Role of threading dislocations on the growth of HgCdTe epilayers investigated using monochromatic X-ray Bragg diffraction imaging

2021 ◽  
Vol 28 (1) ◽  
pp. 301-308
Author(s):  
Can Yildirim ◽  
Philippe Ballet ◽  
Jean-Louis Santailler ◽  
Dominique Giotta ◽  
Rémy Obrecht ◽  
...  
Keyword(s):  
Infrared Detector ◽  
Lattice Parameter ◽  
Bragg Diffraction ◽  
Threading Dislocations ◽  
Characterization Methods ◽  
X Ray ◽  
Weak Beam ◽  
The Matrix ◽  
Diffraction Imaging ◽  
Hgcdte Epilayers

High-quality Hg1–x Cd x Te (MCT) single crystals are essential for two-dimensional infrared detector arrays. Crystal quality plays an important role on the performance of these devices. Here, the dislocations present at the interface of CdZnTe (CZT) substrates and liquid-phase epitaxy grown MCT epilayers are investigated using X-ray Bragg diffraction imaging (XBDI). The diffraction contributions coming from the threading dislocations (TDs) of the CZT substrate and the MCT epilayers are separated using weak-beam conditions in projection topographs. The results clearly suggest that the lattice parameter of the growing MCT epilayer is, at the growth inception, very close to that of the CZT substrate and gradually departs from the substrate's lattice parameter as the growth advances. Moreover, the relative growth velocity of the MCT epilayer around the TDs is found to be faster by a factor of two to four compared with the matrix. In addition, a fast alternative method to the conventional characterization methods for probing crystals with low dislocation density such as atomic force microscopy and optical interferometry is introduced. A 1.5 mm × 1.5 mm area map of the epilayer defects with sub-micrometre spatial resolution is generated, using section XBDI, by blocking the diffraction contribution of the substrate and scanning the sample spatially.

scholarly journals Synchrotron Bragg diffraction imaging characterization of synthetic diamond crystals for optical and electronic power device applications

2017 ◽  
Vol 50 (2) ◽  
pp. 561-569 ◽  
Author(s):  
Thu Nhi Tran Thi ◽  
J. Morse ◽  
D. Caliste ◽  
B. Fernandez ◽  
D. Eon ◽  
...  
Keyword(s):  
Surface Damage ◽  
Lattice Parameter ◽  
Bragg Diffraction ◽  
Fast Method ◽  
Extended Defects ◽  
X Ray ◽  
Single Crystal Diamond ◽  
Local Lattice ◽  
Diffraction Imaging

Bragg diffraction imaging enables the quality of synthetic single-crystal diamond substrates and their overgrown, mostly doped, diamond layers to be characterized. This is very important for improving diamond-based devices produced for X-ray optics and power electronics applications. The usual first step for this characterization is white-beam X-ray diffraction topography, which is a simple and fast method to identify the extended defects (dislocations, growth sectors, boundaries, stacking faults, overall curvature etc.) within the crystal. This allows easy and quick comparison of the crystal quality of diamond plates available from various commercial suppliers. When needed, rocking curve imaging (RCI) is also employed, which is the quantitative counterpart of monochromatic Bragg diffraction imaging. RCI enables the local determination of both the effective misorientation, which results from lattice parameter variation and the local lattice tilt, and the local Bragg position. Maps derived from these parameters are used to measure the magnitude of the distortions associated with polishing damage and the depth of this damage within the volume of the crystal. For overgrown layers, these maps also reveal the distortion induced by the incorporation of impurities such as boron, or the lattice parameter variations associated with the presence of growth-incorporated nitrogen. These techniques are described, and their capabilities for studying the quality of diamond substrates and overgrown layers, and the surface damage caused by mechanical polishing, are illustrated by examples.

scholarly journals Capabilities of X-ray diffuse scattering method for study of microdefects in semiconductor crystals

2018 ◽  
Vol 4 (4) ◽  
pp. 125-134
Author(s):  
Vladimir T. Bublik ◽  
Marina I. Voronova ◽  
Kirill D. Shcherbachev
Keyword(s):  
Diffuse Scattering ◽  
Reciprocal Lattice ◽  
Lattice Parameter ◽  
Formation Mechanisms ◽  
Scattering Method ◽  
X Ray ◽  
Semiconductor Crystals ◽  
The Matrix ◽  
Decomposition Stages ◽  
Defects Analysis

The capabilities of X-ray diffuse scattering (XRDS) method for the study of microdefects in semiconductor crystals have been overviewed. Analysis of the results has shown that the XRDS method is a highly sensitive and information valuable tool for studying early stages of solid solution decomposition in semiconductors. A review of the results relating to the methodological aspect has shown that the most consistent approach is a combination of XRDS with precision lattice parameter measurements. It allows one to detect decomposition stages that cannot be visualized using transmission electron microscopy (TEM) and moreover to draw conclusions as to microdefect formation mechanisms. TEM-invisible defects that are coherent with the matrix and have smeared boundaries with low displacement field gradients may form due to transmutation doping as a result of neutron irradiation and relaxation of disordered regions accompanied by redistribution of point defects and annihilation of interstitial defects and vacancies. For GaP and InP examples, a structural microdefect formation mechanism has been revealed associated with the interaction of defects forming during the decomposition and residual intrinsic defects. Analysis of XRDS intensity distribution around the reciprocal lattice site and the related evolution of lattice constant allows detecting different decomposition stages: first, the formation of a solution of Frenkel pairs in which concentration fluctuations develop, then the formation of matrix-coherent microdefects and finally coherency violation and the formation of defects with sharp boundaries. Fundamentally, the latter defects can be precipitating particles. Study of the evolution of diffuse scattering iso-intensity curves in GaP, GaAs(Si) and Si(O) has allowed tracing the evolution of microdefects from matrix-coherent ones to microdefects with smeared coherency resulting from microdefect growth during the decomposition of non-stoichiometric solid solutions heavily supersaturated with intrinsic (or impurity) components.

A New Tetragonal Boride Phase in FeAl+B Type Alloys

1996 ◽  
Vol 460 ◽  
Author(s):  
Xavier Pierron ◽  
Ian Baker
Keyword(s):  
Energy Loss ◽  
Lattice Parameter ◽  
Tetragonal Symmetry ◽  
Second Phase ◽  
Boride Phase ◽  
X Ray ◽  
Boron Doped ◽  
The Matrix ◽  
Matrix Lattice ◽  
Electron Energy Loss

ABSTRACTThe structure and composition of a previously unreported second phase were investigated in both Fe-43A1–0.12B and Fe-48Al-0.12B alloys. Energy dispersive x-ray and electron energy loss spectroscopy showed that the precipitates contained boron and were enriched in iron. This new boride phase had a tetragonal symmetry, with at = 4aB2 and ct = aB2, where aB2 is the matrix lattice parameter. The effect of iron content and heat treatments on the microstructure of those two boron-doped FeAl alloys are discussed.

Bragg and Fresnel Diffraction Imaging Using Highly Coherent X-Rays

1998 ◽  
Vol 4 (S2) ◽  
pp. 376-377
Author(s):  
P. Cloetens ◽  
J. Baruchel ◽  
J.P. Guigay ◽  
W. Ludwig ◽  
L. Mancini ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Optical Path Length ◽  
Fresnel Diffraction ◽  
Crystal Defects ◽  
Bragg Diffraction ◽  
X Rays ◽  
Transmitted Beam ◽  
X Ray ◽  
Diffraction Imaging ◽  
Phase Variations

X-ray imaging started over a century ago. For several decades its only form was absorption radiography, in which contrast is due to local variations in beam attenuation. About forty years ago, a new form of X-ray imagery, Bragg-diffraction imaging or X-ray topography, developed into practical use. It directly reveals crystal defects in the bulk of large single crystals, and paved the way to microelectronics by leading to the growth of large, practically perfect, crystals. The advent of third-generation synchrotron radiation sources of X-rays such as ESRF and APS is now making possible, through the coherence of the X-ray beams, a novel form of radiography, in which contrast arises from phase variations across the transmitted beam, associated with optical path length differences, through Fresnel diffraction. Phase radiography and its three-dimensional companion, X-ray phase tomography, are providing new information on the mechanics of composites as well as on biological materials.

Misfit dislocations between boron-doped homoepitaxial films and diamond substrates studied by X-ray diffraction topography

2018 ◽  
Vol 51 (6) ◽  
pp. 1684-1690 ◽  
Author(s):  
Marina González-Mañas ◽  
Beatriz Vallejo
Keyword(s):  
Critical Thickness ◽  
Lattice Mismatch ◽  
Lattice Parameter ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Boron Doped Diamond ◽  
X Ray ◽  
Boron Doped ◽  
Slip Planes ◽  
Half Loop

Boron-doped diamond epilayers grown over diamond substrates have a different lattice parameter from the undoped diamond substrate, which introduces a lattice mismatch between substrates and epilayers. This can generate misfit dislocations at the interface when the epilayer reaches a certain critical thickness. For a boron concentration of about 1 × 1020 atoms cm−3, the calculated lattice mismatch is about 1.3 × 10−4 and the critical thickness is of the order of 0.2 µm. In the epilayers studied, grown over high-pressure high-temperature 1b (001) substrates, the lattice mismatch and the epilayer thickness are 1.3 × 10−4, 30 µm and 6.5 × 10−4, 4 µm. The epitaxial strain has been relaxed by the generation of two orthogonal misfit dislocation systems. These are edge dislocations parallel to the [100] and [010] directions with a Burgers vector making an angle of 45° with the (001) interface. Their lengths are 40–60 µm and their lineal densities 200–240 cm−1. They are heterogeneously nucleated, propagated in the form of half-loops along the slip planes (011) and (101), respectively, and related mainly to 〈111〉 threading dislocations emerging from octahedral growth sectors. Another kind of half-loop originates from the substrate growth sector boundaries. Limited X-ray topography has been demonstrated to be a very useful tool to discriminate between substrate and epilayer defects when their lattice mismatch is not sufficient to separate such defects in conventional Lang topography. X-ray section topography has confirmed the presence of [001] dislocations in the epilayers and the misfit half-loops related to threading dislocations propagating from the interface.

scholarly journals Three-dimensional optical trapping and orientation of microparticles for coherent X-ray diffraction imaging

2019 ◽  
Vol 116 (10) ◽  
pp. 4018-4024 ◽  
Author(s):  
Yuan Gao ◽  
Ross Harder ◽  
Stephen H. Southworth ◽  
Jeffrey R. Guest ◽  
Xiaojing Huang ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Optical Trapping ◽  
Three Dimensional ◽  
Bragg Diffraction ◽  
X Ray Diffraction ◽  
Diffractive Imaging ◽  
X Ray ◽  
Diffraction Imaging ◽  
Microscopy Techniques ◽  
Micrometer Scale

Optical trapping has been implemented in many areas of physics and biology as a noncontact sample manipulation technique to study the structure and dynamics of nano- and mesoscale objects. It provides a unique approach for manipulating microscopic objects without inducing undesired changes in structure. Combining optical trapping with hard X-ray microscopy techniques, such as coherent diffraction imaging and crystallography, provides a nonperturbing environment where electronic and structural dynamics of an individual particle in solution can be followed in situ. It was previously shown that optical trapping allows the manipulation of micrometer-sized objects for X-ray fluorescence imaging. However, questions remain over the ability of optical trapping to position objects for X-ray diffraction measurements, which have stringent requirements for angular stability. Our work demonstrates that dynamic holographic optical tweezers are capable of manipulating single micrometer-scale anisotropic particles in a microfluidic environment with the precision and stability required for X-ray Bragg diffraction experiments—thus functioning as an “optical goniometer.” The methodology can be extended to a variety of X-ray experiments and the Bragg coherent diffractive imaging of individual particles in solution, as demonstrated here, will be markedly enhanced with the advent of brighter, coherent X-ray sources.

scholarly journals Inception and movement of a `subgrain boundary precursor' in ice under an applied stress, observed by X-ray synchrotron radiation Bragg imaging

2015 ◽  
Vol 48 (3) ◽  
pp. 672-678 ◽  
Author(s):  
A. Philip ◽  
L. Capolo ◽  
J. Meyssonnier ◽  
J. Baruchel
Keyword(s):  
Synchrotron Radiation ◽  
Basal Slip ◽  
Strain State ◽  
Applied Load ◽  
Subgrain Boundary ◽  
Bragg Diffraction ◽  
Ice Crystals ◽  
X Ray ◽  
Integrated Intensity ◽  
Diffraction Imaging

Basal slip of dislocations, the easiest deformation mechanism of ice crystals, does not allow a response to any strain state. The first steps of another mechanism, with a moving subgrain boundary precursor region, which permits accommodating the effect of an applied load, is investigated on an ice single crystal, mainly using synchrotron radiation Bragg diffraction imaging. During this process, the evolution of the local integrated intensity shows that there is both a general multiplication of dislocations within the crystal and a movement of basal dislocations towards the surface. The `subgrain boundary precursor' region evolves towards a classical grain boundary when further deformed.

Correlation between SEM and X-Ray Diffraction Imaging of Defect Structure in Single-Crystal Ni-Based Superalloy

2012 ◽  
Vol 186 ◽  
pp. 135-138 ◽  
Author(s):  
Włodzimierz Bogdanowicz ◽  
Robert Albrecht ◽  
Jan Sieniawski ◽  
Krzysztof Kubiak ◽  
Arkadiusz Onyszko
Keyword(s):  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Aerospace Materials ◽  
Scattered Electron ◽  
Bridgman Technique ◽  
Sem Images ◽  
X Ray ◽  
University Of Technology ◽  
Diffraction Imaging ◽  
Development Laboratory

In the work the single-crystalline alloy CMSX-4 was studied. The main aim of the study was an attempt to find correlations between images of X-Ray topography, X-ray diffraction maps of lattice parameter and misorientation angle and Scanning Electron Microscopy (SEM) images obtained by back-scattered electron (BSE) technique. Topography images were obtained by Auleytner method with wide beam. Diffractometer provided by EFG company was used for obtaining orientation and lattice parameter maps. Material for research was produced in Research and Development Laboratory for Aerospace Materials of Rzeszów University of Technology. Casts were obtained in ALD furnace by the Bridgman technique. It was found that X-ray topograms were correlated with SEM images of microstructures as well as with orientation and lattice parameter maps. X-Ray topograms showed high contrast bands which corresponded to dendrite arms. There was a correlation between low angle boundary and lattice parameter map.

scholarly journals Lattice Misfit of High Refractory Ruthenium Containing Nickel-Base Superalloys

2011 ◽  
Vol 278 ◽  
pp. 60-65 ◽  
Author(s):  
Steffen Neumeier ◽  
J. Ang ◽  
R.A. Hobbs ◽  
Catherine M.F. Rae ◽  
Howard J. Stone
Keyword(s):  
Lattice Misfit ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Matrix ◽  
Coherency Stress ◽  
Matrix Lattice ◽  
Chemical Segregation ◽  
Nickel Base Superalloys ◽  
Nickel Base

The influence of Ru, Co, Mo and W on the lattice misfit of eight highly alloyed Re containing single crystal nickel-base superalloys was investigated. High resolution X-ray diffraction (XRD) was used to relate the elemental partitioning behavior and the Vegard coefficients of the elements under investigation to the measured lattice parameter of the  and  phase. The residual chemical segregation and especially the coherency stress-induced tetragonal distortion of the  matrix lattice in the high Mo containing alloys results in the observation of two different lattice parameters for the  matrix phase. This leads to three overlapping, but clearly distinguishable {002} X-ray reflections.

scholarly journals Coherent Bragg nanodiffraction at the hard X-ray Nanoprobe beamline

2014 ◽  
Vol 372 (2010) ◽  
pp. 20130118 ◽  
Author(s):  
S. O. Hruszkewycz ◽  
M. V. Holt ◽  
J. Maser ◽  
C. E. Murray ◽  
M. J. Highland ◽  
...  
Keyword(s):  
Bragg Diffraction ◽  
Complex Materials ◽  
Fringe Visibility ◽  
X Ray ◽  
Coherent Diffraction Imaging ◽  
Coherent Beams ◽  
Diffraction Imaging ◽  
Diffraction Patterns ◽  
Scattering Volume

Bragg coherent diffraction with nanofocused hard X-ray beams provides unique opportunities for quantitative in situ studies of crystalline structure in nanoscale regions of complex materials and devices by a variety of diffraction-based techniques. In the case of coherent diffraction imaging, a major experimental challenge in using nanoscale coherent beams is maintaining a constant scattering volume such that coherent fringe visibility is maximized and maintained over the course of an exposure lasting several seconds. Here, we present coherent Bragg diffraction patterns measured from different nanostructured thin films at the Sector 26 Nanoprobe beamline at the Advanced Photon Source and demonstrate that with nanoscale positional control, coherent diffraction patterns can be measured with source-limited fringe visibilities more than 50% suitable for imaging by coherent Bragg ptychography techniques.

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