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Engineering educational research section Applied Physics and Engineering Program |
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Professor |
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FUKUYAMA Atsuhiko
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Degree 【 display / non-display 】
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Doctor (Engineering) ( 2000.3 Tohoku University )
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Master(Engineering) ( 1993.3 University of Miyazaki )
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Bachelor ( 1991.3 University of Miyazaki )
Research Areas 【 display / non-display 】
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Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Electric and electronic materials
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Nanotechnology/Materials / Nanostructural physics
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Nanotechnology/Materials / Thin film/surface and interfacial physical properties
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Nanotechnology/Materials / Applied physical properties
Papers 【 display / non-display 】
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T. Harada, D. Ohori, K. Endo, S. Samukawa, T. Ikari, and A. Fukuyama
Journal of Applied Physics 133 125703-1 - 125703-7 2023.3
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Applied Physics
The laser heterodyne photothermal displacement (LH-PD) method was used to characterize the nonradiative recombination centers of semiconductors, such as defects and deep-lying electronic levels. When a semiconductor surface is irradiated with a modulated continuous wave laser, the irradiated area is periodically heated and expanded owing to the nonradiative recombination of the photoexcited carriers. The LH-PD can measure an absolute value of surface displacement and its time variation at various excitation beam frequencies (f e x). Si and GaAs substrate samples were used to confirm the usefulness of the proposed method. The obtained time variation of the surface displacement was well explained by theoretical calculations considering the carrier generation, diffusion, recombination, heat diffusion, and generated thermal strain. Because nonradiative carrier recombination generates local heat at defects in semiconductors, the LH-PD technique is useful for analyzing defect distributions. Additionally, measurements of intentional Fe-contaminated Si samples confirmed that this technique is suitable for defect mapping. Displacement mapping with changing f e x suggests the potential to measure the distribution of nonradiative recombination centers in the sample depth direction.
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A. Fukuyama, N. Yamamoto, R. Furukawa, M. Sugiyama, T. Ikari
Journal of Physics D: Applied Physics 56 045101-1 - 045101-9 2022.12
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Applied Physics
The laser heterodyne photothermal displacement (LH-PD) method was used to characterize the nonradiative recombination centers of semiconductors, such as defects and deep-lying electronic levels. When a semiconductor surface is irradiated with a modulated continuous wave laser, the irradiated area is periodically heated and expanded owing to the nonradiative recombination of the photoexcited carriers. The LH-PD can measure an absolute value of surface displacement and its time variation at various excitation beam frequencies (f e x). Si and GaAs substrate samples were used to confirm the usefulness of the proposed method. The obtained time variation of the surface displacement was well explained by theoretical calculations considering the carrier generation, diffusion, recombination, heat diffusion, and generated thermal strain. Because nonradiative carrier recombination generates local heat at defects in semiconductors, the LH-PD technique is useful for analyzing defect distributions. Additionally, measurements of intentional Fe-contaminated Si samples confirmed that this technique is suitable for defect mapping. Displacement mapping with changing f e x suggests the potential to measure the distribution of nonradiative recombination centers in the sample depth direction.
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T. Harada, T. Ikari T, A. Fukuyama
Journal of Applied Physics 131 ( 19 ) 195701-1 - 195701-8 2022.5
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Applied Physics
The laser heterodyne photothermal displacement (LH-PD) method was used to characterize the nonradiative recombination centers of semiconductors, such as defects and deep-lying electronic levels. When a semiconductor surface is irradiated with a modulated continuous wave laser, the irradiated area is periodically heated and expanded owing to the nonradiative recombination of the photoexcited carriers. The LH-PD can measure an absolute value of surface displacement and its time variation at various excitation beam frequencies (f e x). Si and GaAs substrate samples were used to confirm the usefulness of the proposed method. The obtained time variation of the surface displacement was well explained by theoretical calculations considering the carrier generation, diffusion, recombination, heat diffusion, and generated thermal strain. Because nonradiative carrier recombination generates local heat at defects in semiconductors, the LH-PD technique is useful for analyzing defect distributions. Additionally, measurements of intentional Fe-contaminated Si samples confirmed that this technique is suitable for defect mapping. Displacement mapping with changing f e x suggests the potential to measure the distribution of nonradiative recombination centers in the sample depth direction.
DOI： 10.1063/5.0085041
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Reduction of non-radiative recombination by inserting a GaAs strain-relaxation interlayer in InGaAs/GaAsP superlattice solar cells investigated by photo-thermal spectroscopy Reviewed
A. Watanabe, T. Ikari, R. Furukawa, M. Sugiyama, and A. Fukuyama
Journal of Applied Physics 128 195702-1 - 195702-10 2020.11
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)
The role of a GaAs strain-relaxation interlayer inserted into InGaAs/GaAsP superlattice solar cells was evaluated by measuring the piezo- electric photothermal (PPT) signals in the temperature range from 100 K to a device operation temperature of around 340 K. The PPT signals caused by the non-radiative recombination of electrons photo-excited to the first quantized level were observed. The temperature- dependent PPT signal intensities were assessed using an electron carrier relaxation model comprising four processes: radiative recombina- tion, non-radiative recombination, thermionic emission, and tunneling of carriers through the e2-miniband after thermal excitation from the e1-level. The contribution of holes in the hh1 state was also included in this model, in which e1 and e2 are the first and second electron levels in the conduction band, respectively, and hh1 is the first heavy hole level in the valence band of the quantum wells. A similar analysis was conducted using photoluminescence (PL) spectra to elucidate the carrier transition dynamics in greater detail, because PPT and PL measurements are complementary to each other in terms of non-radiative and radiative electron transitions. Consequently, although the non-radiative recombination remained dominant around room temperature, the quantum yield of the carrier tunneling process increased and became comparable to that of non-radiative recombination. This implies that the recombination loss of the photo-excited carriers is suppressed by the insertion of the GaAs interlayer. By clarifying the role of the inserted interlayer with respect to the non-radiative recombi- nation process, the usefulness of the PPT method is demonstrated.
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Effectiveness of AlGaAs barrier layers as a redistribution channel of photoexcited carriers on anomalous temperature dependence of photoluminescence properties of GaAs quantum dots Reviewed
Y. Miyauchi, T. Ikari, T. Mano, T. Noda, A. Fukuyama
Journal of Applied Physics 128 055701-1 - 055701-9 2020.8
Language：English Publishing type：Research paper (scientific journal)
Photoluminescence (PL) measurements at a wide temperature range, up to room temperature, for high-quality and high-density GaAs/AlGaAs quantum dots (QDs) fabricated by droplet epitaxy were carried out to investigate the anomalous temperature dependence of the PL peak energy from the QD ensemble. In addition to a reported redshift that deviated from the so-called Varshni’s curve of the PL peak energy in the low temperature region, a new blueshift was observed above 200 K. We analyzed the experimental results using a steady- state rate equation model and observed a good agreement. The distribution of the QD sizes and the presence of the AlGaAs barrier layer as a carrier coupling channel were considered in this model. This means that the wetting layer proposed thus far is not a necessary condition for explaining the anomalous temperature behavior of the PL properties. In addition, it was found that the anomalous temperature behavior was smeared out by the insertion of a GaAs height adjustment layer in order to homogenize the apparent QD size. We found that sufficient control of the QD size is a necessary factor for high temperature stability of QD devices.
Books 【 display / non-display 】
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微結晶シリコン太陽電池の光学的性質
碇哲雄、福山敦彦（ Role： Joint author）
シーエムシー 2009.7
Total pages：107-117 Responsible for pages：107-117 Language：Japanese Book type：Scholarly book
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LED革新のための最新技術と展望
福山敦彦（ Role： Sole author , 第2章第3節を分担執筆）
情報機構 2008.11
Language：Japanese Book type：Scholarly book
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Nonradiative Investigation of Impurity and Defect Levels in Si and GaAsby Piezoelectric Photo-acoustic Spectroscopy
T. Ikari and A. Fukuyama（ Role： Joint author , 第５章を分担執筆）
SPIE Press (Washington, USA) Total 353 page (分担) 145-174 page 2000.6
Language：English Book type：Scholarly book
MISC 【 display / non-display 】
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光ヘテロダイン光熱変位法の構築と鉄汚染させたn型Siの非発光再結合マッピング Invited
原田知季、森田浩右、大山博暉、原田尚吾、碇哲雄、福山敦彦
超音波TECHNO 34 ( 3 ) 88 - 93 2022.6
Authorship：Corresponding author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media) Publisher：日本工業出版
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光ヘテロダイン光熱変位測定による半導体の熱物性評価 (1) 理論解析モデルの構築
原田尚吾、森田浩右、大山博暉、原田知季、碇哲雄、福山敦彦
宮崎大学工学部紀要 51 45 - 49 2022.9
Authorship：Corresponding author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (bulletin of university, research institution) Publisher：宮崎大学工学部
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フォトリフレクタンス法による波状超格子構造の光学的評価
山本尚輝、駒場森太郎、杉山正和、碇哲雄、福山敦彦
宮崎大学工学部紀要 51 57 - 61 2022.9
Authorship：Corresponding author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (bulletin of university, research institution) Publisher：宮崎大学工学部
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PLおよびPR測定を用いたInAs/GaSb超格子構造の遷移エネルギー評価
迫田理久、矢田部龍彦、荒井昌和、碇哲雄、福山敦彦
宮崎大学工学部紀要 51 63 - 67 2022.9
Authorship：Corresponding author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (bulletin of university, research institution) Publisher：宮崎大学工学部
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光ヘテロダイン光熱変位測定による半導体の熱物性評価 (2) Si-NP/SiGe複合膜の測定
森田浩右、原田尚吾、大山博暉、原田知季、大堀大介、寒川誠二、碇哲雄、福山敦彦
宮崎大学工学部紀要 51 51 - 55 2022.9
Authorship：Corresponding author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (bulletin of university, research institution) Publisher：宮崎大学工学部
Presentations 【 display / non-display 】
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Effect of local strains on carrier transport properties of InGaAs/GaAsP superlattice solar cell structures with a different phosphorus composition International conference
N. Yamamoto, T. Ikari, S. Komaba, M. Sugiyama and A. Fukuyama
33th International Photovoltaic Science and Engineering Conference (PVSEC-33) (Lake Biwa Otsu Prince Hotel, Shiga, Japan) 2022.11.13 PVSEC committee
Event date： 2022.11.13 - 2022.11.17
Language：English Presentation type：Oral presentation (general)
Venue：Lake Biwa Otsu Prince Hotel, Shiga, Japan
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Relationships between the distribution of dislocation glide planes and electrical properties of lattice-mismatched InGaAs solar cells. International conference
J. Okubo, A. Ogura, M. Kawano, S. Harada, K. Morita, H. Ohama, T. Harada, T. Ikari, A. Fukuyama, M. Imaizumi, H. Suzuki
33th International Photovoltaic Science and Engineering Conference (PVSEC-33) (Lake Biwa Otsu Prince Hotel, Shiga, Japan) 2022.11.13 PVSEC committee
Event date： 2022.11.13 - 2022.11.17
Language：English Presentation type：Oral presentation (general)
Venue：Lake Biwa Otsu Prince Hotel, Shiga, Japan
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Optical characterization of wire-on-well structure by photoreflectance measurements International conference
S. Komaba, N. Yamamoto, M. Sugiyama, T. Ikari and A. Fukuyama
33th International Photovoltaic Science and Engineering Conference (PVSEC-33) (Lake Biwa Otsu Prince Hotel, Shiga, Japan) 2022.11.13 PVSEC committee
Event date： 2022.11.13 - 2022.11.17
Language：English Presentation type：Oral presentation (general)
Venue：Lake Biwa Otsu Prince Hotel, Shiga, Japan
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Analysis of in-plane thermal conduction in Si-Nanopillar/SiGe composite films by laser heterodyne photothermal displacement signal and theoretical calculation International conference
H. Ohyama, T. Harada, K. Morita, S. Harada, D. Ohori, S. Samukawa, T. Ikari, and A. Fukuyama
19th Int. Conference on Flow Dynamics (オンライン) 2022.11.9 東北大学流体科学研究所
Event date： 2022.11.9 - 2022.11.11
Language：English Presentation type：Oral presentation (general)
Venue：オンライン
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Detection of carrier nonradiative recombination in dislocation glide planes of InGaAs solar cells by a laser heterodyne photothermal displacement method
S. Harada, T. Harada, J. Okubo, H. Suzuki, A. Ogura, T. Ikari, and A. Fukuyama
第41回電子材料シンポジウム (THE KASHIHARA（奈良県）) 2022.10.20 EMS実施委員会
Event date： 2022.10.19 - 2022.10.21
Language：Japanese Presentation type：Oral presentation (general)
Venue：THE KASHIHARA（奈良県）
Awards 【 display / non-display 】
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Best Poster Presentation Award
2022.11 Advanced Fluid Information Committee Analysis of in-plane thermal conduction in Si-Nanopillar/SiGe composite films by laser heterodyne photothermal displacement signal and theoretical calculation
H. Ohyama, T. Harada, K. Morita, S. Harada, D. Ohori, S. Samukawa, T. Ikari, and A. Fukuyama
Award type：Award from international society, conference, symposium, etc.
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Student Poster Award
2022.8 Optics-photonics Design & Fabrication Committee Defect mapping of metal contaminated Si wafers by a laser heterodyne photothermal displacement method
T. Harada, K. Morita, S. Harada, H. Ohyama, T. Ikari, and A. Fukuyama
Award type：Award from international society, conference, symposium, etc.
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令和3年度(第12回)半導体材料・デバイスフォーラム ポスター発表奨励賞
2021.12 熊本高専 半導体材料・デバイス研究部 電子線照射によりSi結晶中に形成された炭素起因欠陥準位の熱処理による回復過程
山根流星, 川畑公佑, 中村泰樹, 迫田理久, 碇哲雄, 福山敦彦, 佐々木駿, 佐俣秀一, 三次伯知
Award type：Award from Japanese society, conference, symposium, etc. Country：Japan
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令和元年度(第11回)半導体材料・デバイスフォーラム 口頭発表最優秀賞
2019.12 熊本高専 半導体材料・デバイス研究部 圧電素子光熱変換分光法による歪緩和層挿入超格子太陽電池のキャリア輸送特性評価
古川諒, 渡部愛理, 岩永凌平, 中村翼, 碇哲雄, 杉山正和, 福山敦彦
Award type：Award from Japanese society, conference, symposium, etc. Country：Japan
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平成28年度(第8回)半導体材料・デバイスフォーラム ポスター発表奨励賞
2016.11 熊本高専 半導体材料・デバイス研究部 フォトルミネッセンス法を用いた超格子構造中のキャリア輸送評価
魯 家男, 武田 秀明, 中村 翼, 松落 高輝, 鈴木 秀俊, 碇 哲雄, K. Toprasertpong, 杉山 正和, 中野 義昭, 福山 敦彦
Award type：Award from Japanese society, conference, symposium, etc. Country：Japan
Grant-in-Aid for Scientific Research 【 display / non-display 】
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無欠陥ナノ周期構造によるフォノン場制御を用いた高移動度半導体素子
Grant number：20H05649 2020.09 - 2025.03
独立行政法人日本学術振興会 科学研究費補助金 基盤研究(S)
Authorship：Coinvestigator(s)
本研究提案では、無欠陥ナノ構造作製技術・フォノンバンドナノオーダー評価解析技術・ ナノオーダートランジスタ作製技術を融合することで、トランジスタチャネル領域でのフォ ノン場を制御するという究極のナノスケールサーマルマネージメントを実現して、高移動度 プレーナー型半導体素子の開発に挑戦する。つまり、独自技術であるバイオマスクと無損傷 中性粒子ビーム加工の組み合わせで形成される周期的で無欠陥なサブ10nm径の半導体ナノピ ラーをマトリックス材料で埋め込んだ複合構造を作製する。作製されたナノピラー複合構造 に対して新たに開発したナノメートルオーダー計測技術と理論的計算を適用し、材料やナノ ピラーサイズ、間隔がフォノン生成・輸送特性制御に有効であることを実験的・理論的解析 から初めて明らかにする。得られた知見をもとに本質的にフォノンによるキャリア移動度散 乱を極限まで抑えたナノピラー複合構造を設計し、同構造をトランジスタチャネルに採用す ることで革新的な高移動度半導体素子を実現する。また、学術的にはナノオーダーサイズの 熱物性評価が可能な新たな測定・解析技術の確立も併せて行い、汎用性の高いフォノン生 成・輸送並びにキャリア輸送を理論的に予測可能な物理モデルを構築する。
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直接遷移型Ⅳ族半導体クラスレートの創成と光デバイス応用
Grant number：21H01365 2021.04 - 2025.03
独立行政法人日本学術振興会 科学研究費補助金 基盤研究(B)
Authorship：Coinvestigator(s)
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光ヘテロダイン光熱変換法によるナノピラー複合材料の熱物性評価と熱電素子応用
Grant number：21J22312 2021.04 - 2024.03
独立行政法人日本学術振興会 科学研究費補助金 特別研究員奨励費
Authorship：Principal investigator
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電子の非発光再結合を用いたGaAs中窒素不純物準位の高感度マッピング
Grant number：21K04130 2021.04 - 2024.03
独立行政法人日本学術振興会 科学研究費補助金 基盤研究(C)
Authorship：Coinvestigator(s)
量子コンピューターへの応用を目的とした区別のつかない希薄な発光素子を研究対象とした顕微分光評価技術の開発を行う。 具体的には、対象となる試料のバンドギャップやバンドギャップ内に存在する中間準位と一致する波長の光を照射する選択励起条件下での顕微 測定の開発を行う。取り組みとして、顕微装置系に新たに励起光照射時に試料表面で発生する「起電力」および非発光再結合の際に生じる「熱波」をそれぞれ検出 可能にする。これらの信号を取得するために、それぞれ固有の検出器と試料ホルダーを設計・作製して実証実験を行い、得られた結果を共同研 究者と議論・測定系の再検討を実施して多様な材料に適用できる評価技術の立ち上げを行う。
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可視光領域の直接ギャップを有するSiGe混晶クラスレートの物性解明
2017.04 - 2021.03
科学研究費補助金 基盤研究(B)
Authorship：Coinvestigator(s)
研究の全体構想は、新材料「SixGe1-x 混晶クラスレート」の特長である「可視光領域のバンドギ ャップ」「直接遷移型」「環境に優しい IV 族材料」「高耐久性」を生かした高効率太陽電池の実現 である。先行研究において我々は、Si(および Ge)クラスレートの薄膜化に成功し、その太陽電池 動作の確認を世界に先駆けて行った。この成果を元に、本課題では、「SixGe1-x 混晶クラスレートの物性を解明し、高効率薄膜太陽電池への応用の指針を示す」ことを目的として研究を実施する。 具体的には、SixGe1-x 混晶混晶クラスレートの作製、薄膜化、物性解明(バンド構造、バンドギャ ップ、吸収係数、キャリア密度・寿命・移動度など)および太陽電池特性評価の実施である。