Oyo Buturi
Online ISSN : 2188-2290
Print ISSN : 0369-8009
Volume 88, Issue 5
OYO-BUTURI Vol.88 No.5
Displaying 1-13 of 13 articles from this issue
Science As Art
Editors' Summary
Comprehensive Research Report
  • Aerosol deposition (AD) method
    Jun AKEDO
    2019 Volume 88 Issue 5 Pages 317-327
    Published: May 10, 2019
    Released on J-STAGE: September 20, 2019
    JOURNAL FREE ACCESS

    Coating processes that are thought to utilize purely collision pressure or impact force such as the aerosol deposition (AD) method or cold spray (CS) method are attracting attention. These accelerate microparticles and ultrafine particles via a carrying gas at several hundred m/sec or more, turning them into a jet stream and colliding them with the substrate, to realize a dense coating with good adhesion just by supplying a purely mechanical energy. It is thought that fine particles of metals and ceramics are macroscopically bonded at room temperature while remaining in a nearly solid state. In fact, it has been confirmed that, with the aerosol deposition method, it is possible to form a dense ceramic thin film or a thick film having a microcrystal structure of several tens of nanometers or less at room temperature and to obtain excellent electromechanical properties. Thus, in the field of semiconductor manufacturing equipment, it has been commercialized as an important coating process. This is called "Room Temperature Impact Consolidation (RTIC)". When viewed as a powder forming process, this phenomenon is fundamentally different from a thermal spray coating and shock compaction in which raw material particles are brought into a molten or semi-molten state to obtain bonding between primary particles. In this presentation, the deposition mechanism of the AD process with the RTIC phenomenon and the importance of this phenomenon for the future of coating technology are explained.

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Tutorial
  • Toshinori MATSUSHIMA
    2019 Volume 88 Issue 5 Pages 328-333
    Published: May 10, 2019
    Released on J-STAGE: September 20, 2019
    JOURNAL FREE ACCESS

    Here I will review recent research trends for light-emitting diodes (LEDs) with metal halide perovskites as an emitter. Metal halide perovskite films can be fabricated by easy processes such as spin coating and vacuum deposition and have high charge carrier mobility and sharp emission spectra with color tunability. By taking these advantages inherent from both organic and inorganic semiconductors, metal halide perovskites can hold promise for display applications. Initially, perovskite LEDs showed electroluminescence only at low temperatures. Systematic optimization of the perovskite fabrication conditions and LED architectures by many researchers have increased the electron-to-photon conversion efficiencies to >20% even at room temperature.

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  • Masashi YOSHIMURA
    2019 Volume 88 Issue 5 Pages 334-340
    Published: May 10, 2019
    Released on J-STAGE: September 20, 2019
    JOURNAL FREE ACCESS

    Deep-ultraviolet coherent light with a wavelength conversion method that combines infrared solid-state lasers and non-linear optical crystals has been widely used as a light source for inspecting semiconductor photo masks and wafers. Also, in recent years, in order to be used in laser processing applications for material with poor workability, such as glass composite substrates and carbon fiber reinforced plastics, the output power of the light source has become more powerful. Crystals used at the final stage of the wavelength conversion are a particularly critical element to determine the output and life of the light source. The author has been involved for a long time in researching CsLiB6O10 (CLBO), a borate crystal, which has superior deep-ultraviolet light conversion properties. This article explains this field, while chronologically looking back at the development of its cultivation technology, the implementation of industrial deep-ultraviolet lasers and recent efforts.

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Our Research
  • Takayuki KOMATSU, Toshinori TAISHI, Takahiro KOJIMA, Masahiro SASAURA
    2019 Volume 88 Issue 5 Pages 341-345
    Published: May 10, 2019
    Released on J-STAGE: September 20, 2019
    JOURNAL FREE ACCESS

    KTN crystals have a significantly large Kerr effect that enables them to be commercialized for optical beam deflectors and varifocal lenses. The deflector is the key part of a swept light source, which is applied to OCT for medical use and position measurement systems for construction use.

    KTN single crystal growth is not an easy task. TSSG is the current mainstream growth method, however, it has problems in mass production. To meet the requirements of mass production, we have been examining the vertical Bridgman method and succeeded in the growth of high quality KTN single crystals by integrating it together with continuous raw material supply technology.

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  • Yuji MASUBUCHI
    2019 Volume 88 Issue 5 Pages 346-350
    Published: May 10, 2019
    Released on J-STAGE: September 20, 2019
    JOURNAL FREE ACCESS

    Novel synthesis methods for perovskite-type oxynitrides without the use of gaseous ammonia are reported in this review. The direct synthesis of SrTaO2N was performed from a mixture of SrCO3 and Ta3N5 below 1000°C under flowing nitrogen. The oxynitride was also obtained from an SrTaO3.5 precursor oxide using C3N4 as both the reduction and nitridation source at 800°C, which is 200°C lower than that required for ammonia nitridation reaction.

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  • Hajime SHIRAI, A.T.M. Saiful ISLAM, Ryo ISHIKAWA
    2019 Volume 88 Issue 5 Pages 351-355
    Published: May 10, 2019
    Released on J-STAGE: September 20, 2019
    JOURNAL FREE ACCESS

    We have investigated solution-processed n-type silicon (n-Si) heterojunction solar cells with a transparent hole-conducting polymer PEDOT:PSS. PEDOT:PSS/n-Si solar cells showed a power conversion efficiency (PCE) of 13〜14% (11〜12%) for a 2×2 cm2 (4 inch) size device. Solar cell modules consisting of ten units of series-connected 2×2 cm2 (4 inch) sized cells, exhibited an output power of 0.37W (7.3W). The junction property at the PEDOT:PSS/n-Si interface was also monitored for varying donor concentrations of n-Si using the current-voltage, capacitance-voltage, Kelvin-probe, and the photoemission yield characterizations. The carrier transport at the PEDOT:PSS/n-Si heterojunction is mainly determined by the diffusion of the minority carrier, which suggests that the PEDOT:PSS/n-Si junction forms a p+n-junction.

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Fundamental Lecture
  • “OYO BUTURI” Editorial Committee
    2019 Volume 88 Issue 5 Pages 356
    Published: May 10, 2019
    Released on J-STAGE: September 20, 2019
    JOURNAL FREE ACCESS
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  • Kohji HOSOKAWA
    2019 Volume 88 Issue 5 Pages 357-361
    Published: May 10, 2019
    Released on J-STAGE: September 20, 2019
    JOURNAL FREE ACCESS

    AI had made incredible progress recently. It is widely recognized that AI is driving a new era of computing with the generation of a wide variety of applications. It is clear that the recent success of AI is due to the combination of big data, algorithmic advances and hardware improvement. However, the hardware has faced challenges due to the limits of Moore's law. Conventional CPUs may not be able to cope with the growing workload of AI. In response to this AI demand, there are emerging hardware technologies to accelerate AI computation. One is the so-called AI chip. The chip architecture as well as the technology trends for these promising hardware developments are explained.

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