bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural anisotropy of InGaAs/GaAs(001) quantum dot chains structures
Authors: Kladko V. P. , Slobodian M. V. , Strelchuk V. V. , Yefanov O. M. , Machulin V. F. , Mazur Yu. I. , Wang Zh. M. , Salamo G. J. 
Published: July 2007

AbstractWe have studied the structural properties of ordered InGaAs/GaAs(001) quantum dot chains multilayer by high‐resolution X‐ray diffraction. Two systems of lateral satellites, one of which being inclined with respect to the sample surface normal, i.e. the growth direction [001], were observed. The measured inclination of 30.0° ± 2.5° does not affect the diffraction profile from planar superlattice (SL), i.e. SL peaks are not inclined with respect to the GaAs substrate peak. We identify the splitting of coherent SL satellites for all orders as well as for two perpendicular directions. This splitting most likely indicates that two discrete periods exist in SL structure. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of dislocations in orthorhombic hen egg‐white lysozyme crystals by synchrotron X‐ray topography
Authors: Koizumi H. , Shimizu M. , Tachibana M. , Kojima K. 
Published: July 2007

AbstractOrthorhombic hen egg‐white (HEW) lysozyme crystals were examined by means of synchrotron X‐ray topography by the white beam technique. Four kinds of straight dislocations were clearly observed. From the extinction criterion of the dislocation images, Burgers vectors were identified to be [001], [$ \bar 1 $10] and [0$ \bar 1 $1]. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evolution of the microdefect structure in silicon on isothermal annealing as determined by X‐ray diffractometry
Authors: Kyslovskyy Ye. M. , Vladimirova T. P. , Olikhovskii S. I. , Molodkin V. B. , Kochelab E. V. , Seredenko R. F. 
Published: July 2007

AbstractThe dynamical theory of X‐ray diffraction by imperfect crystals with randomly distributed microdefects, applicable to double‐crystal diffractometry (DCD), has been extended to account for the simultaneous presence of several types of microdefects. The obtained formulae for coherent and diffuse components of the rocking curve (RC) have been applied to the quantitative characterization of the complex microdefect structure in silicon samples annealed at 750 °C for various time intervals by using high‐resolution double‐crystal X‐ray diffraction measurements. Time dependencies of concentrations and average sizes of oxygen precipitates and dislocation loops have been determined by using characterization results. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interface stability of magnetic tunnel barriers and electrodes
Authors: Lamperti A. , Pym A. T. G. , Eastwood D. S. , Cardoso S. , Wisniowski P. , Freitas P. P. , Anderson G. I. R. , Marrows C. H. , Tanner B. K. 
Published: July 2007

AbstractGrazing incidence X‐ray scattering during in‐situ annealing has been used to study the interface stability in MgO‐based electrodes and barriers in magnetic tunnel junctions (MTJs). In MTJs based on Co60Fe20B20/MgO, low temperature annealing at about 200 °C can result in a drop in the tunnelling magnetoresistance (TMR). Specular reflectivity measurements show a change in fringe structure at high scattering vector, at the temperature at which the TMR drops. Also, a change in diffuse scatter relative to the specular scatter is observed. Annealing of [Co60Fe60B20/MgO]×14 multilayers prepared by three different techniques shows no change in the specular Bragg peaks with no loss of Kiessig fringe structure on crystallization and no change in the diffuse scatter up to 200 °C. We suggest that diffusion of Mn from the IrMn pinning layer, present in the MTJs but not in the multilayers, may be responsible for the differences in TMR behaviour. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High resolution X‐ray diffraction analyses of ion‐implanted GaN/AlN/Si heterostructures
Authors: Matyi R. J. , Jamil M. , Shahedipour‐Sandvik F. 
Published: July 2007

AbstractHigh resolution triple‐axis X‐ray diffraction has been used to characterize the effects of nitrogen ion implantation into thin (15 nm and 55 nm) AlN buffer layers on the resultant structural quality of nominally 2 μm epitaxial GaN layers grown on silicon substrates. The GaN symmetric (0002) and the asymmetric (10$ \bar 1 $4) and (10$ \bar 1 $5) Bragg reflections shows that in all cases, the extent of the off‐peak kinematic diffuse scattering was reduced when growth was performed on the ion‐implanted AlN buffer layers. Analysis of the log I – log q dependence of the kinematic intensity shows linear behavior but with slopes changing from –4.3 to –3.7 (in the case of the (0002) reflection) in the unimplanted and ion‐implanted buffer layers, respectively, indicating a change in the defect character in the layers. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hydrogen diffusion in titanium‐hydride observed by the diffraction‐enhanced X‐ray imaging method
Authors: Mizuno K. , Furuya Y. , Hirano K. , Okamoto H. 
Published: July 2007

AbstractThe X‐ray refraction imaging technique was applied to the quantitative study of hydrogen diffusion in titanium‐hydride. Diffusivity and activation energy of hydrogen diffusion were determined by direct observation of the hydride. The hydride was formed on the surface of titanium by electrolytic‐charging at 31, 63 and 98 °C. The specimens were cut into 1 mm thick slices for cross‐sectional observations. The hydride layer was observed using the diffraction‐enhanced X‐ray imaging (DEI) method. Boundaries between titanium and the hydride were observed as thick black or white lines parallel to the specimen surface in the DEI images similar to previously reported results. Hydride distribution caused by hydrogen diffusion from the surface was calculated using an assumed hydrogen diffusivity value and from the solution of the appropriate diffusion equation. The results were converted to the intensity profiles of refraction images of the hydride using the measured rocking curve from an analyzer. The calculated intensity profiles were compared to those obtained from the experimental results and the fitted diffusivity was determined by trial and error. The activation energy of hydrogen in titanium‐hydride thus obtained, 0.55 ± 0.07 eV, showed good agreement with the widely accepted value obtained by the internal friction. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of InP porous layer by high‐resolution X‐ray diffraction
Authors: Punegov V. I. , Lomov A. A. , Shcherbachev K. D. 
Published: July 2007

AbstractA high resolution X‐ray diffraction method has been effectively used for the structural characterization of InP porous layers. It was revealed that strong diffuse scattering from pores around reciprocal lattice points does depend on the azimuth positions of samples. To extract structural information about porous layers fabricated under different conditions theoretical analysis of the measured reciprocal space maps (RSM) was performed. The statistical dynamical X‐ray diffraction theory was used to describe coherent and diffuse scattering from a layer with cylindrical pores. A numerical analysis of the RSMs for two azimuth positions φ (φ = 0 and φ = 90°) and detailed sections of RSMs (linescans) allowed determination of the radius, the length of the pores and tilting angle with respect to the surface normal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A sensitive method for detecting long‐range strain in nearly perfect crystals using X‐ray dynamical diffraction
Authors: Saka Takashi 
Published: July 2007

AbstractA very sensitive method is proposed for the detection of long‐range strain in otherwise perfect crystalline materials. In this method, the specimen is rotated around the scattering vector in the symmetrical Laue case. Long‐range strains due to a uniform bending or torsion, that are not detectable with the symmetrical Laue condition, are sensitively detected by the proposed method of rotating the specimen. Several demonstrative topographic observations are presented. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Radiation‐induced structural transformations in a silicon layer of SOI
Authors: Shcherbachev K. D. , Bublik V. T. , Mordkovich V. N. , Pazhin D. M. , Alves E. , Barradas N. P. 
Published: July 2007

AbstractThe differences in the secondary processes proceeding in the silicon layer of SOI and reference bulk silicon wafers are revealed by using High‐Resolution X‐ray diffraction and Rutherford Backscattering spectroscopy methods. The damage depth profiles in the implanted layers described by both strain and static Debye–Waller factor profiles, were reconstructed from the diffraction patterns using an autofitting procedure, based on a genetic algorithm. The contribution of diffuse scattering was excluded using the triple‐crystal diffractometry technique. The defect density profiles were obtained from the RBS/Channelling measurements, which were carried out using 4He+ beam at 2.0 MeV. The DICADA code, based on the theoretical description of dechanneling was used to interpret the RBS/C data. Accumulation kinetics, spatial distribution, and concentration of radiation‐induced defects in the topmost silicon layer of SOI and a bulk silicon were shown to be essentially different. The influence of the fields was shown to lead to the loss of crystallinity of the thin surface layer of silicon in SOI due to accumulation of vacancy‐type defects and increase of concentration of interstitial atoms near the internal interphase boundary “Si–SiO2”. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Combined double‐ and triple‐crystal X‐ray diffractometry with account for real defect structures in all crystals of X‐ray optical schemes
Authors: Shpak A. P. , Molodkin V. B. , Olikhovskii S. I. , Kyslovskyy Ye. M. , Reshetnyk O. V. , Vladimirova T. P. , Len E. G. , Nizkova A. I. , Venger V. M. , Dmitriev S. V. 
Published: July 2007

AbstractAnalytical expressions for coherent and diffuse scattering intensities with account for imperfections in all the crystals of double‐ and triple‐crystal diffractometers (DCD and TCD) have been derived from the generalized dynamical theory of X‐ray scattering in real single crystals which contain microdefects of various types. The analysis of TCD and DCD profiles measured from Czochralski‐grown silicon single crystal with oxygen precipitates and dislocation loops has been carried out. Characteristics of defect structures in sample and monochromator have been determined by using the combined DCD+TCD method. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Focusing high energy X‐rays with stacked Fresnel zone plates
Authors: Snigireva I. , Snigirev A. , Kohn V. , Yunkin V. , Grigoriev M. , Kuznetsov S. , Vaughan G. , Di Michiel M. 
Published: July 2007

AbstractStacking technique was developed in order to increase focusing efficiency of Fresnel zone plates at high energies. Two identical Si chips each of which containing Fresnel zone plates were used for stacking. Alignment of the chips was achieved by on‐line observation of the moiré pattern from the two zone plates. The formation of moiré patterns was studied theoretically and experimentally at different experimental conditions. To provide the desired stability Si‐chips with zone plates were bonded together with slow solidification speed epoxy glue. Technique of angular alignment in order to compensate a linear displacement in the process of gluing was proposed. Two sets of stacked FZPs were produced and experimentally tested to focus 15 and 50 keV X‐rays. Gain in the efficiency by factor 2.5 was demonstrated at 15 keV. Focal spot of 1.8 μm vertically and 14 μm horizontally with 35% efficiency was measured at 50 keV. Forecast for the stacking of nanofocusing Fresnel zone plates was discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Three‐dimensional topography using an X‐ray microbeam and novel slit technique
Authors: Tanuma R. , Kubo T. , Togoh F. , Tawara T. , Saito A. , Fukuda K. , Hayashi K. , Tsusaka Y. 
Published: July 2007

AbstractThis paper describes section topography using an X‐ray microbeam and a novel slit having a V‐shaped crevice (V‐slit). The V‐slit is characterized by a sharp‐pointed exponential transmission curve, which enables depth‐resolved imaging with high spatial resolution. An iterative deconvolution for image restoration is effectively executable, providing submicron resolution in cross‐sectional diffraction imaging. The new method is applied to the analysis of screw dislocation in a SiC diode. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
X‐ray characterization of periodic sub‐nm surface relief gratings
Authors: Zaumseil P. , Birkholz M. , Weidner G. 
Published: July 2007

AbstractLine and cross lattices of 260 and 360 nm pitch were prepared by covering p‐doped Si(100) substrates with photoresist, structuring and implanting with 3 × 1015 cm–2, 45 keV As+ ions. These doping lattices with n+–p periodicity were investigated by X‐ray diffraction (XRD) and reflectivity (XRR). While XRD did not show any signal of the periodic structure, XRR revealed a clear periodic diffraction pattern related to the pitch of the doping lattice. The features of this pattern as a function of the lattice orientation are discussed in detail for the cross lattice. Atomic force microscopy showed that the measured diffraction pattern is caused by a surface relief grating with sub‐nm amplitude, which was generated by a final doping‐dependent etching step during sample preparation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
X‐ray diffraction spot mapping – a tool to study structural properties of semiconductor disk laser devices
Authors: Zeimer U. , Grenzer J. , Korn D. , Döring S. , Zorn M. , Pittroff W. , Pietsch U. , Saas F. , Weyers M. 
Published: July 2007

AbstractLocal lattice plane curvature of semiconductor disk laser devices is determined by an X‐ray spot mapping technique using white beam synchrotron radiation. This method allows for in‐situ studies of the dependence of the lattice plane profile on device temperature and local heating by optical pumping. The influence of different device mounting procedures on the structural and optical device parameters was investigated. This knowledge was used for device technology optimisation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synchrotron‐radiation computed laminography for high‐resolution three‐dimensional imaging of flat devices
Authors: Helfen Lukas , Myagotin Anton , Rack Alexander , Pernot Petra , Mikulík Petr , Di Michiel Marco , Baumbach Tilo 
Published: July 2007

AbstractSynchrotron‐radiation computed laminography (SRCL) is developed as a method for high‐resolution three‐dimensional (3D) imaging of regions of interest (ROIs) in all kinds of laterally extended devices. One of the application targets is the 3D X‐ray inspection of microsystems. In comparison to computed tomography (CT), the method is based on the inclination of the tomographic axis with respect to the incident X‐ray beam by a defined angle. With the microsystem aligned roughly perpendicular to the rotation axis, the integral X‐ray transmission on the two‐dimensional (2D) detector does not change exceedingly during the scan. In consequence, the integrity of laterally extended devices can be preserved, what distinguishes SRCL from CT where ROIs have to be destructively extracted (e.g. by cutting out a sample) before being imaged. The potential of the method for three‐dimensional imaging of microsystem devices will be demonstrated by examples of flip‐chip bonded and wire‐bonded devices. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Real‐time and in situ solidification of Al‐based alloys investigated by synchrotron radiation: a unique experimental set‐up combining radiography and topography techniques
Authors: Buffet A. , Reinhart G. , Schenk T. , Nguyen‐Thi H. , Gastaldi J. , Mangelinck‐Noël N. , Jung H. , Härtwig J. , Baruchel J. , Billia B. 
Published: July 2007

AbstractThis special issue's cover shows a radiograph and a topograph recorded during Al–3.5 wt% Ni alloy solidification. On the radiograph (left), one can observe the development of a branching structure known as dendrite. The high quality of the dendrite in the early stage of the growth is confirmed by the equal‐thickness fringes which are visible within the solid in the topograph (middle and right). Those fringes evidence the absence of defects within the microstructure.The alloy's properties are largely controlled by the microstructure emerging during the growth process. As most of the phenomena involved during directional solidification are dynamic, it is crucial to perform an in situ and real‐time investigation. A unique experimental set‐up combining X‐ray radiography and topography has been recently developed at the ESRF (European Synchrotron Radiation Facility). It allows direct observation of the microstructure during directional solidification [1].The first author of the article is a PhD student at the ESRF (Grenoble). Her research focuses on Al‐based alloy solidification and more particularly on strains, stresses and defect formation during directional solidification. She is working in collaboration with the L2MP (CNRS, Marseille). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A comparison of two‐particle models for conduction electron scattering on hydrogen‐like impurity ions in non‐degenerate semiconductors
Authors: Poklonski N. A. , Kocherzhenko A. A. , Vyrko S. A. , Vlassov A. T. 
Published: July 2007

AbstractModels of electron mobility limited by scattering of conduction electrons on hydrogen‐like impurity ions in non‐degenerate crystalline semiconductors are discussed. It is shown that the best agreement with experimental data is given by a model earlier proposed by the authors, in which the time of electron‐ion interaction, equal to the time of transfer of a conduction electron across a spherical region corresponding to one impurity ion in the crystal, is taken into account, the minimum scattering angle is chosen according to Conwell–Weisskopf, and scattering acts of an electron on impurity ions are considered independent and incompatible events. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of strain relaxation mechanism in small SiGe clusters
Authors: Marim L. R. , Ueno L. T. , Machado F. B. C. , Dal Pino A. 
Published: July 2007

AbstractWe have performed a systematic search for the ground‐state geometry of Sin Gem neutral clusters (n + m = 3–5, 7). A number of low‐energy geometric isomers were optimized using reliable total‐energy calculations through B3LYP hybrid method. Harmonic vibrational analysis has been performed to assure that the optimized geometries are stable. Due to its larger size, the replacement of a silicon atom by a germanium one generates strain that affects the atomic configurations. Our results indicate that a bond‐stretching mechanism is the dominant effect that determines the geometry of the clusters. Our calculations have shown that as the number of Ge atoms increases, the average interatomic distance among all atoms in the cluster grows linearly. Such behavior can be understood as a cluster analog to Vegard's law for alloys. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical studies of mechanism of cycloaddition reaction between germylidene and formaldehyde
Authors: Lu Xiu Hui , Xu Yue Hua , Xiang Ping Ping , Che Xin 
Published: July 2007

AbstractMechanism of the cycloadditional reaction between singlet germylidene (R1) and formaldehyde (R2) has been investigated with MP2/6‐31G* method, including geometry optimization, and vibrational analysis for the involved stationary points on the potential energy surface. The energies of the different conformations are calculated by CCSD(T)//MP2/6‐31G* method. From the potential energy profile, it can be predicted that the dominant reaction pathway of the cycloadditional reaction between singlet germylidene and formaldehyde is reaction (4), which consists of three steps: the two reactants (R1, R2) first form an intermediate INT1b through a barrier‐free exothermic reaction of 28.1 kJ/mol; this intermediate reacts further with formaldehyde (R2) to give an intermediate INT4, which is also a barrier‐free exothermic reaction of 37.2 kJ/mol; subsequently, the intermediate INT4 isomerizes to a heteropolycyclic germanic compound P4 via a transition state TS4, for which the barrier is 18.6 kJ/mol. The dominant reaction has an excellent selectivity and differs considerably from its competitive reactions in thermodynamic property and reaction rate. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
First‐principles properties of organic polymer photovoltaic materials
Authors: Jayasekera T. , Monigold M. S. , Elizondo S. L. , Mintmire J. W. 
Published: July 2007

AbstractOne major approach for efficient photovoltaic devices based on polymeric materials lies in the use of bulk heterojunctions, which mix two different organic polymeric materials acting as donor and acceptor semiconductors. In these bulk heterojunctions the donor polymer typically acts as the light absorber, creating an electron‐hole pair and then donating the excited electron to the acceptor polymer. A deep theoretical understanding of the physical processes at work in these materials will require a knowledge of the electron states near the Fermi level for both the donor and acceptor. Bulk heterojunction systems based on mixtures of single‐wall carbon nanotubes and poly(3‐octylthiophene) have recently been reported in the literature. We calculate the electronic structure for both semiconducting and metallic single‐wall nanotubes, and compare these with electronic structure results for poly(3‐methylthiophene) as a model for the poly(3‐alkyl‐thiophenes). We also present results for the effective mass of single‐wall carbon nanotubes and poly(3‐methyl‐thiophene) using the calculated electronic band structures. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Solvation effect on the interaction between sodium and chloride ions in aqueous solution: An analysis based on the new resonance theory
Authors: Ikeda Atsushi , Yokogawa Daisuke , Sato Hirofumi , Sakaki Shigeyoshi 
Published: July 2007

AbstractThe solvation effect on the nature of the interaction between sodium and chloride ions in aqueous solution is investigated theoretically by using the combination of RISM‐SCF method and the analysis of molecular orbital wave function based on the new resonance theory. This strategy offers unified understandings of the nature of the interatomic interaction in solution together with the statistical distribution of solvent water molecules. The results show that, in aqueous phase, the weight of covalent interaction decrease rapidly with increase the distance between sodium and chloride and, at the same time, coordination number of solvent increase. We also find the solvation effect enhances the ionic character of the interaction by up to 20%. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Peptide retention prediction applied to proteomic data analysis
Authors: Gilar Martin , Jaworski Aleksander , Olivova Petra , Gebler John C. 
Published: July 2007

AbstractA retention prediction model was developed for peptides separated in reversed‐phase chromatography. The model was utilized to identify and exclude the false positive (FP) peptide identifications obtained via database search. The selected database included human proteins, as well as decoy sequences of random proteins. The FP peptide detection rate was defined either as number of retention time outliers, or random decoy sequence identifications. The FP rate for various MASCOT scores was calculated. The peptides identified in one‐dimensional (1D) and two‐dimensional (2D) liquid chromatography/mass spectrometry (LC/MS) experiments were validated by prediction models. Multi‐dimensional LC was based on two orthogonal reversed‐phase chromatography modes; prediction models were successfully applied for data filtering in both separation dimensions. Copyright © 2007 John Wiley & Sons, Ltd.