Multiple Bragg reflection by a thick mosaic crystal. Corrigendum

An inconsistent approximation in Wuttke [Acta Cryst. (2014), A70, 429–440] is corrected. Section 3.5 on the polar angle random walk is withdrawn.

High resolution multielement XRF spectroscopy of extended and diffused sources with a graphite mosaic crystal based Von Hamos spectrometer

High resolution Bragg spectroscopy from millimetric size sources has been performed in 6–20 keV range with the VOXES HAPG spectrometer.

Dynamical X-Ray Diffraction Analysis of a GaAs/In0.3Ga0.7As Single Quantum Well Grown on a GaAs (001) Substrate

We applied the mosaic crystal model to calculate the dynamical x-ray rocking curves for a coherently-strained GaAs/In0.3Ga0.7As/GaAs single quantum well grown epitaxially on a GaAs (001) substrate for a number of reflection profiles, including 004, 113, 224, 044 and 444 reflections. We show that it is possible to estimate the threading dislocation density in the quantum well, and therefore detect the pseudomorphic-metamorphic transition, using the widths or normalized intensities of the primary quantum well Bragg peak, or using the widths of the Pendellösung fringes associated with the quantum well structure.

Mosaic Crystal Model for Dynamical X-Ray Diffraction from Step-Graded InxGa1-xAs and InxAl1-xAs/GaAs (001) Metamorphic Buffers and Device Structures

In this paper we apply a mosaic crystal model for dynamical x-ray diffraction to step-graded metamorphic semiconductor device structures containing dislocations. This model represents an extension of the previously-reported phase-invariant model, which is broadly applicable and serves as the basis for the x-ray characterization of metamorphic structures, allowing determination of the depth profiles of strain, composition, and dislocation density. The new model has more general applicability and is more appropriate for step-graded metamorphic device structures, which are of particular interest for high electron mobility transistors and light emitting diodes. Here we present the computational details of the mosaic crystal model and demonstrate its application to step-graded InxGa1-xAs/GaAs (001) and InxAl1-xAs/GaAs (001) metamorphic buffers and device structures.

High-efficiency diffraction and focusing of X-rays through asymmetric bent crystalline planes

The grooving technique was employed for manufacturing a self-standing curved Ge crystal. The crystal focuses hard X-rays with high efficiency by diffraction in Laue geometry through asymmetric bent planes. The sample was tested at the Institut Laue–Langevin (Grenoble, France), undergoing two types of characterization. A monochromatic and low-divergence γ-ray beam was used to test the curvature of asymmetric planes, showing a diffraction performance better than for any mosaic crystal under equal conditions. Then, the focusing capability of the crystal was probed through a polychromatic and fine-focus hard X-ray beam. Asymmetric (220) planes were chosen for analysis because of the impossibility of obtaining a curvature along this family of planesviaany symmetric configuration in focusing crystals. A method for calculating the curvatures induced in any family of lattice planes is also presented.

XAFS spectroscopy by an X-ray tube based spectrometer using a novel type of HOPG mosaic crystal and optimized image processing

This paper presents a XAFS laboratory spectrometer with optimized image treatment suitable for determination of bond lengths and chemical species.