Investigation of fascinating conductivity at superstructure interfaces using oxide atomic sheets

• Project/Area Number: 16H06116
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Inorganic materials/Physical properties
• Research Institution: National Institute for Materials Science
• Principal Investigator: Ohsawa Takeo 国立研究開発法人物質・材料研究機構, 機能性材料研究拠点, 主任研究員 (00450289)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥26,130,000 (Direct Cost: ¥20,100,000、Indirect Cost: ¥6,030,000); Fiscal Year 2018: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2017: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000); Fiscal Year 2016: ¥22,750,000 (Direct Cost: ¥17,500,000、Indirect Cost: ¥5,250,000)
• Keywords: 薄膜・表面界面物性 / 酸化物薄膜 / 原子シート / ホール効果 / 光電子分光 / 走査型トンネル顕微鏡 / エピタキシャル成長 / 表面・界面物性 / 酸化物エレクトロニクス

Outline of Final Research Achievements

Transition-metal oxides exhibit a broad range of functionalities that is not observed in conventional semiconductors. Recent progress in epitaxial growth of oxide films enables artificial synthesis of low-dimensional interfacial structures and therefore we can expect novel electronic properties. In this research, we investigated a TiO2 atomic sheet spontaneously formed on a LaAlO3/SrTiO3 heterostructures to reveal how the sheet can contribute to the electronic properties.
Epitaxial growth of the heterostructures on atomically-ordered SrTiO3 substrates resulted in the decrease of critical thickness for electrical conductivity and accumulation of higher electron density at the interfaces. These results clarified the impact of the TiO2 atomic sheet on the electronic transport properties.

Academic Significance and Societal Importance of the Research Achievements

気相合成時に自発的に形成されるTiO2原子シートは、構造的特長を有していることから、構造の特異性や対称性によって、通常の3次元結晶とは異なる性質を利用した新たなエレクトロニクスデバイス創製や電子素子を開発する指導原理を創出することに繋がると期待できる。

Research Products

• [Journal Article] IR photoresponse characteristics of Mg2Ge pn-junction photodiodes fabricated by rapid thermal annealing (2019)
  • Author(s): El-Amir Ahmed A.M.、Ohsawa Takeo、Oshima Yuichi、Nakamura Masaru、Shimamura Kiyoshi、Ohashi Naoki
  • Journal Title: Journal of Alloys and Compounds Volume: 787 Pages: 578-584
  • DOI: 10.1016/j.jallcom.2019.02.147
  • Peer Reviewed
• [Journal Article] Ecofriendly Mg2Si-based photodiode for short-wavelength IR sensing (2019)
  • Author(s): El-Amir Ahmed A.M.、Ohsawa Takeo、Nabatame Toshihide、Ohi Akihiko、Wada Yoshiki、Nakamura Masaru、Fu Xiuwei、Shimamura Kiyoshi、Ohashi Naoki
  • Journal Title: Materials Science in Semiconductor Processing Volume: 91 Pages: 222-229
  • DOI: 10.1016/j.mssp.2018.11.033
  • Peer Reviewed
• [Journal Article] Impact of a surface TiO2 atomic sheet on the electronic transport properties of LaAlO3/SrTiO3 heterointerfaces (2018)
  • Author(s): T. Ohsawa, M. Saito, R. Shimizu, K. Iwaya, S. Shiraki, Y. Ikuhara, and T. Hitosugi
  • Journal Title: Applied Physics Letters Volume: 113 Issue: 14 Pages: 141602-141602
  • DOI: 10.1063/1.5046876
  • Peer Reviewed
• [Journal Article] Electronic Transport Properties Governed by Polarity Control through Tailoring of ZnO Bilayer Structures (2018)
  • Author(s): Ohsawa Takeo、Tsunoda Kei、Yamagata Yoshihito、Dierre Benjamin、Grachev Sergey、Montigaud Herve、Ishigaki Takamasa、Ohashi Naoki
  • Journal Title: Crystal Growth & Design Volume: 18 Issue: 10 Pages: 5824-5831
  • DOI: 10.1021/acs.cgd.8b00396
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Growth-Parameter Dependence of Polarity and Electronic Transports in ZnO Thin Films Deposited by Magnetron Sputtering (2018)
  • Author(s): Ohsawa Takeo、Tsunoda Kei、Dierre Benjamin、Grachev Sergey、Montigaud Herve、Ishigaki Takamasa、Ohashi Naoki
  • Journal Title: physica status solidi (a) Volume: 215 Issue: 16 Pages: 1700838-1700838
  • DOI: 10.1002/pssa.201700838
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Controlling the electrical conductivity of ternary wurtzite-type and metastable β-AgGaO2 by impurity doping (2018)
  • Author(s): Nagatani Hiraku、Suzuki Issei、Takemura Sayuri、Ohsawa Takeo、Ohashi Naoki、Fujimoto Shinji、Omata Takahisa
  • Journal Title: AIP Advances Volume: 8 Issue: 8 Pages: 085203-085203
  • DOI: 10.1063/1.5046361
  • Peer Reviewed / Open Access
• [Journal Article] Preparation and some properties of Mg2Si0.53Ge0.47 single crystal and Mg2Si0.53Ge0.47 pn-junction diode (2018)
  • Author(s): El-Amir Ahmed A. M.、Ohsawa Takeo、Matsushita Yoshitaka、Wada Yoshiki、Shimamura Kiyoshi、Ohashi Naoki
  • Journal Title: AIP Advances Volume: 8 Issue: 11 Pages: 115005-115005
  • DOI: 10.1063/1.5056221
  • Peer Reviewed
• [Journal Article] Atomic-scale visualization of oxide thin-film surfaces (2018)
  • Author(s): Iwaya Katsuya、Ohsawa Takeo、Shimizu Ryota、Okada Yoshinori、Hitosugi Taro
  • Journal Title: Science and Technology of Advanced Materials Volume: 19 Issue: 1 Pages: 282-290
  • DOI: 10.1080/14686996.2018.1442616
  • Peer Reviewed / Open Access
• [Journal Article] Potential barrier formed at domain boundaries in twinned tetragonal BaTiO3 single crystals (2017)
  • Author(s): Ohsawa Takeo、Hirose Sakyo、Ohashi Naoki
  • Journal Title: Applied Physics Letters Volume: 110 Issue: 1 Pages: 011604-011604
  • DOI: 10.1063/1.4972849
  • Peer Reviewed
• [Journal Article] Crystalline polarity of ZnO thin films deposited under dc external bias on various substrates (2017)
  • Author(s): Ohsawa Takeo、Tsunoda Kei、Dierre Benjamin、Zellhofer Caroline、Grachev Sergey、Montigaud Herve、Ishigaki Takamasa、Ohashi Naoki
  • Journal Title: Journal of Crystal Growth Volume: 463 Pages: 38-45
  • DOI: 10.1016/j.jcrysgro.2017.01.048
  • Peer Reviewed
• [Journal Article] Solvent-mediated purification of hexa-molybdenum cluster halide, Cs2[Mo6Cl14] for enhanced optical properties (2017)
  • Author(s): Saito Norio、Lemoine Pierric、Cordier Stephane、Wada Yoshiki、Ohsawa Takeo、Saito Noriko、Grasset Fabien、Cross Jeffrey Scott、Ohashi Naoki
  • Journal Title: CRYSTENGCOMM Volume: 19 Issue: 40 Pages: 6028-6038
  • DOI: 10.1039/c7ce01440f
  • Peer Reviewed
• [Journal Article] Lattice and Valence Electronic Structures of Crystalline Octahedral Molybdenum Halide Clusters-Based Compounds, Cs2[Mo6X14] (X = Cl, Br, I), Studied by Density Functional Theory Calculations (2017)
  • Author(s): Saito Norio、Cordier Stephane、Lemoine Pierric、Ohsawa Takeo、Wada Yoshiki、Grasset Fabien、Cross Jeffrey S.、Ohashi Naoki
  • Journal Title: Inorganic Chemistry Volume: 56 Issue: 11 Pages: 6234-6243
  • DOI: 10.1021/acs.inorgchem.7b00265
  • Peer Reviewed
• [Journal Article] Transparent tantalum cluster-based UV and IR blocking electrochromic devices (2017)
  • Author(s): Renaud A.、Wilmet M.、Truong T. G.、Seze M.、Lemoine P.、Dumait N.、Chen W.、Saito N.、Ohsawa T.、Uchikoshi T.、Ohashi N.、Cordier S.、Grasset F.
  • Journal Title: Journal of Materials Chemistry C Volume: 5 Issue: 32 Pages: 8160-8168
  • DOI: 10.1039/c7tc01964e
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Metallic versus Semiconducting SWCNT Chemiresistors: A Case for Separated SWCNTs Wrapped by a Metallosupramolecular Polymer (2017)
  • Author(s): Ishihara Shinsuke、O’Kelly Curtis J.、Tanaka Takeshi、Kataura Hiromichi、Labuta Jan、Shingaya Yoshitaka、Nakayama Tomonobu、Ohsawa Takeo、Nakanishi Takashi、Swager Timothy M.
  • Journal Title: ACS Applied Materials & Interfaces Volume: 9 Issue: 43 Pages: 38062-38067
  • DOI: 10.1021/acsami.7b12992
  • Peer Reviewed
• [Journal Article] Simulation of crystal and electronic structures of octahedral molybdenum cluster complex compound Cs₂[Mo₆Cl₁₄] using various DFT functionals (2017)
  • Author(s): Saito Norio、Lemoine Pierric、Cordier Stephane、Ohsawa Takeo、Wada Yoshiki、Grasset Fabien、Cross Cross Jeffrey、Ohashi Naoki
  • Journal Title: Journal of the Ceramic Society of Japan Volume: 125 Issue: 10 Pages: 753-759
  • DOI: 10.2109/jcersj2.17039
  • NAID: 130006110748
  • ISSN: 1348-6535, 1882-0743
  • Peer Reviewed
• [Journal Article] Negligible Sr segregation on SrTiO3 (001) √13 x √13 reconstructed surfaces (2016)
  • Author(s): Takeo Ohsawa, Ryota Shimizu, Katsuya Iwaya, Susumu Shiraki and Taro Hitosugi
  • Journal Title: Appl. Phys. Lett. Volume: 108 Issue: 16 Pages: 161603-161603
  • DOI: 10.1063/1.4947441
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Isotope tracer investigation and ab-initio simulation of anisotropic hydrogen transport and possible multi-hydrogen centers in tin dioxide (2016)
  • Author(s): K. Watanabe, I. Sakaguchi, M. Hashiguchi, N. Saito, E. Ross, H. Haneda, T. Ohsawa, N. Ohashi
  • Journal Title: Journal of Applied Physics Volume: 119 Issue: 22 Pages: 225704-225704
  • DOI: 10.1063/1.4953387
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Theoretical and experimental determination of the crystal structures of cesium?molybdenum chloride (2016)
  • Author(s): Saito Norio、Wada Yoshiki、Lemoine Pierric、Cordier Stephane、Grasset Fabien、Ohsawa Takeo、Saito Noriko、Cross Jeffrey S.、Ohashi Naoki
  • Journal Title: Japanese Journal of Applied Physics Volume: 55 Issue: 7 Pages: 075502-075502
  • DOI: 10.7567/jjap.55.075502
  • NAID: 210000146761
  • Peer Reviewed
• [Presentation] LaAlO3/SrTiO3界面の電子輸送特性におけるTiO2 表面原子シートの効果 (2018)
  • Author(s): 大澤 健男、白木 將、清水 亮太、一杉 太郎
  • Organizer: 日本セラミックス協会 2019年年会
• [Presentation] Investigation on electronic Structure at metal/oxide interfaces (2018)
  • Author(s): 大橋 直樹、廣瀬 左京、大澤 健男、上田 茂典
  • Organizer: 43RD INTERNATIONAL CONFERENCE AND EXPOSITION ON ADVANCED CERAMICS AND COMPOSITES
  • Int'l Joint Research / Invited
• [Presentation] ZnO/Ag 接合の加熱処理における界面電子状態の評価 (2018)
  • Author(s): 山形 栄人、大澤 健男 、保坂 拓己、Herve Montigaud、石垣 隆正、大橋 直樹
  • Organizer: 第66回応用物理学会春季学術講演会
• [Presentation] Electrical and optical properties of Zn3N2 thin films (2018)
  • Author(s): Yong Wang, Takeo Ohsawa, Naoki Ohashi
  • Organizer: 第66回応用物理学会春季学術講演会
• [Presentation] Electrical properties of non-degenerate ZnSnN2 thin films grown by non-equilibrium deposition (2018)
  • Author(s): Yong Wang, Takeo Ohsawa, Naoki Ohashi
  • Organizer: 第66回応用物理学会春季学術講演会
• [Presentation] Ag/ZnO接合薄膜の加熱処理における界面電子状態評価 (2018)
  • Author(s): 山形 栄人、大澤 健男 、保坂 拓己、Sergey Grachev、Herve Montigaud、石垣 隆正、大橋 直樹
  • Organizer: 第57回セラミックス基礎科学討論会
• [Presentation] IR photoresponse characteristics of Mg2Si pn-junction diode fabricated by RTA (2018)
  • Author(s): エルアミル アアハメド モハメド エルサイド アハメド、大澤 健男、生田目 俊秀、大井 暁彦、和田 芳樹、中村 優 、島村 清史、大橋 直樹
  • Organizer: 第47回結晶成長国内会議
• [Presentation] チタン酸ストロンチウムの欠陥と誘電特性に関するショットキー接合からの検討 (2018)
  • Author(s): 大橋 直樹、廣瀬 左京、上田 茂典、大澤 健男
  • Organizer: 第38 回エレクトロセラミックス研究討論会
• [Presentation] スパッタ粒子の入射角度に着目した酸化亜鉛薄膜成長とその評価 (2018)
  • Author(s): 保坂 拓己、山形 栄人、大澤 健男、Sergey Grachev、Herve Montigaud、石垣 隆正、大橋 直樹
  • Organizer: 第38 回エレクトロセラミックス研究討論会
• [Presentation] 加熱処理によるZnO/Ag/ZnO薄膜の界面特性評価 (2018)
  • Author(s): 山形 栄人、大澤 健男、保坂 拓己、Sergey Grachev、Herve Montigaud、石垣 隆正、大橋 直樹
  • Organizer: 第38 回エレクトロセラミックス研究討論会
• [Presentation] 角度制御型マグネトロンスパッタリング装置を用いた 酸化亜鉛薄膜の作製と成膜条件の検討 (2018)
  • Author(s): 保坂 拓己、山形 栄人、大澤 健男、Sergey Grachev、Herve Montigaud、石垣 隆正、大橋 直樹
  • Organizer: 日本セラミックス協会第31回秋季シンポジウム
• [Presentation] 角度制御型マグネトロンスパッタリング装置を用いた 酸化亜鉛薄膜の作製と成膜条件の検討 (2018)
  • Author(s): 保坂 拓己、山形 栄人、大澤 健男、Sergey Grachev、Herve Montigaud、石垣 隆正、大橋 直樹
  • Organizer: 第79回応用物理学会秋季学術講演会
• [Presentation] Electronic States at Buried Metals/SrTiO3 Schottky Junctions Studied by HAXPES (2017)
  • Author(s): Takeo Ohsawa, Sakyo Hirose, Shigenori Ueda, Naoki Ohashi
  • Organizer: 7th International Conference on Hard X-Ray Photoelectron Spectroscopy
  • Int'l Joint Research
• [Presentation] Valence Band DOS of Wide-gap compounds Studied by HAXPES Utilizing Polarized X-ray and DFT simulations (2017)
  • Author(s): Naoki Ohashi, Takeo Ohsawa, Shigenori Ueda
  • Organizer: 7th International Conference on Hard X-Ray Photoelectron Spectroscopy
• [Presentation] 極性制御したZnO薄膜を用いたZnO/Si 接合の特性評価 (2017)
  • Author(s): 大澤 健男, 山形 栄人, 石垣 隆正, 大橋 直樹
  • Organizer: 第78回 応用物理学会 秋季学術講演会
• [Presentation] ドメインを導入したBaTiO3単結晶の異方的電気伝導性と局所電子状態 (2017)
  • Author(s): 大澤 健男
  • Organizer: 透明酸化物光・電子材料第166委員会
• [Presentation] 極性制御した酸化亜鉛薄膜の成長，電子状態および接合特性 (2017)
  • Author(s): 山形 栄人、大澤 健男、Sergey Grachev、Herve Montigaud、石垣隆正、大橋直樹
  • Organizer: 第37回エレクトロセラミックス研究討論会
• [Presentation] Growth, Electronic States, and Junction Properties of Polarity-Controlled ZnO Thin Films on Silicon Substrates (2017)
  • Author(s): Yoshihito Yamagata, Takeo Ohaswa, Sergey Grachev, Herve Motigaud, Takamasa Ishigaki, Naoki Ohashi
  • Organizer: IUMRS-ICAM 2017
• [Presentation] Impurities, Defects, and Electronic Transport Properties in Semiconducting ZnO Single Crystals (2017)
  • Author(s): Takeo Ohsawa, Naoki Ohashi
  • Organizer: IUMRS-ICAM 2017
• [Presentation] Defect and hydrogen impurity in zinc oxide studied with various single crystals (2017)
  • Author(s): Naoki Ohashi, Takeo Ohsawa, Isao Sakaguchi
  • Organizer: EMRS 2017 Fall meeting
• [Presentation] Impurities, Polarity, and Electronic Transport Properties of ZnO Crystals and Films (2017)
  • Author(s): Takeo Ohsawa, Naoki Ohashi
  • Organizer: STAC-10
  • Int'l Joint Research / Invited
• [Presentation] 元素戦略の視点で見た酸化物中の欠陥・不純物の振る舞い (2017)
  • Author(s): 大橋 直樹, 大澤 健男, 坂口 勲, 上田 茂典.
  • Organizer: 第55回セラミックス基礎科学討論会
• [Presentation] Negligible Sr segregation on SrTiO3(001)-(√13×√13)-R33.7° reconstructed surfaces (2016)
  • Author(s): Takeo Ohsawa, Ryota Shimizu, Katsuya Iwaya, Susumu Shiraki, Taro Hitosugi
  • Organizer: MRS Fall Meeting & Exhibit. 2016
  • Int'l Joint Research
• [Presentation] TiO2(110)表面のsub-surface Tiサイトにおける余剰電子の強い局在化 (2016)
  • Author(s): 神坂 英幸, 清水 亮太, 岩谷 克也, 大澤 健男, 白木 将, 長谷川 哲也, 一杉 太郎
  • Organizer: 第10回分子科学討論会
• [Presentation] Crystalline Polarity Control of ZnO Thin Films Grown Under External Electric Bias During Magnetron Sputtering (2016)
  • Author(s): Takeo Ohsawa, Kei Tsunoda, Takamasa Ishigaki, Naoki Ohashi
  • Organizer: The 10th Asian Meeting on Electroceramics
  • Int'l Joint Research
• [Presentation] 水素を添加したZnO単結晶の欠陥と電気特性 (2016)
  • Author(s): 大澤 健男, 坂口 勲, 上田 茂典, 大橋 直樹.
  • Organizer: 第63回応用物理学会春季学術講演会
• [Presentation] 放射光光電子分光による金属・半導体界面の解析 (2016)
  • Author(s): 大橋 直樹, 廣瀬 左京, 上田 茂典, 大澤 健男, 坂口 勲, 安藤陽, 大串 秀世
  • Organizer: 文部科学省 元素戦略プロジェクト＜研究拠点形成型＞/大型研究施設
• [Presentation] 偏光X 線を用いた放射光光電子分光 (2016)
  • Author(s): 大橋 直樹, 大澤 健男, 上田 茂典, 鈴木基寛, ウィリアムズ ジェシー ロバート, 館山 佳尚
  • Organizer: 文部科学省 元素戦略プロジェクト＜研究拠点形成型＞/大型研究施設
• [Book] SPring-8/SACLA利用者情報 (2017)
  • Author(s): 大澤 健男、上田 茂典、鈴木基寛、大橋 直樹
  • Total Pages: 5
  • Publisher: JASRI