Yamada, Junpei

写真a

Affiliation

Graduate School of Science and Technology (Yagami)

Position

Project Assistant Professor (Non-tenured)/Project Research Associate (Non-tenured)/Project Instructor (Non-tenured)
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Career 【 Display / hide 】

  • 2017.04
    -
    2020.03

    名城大学, 理工学部, 特任助手

  • 2020.05
    -
    2023.03

    上智大学, ナノテクノロジーセンター, 特別研究員

  • 2023.04
    -
    Present

    慶應義塾大学, 理工学研究科, 特任助教

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Research Areas 【 Display / hide 】

  • Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Electric and electronic materials

  • Nanotechnology/Materials / Nanomaterials

  • Nanotechnology/Materials / Crystal engineering

  • Nanotechnology/Materials / Optical engineering and photon science

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Research Keywords 【 Display / hide 】

  • グラフェン

  • ナノカーボン

  • 光デバイス

  • GaN

  • 窒化物半導体

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Papers 【 Display / hide 】

  • Improving the luminous efficiency of red nanocolumn μ-LEDs by reducing electrode size to ϕ2.2 μm

    Katsumi Kishino, Ai Mizuno, Tatsuya Honda, Jumpei Yamada, Rie Togashi

    Applied Physics Express (IOP Publishing)  17 ( 1 ) 014004 - 014004 2023.12

    Lead author, Corresponding author,  ISSN  1882-0778

    　View Summary

    Abstract

    A red InGaN-based nanocolumn micro μLED with an emission diameter of ϕ2.2 μm was demonstrated to achieve an on-wafer external quantum efficiency (EQE) of 2.1% at the peak wavelength of 615 nm. The LED was fabricated by repeating the electrode process on the same nanocolumn pattern area and reducing the emission diameter from ϕ80 to ϕ2.2 μm. The peak EQE, which was maximized at ∼25 A cm<sup>−2</sup>, increased by decreasing the emission diameter from 1.2% to 2.1%. This behavior, which differs from that of InGaN-film LEDs, is characterized as a unit of independent nano-LEDs with passivated sidewalls of nanocolumn LEDs.

  • InGaN/GaN superlattice underlayer for fabricating of red nanocolumn μ-LEDs with (10-11) plane InGaN/AlGaN MQWs

    Jumpei Yamada, Ai Mizuno, Tatsuya Honda, Keigo Yoshida, Rie Togashi, Ichirou Nomura, Tomohiro Yamaguchi, Tohru Honda, Katsumi Kishino

    Nanotechnology (IOP Publishing)  34 ( 43 ) 435201 - 435201 2023.08

    Lead author,  ISSN  0957-4484

    　View Summary

    Abstract

    In this study, the growth behavior of Indium gallium nitride (InGaN)-based nanocolumn arrays was investigated, and red emission nanocolumn micro-light emitting diodes (μ-LEDs) were fabricated. The internal structure of the InGaN/GaN superlattice (SL) layer under the multiple-quantum-well (MQW) active layers was evaluated using scanning transmission electron microscopy (STEM) analysis. It was revealed that the InGaN crystal plane at the top of the nanocolumn changed from the c-plane, (1-102) plane, to the (10-11) plane as the number of SL pairs increased. A semipolar (10-11) plane was completely formed on top of the nanocolumn by growing InGaN/GaN SLs over 15–20 pairs, where the InGaN/GaN SL layers were uniformly piled up, maintaining the (10-11) plane. Therefore, when InGaN/AlGaN MQWs were grown on the (10-11) plane InGaN/GaN SL layer, the growth of the (10-11) plane semipolar InGaN active layers was observed in the high-angle annular dark field (HAADF)-STEM image. Moreover, the acute nanocolumn top of the (10-11) plane of the InGaN/GaN SL underlayer did not contribute to the formation of the c-plane InGaN core region. Red nanocolumn μ-LEDs with an φ12 μm emission window were fabricated using the (10-11) plane MQWs to obtain the external quantum efficiency of 1.01% at 51 A cm<sup>−2</sup>. The process of nanocolumn μ-LEDs suitable for the smaller emission windows was provided, where the flat p-GaN contact layer contributed to forming a fine emission window of φ5 μm.

  • Effect of crystallization of Ni catalyst on direct precipitation of multilayer graphene using W capping layer

    Jumpei Yamada, Yuki Ueda, Takahiro Maruyama, Seiji Fujikawa, Takuo Sasaki, Masamitu Takahasi, Shigeya Naritsuka

    Journal of Crystal Growth (Elsevier BV)  555   125969 - 125969 2021.02

    Lead author,  ISSN  0022-0248

    　View Summary

    In recent years, graphene growth technology has been greatly progressed, and it is possible to grow graphene with millimeter-size single crystals using metal-catalysis CVD. However, the transfer process is unavoidably which largely deteriorates the graphene. We have proposed direct precipitation method of graphene using a W capping layer. The method does not only require a transfer process, but also the introduction of wrinkles will be suppressed by optimizing the cooling rate at the graphene precipitation. The growth conditions such as thickness of amorphous carbon, annealing temperature, cooling rate and crystallinity of Ni catalyst were systematically changed to study the mechanism of the precipitation method using the W cap layer. By the optimization of the conditions, wrinkle-free multilayer graphene with D/G ratio of less than 0.1 were successfully obtained directly on a sapphire substrate.

  • X-ray in situ observation of graphene precipitating directly on sapphire substrate with and without Ti capping layer

    Shigeya Naritsuka, Jumpei Yamada, Yuki Ueda, Asato Nakashima, Tatsuya Kashio, Takahiro Maruyama, Seiji Fujikawa, Takuo Sasaki, Masamitu Takahasi

    Journal of Crystal Growth (Elsevier BV)  549   125861 - 125861 2020.11

    Lead author, Corresponding author,  ISSN  0022-0248

    　View Summary

    In situ X-ray diffraction measurement was performed to study the precipitation mechanism of graphene from Ni catalyst with and without Ti capping layer using X-ray beam from a synchrotron radiation facility. The graphene precipitated on the surface of the catalyst in the case without the Ti capping layer while it did at the interface between the catalyst and the sapphire substrate in the case with the Ti capping layer. Each process, such as graphene nucleation and precipitation was successfully monitored even though graphene precipitated under the metal catalyst. The detailed mechanisms for both cases were discussed using the experimental results. Consequently, the crystallization of the catalyst is found to effectively suppress the precipitation at low temperature, which is useful to improve the quality of the precipitated graphene. The adjustment of the amount of the carbons is another important factor to precisely control the precipitation because graphene also precipitates after the carbons saturate the catalyst.

  • Precipitation of multilayer graphene directly on gallium nitride template using Tungsten capping layer

    Jumpei Yamada, Yuki Ueda, Takahiro Maruyama, Shigeya Naritsuka

    Journal of Crystal Growth (Elsevier BV)  534   125493 - 125493 2020.03

    Lead author, Corresponding author,  ISSN  0022-0248

    　View Summary

    The direct growth of graphene was investigated with precipitating graphene on a GaN template at various temperatures. In the method, a carbon source and catalyst were firstly deposited, and the sample was annealed to precipitate graphene. Tungsten capping layer was deposited on the surface to suppress the graphene precipitating to the sample surface. Consequently, the graphene was precipitated at the interface between the catalyst and the GaN template. After the removal of the catalyst, the graphene was successfully obtained on the GaN template. The Raman D/G ratio of the graphene decreased with increasing the annealing temperature. At 700 °C, fine graphene was obtained on the GaN template while maintaining the flatness and smoothness of the GaN surface. XRD and XPS measurements were also performed to investigate the precipitation of the graphene in detail.

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Reviews, Commentaries, etc. 【 Display / hide 】

  • 様々な結晶面を利用したInGaN系ナノコラム結晶の成長と発光デバイス応用

    山田純平, 水野愛, 富樫理恵, 野村一郎, 岸野克巳

    電子情報通信学会技術研究報告(IEICE Technical Report) 122 ( 273 ) 99 - 102 2022

  • 同芯型多段構造をもつグラフェン被覆銅線作製のための電解メッキ薄膜化について

    藤原 亨介, 伊藤 幹人, 上田 悠貴, 山田 純平, 成塚 重弥, 丸山 隆浩

    名城大学総合研究所紀要  ( 24 ) 29 - 32 2019

  • 減圧窒素マイクロプラズマ処理における処理圧力とプラズマ到達距離との関係

    杉山 隼大, 日下部 安宏, 竹中 駿, 上田 悠貴, 山田 純平, 丸山 隆浩, 成塚 重弥

    名城大学総合研究所紀要  ( 23 ) 45 - 48 2018

  • グラフェン析出成長法における酸化アルミニウムバリア層を用いた核発生制御

    成塚重弥, 山田純平, 上田悠貴, 丸山隆浩

    名城大学総合研究所紀要  ( 22 ) 41 - 44 2017

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Intellectual Property Rights, etc. 【 Display / hide 】

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Awards 【 Display / hide 】

  • JSAP Poster Award

    山田 純平, 2023.05, 第70回応用物理学会春季学術講演会

  • 発表奨励賞

    山田 純平, 2021.12, 第13回ナノ構造・エピタキシャル成長講演会

  • 学長表彰

    山田 純平, 2020.03, 名城大学

  • Poster Award

    Jumpei Yamada, 2019.08, 19th International Conference on Crystal Growth and Epitaxy

  • 若手ポスター賞

    山田純平, 2015.09, 第39回 結晶成長討論会

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