Characterization of Threading Dislocations in PVT-Grown AlN Substrates via x-Ray Topography and 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.

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Studies of c-Axis Threading Screw Dislocations in Hexagonal SiC

MRS Proceedings ◽

10.1557/proc-1069-d02-03 ◽

2008 ◽

Vol 1069 ◽

Author(s):

Yi Chen ◽

Xianrong Huang ◽

Ning Zhang ◽

Govindhan Dhanaraj ◽

Edward Sanchez ◽

...

Keyword(s):

Ray Tracing ◽

Grazing Incidence ◽

Screw Dislocations ◽

Burgers Vector ◽

X Ray ◽

Back Reflection ◽

Partial Dislocations ◽

Ray Tracing Simulation ◽

Vector Magnitude

ABSTRACTIn our study, closed-core threading screw dislocations and micropipes were studied using synchrotron x-ray topography of various geometries. The Burgers vector magnitude of TSDs can be quantitatively determined from their dimensions in back-reflection x-ray topography, based on ray-tracing simulation and this has been verified by the images of elementary TSDs. Dislocation senses of closed-core threading screw dislocations and micropipes can be revealed by grazing-incidence x-ray topography. The threading screw dislocations can be converted into Frank partial dislocations on the basal planes and this has been confirmed by transmission synchrotron x-ray topography.

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Raytracing simulation and Augrids experimental test on spatial resolution of KBA Xray microscope

High Power Laser and Particle Beams ◽

10.3788/hplpb20112309.2415 ◽

2011 ◽

Vol 23 (9) ◽

pp. 2415-2417

Author(s):

董建军 Dong Jianjun ◽

杨正华 Yang Zhenghua ◽

曹柱荣 Cao Zhurong ◽

韦敏习 Wei Minxi ◽

詹夏宇 Zhan Xiayu ◽

...

Keyword(s):

Ray Tracing ◽

Spatial Resolution ◽

Experimental Test ◽

X Ray ◽

Ray Tracing Simulation

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Using Ray Tracing Simulations for Direct Determination of Burgers Vectors of Threading Mixed Dislocations in 4H-SiC c-Plane Wafers Grown by PVT Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.858.15 ◽

2016 ◽

Vol 858 ◽

pp. 15-18 ◽

Cited By ~ 4

Author(s):

Jian Qiu Guo ◽

Yu Yang ◽

Fang Zhen Wu ◽

Joseph J. Sumakeris ◽

R.T. Leonard ◽

...

Keyword(s):

Ray Tracing ◽

Mixed Type ◽

Direct Determination ◽

Relative Orientation ◽

Threading Dislocations ◽

Systematic Method ◽

X Ray ◽

Growth Axis

The presence of threading mixed dislocations (TMDs) (with both edge and screw component) in 4H-SiC crystals grown by PVT method has been reported both from axial slices (wafers cut parallel to the growth axis) and commercial offcut wafers (cut almost perpendicular to the growth axis). In this paper, a systematic method is developed and demonstrated to unambiguously determine the Burgers vectors of TMDs in 4H-SiC commercial offcut wafers using both Synchrotron Monochromatic X-ray Topography (SMBXT) and Ray Tracing Simulations. The principle of this method is that the contrast of dislocations on different reflections varies with the relative orientation of Burgers vectors with respect to the diffraction vectors. Measurements confirm that in commercial offcut wafers the majority of the threading dislocations with screw component are mixed type dislocations.

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X-Ray Topography Characterization of Large Diameter AlN Single Crystal Substrates

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1004.63 ◽

2020 ◽

Vol 1004 ◽

pp. 63-68

Author(s):

Rafael Dalmau ◽

Jeffrey Britt ◽

Hao Yang Fang ◽

Balaji Raghothamachar ◽

Michael Dudley ◽

...

Keyword(s):

Single Crystal ◽

Large Diameter ◽

Grazing Incidence ◽

Threading Dislocation ◽

Threading Dislocations ◽

X Ray ◽

Dislocation Densities ◽

Transmission Geometry ◽

Threading Dislocation Density

Large diameter aluminum nitride (AlN) substrates, up to 50 mm, were manufactured from single crystal boules grown by physical vapor transport (PVT). Synchrotron-based x-ray topography (XRT) was used to characterize the density, distribution, and type of dislocations. White beam topography images acquired in transmission geometry were used to analyze basal plane dislocations (BPDs) and low angle grain boundaries (LAGBs), while monochromatic beam, grazing incidence images were used to analyze threading dislocations. Boule diameter expansion, without the introduction of LAGBs around the periphery, was shown. A 48 mm substrate with a uniform threading dislocation density below 7.0 x 102 cm-2 and a BPD of 0 cm-2, the lowest dislocation densities reported to date for an AlN single crystal this size, was demonstrated.

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Spatially Resolved Characterization of Microstructure, Defects and Tilts in GaN Layers Grown on Si(111) Substrates by Maskless Cantilever Epitaxy

MRS Proceedings ◽

10.1557/proc-0934-i09-06 ◽

2006 ◽

Vol 934 ◽

Author(s):

Rozaliya Barabash ◽

C. Roder ◽

G. E. Ice ◽

S. Einfeldt ◽

J. D. Budai ◽

...

Keyword(s):

Orientation Imaging Microscopy ◽

Growth Conditions ◽

Threading Dislocations ◽

Misfit Dislocations ◽

X Ray ◽

Orientation Imaging ◽

Spatially Resolved ◽

Dislocation Arrays ◽

Tilt Boundaries

ABSTRACTThe spatially resolved distribution of strain, misfit and threading dislocations, and crystallographic orientation in uncoalesced GaN layers grown on Si(111) substrates by maskless cantilever epitaxy was studied by white-beam Laue x-ray microdiffraction, scanning electron microscopy, and orientation imaging microscopy. Tilt boundaries formed at the column/wing interface with the misorientation strongly depending on the growth conditions. A depth-dependent deviatoric strain gradient is found in the GaN. Types and density of misfit dislocations as well as their arrangement within different dislocation arrays was quantified. The results are discussed with respect to the miscut of the Si(111) surface and misfit dislocations formed at the interface.

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Quantitative characterization of the contrast mechanisms of ultra-small-angle X-ray scattering imaging

Journal of Applied Crystallography ◽

10.1107/s0021889808000733 ◽

2008 ◽

Vol 41 (2) ◽

pp. 416-427 ◽

Cited By ~ 9

Author(s):

F. Zhang ◽

G. G. Long ◽

L. E. Levine ◽

J. Ilavsky ◽

P. R. Jemian

Keyword(s):

Ray Tracing ◽

Small Angle ◽

Diffraction Theory ◽

X Ray ◽

X Ray Scattering ◽

X Ray Imaging ◽

Contrast Mechanism ◽

Good Agreement ◽

Ray Scattering

A general treatment of X-ray imaging contrast for ultra-small-angle X-ray scattering (USAXS) imaging is presented; this approach makes use of phase propagation and dynamical diffraction theory to account quantitatively for the intensity distribution at the detector plane. Simulated results from a model system of micrometre-sized spherical SiO2particles embedded in a polypropylene matrix show good agreement with experimental measurements. Simulations by means of a separate geometrical ray-tracing method also account for the features in the USAXS images and offer a complementary view of small-angle X-ray scattering as a contrast mechanism. The ray-tracing analysis indicates that refraction, in the form of Porod scattering, and, to a much lesser extent, X-ray reflection account for the USAXS imaging contrast.

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Investigation of Dislocations in 6H-SiC Axial Samples Using Synchrotron X-Ray Topography and Ray Tracing Simulation

ECS Meeting Abstracts ◽

10.1149/ma2021-02341006mtgabs ◽

2021 ◽

Vol MA2021-02 (34) ◽

pp. 1006-1006

Author(s):

Hongyu Peng ◽

Yafei Liu ◽

Tuerxun Ailihumaer ◽

Balaji Raghothamachar ◽

Michael Dudley ◽

...

Keyword(s):

Ray Tracing ◽

X Ray ◽

Ray Tracing Simulation

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3D ray-tracing simulation of X-ray laser amplification

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:2001258 ◽

2001 ◽

Vol 11 (PR2) ◽

pp. Pr2-305-Pr2-308

Author(s):

M. Temporal ◽

S. Jacquemot ◽

L. Bonnet ◽

A. Decoster

Keyword(s):

Ray Tracing ◽

X Ray ◽

Laser Amplification ◽

3D Ray Tracing ◽

Ray Tracing Simulation

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Multi-Lens Array Full-Field X-ray Microscopy

Applied Sciences ◽

10.3390/app11167234 ◽

2021 ◽

Vol 11 (16) ◽

pp. 7234

Author(s):

Alexander Opolka ◽

Dominik Müller ◽

Christian Fella ◽

Andreas Balles ◽

Jürgen Mohr ◽

...

Keyword(s):

Ray Tracing ◽

Numerical Aperture ◽

Field Of View ◽

Cone Beam ◽

Photon Flux ◽

Full Field ◽

X Ray ◽

Ray Tracing Simulation ◽

Metal Jet ◽

Proof Of Principle

X-ray full-field microscopy at laboratory sources for photon energies above 10 keV suffers from either long exposure times or low resolution. The photon flux is mainly limited by the objectives used, having a limited numerical aperture NA. We show that this can be overcome by making use of the cone-beam illumination of laboratory sources by imaging the same field of view (FoV) several times under slightly different angles using an array of X-ray lenses. Using this technique, the exposure time can be reduced drastically without any loss in terms of resolution. A proof-of-principle is given using an existing laboratory metal-jet source at the 9.25 keV Ga Kα-line and compared to a ray-tracing simulation of the setup.

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