篭島 靖

Abstract In coherent X-ray diffraction imaging, speckles on a coherent diffraction pattern must be sampled at intervals sufficiently finer than the Nyquist interval, which imposes an upper limit on the sample size. To overcome the size limitation, a sub-pixel shift method for upsampling coherent diffraction patterns was proposed. This paper reports on the evaluation of the noise tolerance of the upsampling algorithm by a simulation. The quality of the images reconstructed from the upsampled diffraction pattern and pattern recorded by a detector with an equivalent pixel size was comparable when the optimum number of upsampling iterations is adopted.

<title>Abstract</title>The quest for understanding the structural mechanisms of material properties and biological cell functions has led to the active development of coherent diffraction imaging (CDI) and its variants in the hard X-ray regime. Herein, we propose multiple-shot CDI, a full-field CDI technique dedicated to the visualisation of local nanostructural dynamics in extended objects at a spatio-temporal resolution beyond that of current instrumentation limitations. Multiple-shot CDI reconstructs a “movie” of local dynamics from time-evolving diffraction patterns, which is compatible with a robust scanning variant, ptychography. We developed projection illumination optics to produce a probe with a well-defined illumination area and a phase retrieval algorithm, establishing a spatio-temporal smoothness constraint for the reliable reconstruction of dynamic images. The numerical simulations and proof-of-concept experiment using synchrotron hard X-rays demonstrated the capability of visualising a dynamic nanostructured object at a frame rate of 10 Hz or higher.

Abstract The optical transfer function (OTF) of an inverse-phase composite zone plate under incoherent illumination was numerically evaluated by convoluting the point spread function (PSF) and transmission distribution of a model sample with gradually changing spatial frequency. The PSF used in the simulation was obtained from our previous study on deep-focusing X-ray microscopes. As expected, the contrast in the sample image was lesser than that produced by a conventional zone plate. Phase-reversed contrast—spurious resolution—appeared at a high spatial frequency. Although the calculated OTF is slightly aberrated, its deep-focusing capability is advantageous for X-ray microimaging of thick samples.

© 2020 Elsevier B.V. An oxide ion (O2−) conducting membrane cell, based on lanthanum silicate oxyapatite (La9.33+xSi6O26+1.5x, LSO), exhibiting low ohmic and polarization resistances in the intermediate-temperature region (~873 K) was developed. As a solid electrolyte, highly conductive Mg-doped LSO, La9·8(Si5·7Mg0.3)O26.4 (MDLS), modified with another kind of non-conductive lanthanum silicate, La2SiO5 was employed. Two kinds of silicate layers were successively spin-coated on a Ni-MDLS porous anode support, followed by thermal treatment aimed at improving ionic conductivity as well as densification of MDLS through solid state reactive diffusion. In addition, the Gd-doped CeO2, (Ce0.9Gd0.1)O1.95 (GDC) electrolyte layer, which plays an important role to prevent a reaction between the electrolyte and cathode materials, was spin-coated on the modified MDLS electrolyte. Finally, the cathode layer of porous (La,Sr)(Co,Fe)O3-δ was screen printed on the electrolyte layers. The resulting cell obtained from this study showed good fuel cell performance with a maximum power density of 94 mW cm−2 at 873 K, when operated with argon-diluted hydrogen and pure oxygen gasses.

A novel type of zone plate (ZP), termed an inverse-phase composite ZP, is proposed to gain a deeper focus than the standard diffraction-limited depth of focus, with little reduction in spatial resolution. The structure is a combination of an inner ZP functioning as a conventional phase ZP and an outer ZP functioning with third-order diffraction with opposite phase to the inner ZP. Two-dimensional complex amplitude distributions neighboring the focal point were calculated using a wave-optical approach of diffraction integration with a monochromatic plane-wave illumination, where one dimension is the radial direction and the other dimension is the optical-axis direction. The depth of focus and the spatial resolution were examined as the main focusing properties. Two characteristic promising cases regarding the depth of focus were found: a pit-intensity focus with the deepest depth of focus, and a flat-intensity focus with deeper depth of focus than usual ZPs. It was found that twice the depth of focus could be expected with little reduction in the spatial resolution for 10 keV X-ray energy, tantalum zone material, 84 nm minimum fabrication zone width, and zone thickness of 2.645 µm. It was also found that the depth of focus and the spatial resolution were almost unchanged in the photon energy range from 8 to 12 keV. The inverse-phase composite ZP has high potential for use in analysis of practical thick samples in X-ray microbeam applications.

© 2018 Elsevier B.V. Effects of dopant content and synthesis temperature on phase relations and conducting behavior of lanthanum silicate, La9.33+xSi6O26+1.5x (LSO) electrolytes were investigated. The La-excess-type Fe-doped LSO, La10(Si5.5Fe0.5)O26.75 synthesized at 1973 K showed lower grain boundary as well as grain interior resistances, and then, had high total conductivity (6.9 × 10−3 S cm−1 at 873 K and 3.6 × 10−5 S cm−1 at 573 K). In addition, the chemical instability owing to a high lanthanum activity in the La-excess-type LSO (x = 0.67) specimen could be eliminated by incorporating iron into the specimen. The synchrotron radiation microbeam X-ray diffraction technique revealed that this specimen contains a small amount of new secondary phase, which differs from the situation found in a highly conductive but chemically unstable Al-doped LSO specimen with the same x value and the same synthesis temperature.

We develop a dark-field X-ray microscope using full-field optics based on a synchrotron beamline. Our setup consists of a condenser system and a microscope objective with an angular acceptance larger than that of the condenser. The condenser system is moved downstream from its regular position such that the focus of the condenser is behind the objective. The dark-field microscope optics are configured by excluding the converging beam from the condenser at the focal point. The image properties of the system are evaluated by observing and calculating a Siemens star test chart with 10 keV X-rays. Our setup allows easy switching to bright-field imaging. (C) 2016 The Japan Society of Applied Physics

X-ray topographs are taken for a sapphire wafer with the [0001] surface normal, as an example, by forward transmitted synchrotron x-ray beams combined with two-dimensional electronic arrays in the x-ray detector having a spatial resolution of 1 mu m. They exhibit no shape deformation and no position shift of the dislocation lines on the topographs. Since the topography is performed under multiple-beam diffraction conditions, the topographic images of a single diffraction (two-wave approximation condition) or plural diffractions (six-wave approximation condition) can be recorded without large specimen position changes. As usual Lang topographs, it is possible to determine the Burgers vector of each dislocation line. Because of high parallelism of the incoming x-rays and linear sensitivity of the electronic arrays to the incident x-rays, the present technique can be used to visualize individual dislocations in single crystals of the dislocation density as high as 1 x 10(5) cm(-2). (C) 2016 Author(s).

Dislocations in an epitaxial GaN film with a (1010) surface (m-GaN) were investigated by means of X-ray diffractometry. It was clarified that a-type screw dislocations existed in the sample by evaluating diffraction contrast on X-ray topographs (XRTs). In addition, local lattice inclinations of the (1010) plane toward the [0001] direction were observed with spatial intervals similar to the separation distances of those a-type screw dislocations slipping on the (0001) basal plane and also on other cross-slip planes in the sample. (C) 2015 The Japan Society of Applied Physics

The experimental procedure for obtaining the point spread function (PSF) of a focusing beam generated using an X-ray multilayer zone plate (MZP) with a narrow annular aperture has been developed. It was possible to reconstruct the PSF by applying the tomographic process to the measured dataset consisting of line spread functions (LSFs) in every radial direction on the focal plane. The LSFs were measured by a knife-edge scanning method of detecting scattered intensity. In the experimental work, quasi-monochromatic undulator radiation with a first harmonic energy of 20 keV was directly focused without a monochromator by the MZP, and the PSF was measured using this procedure. As a result, a near diffraction-limited focused beam size of 46 nm full width at half-maximum was obtained. © 2014 International Union of Crystallography.

A simple hard X-ray imaging method achieving a high spatial resolution is proposed. Images are obtained by scanning a metal wire through the wave field to be measured and rotating the sample to collect data for back projection calculations; the local diffraction occurring at the edges of the metal wire operates as a narrow line probe. In-line holograms of a test sample were obtained with a spatial resolution of better than 100 nm. The potential high spatial resolution of this method is shown by calculations using diffraction theory. (C) 2014 AIP Publishing LLC.

The cotyledon of legume seeds is a storage organ that provides nutrients for seed germination and seedling growth. The spatial and temporal control of the degradation processes within cotyledons has not been elucidated. Calcium oxalate (CaOx) crystals, a common calcium deposit in plants, have often been reported to be present in legume seeds. In this study, micro-computed tomography (micro-CT) was employed at the SPring-8 facility to examine the three-dimensional distribution of crystals inside cotyledons during seed maturation and germination of Lotus miyakojimae (previously Lotus japonicus accession Miyakojima MG-20). Using this technique, we could detect the outline of the embryo, void spaces in seeds and the cotyledon venation pattern. We found several sites that strongly inhibited X-ray transmission within the cotyledons. Light and polarizing microscopy confirmed that these areas corresponded to CaOx crystals. Three-dimensional observations of dry seeds indicated that the CaOx crystals in the L. miyakojimae cotyledons were distributed along lateral veins; however, their distribution was limited to the abaxial side of the procambium. The CaOx crystals appeared at stage II (seed-filling stage) of seed development, and their number increased in dry seeds. The number of crystals in cotyledons was high during germination, suggesting that CaOx crystals are not degraded for their calcium supply. Evidence for the conservation of CaOx crystals in cotyledons during the L. miyakojimae germination process was also supported by the biochemical measurement of oxalic acid levels.

A constant-pitch microprism-array optical device has been developed. It is a modified version of the previously reported quasi-Fresnel lens [Kagoshima et al., Appl. Phys. Lett. 101, 163102 (2012)]. The modification eases the fabrication of the lens, although it degrades some of the focusing performance. It consists of twenty 50-mu m-wide right-angle microprisms, whose slope angles gradually increase to 67.8 degrees at the outer side. By inclining the array, the aspect ratio of the microprisms becomes large enough for X-ray use. The effective slope angle can be enlarged to 86.4 degrees at an inclination angle of 80.5 degrees. A 10-keV synchrotron beam with a size of 680 mu m (V) x 660 mu m (H) was two-dimensionally condensed to 130 mu m (V) x 380 mu m (H) with a photon flux density gain of similar to 3. We also show that the microprism array is suitable for practical use below the critical radiation dose rate. (C) 2013 AIP Publishing LLC.

We have developed a phase-contrast X-ray microtomography system based on scanning microscopy with X-ray focusing optics. The system is very simple because only two conventional intensity detectors and a half-obstructing-plate for the second detector are installed into the conventional scanning microscopy setup. We constructed the system with a 450-nm-size focused beam of a 10 keV X-ray. The system is operated with a sampling rate of 100 Hz. Adopting data correction using a guide object and data interpolation procedure in sinograms, tomographic reconstruction images with a high spatial resolution and phase sensitivity are obtained. (C) 2013 The Japan Society of Applied Physics

An inclined-incidence quasi-Fresnel lens made of acrylic resin has been developed for prefocusing in synchrotron radiation x-ray beamlines. By inclining the lens, the grating aspect ratio is large enough for x-ray use. As it operates in transmission mode with negligible beam deflection and offset, little additional equipment is needed to introduce it into existing beamlines. It is fabricated by sheet-press forming, enabling inexpensive mass production. The prototype was able to focus a 730-mu m-wide beam to a width of 80 pm with a photon flux density gain of 5.6 at an x-ray energy of 10 keV. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4759150]

A circular multilayer zone plate (MZP) was fabricated and its focusing performance was evaluated using 20-keV x-rays. MoSi2 and Si layers were alternately deposited by DC magnetron sputtering on a wire core; all the interfaces satisfied the Fresnel zone condition. The measured line spread function was converted to a point spread function by tomographic reconstruction. The results suggest that the MZP has the potential to realize the diffraction-limited resolving power, which is calculated to be 35 nm using the diffraction integral. Furthermore, scanning transmission microscopy using the MZP could resolve a 50-nm line-and-space pattern. (C) 2012 American Institute of Physics. [doi:10.1063/1.3676165]

An optical system consisting of two phase zone plates closely arranged in tandem was constructed for focusing high-energy X-rays. The phase zone plates were made from tantalum and their combined thickness was 4.8 mu m. An ideal diffraction efficiency of 30% is expected at 30 keV, which is about 3 times higher than that of a single zone plate. The focusing properties at 30 keV were studied both numerically and experimentally. The coaxial tandem arrangement was precisely achieved by observing Young's interference patterns in the far-field produced by the two point foci. A focus size of similar to 4 mu m was obtained. The photon flux density was 2.2 x 10(13) photons/s/mm(2), which is 2.4 and 85 times higher than that obtained with a single zone plate and without focusing, respectively. The focused beam was used for scanning X-ray fluorescence microscopy and the residual tin distribution on a float glass surface was imaged. (C) 2011 The Japan Society of Applied Physics

A simple and new procedure to measure the optimal intensity distribution of an x-ray wavefield in nanoscale resolution is proposed. A heavy-metal wire can work as a "nanoslit" with a nanoscale aperture size. Its basic function can be described simply with geometrical optics using total reflection. The further function is investigated with numerical calculation of a diffraction edge. In the experiment, Fresnel fringes generated by a rectangular aperture were measured by using a 300-mu m platinum wire as the nanoslit. Its high potential use in imaging applications is discussed.

A new method is proposed for nanoscale hard x-ray measurements. This method uses a reflection on a heavy-metal wire that functions as a single slit with a nanoscale aperture for a parallel x-ray beam. This "nanoslit" can be used to perform high-spatial-resolution measurements of the intensity distribution of a wavefront that diverges from an aperture. In experiments, Fresnel fringes generated by a rectangular aperture were measured using a 300-mu m-diameter platinum wire as the nanoslit. In these experiments, the finest fringes with a period of 26 nm could be successfully resolved. (C) 2010 American Institute of Physics. [doi:10.1063/1.3456447]

A total reflection zone plate (TRZP) was developed and fabricated as a hard X-ray focusing device. It consists of a Au zone pattern drawn on a flat SiO(2) substrate. The reflection only from the zone pattern can be extracted by operating the TRZP with a grazing incident angle between critical angles of Au and SiO(2). The effective zone size is fully reduced to the drawn zone size with a small reduction ratio below 1/100. A focusing test using 10 keV X-rays was performed at the "Hyogo-ID&apos;&apos; beamline (BL24XU) of SPring-8, and a focusing beam with diffraction-limited size was achieved. (C) 2010 The Japan Society of Applied Physics

A new total-reflection zone plate that consists of a reflective zone pattern with varied-space on a flat substrate was fabricated for hard X-ray nanofocusing. This device is much easier to fabricate than other focusing devices. This is because its focusing size is much smaller than its finest constituent structure since it exploits the effect of glancing X-rays by having a small total reflection angle. Its focusing properties were evaluated using 10-keV X-rays and a focusing size of 14.4 nm was achieved. (C) 2010 The Japan Society of Applied Physics

In-plane strain in ultrathin silicon nanolayers of separation by implantation of oxygen wafers was characterized in real time by the grazing incidence X-ray diffraction during thermal oxidation in a newly developed oxidation furnace. The strain in the ultrathin silicon nanolayer during the growth is on the order of 10-4. The amount of strain does not change for the thicknesses of 6nm to about 2nm, but it increases twofold at the thicknesses of less than 2nm at the oxidation temperature of 1220°C. The strain originates from the volume difference between the Si nanolayers and SiO2. © 2009 The Japan Society of Applied Physics.

By combining atomic force microscopy and x-ray reflectivity measurements, the morphological evolution at the SiO2/Si(001) interface during thermal silicon oxidation was systematically studied as a function of oxidation temperatures. We found that the oxidation-induced roughening switches to smoothening at an oxidation temperature of 1250 degrees C on the oxidation front. The transition is governed by how the strain induced by oxidation is spatially relieved at the interfaces in the silicon oxide bulk film through the interfacial transition layers, which is inevitably important for the strain-relief mechanism.

In this study, we designed and fabricated a multilayer Laue lens (MLL) as a hard X-ray focusing device. MOSi2 and Si were chosen to form the layers by DC magnetron sputtering owing to their superior properties. The optical properties of the MLL were measured at BL24XU of SPring-8 for 20-keV X-rays. In order to confirm the effect of dynamical diffraction, far-field diffraction images were captured at various incidence angles and depths. The resultant intensity distributions showed a similar structure to those derived through calculations. An almost diffraction-limited size of 28.2 nm was obtained. The maximum local diffraction efficiency was 64.7%. (C) 2008 The Japan Society of Applied Physics

We have investigated the crystallinity of compositionally graded SiGe layers of strained Si (s-Si) wafers in the growth direction by irradiating, a synchrotron X-ray microbeam with a high parallelism on a cross section of s-Si wafers. As a result. we can confirm the presence Of Surface parallel SiGe lattice rotation and lattice rotation distribution (LRD). The Surface parallel LRD and relaxation ratio of SiGe start to decrease in the depth direction below approximately 3 put from the wafer surface. It is inferred that the insufficient relaxation of SiGe near the Wafer Surface is caused by the characteristics of the free wafer surface. Furthermore. such characteristics are thought to lead to a reduction in LRD near the wafer Surface.

A thin silicon nanooverlayer (SNOL) fabricated by oxidation and etch-back in a Separation by IMplantation of OXygen wafer was investigated by grazing incident X-ray diffraction at incident angles between 0.01° and 0.1° below the critical angle of total reflection (0.18°). We measured {220} reflections by probing the sample with respect to surface normal and found that the SNOL has finite domains under strain close to the surface. We also found that annealing the sample up to 1000°C significantly reduced inhomogeneous strain and increased the size of the domains in the surface region of the SNOL.

Using an X-ray reflectivity method we estimated the density of several Diamond-Like carbon (DLC) films. Those films were about 100-nm-thick and formed on Si substrates by Gas-Cluster Ion Beam assisted (GCIB), RF-plasma-CVD (RF), ECR-plasma-CVD (ECR), ion plating (IP) and filtered-cathodic-vacuum-arc (FCVA) deposition methods. The X-ray reflectivity measurement using a conventional X-ray source revealed that the average density values of the GCIB and FCVA DLC films were larger than 2.7 g/cm(3), while those of other samples were less than 2.1 g/cm(3). We also performed the X-ray reflectivity measurement using a highly parallel X-ray microbeam, formed from synchrotron X-rays, of 2.0 mu m x 2.5 mu m in size which is about two orders of magnitude smaller than the conventional X-ray probe. The X-ray microbeam enables us to evaluate a local fluctuation of the film density and the thickness with a spatial resolution of the probe size. It is revealed that the density of some DLC films varies abruptly near the interface on a Si substrate. (c) 2007 Elsevier B.V. All rights reserved.

Tornographic quantitative phase measurement has been carried out by using a hard X-ray micro-interferometer in Hyogo-ID at SPiing-8. The micro-interferometer combines an imaging microscope and a wavefront-div is i on- type interferometer by using a novel optical element called a "Min zone plate." A three-dimensional quantitative phase distribution of a glass capillary with an outer diameter of 6 mu m was successfully obtained with the tornographic technique. The measured refractive index corresponded to the ideal value. The spatial resolution of the tornographic image was estimated to be 250 nm and the density resolution was estimated to be 0.6 g/CM3. (c) 2007 Elsevier B.V All rights reserved.

Real-time observation of InP nanowire formation was performed using grazing incidence small angle x-ray scattering (GISAXS). Prior to the nanowire growth gold colloidal particles were spread on the substrate as the catalyst and annealed at 500 °C. Changes of GISAXS images were clearly observed after annealing, suggesting the formation of molten metal droplets, which were used for nanowire growth. After staring the growth little change except for the increase of GISAXS intensity was observed, suggesting that x-ray scattering from nanowires overlapped with that from the catalysts. From the GISAXS images calculated using a sphere and cylinder model, scattering from the nanowires shows the streak along the qydirection, and that from droplets shows an increase of intensity around the specular reflection, which qualitatively explains the measured GISAXS image after the growth. © 2007 IOP Publishing Ltd.

Interfacial structure of laminated polyethylene (PE)/polypropylene (PP) films was investigated by synchrotron X-ray microbeam. The X-ray microbeam (0.9 mu m (vertical) x 1.7 mu m (horizontal)) formed using a phase zone plate was irradiated on the cross-section of the laminated films. In order to irradiate X-ray microbeam in the direction perpendicular to the cross-section of the film sample, adjustment of the sample setting was performed by Thomson scattering method. The Thomson scattering intensity is proportional to the number of the irradiated electrons, so the irradiated position of the X-ray microbeam could be determined from the intensity profile with high spatial resolution. By changing the sample position, diffraction patterns could be obtained from the laminated films across the PE/PP interfacial region. The thickness of the interfacial region of the annealed laminate was estimated as 5 mu m judging from the changes of the diffraction intensities from the PE crystallites to the PP ones. The interfacial thickness depended on the thermal treatment of the film. It was found that the adhesion strength of the PE/PP laminate increased with increasing the interfacial thickness. Both of PE and PP chains entangled each other during laminate processing. The entangled molecular chains play important role as anchoring effect at the PE/PP interdiffusion region. However, the phase separation progressed with further crystallization by annealing. Thus, the adhesion strength of the PE/PP laminate was considered to be influenced by the interfacial thickness.

The average and-local lattice structures of a strained-Si layer and a SiGe layer epitaxially grown on a [001]-oriented Si wafer are evaluated by means of high-resolution X-ray diffractometry using a usual X-ray beam and a highly parallel synchrotron Xray microbeam. Lattices in the constant composition of the SiGe (CC) layer are greatly disarranged mainly due to an anisotropic lattice tilt feature with respect to the [110] and [110] directions in the surface plane. Although the crystallinity of the strained-Si layer was found to follow directly that of lattice tilt variations in the CC layer, the lattice parameter of the strained-Si layer still has the expected value.

A hard X-ray nano-interferometer using two types of zone plate has been developed. One is an ordinary zone plate for a microscope objective, and the other is a newly designed zone plate called an "annular zone plate" for configuring reference waves. We have succeeded in producing interference fringes with variable periods up to a fringeless pattern. The phase-shift distribution of polystyrene microparticles could be imaged clearly with a spatial resolution of 60 nm and a phase sensitivity of lambda/40 at a photon energy of 8 keV. Furthermore, this interferometer was applied to phase tomography for high-spatial-resolution three-dimensional observation.

An X-ray microbeam with a small angular divergence and a narrow energy bandwidth has been produced at BL24XU at SPring-8. The beam size was measured to be 3.1 μm and 1.6 μm in the horizontal and vertical directions, respectively, and the horizontal angular divergence was 4.0 arcsec. Using this microbeam the crystallinity estimation of thin layers on silicon-on-insulator (SOI) wafers is demonstrated. In reciprocal-space maps the lattice tilt variations were 80 arcsec and more than 220 arcsec in the SOI layers on bonded and SIMOX wafers, respectively. In equi-tilt maps, the typical equi-tilt areas of the SOI layers were 7 μm and 4 μm in size on the bonded and SIMOX wafers, respectively. © 2006 International Union of Crystallography Printed in Great Britain - all rights reserved.

Interfacial structure of laminated polyethylene (PE) /polypropylene (PP) films was investigated by synchrotron X-ray microbeam. The X-ray microbeam (0.9 mu m (vertical)) formed using, a phase zone plate was irradiated on the cross-section of the laminated films. In order to irradiate X-ray microbeam in the direction perpendicular to the cross-section of the film sample, adjustment of the sample setting was performed by Thomson scattering method. By changing the sample position, diffraction patterns could be obtained from the laminated films across the PE/PP interfacial region. The thickness of the interfacial region of the annealed laminate was estimated as 5 mu m judging from the changes of the diffraction intensities from the PE crystallites to the PP ones. The interfacial thickness depended on the thermal treatment of the film. It was found that the adhesion strength of the PEW laminate increased with increasing the interfacial thickness. Both of PE and PP chains entangled each other during laminate processing. The entangled molecular chains play important role as anchoring effect at the PE/PP interdiffusion region. However, the phase separation progressed with further crystallization by annealing. Thus, the adhesion strength of the PE/PP laminate was considered to be influenced by the interfacial thickness.

A thin silicon nano-overlayer (SNOL) fabricated by oxidation and etchback in a separation by implantation of oxygen wafer was investigated by grazing incident x-ray diffraction at incident angles between 0.01 degrees and 0.1 degrees below the critical angle of total reflection (0.18 degrees). We measured {220} reflections by probing the sample in depth and found that the SNOL has finite domains under strain close to the surface. We also found that annealing the sample up to 1000 degrees C significantly reduced inhomogeneous in depth strain and increased the size of the domains in the surface region of the SNOL. (c) 2005 American Institute of Physics.

Indium phosphide (InP) nanowires epitaxially grown on InP (111)B were investigated by using grazing incidence x-ray diffraction. A broad scattering at the tail of InP (2 (2) over bar0) diffraction and an additional peak at the low angle side were observed, showing the formation of nanowires and alloys of the gold catalysts and indium. Scattering intensity along the [1 (1) over bar0] direction was compared with calculations based on a cylinder model. The best fit was obtained for a 5.5-nm radius with a 2.5-nm deviation, which was smaller than the values determined from the secondary electron microscopy and photoluminescence spectroscopy measurements. This result is explained by an oxide layer on the nanowire sidewalls and the low quantum efficiency of photoluminescence yields for small nanowires since x-ray diffraction directly detects crystalline structure of nanowires. (C) 2005 American Institute of Physics.

Fractional -order X-ray reflection profiles of (2 x 1)-InP(001) have been observed for the first time during step-flow growth of metalorganic chemical vapor deposition. Changes of the profiles have revealed that the coverage of (2 x 1) structures during the growth depends on the flow rates of indium and phosphorus sources. After stopping the growth, a slow recovery of peak intensity was observed with a time constant of lager than 1 min which corresponds to the residence time of indium atoms on the surface.

A new and simple idea for scanning differential-phase-contrast (S-DPC) hard X-ray microscopy has been proposed. It only uses a wedge absorber coupled with two intensity detectors, and is much more sensitive to sample structures than absorption contrast. It can also extract pure quantitative one-dimensional phase gradient given by a sample without an effect of sample absorption. The S-DPC microscope has been constructed at BL24XU of SPring-8, and its feasibility has been successfully demonstrated at the photon energy of 10keV by clearly visualizing structures of samples. Further, the experimental phase gradient profile agrees well with simulation. By integrating the resultant phase gradient, the corresponding phase shift distribution could be also imaged.

With the aim towards high-spatial-resolution phase measurement, a novel hard X-ray micro-interferometer using an imaging microscope has been proposed and constructed at Hyogo-BL of SPring-8. It is a wavefront-division-type interferometer consisting of a twin zone plate arranged in the same plane. We have succeeded in producing good interference fringes with a visibility of as high as 60% at the photon energy of 9 keV. The fringe scanning method was applied to retrieve phase-shift distribution of a sample. The phase-shift distribution. of a 75-mum-thick kapton film and polystyrene microparticles could be imaged clearly with a spatial resolution of 160 nm and the obtained phase shift agreed well with the expected value.

We have characterized superstructures of thiacyanine J aggregates in aqueous electrolyte solution in the dye concentration range between 2.5 and 80 mM. Fluorescence microscopy, polarized-light microscopy, and atomic force microscopy proved that the individual thiacyanine J aggregate possessed a mesoscopic rectangular sheetlike morphology (similar to3-7 mum wide and similar to10-30 mum long) consisting of a two-dimensional monomolecular layer of molecules. Synchrotron small-angle X-ray scattering revealed the superstructure of oriented monomolecular sheets which shows a disordered (nematic-like) or an ordered (smectic) layer alignment in solution. These superstructural behaviors can be interpreted in terms of the packing or alignments of the mesoscopic monomolecular sheets of the J aggregate as a function of the dye concentration.

Measurement of real-time rocking curves of semiconductor heterostructures at various stages of metal organic vapor epitaxy (MOVPE) process may provide useful informations about the composition, thickness and in-built strain in the growing epilayer. In this study, we have used a previously grown lattice-matched GaInP/GaAs heterostructure as the reference substrate on which Ga(x)ln(1-x)P epilayers of different composition and thickness were successively grown by MOVPE while recording rocking curves of each layer in real-time during the growth by using synchrotron X-ray source. Strain redistribution at the interface of the GaInP/GaAs substrate due to the different linear thermal expansion coefficients of GaInP and GaAs was determined from rocking curve of the heterostructure measured at 570 degreesC. We could detect the change in rocking curve due to the growth of as thin as 16 nm of In-rich Ga0.42In0.58P epilayer at the initial stage of growth. Data from the simulation of each intermediate rocking curve during growth was systematically used to grow a lattice-matched GaInP epilayer. We believe, this is the first report of measurement of rocking curves at high temperature and during MOVPE growth of GaxIn1-xP. (C) 2003 Elsevier Science B.V. All rights reserved.

Step-terrace structures on MOVPE grown InP(001) surface were investigated by using grazing X-ray scattering. After buffer layers were formed on the substrate, X-ray scattering profiles were measured in the same chamber without exposing the sample to air. Small peaks were observed at the tail of the specular reflections, suggesting the in-plane periodicity of surface morphology. The azimuth angle dependence of peak position suggests a one-dimensional structure on the surface, and considering the AFM images of the sample, the bunched step-terrace structure toward [100] is the reason of this structure. Analyses based on a simple grating approximation shows the period of the one-dimensional structure is about 550 nm, which is consistent with the spacing value determined from AFM images. (C) 2003 Elsevier Science B.V. All rights reserved.

The structure of vertical InP nanowires on InP (111)B were investigated using grazing incidence X-ray diffraction and grazing incidence small angle X-ray scattering. The size distribution of the nanowires was evaluated from the diffuse scattering at (22¯0) diffraction and analyzed using a cylinder model. The average diameter was about 15 nm, which was 10 nm smaller than that in the SEM observation. This can be explained by an oxide layer on the nanowire's sidewall. Nanowire height was investigated using grazing incidence small angle X-ray scattering. Sharp streaks along the horizontal axis were observed, suggesting the formation of nanowires with uniform height. Form the distance between streaks, the average height of the nanowires was determined and the length of nanowires was estimated to be about 700 nm, which was consistent with the SEM observation.