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A slab of synthetic diamond 4×4×1.5 mm3 has been studied in Bragg-case, simultaneously in reflected and transmitted beams, using a double-crystal topographic method with a synchrotron source of x-rays. The examined diamond had been grown by the reconstitution method and was of a cuboctahedral habit with two large artificially cut surfaces parallel to (001) planes. A very sensitive double-crystal arrangement was used with the 008 diamond reflexion matching the 1151 silicon reflexion selecting 0.802 Å radiation. Both reflected Kvector g and transmitted Kvector 0 beam topographs revealed the images of dislocations and many details of the growth sector structure. The pairs of topographs thus obtained were not entirely complementary. Apart from the different foreshortening, the transmitted beam topographs were less sensitive and reproduced more distinctly defects closer to the exit surface. The results are compared with those obtained using other methods, especially the single-crystal section and projection topography. The images of dislocations in Kvector g and Kvector 0 topographs were compared with theoretical images obtained by numerical integration of the Takagi-Taupin equations, including modeling of impurity segregation in growth bands and taking into account the angular divergence of the monochromatized beam. The applied method provided a reasonable correspondence between the simulated and experimental images and confirmed that the images of dislocation outcrops on the entrance surface dominate both the Kvector g and Kvector 0 topographs. [ABSTRACT FROM AUTHOR]

Calcium molybdate CaMoO4 crystals are perspective materials for many applications in acoustic-electronics, acoustic-optics and nonlinear optics. They are also used as laser hosts, scintillators, different kinds of substrates and active elements of ionizing radiation detectors. For all these applications large-sized single crystals of high structural quality are required. The samples of CaMoO4 crystals have been investigated by means of synchrotron white beam topography, monochromatic beam topography and conventional X-ray Lang projection topography. The high-resolution rocking curves have also been taken using synchrotron and conventional arrangements. The topographs showed a rather good crystallographic perfection of the crystals. In particular, they did not reveal any segregation fringes proving high homogeneity of the chemical composition. Relatively high densities (<104 cm−2) of weak point-like diffraction contrasts were observed, which can be most probably interpreted as dislocation outcrops. The distinct main imperfection of the investigated crystals was variously developed block structure. The evaluation of lattice misorientation was realized by means of projection and section white beam synchrotron radiation topographs. The evaluated misorientation between various blocks was in the range of several arc minutes. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A domain structure and crystallographic defects in Czochralski grown single crystals of PrxLa1-xAlO3 and PrxLa1-x-yMgyAlO3 were characterised with a number of methods including conventional and synchrotron X-ray diffraction topography, and polariscopic micrography. The observed twin domain systems were located perpendicularly to {100}pcub and {110}pcub (pseudocubic) directions. It has been confirmed that the domains are of the same orientation and a twin character as those described in literature for LaAlO3 and LaGaO3 crystals. The use of section transmission topography enabled to indicate that the domains are perpendicular to the (100)pcub surface of the samples. The misorientation of lattice in the domains was evaluated from the white beam topographs and a tendency of its increase with increasing concentration of praseodymium was revealed. [ABSTRACT FROM AUTHOR]

The GdVO4 single crystals, both undoped and doped with erbium or thulium, were studied by means of X-ray diffraction topographic methods exploring laboratory and synchrotron radiation sources. Variously developed block structure, caused probably by thermal stresses, was revealed. The highest crystallographic perfection was observed in the crystal doped with 4 at.% of thulium, which was free of the grain boundaries in the end part. Contrary to that, the differences in structural perfection between samples cut out from various regions of the crystal and for different kinds of doping, were less distinct in other crystals. The diffraction topographic methods enabled the statement that the misorientation between various blocks is in the range of several arc minutes. [ABSTRACT FROM AUTHOR]

The numerical simulation has been applied for studying of Bragg-case section topographic images of dislocation and rod-like inclusions. The validity of simple approximation of extinction contrast was confirmed in the case of screw dislocations in silicon carbide crystals. A procedure for approximate calculation of the strain field of rod-like inclusion was constructed, consisting of adding the contributions from a very large number of point-like inclusions uniformly distributed inside the assumed volume of the inclusion. The procedure ensured a reasonable similarity between the simulated topographs and experimental Bragg-case section topographic images of some pipe-formed cavities in silicon carbide crystals. The method is useful for some other materials, e.g. it enabled to compute realistic simulation of plane-wave topographs of the rod-like inclusions in YAG. [ABSTRACT FROM AUTHOR]

Defect structure of Czochralski grown silicon (Cz-Si) with nitrogen admixture, cN ⩽ 5×1014 cm-3 (Cz-Si:N), annealed for up to 10 h at 1270-1400 K under hydrostatic Ar pressure ⩽ 1:1 GPa, was investigated by synchrotron diffraction topography (HASYLAB, Germany), X-ray reciprocal space mapping, and infrared spectroscopy. Extended defects were not detected in Cz-Si:N processed at up to 1270 K. Such defects were created, however, in Cz-Si:N pre-annealed at 923 K and next processed at 1270 K or in as-grown Cz-Si:N processed at 1400 K. Investigation of temperature-pressure effects in nitrogen-doped silicon contributes to the understanding of defect formation in Cz-Si:N [ABSTRACT FROM AUTHOR]

X-ray reflectometric and diffraction topographic methods were applied for examination of 4H and 6H silicon carbide substrates finished with various regimes, as well as, silicon carbide epitaxial layers. The investigations indicated a very good quality of the substrate surfaces finished with the process established at the Institute of Electronic Materials Technology, which provided the surface roughness σ = 0:55 ± 0:07 nm for 4H-SiC wafers. These values were better than those of substrate wafers offered by many commercial producers. The surface roughness was decreased during the initial high temperature etching to σ = 0:22 ± 0:07 nm. A relatively good structural quality was confirmed in the case of 4H epitaxial wafers deposited on the substrates prepared from the crystals manufactured at the IEMT, with the 8° off-cut from the main (001) plane. [ABSTRACT FROM AUTHOR]

Depth distribution of implanted species and microstructure of oxygen-containing Czochralski grown silicon (Cz-Si) implanted with light ions (such as H+) are strongly influenced by hydrostatic pressure applied during the post-implantation treatment. Composition and structure of Si:H prepared by implantation of Cz-Si with H+ 2 ; fluence D = 1:7 × 1017 cm-2, energy E = 50 keV (projected range of H+(H) = 275 nm), processed at up to 923 K under Ar pressure up to 1.2 GPa for up to 10 h, were investigated by elastic recoil detection Rutherford backscattering methods and the depths distributions of implanted hydrogen and also carbon, oxygen and silicon in the near surface were determined for all samples. The defect structure of Si:H was also investigated by synchrotron diffraction topography at HASYLAB (Germany). High sensitivity to strain associated with small inclusions and dislocation loops was provided by monochromatic (λ = 0:1115 nm) beam topography. High resolution X-ray diffraction was also used. [ABSTRACT FROM AUTHOR]2 , Rp(H) = 275 nm), processed at up to 923 K under Ar pressure up to 1.2 GPa for up to 10 h, were investigated by elastic recoil detection Rutherford backscattering methods and the depths distributions of implanted hydrogen and also carbon, oxygen and silicon in the near surface were determined for all samples. The defect structure of Si:H was also investigated by synchrotron diffraction topography at HASYLAB (Germany). High sensitivity to strain associated with small inclusions and dislocation loops was provided by monochromatic (λ = 0:1115 nm) beam topography. High resolution X-ray diffraction was also used. [ABSTRACT FROM AUTHOR]

The defect structure of YVO4 single crystals doped with Er3+, Ho3+ and Ca2+ were studied by X-ray diffraction topographic methods, using laboratory and synchrotron radiation sources. Variously developed block structure was the dominating imperfection of the investigated crystals observed both in conventional Lang and synchrotron topographs. The evaluation of block misorientation was realised by means of superimposed projection and section white beam synchrotron radiation topographs. More possibilities of following the mutual rotation of blocks were provided by means of white beam synchrotron radiation WBSR projection topographs exposed through the fine mesh. [ABSTRACT FROM AUTHOR]

Abstract: The GdCa4O(BO3)3 single crystals of monoclinic structure grown by the Czochralski technique were investigated by the synchrotron radiation white beam (SRWB) and conventional X-ray topography. The samples cut out parallel to the crystal growth axis b have been investigated in order to reveal the distribution of defects along the growth axis. Dislocations bundles, correlated with periodical changes of crystal diameter and large volume defects have been observed. The white beam synchrotron projection topography allowed better recognition of many details of the defect structure. [Copyright &y& Elsevier]

Abstract: Strontium lantanum gallate SrLaGaO4 tetragonal single crystal was investigated by white beam synchrotron radiation topography. Projection and section topographs were taken in back reflection and transmission geometry. The central “core” crystal region was practically free of defects; only one extended “oval” defect with strong boundary contrast was observed. The strong white–black contrasts connected with elongated volume defects and cracks were observed in surrounding the “core” region. [Copyright &y& Elsevier]

Effect of stress created by Ar hydrostatic pressure (HP) up to 1.1 GPa during annealing at the high temperature (HT) 1070 K (HT-HP treatment) on microstructure of Czochralski grown silicon co-implanted with helium and hydrogen Si:(He,H) using the same doses of He+ and H2+(DH,He= 5.1016 cm-2, at energy 50 and 150 keV, respectively) was investigated by means of X-ray (synchrotron) diffraction, transmission electron microscopy, and electrical measurements. The nanostructured sponge-like buried layers are formed in Si:(He,H) by annealing / high pressure treatment. Decreased interference, diffuse scattering and individual contrast are observed in the synchrotron topograms for HT-HP treated Si:(He,H). The treatment at 723 K and HP results in an additional donor formation as a sequence of the implantation-disturbed layer. The HP-mediated (retarded) out-diffusion of hydrogen and helium is in part responsible for the effects observed. [ABSTRACT FROM AUTHOR]

A slab formed sample cut out from low doped Czochralski-grown silicon crystal was implanted with 117 MeV (3 MeV/nucleon) Ar ions to the dose 5 × 1014 cm-2 and thermally annealed at 400 and 700 °C. The crystal was characterized with a number of complementary X-ray diffraction methods.The annealing did not completely remove the lattice strain induced by the implantation. The residual strain caused the series of interference maxima on the low angle side of the substrate maximum in the rocking curves. The rocking curves were different in different regions of the implanted area and characteristic fringes in plane wave topographs were observed. The analysis of rocking curves including the numerical simulation pointed to the existence of a local strain profile maximum situated below the shot-through layer with a relatively small deformation. The Bragg-case section topography experiment indicated a layer containing non-resolvable defects situated at the depths corresponding to the average ion range. [Copyright &y& Elsevier]

Oxygen precipitates in samples of Czochralski grown silicon crystal annealed at various temperatures from 750 to 1100 °C were studied with X-ray methods realized both with white and monochromatic synchrotron radiation, particularly Bragg-case section topography. The samples were additionally controlled by observation of selective etching pattern, infrared, Fourier spectroscopy and laser scattering tomography. The visibility of oxygen precipitates in synchrotron topographic methods was strongly dependent on annealing temperature and time. For annealing performed at 750 °C the effect was relatively weak and consisted of small irregularities of Pendello¨sung fringes. The back reflection section topographs usually revealed fringes characteristic for bent crystals with some irregularities caused by oxygen precipitates. The significant effect was observed with X-ray diffraction methods for 3-h annealing at 1100 °C, when the individual precipitates were resolved in the topographs. In case of longer combined annealing cycles including annealing at 1050 °C, an irresolvable quantity of defects and complete dampening of interference fringes were observed The concentration of precipitates strongly increased along some striations while in other parts of the crystal the interference fringes were present. [Copyright &y& Elsevier]

The MOCVD-grown epitaxial layers of AlxGa1−xAs with x=0.43 were implanted at room temperature with 1.5 MeV As ions to different doses in the range from 5×1013 to 5×1015 cm−2. The samples were studied with a number of X-ray diffraction methods using synchrotron radiation, in particular, recording of rocking curves with a very small 50×50 μm2 probe beam and with Bragg-case section topography. The strain profiles were determined by fitting the theoretical rocking curves obtained by numerical integration of the Takagi–Taupin equations.It was found that for the doses up to 1×1015 cm−2, the strain profiles were dominated by a component caused by introduced interstitial atoms with almost constant strain in the region close to the surface. A second strain component directly corresponding to the distribution of introduced As atoms was indicated for the higher doses. For the highest dose of 5×1015 cm−2, considerable lateral variations of introduced strain were detected by both Bragg-case topography and synchrotron reciprocal space mapping. [Copyright &y& Elsevier]

Abstract: Defect structure of Czochralski grown (111) oriented silicon single crystals (Cz-Si), irradiated with fast neutrons (energy 5MeV, dose 5×1016 cm−2) and annealed at up to 1400K, also under hydrostatic Ar pressure equal to 1.1GPa, has been investigated by high-resolution X-ray diffraction and synchrotron topography at HASY Laboratory. The annealing, especially at 1270 and 1400K, results in precipitation of interstitial oxygen and creation of extended defects. A thermally induced oxygen precipitation at high temperatures–pressures in neutron-irradiated Cz-Si reveals the irradiation-related history of investigated samples. [Copyright &y& Elsevier]

Abstract: Defect structure of Czochralski-grown oxygen-containing silicon–germanium (Si–Ge) samples with Ge content 1.5×1018 cm−3, subjected to processing for 5h at up to 1400K under hydrostatic Ar pressure up to 1.1GPa, has been investigated by synchrotron topography (at HASYLAB), high-resolution X-ray diffraction, photoluminescence and related methods. Ge admixture prevents formation of extended defects at processing done under 105 Pa. Such defects are created, however, in Si–Ge processed at 1400K under high pressure (1.1GPa). [Copyright &y& Elsevier]

Abstract: The study of structural perfection of GGG homoepitaxial layers with incorporated divalent Ni ions Ni,Ge:GGG has been performed by means of HR X-ray diffraction and optical spectroscopy. Epitaxial layers were grown by the LPE technique from supercooled high temperature solution with different concentration of NiO and GeO2 on both sides of the polished <111> oriented GGG substrates. Incorporation of optically inert Ge4+ ions made it possible to incorporate Ni2+ ions in the garnet lattice. High structural perfection and the relevant absorption spectra are prerequisite for the use of Ni,Ge:GGG epitaxial layers as infrared saturable absorbers. [Copyright &y& Elsevier]

The investigations of GdCa4O(BO3)3 single crystals grown by the Czochralski technique were performed by conventional and synchrotron radiation (SR) monochromatic wave topography mainly in back reflection geometry. It was found that back reflection topography is effectively able to reveal the dislocation structure even in thin samples. Different distribution of defects was observed in samples cut off from the top, middle and end part of the “as-grown” crystal. SR monochromatic wave topographs taken for two flanks of the rocking curve show the characteristic inversion of diffraction contrast. Both monochromatic wave and projection Lang topographs did not reveal any segregation fringes proving high homogeneity of the chemical composition of the examined crystal. [Copyright &y& Elsevier]

Abstract: Knowledge on the defect and electronic structure allows for improved modeling of material properties. A short literature review has shown that the information on defect structure of rare earth orthovanadate single crystals is limited. In this paper, defect and electronic structure of a needle-shaped Yb:LuVO4 single crystal grown by the slow cooling method have been studied by means of X-ray diffraction topography employing white synchrotron beam, high-resolution diffraction (HRD) and photoelectron spectroscopy (XPS) techniques. Topographic investigations show that the crystal is composed of two blocks disoriented by about 1.5° and separated by a narrow deformed region. Some contrasts observed within the crystal volume may be attributed to glide bands and sector boundaries. The contrasts appearing in the vicinity of the surface may be interpreted as due to the presence of small inclusions. The HRD study indicates, in particular, that among point defects, the vacancy type defects dominate and that the density of other defects is small in comparison. The XPS measurements enabled, despite highly insulating properties of the studied crystal, an analysis of its bulk electronic structure, including the main core-levels (O 1s, V 2p, Lu 4f) as well as the valence band range. [Copyright &y& Elsevier]

Abstract: Structural perfection of gadolinium gallium garnet (GGG; Gd3Ga5O12) epitaxial layers with incorporated divalent Co ions has been studied by means of high resolution X-ray diffraction, X-ray topography, transmission electron microscopy and optical spectroscopy. Epitaxial layers were grown by liquid phase epitaxy from super-cooled high temperature solution with different concentration of Co3O4 and GeO2 on both sides of the polished <111> oriented GGG substrates. In order to facilitate incorporation of Co2+ ions into the garnet lattice optically inert Ge4+ ions have to be introduced first. High structural perfection is a prerequisite to obtain absorption spectra required for the use GGG epitaxial layers as tunable infrared absorbers. [ABSTRACT FROM AUTHOR]

Abstract: In x Ga1−x As layers on InP substrate can be subjected to compressive or tensile strain due to lattice parameter differences depending on the alloy composition. In order to examine in details the strain of InGaAs/InP epiatxial layers and its evolution after subjecting the layers to annealing at high pressure, X-ray synchrotron topography, high resolution X-ray diffraction and atomic force microscopy have been employed. The data show that the changes of structural properties of the InGaAs layers subjected to high temperature–high pressure treatment at 670K–1.2Gpa, strongly depend on initial strain state and defect structure. The annealing of samples under high pressure results in change of strain in tensile layers only. The behaviour of observed defects is discussed. [Copyright &y& Elsevier]

Abstract: In x Al1− x As layers on InP substrate can be subjected to compressive as well as tensile strain due to lattice parameter differences induced by suitable alloy composition changes. The 2μm thick In x Al1− x As (0.50≤ x ≤0.53) layers were grown on the (001) oriented InP substrates by molecular beam epitaxy (MBE). They were investigated using X-ray diffraction and chemical etching. X-ray studies were performed applying high-resolution diffractometry in the double (DAD) and triple (TAD) axis configuration. It was found that the In0.53Al0.47As/InP layer under compressive strain relaxes partially along two 〈110〉 directions. On the other hand, the In0.50Al0.50As/InP layers, being under tensile strain, consist of two sub-layers; the first one, adjacent to the substrate is pseudomorphic whereas the upper sub-layer is partially relaxed and the relaxation is anisotropic. The upper sub-layer is fully strained in the [110] direction while partially relaxed in the [−110] one. [Copyright &y& Elsevier]

(111) oriented Fz-Si crystals were implanted with N+ or Si+ at 150 keV energy to a dose of 2×1016 cm−2. After implantation the samples were treated at a high temperature (up to 1400 K) under hydrostatic argon pressure (up to 1.1 GPa) for 1–5 h. Structural properties of Si:N and Si:Si before and after the treatment were investigated by high-resolution X-ray diffraction, synchrotron topography, transmission electron microscopy and photoluminescence methods. The structural properties of Si:N and Si:Si treated under hydrostatic pressure at 1270 K are different. A buried layer of uniform thickness with smooth interface was formed in Si:N under HP=1.1 GPa; the buried layer/Si interface becomes less smooth with rising treatment time. The shape of interference fringes and their changing distance at rocking curves are explained as an effect of nitrogen diffusion to the buried layer during the treatment. For the treated Si:Si samples, the observed strain changes are related to the out-diffusion of interstitial silicon atoms from the implanted layer to the sample surface and to creation of numerous extended defects near the implanted atoms range. Prolonged treatment (for 5 h) at 1.1 GPa and 1400 K results in creation of dislocations for Si:N while for Si:Si samples the structure of treated samples is more complex, involving also creation of amorphous-like surface film. [Copyright &y& Elsevier]