Oyo Buturi
Online ISSN : 2188-2290
Print ISSN : 0369-8009
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Volume 91, Issue 4
OYO-BUTURI Vol.91 No.4
Displaying 1-16 of 16 articles from this issue
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Preface
Science As Art
Editors' Summary
Comprehensive Research Report
  • Optical Fiber : Progress in half a century and recent trend
    Hiroo KANAMORI
    2022 Volume 91 Issue 4 Pages 205-215
    Published: April 01, 2022
    Released on J-STAGE: April 01, 2022
    DOIhttps://doi.org/10.11470/oubutsu.91.4_205
    JOURNAL FREE ACCESS
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    In 1970, Kapron et. al. reported an optical fiber with a transmission loss of 20 dB/km, and a semiconductor laser continuously oscillating at room temperature was demonstrated as well. After then, technology development for optical fiber communication started in full swing. Optical fibers have been evolutionally advanced and, now, optical networks are indispensable life lines for human society.　In this report, the progress of optical fibers in half a century is reviewed, and a recent trend is also introduced.

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Recent Developments
  • Influence of alkaline metal additives for practical use of perovskite solar cells
    Taisuke MATSUI
    2022 Volume 91 Issue 4 Pages 216-219
    Published: April 01, 2022
    Released on J-STAGE: April 01, 2022
    DOIhttps://doi.org/10.11470/oubutsu.91.4_216
    JOURNAL FREE ACCESS
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    Perovskite solar cells have recently attracted great interest for next generation solar cells such as low-cost, light-weight, and/or flexible solar cells. While power conversion efficiency has reached as high as conventional widely used crystal Si solar cells, long-term stability and large area module production need to be improved for practical use. We found stability and crystal quality of perovskite films are improved by addition of small amount of alkaline metals such as Cs and Rb, which enables to achieve highly stable and large area perovskite solar cells. Here we review the effect of alkaline metal additives for lead-halide perovskite materials.

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Our Research
  • SPAD ranging sensor for automotive LiDAR system
    Yoshiaki TASHIRO, Kyosuke ITO
    2022 Volume 91 Issue 4 Pages 220-223
    Published: April 01, 2022
    Released on J-STAGE: April 01, 2022
    DOIhttps://doi.org/10.11470/oubutsu.91.4_220
    JOURNAL FREE ACCESS
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    A state of the art Back Illuminated （BI） Single Photon Avalanche Diode （SPAD） array sensor realized via a 90 nm CMOS compatible process on a 300 mm silicon platform is reported in the following. The array consists of 10 µm pixels, each using a 7 µm thick silicon active layer, which allows to extend the device’s optical sensitivity up to the Near-Infrared （NIR） spectrum. Furthermore, buried metal Full Trench Isolation （FTI） was employed to suppress crosstalk （Xtalk）,a critical feature in a device sensitive enough to be triggered by a single electro-luminescence photon emitted by a neighboring pixel. Finally, in order to maximize the Fill Factor （F.F） and allow a BI structure, a Cu-Cu bonding process was carried out.

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  • Efficient materials development utilizing the combination of thin-film growth techniques and machine learning approaches toward energy applications
    Isao OHKUBO, Masahiro GOTO
    2022 Volume 91 Issue 4 Pages 224-228
    Published: April 01, 2022
    Released on J-STAGE: April 01, 2022
    DOIhttps://doi.org/10.11470/oubutsu.91.4_224
    JOURNAL FREE ACCESS
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    Machine learning is attracting increased attention in the research field of novel materials development. Among the various material preparation methods, thin-film technology is actively used in various fundamental researches, industries, and applications for preparing thin films of various types of materials and nanostructured materials. In this article, our recent researches concerning novel materials development utilizing the combination of thin-film technologies and machine learning approaches are provided. Our methods using machine learning approaches were achieved to more efficient materials development, and would be able to be used for the exploration of novel thermoelectric materials.

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Fundamental Lecture
Inside Out
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