Reciprocal-Space Maps of X-Ray Diffraction Intensity Distribution and Their Relation to the Dislocation Structure of Epitaxial Layers

2018 ◽  
Vol 44 (6) ◽  
pp. 548-550
Author(s):  
R. N. Kyutt ◽  
M. P. Shcheglov
Keyword(s):  
Dislocation Structure ◽  
Intensity Distribution ◽  
Reciprocal Space ◽  
Epitaxial Layers ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
X Ray

Reciprocal Space Mapping of X-Ray Diffraction Intensity of GaN-Based Laser Diodes Grown on GaN Substrates

2003 ◽  
Vol 798 ◽  
Author(s):  
K. Tachibana ◽  
Y. Harada ◽  
S. Saito ◽  
S. Nunoue ◽  
H. Katsuno ◽  
...  
Keyword(s):  
Output Power ◽  
Sapphire Substrate ◽  
Light Output ◽  
Space Mapping ◽  
Reciprocal Space ◽  
Epitaxial Layers ◽  
X Ray Diffraction ◽  
Light Output Power ◽  
Reciprocal Space Mapping ◽  
X Ray

ABSTRACTCharacterization by reciprocal space mapping of x-ray diffraction (XRD) intensity was carried out for epitaxial layers of GaN-based laser structures on two GaN substrates: GaN substrate and GaN template on sapphire substrate. The difference between these two substrates was shown clearly. The distribution of XRD intensity of the epitaxial layers on GaN substrate was smaller than that of the epitaxial layers on GaN template on sapphire substrate. In the lasers with the epitaxial structure on GaN substrate, the light output power was as high as 200 mW under continuous-wave operation at room temperature. Excellent noise characteristics with relative intensity noise of -132 dB/Hz were also obtained at a low light output power of 3 mW without any high-frequency modulation. These results support that GaN substrates are promising for realizing GaN-based lasers with high performance.

X-ray microbeam diffraction in a crystal

2021 ◽  
Vol 77 (2) ◽  
Author(s):  
Vasily I. Punegov ◽  
Andrey V. Karpov
Keyword(s):  
Geometrical Optics ◽  
Reciprocal Space ◽  
The Other ◽  
Angular Distributions ◽  
Scattered Intensity ◽  
Exit Slit ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
X Ray ◽  
Boundary Functions

Using the formalism of dynamical scattering of spatially restricted X-ray fields, the diffraction of a microbeam in a crystal with boundary functions for the incident and reflected amplitudes was studied in the case of geometrical optics and the Fresnel approximation (FA). It is shown that, for a wide front of the X-ray field, the angular distributions of the scattered intensity in the geometrical optics approximation (GOA) and the FA are approximately the same. On the other hand, it is established that, for a narrow exit slit in the diffraction scheme, it is always necessary to take into account the X-ray diffraction at the slit edges. Reciprocal-space maps and the distribution of the diffraction intensity of the microbeam inside the crystal were calculated.

Materials characterization from diffraction intensity distribution in the γ-direction

2014 ◽  
Vol 29 (2) ◽  
pp. 113-117 ◽  
Author(s):  
Bob B. He
Keyword(s):  
Intensity Distribution ◽  
Crystal Size ◽  
Profile Analysis ◽  
Structure Refinement ◽  
Size Analysis ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
X Ray ◽  
Orientation Relations

Two-dimensional X-ray diffraction (XRD2) pattern can be described by the diffraction intensity distribution in both 2θ and γ-directions. The XRD2 images can be reduced to two kinds of profiles: 2θ-profile and γ-profile. The 2θ-profile can be evaluated for phase identification, crystal structure refinement, and many applications with many existing algorithms and software. In order to evaluate the materials structure associated with the intensity distribution along γ-angle, either the XRD2 pattern should be directly analyzed or the γ-profile can be generated by 2θ-integration. A γ-profile contains information on texture, stress, crystal size, and crystal orientation relations. This paper introduces the concept and fundamental algorithms for stress, texture, and crystal size analysis by the γ-profile analysis.

scholarly journals Распределение интенсивности трехволновой дифракции от дислокационных эпитаксиальных слоев в обратном пространстве

2018 ◽  
Vol 60 (4) ◽  
pp. 691
Author(s):  
Р.Н. Кютт
Keyword(s):  
Dislocation Density ◽  
Intensity Distribution ◽  
Wave Diffraction ◽  
Block Structure ◽  
Reciprocal Space ◽  
X Ray Diffraction ◽  
X Ray ◽  
Common Peak ◽  
Edge Dislocations ◽  
Voigt Function

AbstractThe three-wave X-ray diffraction in strongly disordered epitaxial layers of GaN and ZnO is experimentally investigated. The charts of the intensity distribution in the reciprocal space are plotted in coordinates q _θ and q _ϕ for the most intensive three-wave combination (1010)/(1011) by means of subsequent θ- and ϕ-scanning. A nontrivial shape of the θ-sections of these contours at a distance from the ϕ center of reflection is revealed; it is different for different samples. For the θ-curves at the center of reflection, we observed a common peak that may be approximated by the Voigt function with a power-low decrease in the intensity at the wings; the decrease law (from–4.5 to–5.0) is found to be considerably greater than that for the similar curves of two-wave diffraction and not depending on the dislocation density and distribution in layers. In some films we observed a coarse-block structure; in addition, it follows from the distribution in the reciprocal space that these blocks are turned with respect to each other around a normal to the surface, which allows us to suggest the existence of low-angle boundaries between them, consisting exclusively of edge dislocations.

Anisotropic strain in YBa2Cu3O7−δfilms analysed by deconvolution of two-dimensional intensity data

2001 ◽  
Vol 34 (1) ◽  
pp. 13-15
Author(s):  
J. Brötz ◽  
H. Fuess
Keyword(s):  
Superconducting Films ◽  
Reciprocal Space ◽  
Intensity Data ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
X Ray ◽  
Anisotropic Strain ◽  
Crystalline Substrate ◽  
Instrumental Resolution

The influence of the instrumental resolution on two-dimensional reflection profiles of epitaxic YBa2Cu3O7−δfilms on SrTiO3(001) has been studied in order to investigate the strain in the superconducting films. The X-ray diffraction intensity data were obtained by two-dimensional scans in reciprocal space (q-scan). Since the reflection broadening caused by the apparatus differs for each position in reciprocal space, a highly crystalline substrate was used as a standard. Thus it was possible to measure a standard very close to the YBa2Cu3O7−δreflections in reciprocal space. The two-dimensional deconvolution of reflections by a new computer program revealed an anisotropic strain of the two twinning systems of the film.

Determination of dispersion and polarization of thermal plane waves in crystals

1971 ◽  
Vol 134 (3-4) ◽  
Author(s):  
P. L. La Fleur
Keyword(s):  
Intensity Distribution ◽  
Phonon Scattering ◽  
Reciprocal Lattice ◽  
Plane Waves ◽  
Lattice Points ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
Reciprocal Lattice Point ◽  
X Ray

AbstractThe dispersion of the thermal plane waves (phonons) in crystals can be determined from the x-ray diffraction intensity distribution around a reciprocal lattice point. In the method presented here no higher-order phonon-scattering corrections are necessary. It is shown furthermore that polarizations and dispersion of the phonons can be determined from the intensity distributions around six properly chosen reciprocal lattice points.

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