Junji Matsui

Crystallinity estimation of thin silicon-on-insulator layers by means of diffractometry using a highly parallel X-ray microbeam

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 microm and 1.6 microm 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 microm and 4 microm in size on the bonded and SIMOX wafers, respectively.

Formation and Growth Mechanism of Calcium Carbonate Nanoparticles via a Bubbling Method

The mechanism of formation and growth of calcium carbonate (CaCO3) nanoparticles by bubbling carbon dioxide in aqueous suspensions of calcium hydroxide was investigated using time-resolved in situ synchrotron small-angle X-ray scattering (SAXS) and transmission electron microscopey (TEM). In situ SAXS showed a significant change in the particles size in the primary reaction. This suggests that the nucleus forms CaCO3 at in this period. After the nucleation, the crystal grow with the reaction time to yield 40 nm CaCO3 nanoparticles. TEM showed fibrous or chain-like intermediates formed by aggregation of fine particles of CaCO3 as calcite. We propose that CaCO3 crystal nuclei generated in the primary reaction grow to yield fibrous or chain-like CaCO3 which then separates into individual particles to form CaCO3 nanoparticles.

High-resolution X-ray Microdiffraction System for Characterization of Selectively Grown Layers using a Zone Plate Combined with a Narrow Slit

We have developed a high‐resolution x‐ray microdiffraction system at the BL24XU of the SPring‐8. This system uses a focused beam produced by using a zone plate combined with a narrow slit. The size of the focused beam is 0.32 μm vertically and 1.3 μm horizontally and the angular divergence in the horizontal direction is about 70 μrad at a photon energy of 15 keV. This low‐divergence microbeam enables us to perform high‐resolution x‐ray microdiffraction experiments using a precise θ‐2θ goniometer with sub‐100‐nm‐resolved XYZ sample positioning stages. We demonstrate that the spatial non‐uniformity of the strain and the period in InGaAsP multi‐quantum‐well structures, fabricated by selective metalorganic‐vapor‐phase epitaxy, can be measured with sufficient accuracy using this system.

Crystallinity Investigation of Compositionally Graded SiGe Layers by Synchrotron X-ray Cross-Sectional Diffraction

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 ?m 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.

Live X‐Ray Refraction Imaging Using Vertically and Horizontally Wide X‐Rays

Since the synchrotron X‐rays are intense enough even after the sequential expansion of the X‐ray beam by successive asymmetric Bragg reflections, live refraction images of internal structure for biological materials can be seen on an X‐ray image sensor. Video images of some living insects or a frog or a mouse show clearly their internal structures of the body, for instance, cellular structures in a lung.

Crystallinity estimation of area-selective Ge epitaxial layer grown on Si substrate by means of high-resolution X-ray microdiffraction

Crystallinity of area-selective Ge layer with a (0 0 1) surface grown on Si substrate has been investigated by means of diffractometry using a parallel X-ray microbeam. The measured lattice parameters of 〈0 0 1〉 direction were about 0.17% smaller than that of bulk Ge crystal. This tensile strain value was almost the same as the simulated ones that used the finite-element method.