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Different techniques of the X-ray Diffraction Line Profile Analysis (XRDLPA) have been used to assess the microstructure of the irradiated Zr-1.0%Nb-1.0%Sn-0.1%Fe alloy. The domain size, microstrain, density of dislocation and the stacking…

Materials Science · Physics 2007-05-23 A. Sarkar , P. Mukherjee , P. Barat

In this paper we investigate x-ray and $\gamma$-ray propagation in crystals having a constant strain gradient and flat or cylindrical surfaces. When a displacement field is present, we solve the Takagi-Taupin equations either by the…

Instrumentation and Detectors · Physics 2008-09-17 A. Apolloni , G. Mana , C. Palmisano , G. Zosi

We demonstrate selective area epitaxy of GaAs films using patterned graphene masks on a Ge (001) substrate. The GaAs selectively grows on exposed regions of the Ge substrate, for graphene spacings as large as 10 microns. The selectivity is…

GaAs/Fe$_{3}$Si core/shell nanowire structures were fabricated by molecular-beam epitaxy on oxidized Si(111) substrates and investigated by synchrotron x-ray diffraction. The surfaces of the Fe$_3$Si shells exhibit nanofacets. These facets…

Materials Science · Physics 2016-05-19 Bernd Jenichen , Michael Hanke , Maria Hilse , Jens Herfort , Achim Trampert , Steven C. Erwin

We consider scattering of elastic waves on parallel wedge dislocations in the geometric theory of defects or, equivalently, scattering of point particles and light rays on cosmic strings. Dislocations are described as torsion singularities…

General Relativity and Quantum Cosmology · Physics 2009-10-31 M. O. Katanaev , I. V. Volovich

Molecular beam epitaxy of Fe3Si on GaAs(001) is studied in situ by grazing incidence x-ray diffraction. Layer-by-layer growth of Fe3Si films is observed at a low growth rate and substrate temperatures near 200 degrees Celsius. A damping of…

Materials Science · Physics 2012-06-12 Bernd Jenichen , Vladimir Kaganer , Wolfgang Braun , Roman Shayduk , Bradley Tinkham , Jens Herfort

In this study we report on a novel two-step epitaxial growth technique that enables a significant improvement of the crystal quality of nitrogen-polar GaN. The starting material is grown on 4{\deg} vicinal sapphire substrates by metal…

Materials Science · Physics 2024-08-06 Pietro Pampili , Vitaly Z. Zubialevich , Peter J. Parbrook

The dynamics of dislocations confined to grain boundaries in a striped system are studied using electroconvection in the nematic liquid crystal N4. In electroconvection, a striped pattern of convection rolls forms for sufficiently high…

Soft Condensed Matter · Physics 2009-11-10 Carina Kamaga , Fatima Ibrahim , Michael Dennin

Series of GaN/AlN superlattices (SLs) with various periods and the same thicknesses of GaN quantum wells and AlN barriers have been investigated. X-ray diffraction, photoluminescence (PL) and transmission electron microscopy (TEM)…

We have selectively grown thin epitaxial GaAs films on Ge substrates with the aid of a 200 nm thin SiO2 mask layer. The selectively grown structures have lateral sizes ranging from 1 um width up to large areas of 1 by 1 mm2. The growth with…

We studied the diffusion coefficient of hot electrons of GaN crystals in moderate electric (1...10 kV/cm) and magnetic (1...4 T) fields. Two configurations, parallel and crossed fields, are analysed. The study was carried out for…

Materials Science · Physics 2019-04-19 G. I. Syngayivska , V. V. Korotyeyev , V. A. Kochelap

Scanning electron microscopy (SEM) based electron channeling contrast imaging (ECCI) is used to observe and quantify misfit dislocation (MD) networks formed at the heteroepitaxial interface between ZnS and GaP grown by molecular beam…

Conventional X-ray methods use incoming plane waves and result in discrete diffraction patterns when scattered at crystals. Here we find, by a systematic method, incoming waveforms which exhibit discrete diffraction patterns when scattered…

Optics · Physics 2015-06-16 Gero Friesecke , Richard D. James , Dominik Jüstel

We report on thermal transport properties of wurtzite GaN in the presence of dislocations, by using molecular dynamics simulations. A variety of isolated dislocations in a nanowire configuration were analyzed and found to reduce…

Dislocation patterning and self-organization during plastic deformation are associated with work hardening, but the exact mechanisms remain elusive. This is partly because studies of the structure and local strain during the initial stages…

The microstructural parameters like the average domain size, effective domain size at a particular crystallographic direction and microstrain within the domains of titanium and Ti-5%Ta-2%Nb, irradiated with 116 MeV O5+ ion, have been…

Materials Science · Physics 2007-05-23 P. Mukherjee , A. Sarkar , P. Barat , Baldev Raj , U. Kamachi Mudali

The strain of GaN layers grown by Metal Organic Chemical Vapor Deposition (MOCVD) on three vicinal 4H-SiC substrates (0, 3.4 and 8 offcut from [0001] towards [11-20] axis) is investigated by X-ray Diffraction (XRD), Raman Scattering and…

Materials Science · Physics 2007-05-23 Julien Pernot , Etienne Bustarret , Mariusz Rudzinski , Paul R. Hageman , Poul K. Larsen

Comparative studies of the resonant transmission of light in the vicinity of exciton resonances, measured for 15 few-micron GaAs crystal slabs with different impurity concentrations $N$, reveal an unexpected tendency. While $N$ spans almost…

Mesoscale and Nanoscale Physics · Physics 2015-01-13 D. A. Zaitsev , N. D. Ilinskaya , A. V. Koudinov , N. K. Poletaev , A. Yu. Egorov , A. V. Kavokin , R. P. Seisyan

Raman light scattering, low-temperature photoluminescence, light-scattering tomography, and hydrogenation were used to investigate optical properties of defects in strain-relaxed Si_{1-x}Ge_x (0.05 \le x \le 0.50) alloys. The…

Materials Science · Physics 2021-10-12 Seref Kalem

Recent \textit{ab initio} calculations predict 1D dispersive electronic bands confined to the atomic scale cores of dislocations in the wide bandgap (3.84 eV) semiconductor ZnS. We test these predictions by correlating sub-bandgap optical…