Adachi-ku, Japan
Adachi-ku, Japan

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Tajima F.,Yokohama National University | Nishiyama Y.,Yokohama National University | Hiroi N.,Namiki Precision Jewel Co. | Hiroi N.,NEC Corp | Hashimoto Y.,Adamant Kogyo Co.
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2010

A plane-polarized laser wave with a wavelength of 441.6 nm illuminates a cladding optical fiber with a diameter of about 18 to 38 μm at normal incidence. A measured angular distribution of the intensity of the scattered wave corresponds well with the differential cross section of a rigorous theoretical calculation of a coaxial double cylinder over a wide range of scattering angle. The diameter and refractive index of the cladding and core of the illuminated part of a fiber have been determined accurately for each uncertainty. © 2009 Optical Society of America.

Richard P.,CAS Institute of Physics | Sato T.,Tohoku University | Souma S.,Tohoku University | Nakayama K.,Tohoku University | And 6 more authors.
Applied Physics Letters | Year: 2012

We performed an angle-resolved photoemission spectroscopy study of Si-doped β Ga2O3. We observed very small photoemission intensity near the Fermi level corresponding to non-dispersive states assigned to Si impurities. We show evidence for a quantization of these states that is accompanied by a confinement in the momentum space consistent with a real-space finite confinement observed in a previous scanning tunneling microscopy study. Our results suggest that this semi-localization in the conjugate spaces plays a crucial role in the electronic conduction of this material. © 2012 American Institute of Physics.

Iwaya K.,Tohoku University | Shimizu R.,Tohoku University | Aida H.,Namiki Precision Jewel Co. | Hashizume T.,Tohoku University | And 2 more authors.
Applied Physics Letters | Year: 2011

The electronic states of silicon donors in a wide gap semiconductor, β-Ga2O3 (100), have been studied using low-temperature scanning tunneling microscopy. We observe one-dimensional rows along [010], as expected from the crystal structure. In addition, substitutional Si donors are identified up to the fourth subsurface layer with clear spectroscopic features at the bottom of the conduction band. The decay length of each subsurface Si donor is systematically measured, and reasonably agrees with a picture of the Si donor in bulk β-Ga2O3. These results strongly suggest that Si impurities are shallow donors and responsible for the high electrical conductivity of β-Ga2O3. © 2011 American Institute of Physics.

Uneda M.,Kanazawa Institute of Technology | Uneda M.,Kyushu University | Maeda Y.,Kanazawa Institute of Technology | Ishikawa K.-I.,Kanazawa Institute of Technology | And 4 more authors.
Journal of the Electrochemical Society | Year: 2012

In chemical mechanical polishing (CMP) process, the removal rate is affected by the actual contact conditions between the wafer and the polishing pad. Further, the free abrasives in the slurry attack the wafer at the regions of actual contact. The polishing pad is one of the most important consumable materials in CMP since the pad surface texture changes during wafer polishing and substantially influences the actual contact conditions. Therefore, methods for quantitative evaluation of the pad surface texture have been proposed by various research institutes. We have developed a novel method for the quantitative evaluation of the polishing pad surface texture; this method is based on contact image analysis using an image rotation prism. We have proposed the use of four effective evaluation parameters: the number of contact points, the contact ratio, the maximum value of the minimum spacing of the contact points, and the half-width of the peak of the spatial fast Fourier transform (FFT) of a contact image. We determine the changes in the polishing pad surface texture on the basis of the proposed evaluation parameters in serial batch polishing tests. In particular, we focus on the relationships between the proposed evaluation parameters and the removal rate, which changes with an increase in the number of batch polishing tests. The evaluation parameters are linearly correlated with the removal rate. Hence, the removal rate is improved not only with an increase of the number of contact points and the contact ratio but also with a decrease in the size of the cohesion regions and the spacing between the contact points. © 2011 The Electrochemical Society.

Aida H.,Namiki Precision Jewel Co. | Aida H.,Kyushu University | Kim S.-W.,Namiki Precision Jewel Co. | Suzuki T.,Nippon Institute of Technology | And 4 more authors.
ECS Journal of Solid State Science and Technology | Year: 2014

The possibility of chemical mechanical polishing (CMP) as an intermediate ex-situ surface planarization process for thin-film epitaxy devices has been investigated. The surface quality of the homoepitaxial GaN after a surface pretreatment of CMP on the GaN-on-sapphire template drastically improved as compared to that with the regular homoepitaxial process. In addition, it was found that CMP contributed to a reduction in the dislocation densities in the subsequent homoepitaxial GaN layers. The CMP-treated GaN surface exhibited pits, with an average diameter of 0.3 μm, due to the chemical etching effect of the CMP slurry. These pits are thought to enhance the epitaxial lateral over growth of the GaN thin films, leading to a reduction in the dislocation densities in the homoepitaxial GaN layers. © 2014 The Electrochemical Society.

Aota N.,Namiki Precision Jewel Co. | Aida H.,Namiki Precision Jewel Co. | Kimura Y.,Namiki Precision Jewel Co. | Kawamata Y.,Namiki Precision Jewel Co. | Uneda M.,Kanazawa Institute of Technology
ECS Journal of Solid State Science and Technology | Year: 2014

Patterned sapphire substrate (PSS) was fabricated by wet etching solutions with different mixture ratios of H2SO4 to H 3PO4 and different temperatures to investigate the fabrication mechanisms. It was found that the mixture ratio and temperature of the etching solutions affect the ratio of the pattern diameter to the pattern depth. In addition, the observed pattern shape was strongly affected by the mixture ratio. To discuss the reaction mechanisms of sapphire with H 2SO4 and H3PO4 separately, we estimated the activation energies and reaction frequency factors for each reaction. By the estimated results, the behavior of the observed pattern shape for the etching conditions was well explained. To confirm the fabrication mechanism of pattern shape in the microscopic scale, the electron probe microanalysis (EPMA) inspection of the sapphire surface after H 2SO4 and H3PO4 etching were carried out. As a result, it was indicated that the pattern shape is controlled by the step flow reaction with and without impurities in the etching solutions. From the observation of the pattern shape, the estimation of the activation energies and reaction frequency factors, and EPMA inspection of the reaction products for each reaction, a schematic model of the fabrication mechanisms for the wet etching of a PSS was established. © 2014 The Electrochemical Society.

Aida H.,Namiki Precision Jewel Co. | Doi T.,Kyushu University | Takeda H.,Namiki Precision Jewel Co. | Katakura H.,Namiki Precision Jewel Co. | And 4 more authors.
Current Applied Physics | Year: 2012

Chemical mechanical polishing (CMP) of sapphire, GaN, and SiC substrates, which are categorized as hard-to-process materials, is demonstrated with a colloidal silica slurry under acidic and alkaline slurry pH conditions. Atomic level surface flatness was achieved by CMP and was confirmed to be equivalent to an almost ideally minimized surface roughness. By comparing the Preston coefficients under different slurry conditions, differences in the CMP properties among the three substrate materials and difficulties in the CMP of the GaN and SiC substrates are presented. The difference in CMP properties between the (0001) and (000-1) planes of GaN and SiC due to their non-revers crystallographical symmetry is also presented. Oxidation processes that occur during CMP of GaN and SiC are also discussed. By comparing the removal rate among GaN, SiC, and their oxides, it was found that the rate-limiting step in the total CMP process for GaN and SiC was surface oxidation reaction of GaN and SiC. © 2012 Elsevier B.V. All rights reserved.

PubMed | Osaka University, Namiki Precision Jewel Co., Tokyo Institute of Technology and Toshima Manufacturing Co.
Type: | Journal: Scientific reports | Year: 2015

Thin-film epitaxy is critical for investigating the original properties of materials. To obtain epitaxial films, careful consideration of the external conditions, i.e. single-crystal substrate, temperature, deposition pressure and fabrication method, is significantly important. In particular, selection of the single-crystal substrate is the first step towards fabrication of a high-quality film. Sapphire (single-crystalline -Al2O3) is commonly used in industry as a thin-film crystal-growth substrate, and functional thin-film materials deposited on sapphire substrates have found industrial applications. However, while sapphire is a single crystal, two types of atomic planes exist in accordance with step height. Here we discuss the need to consider the lattice mismatch for each of the sapphire atomic layers. Furthermore, through cross-sectional transmission electron microscopy analysis, we demonstrate the uniepitaxial growth of cubic crystalline thin films on bistepped sapphire (0001) substrates.

Namiki Precision Jewel Co. | Date: 2014-08-27

A bending device to bend a flexible tube from inside electrically includes an electric actuator to drive a movable shaft electrically along the longitudinal direction of the tube in the axial direction and in the rotational direction, and an elongated member of which one end is connected to the movable shaft and the other end is connected to the inner surface of the tube at the location distanced, in the longitudinal direction of the tube, from the connecting point connecting the one end of the elongated member and the movable shaft, the connecting point connecting the one end of the elongated member and the movable shaft being located eccentric to the center of the movable shaft so that the towing direction of the elongated member towed by retreating the movable shaft changes along the circumferential direction by rotation of the movable shaft.

ADAMANT Co. and Namiki Precision Jewel Co. | Date: 2015-05-14

Printed circuit boards made of low temperature co-fired ceramics; printed wiring boards made of low temperature co-fired ceramics; circuit board embedded with micro electro mechanical systems; packages for semiconductor integrated circuits, packages for electronic and electric components; measuring or testing machines and instruments; electric or magnetic meters and testers; telecommunication machines and apparatus; electronic machines, apparatus and their parts.

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