  
Stacking Fault ◽  
Structural Defects ◽  
Laser Shock ◽  
X Ray Diffraction ◽  
Laser Shock Processing ◽  
Alloy Plate ◽  
X Ray ◽  
Nano Scale ◽  
Shock Processing

In this study, nano-scale microstructural evolution in 6061-T6 alloy after laser shock processing (LSP) were studied. 6061-T6 alloy plate were subjected to multiple LSP. The LSP treated area was characterized by X-ray diffraction and the microstructure of the samples was analyzed by transmission electron microscopy. Focused Ion Beam (FIB) tools were used to prepare TEM samples in precise areas. It was found that even though aluminum had high stacking fault energy, LSP yielded to formation of ultrafine grains and deformation faults such as dislocation cells, stacking faults. The stacking fault probability (PSF) was obtained in LSP-treated alloy using X-Ray diffraction. Deformation induced stacking faults lead to the peak position shifts, broadening and asymmetry of diffraction. XRD analysis and TEM observations revealed significant densities of stacking faults in LSP-treated 6061-T6 alloy. And mechanical properties of LSP-treated alloy were also determined to understand the hardening behavior with high concentration of structural defects.

Stacking fault model of ∊-martensite and itsDIFFaXimplementation

2011 ◽  
Vol 44 (4) ◽  
pp. 779-787 ◽  
Author(s):  
Stefan Martin ◽  
Christiane Ullrich ◽  
Daniel Šimek ◽  
Ulrich Martin ◽  
David Rafaja
Keyword(s):  
Electron Microscopy ◽  
Electron Backscatter Diffraction ◽  
Stacking Faults ◽  
Stacking Fault ◽  
X Ray Diffraction ◽  
Contrast Imaging ◽  
X Ray ◽  
Austenitic Transformation ◽  
Electron Channelling ◽  
Diffraction Patterns

Plastic deformation of highly alloyed austenitic transformation-induced plasticity (TRIP) steels with low stacking fault energy leads typically to the formation of ∊-martensite within the original austenite. The ∊-martensite is often described as a phase having a hexagonal close-packed crystal structure. In this contribution, an alternative structure model is presented that describes ∊-martensite embedded in the austenitic matrixviaclustering of stacking faults in austenite. The applicability of the model was tested on experimental X-ray diffraction data measured on a CrMnNi TRIP steel after 15% compression. The model of clustered stacking faults was implemented in theDIFFaXroutine; the faulted austenite and ∊-martensite were represented by different stacking fault arrangements. The probabilities of the respective stacking fault arrangements were obtained from fitting the simulated X-ray diffraction patterns to the experimental data. The reliability of the model was proven by scanning and transmission electron microscopy. For visualization of the clusters of stacking faults, the scanning electron microscopy employed electron channelling contrast imaging and electron backscatter diffraction.

Stacking fault energy in austenitic steels determined by usingin situX-ray diffraction during bending

2014 ◽  
Vol 47 (3) ◽  
pp. 936-947 ◽  
Author(s):  
D. Rafaja ◽  
C. Krbetschek ◽  
C. Ullrich ◽  
S. Martin
Keyword(s):  
Critical Stress ◽  
Partial Dislocation ◽  
Stacking Faults ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Austenitic Steels ◽  
X Ray Diffraction ◽  
X Ray ◽  
Partial Dislocations

A method is presented which determines the stacking fault energy in face-centred cubic materials from the critical stress that is inducedviasample bending in the early stages of plastic deformation. The critical stress is gauged byin situX-ray diffraction. This method utilizes the results of Byun's consideration of the stress dependence of the partial dislocation separation [Byun (2003).Acta Mater.51, 3063–3071]. Byun showed that the separation distance of the partial dislocations increases rapidly when the critical stress is reached and that the critical stress needed for the rapid separation of the partial dislocations is directly proportional to the stacking fault energy. In the approach presented here, the partial dislocation separation and the corresponding triggering stress are monitored by usingin situX-ray diffraction during sample bending. Furthermore, thein situX-ray diffraction measurement checks the possible interactions between stacking faults present on equivalent lattice planes and the interactions of the stacking faults with other microstructure defects. The capability of the proposed method was tested on highly alloyed austenitic steels containing chromium (∼16 wt%), manganese (∼7 wt%) and nickel as the main alloying elements. For the steels containing 5.9 and 3.7 wt% Ni, stacking fault energies of 17.5 ± 1.4 and 8.1 ± 0.9 mJ m−2were obtained, respectively.

An X-ray diffraction technique for analyzing basal-plane stacking faults in GaN

2010 ◽  
Vol 207 (11) ◽  
pp. 2446-2455 ◽  
Author(s):  
Qing S. Paduano ◽  
David W. Weyburne ◽  
Alvin J. Drehman
Keyword(s):  
Basal Plane ◽  
Stacking Faults ◽  
X Ray Diffraction ◽  
X Ray

Investigations on Polytype Stability and Dislocation Formation in 4H-SiC Grown by PVT

2008 ◽  
Vol 600-603 ◽  
pp. 11-14 ◽  
Author(s):  
Erwin Schmitt ◽  
Thomas L. Straubinger ◽  
Michael Rasp ◽  
Michael Vogel ◽  
Andreas Wohlfart
Keyword(s):  
Electron Microscopy ◽  
Optical Microscopy ◽  
Material Properties ◽  
Basal Plane ◽  
Stacking Faults ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
Defect Reduction ◽  
X Ray ◽  
Entire Process

We carried out investigations to elucidate the reasons for polytype changes in 4H. The aim was to sustain polytype stability throughout the entire process. The investigations were accompanied by studies on the formation of basal plane dislocations and their role as source for stacking faults. Several methods for the evaluation of material properties were applied to determine quality most precisely, e.g. KOH-defect-etching, optical microscopy, electron microscopy and X-ray-diffraction. We found out that several influences in growth conditions have to be controlled in a proper manner to achieve defect reduction. Based on these investigations we were able to improve our process and the crystal quality significantly. Best values for 3” 4H wafers show that EPD = 5x103 cm-2 , MPD < 0.1 cm-2 and FWHM-values < 15 arcsec can be achieved.

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