山田 純平 (ヤマダ ジュンペイ)

Yamada, Junpei

写真a

所属(所属キャンパス)

理工学研究科 (矢上)

職名

特任助教(有期)

経歴 【 表示 / 非表示

  • 2017年04月
    -
    2020年03月

    名城大学, 理工学部, 特任助手

  • 2020年05月
    -
    2023年03月

    上智大学, ナノテクノロジーセンター, 特別研究員

  • 2023年04月
    -
    継続中

    慶應義塾大学, 理工学研究科, 特任助教

 

研究分野 【 表示 / 非表示

  • ものづくり技術(機械・電気電子・化学工学) / 電気電子材料工学

  • ナノテク・材料 / ナノ材料科学

  • ナノテク・材料 / 結晶工学

  • ナノテク・材料 / 光工学、光量子科学

研究キーワード 【 表示 / 非表示

  • グラフェン

  • ナノカーボン

  • 光デバイス

  • 窒化ガリウム

  • 窒化物半導体

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論文 【 表示 / 非表示

  • 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年12月

    筆頭著者, 責任著者,  ISSN  1882-0778

     概要を見る

    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年08月

    筆頭著者,  ISSN  0957-4484

     概要を見る

    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 and Yuki Ueda and Takahiro Maruyama and Seiji Fujikawa and Takuo Sasaki and Masamitu Takahasi and Shigeya Naritsuka

    Journal of Crystal Growth (Elsevier {BV})  555   125969 - 125969 2021年02月

    筆頭著者,  ISSN  0022-0248

     概要を見る

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

    Journal of Crystal Growth (Elsevier {BV})  549   125861 - 125861 2020年11月

    筆頭著者, 責任著者,  ISSN  0022-0248

     概要を見る

    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 and Yuki Ueda and Takahiro Maruyama and Shigeya Naritsuka

    Journal of Crystal Growth (Elsevier {BV})  534   125493 - 125493 2020年03月

    筆頭著者, 責任著者,  ISSN  0022-0248

     概要を見る

    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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知的財産権等 【 表示 / 非表示

受賞 【 表示 / 非表示

  • JSAP Poster Award

    山田 純平, 2023年05月, 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年12月, 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年03月, 名城大学

  • Poster Award

    Jumpei Yamada, 2019年08月, 19th International Conference on Crystal Growth and Epitaxy

  • 若手ポスター賞

    山田純平, 2015年09月, 第39回 結晶成長討論会