Discovery of a flexible spin thin-film transistor

• Project/Area Number: 18K18859
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 21:Electrical and electronic engineering and related fields
• Research Institution: Osaka University
• Principal Investigator: Kohei Hamaya 大阪大学, 基礎工学研究科, 教授 (90401281)
• Co-Investigator(Kenkyū-buntansha): 山田 晋也 大阪大学, 基礎工学研究科, 助教 (30725049)
• Project Period (FY): 2018-06-29 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000); Fiscal Year 2019: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000); Fiscal Year 2018: ¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000)
• Keywords: 薄膜トランジスタ / フレキシブル / スピン / スピントロニクス

Outline of Final Research Achievements

We have experimentally demonstrated a flexible thin-film transistor (TFT) with pseudo-single-crystalline Ge (PSC-Ge) films grown by a gold-induced crystallization (GIC) method. A field-effect mobility of ~10 cm2/Vs was obtained. For improvement of electrical properties of PSC-Ge films, we have explored the effect of Sn addition to the PSC-Ge layer. As a result, a Hall mobility of ~300 cm2/Vs was obtained at room temperature. This result will lead to a high-performance flexible TFT. We have also explored the growth of a ferromagnetic full-Heusler alloy, Co2FeSi, on a (111)-oriented PSC-Ge/polyimide flexible template. Using a low-temperature molecular beam epitaxy technique, crystalline Co2FeSi films were obtained on the flexible Ge at less than 80°C. We believe that this project is an important step for flexible Ge-channel spin MOSFETs.

Academic Significance and Societal Importance of the Research Achievements

本研究では，これまでのフレキシブルエレクトロニクスの概念を覆す「結晶性半導体を用いた高性能フレキシブルエレクトロニクスシステム」のコアとなる技術を開発するための基礎検討を行い、比較的性能の高いフレキシブルスピンTFTの実現の可能性を示した．スマートフォン市場で低消費電力化に貢献したIGZOなどの次世代を担う革新的フレキシブル基盤技術の創成であると期待され，挑戦的研究として十分な意義がある．また，エレクトロニクス分野全体の学術・研究体系を大きく変革する可能性を秘めた意義深い研究でもある．

Research Products

• [Journal Article] Growth of ferromagnetic Co2FeSi films on flexible Ge(111) (2020)
  • Author(s): Yamada Shinya、Higashi Hidenori、Kanashima Takeshi、Hamaya Kohei
  • Journal Title: Materials Science in Semiconductor Processing Volume: 112 Pages: 104997-104997
  • DOI: 10.1016/j.mssp.2020.104997
  • Peer Reviewed
• [Journal Article] Electrical properties of pseudo-single-crystalline Ge films grown by Au-induced layer exchange crystallization at 250?°C (2018)
  • Author(s): Higashi H.、Kudo K.、Yamamoto K.、Yamada S.、Kanashima T.、Tsunoda I.、Nakashima H.、Hamaya K.
  • Journal Title: Journal of Applied Physics Volume: 123 Issue: 21 Pages: 215704-215704
  • DOI: 10.1063/1.5031469
  • Peer Reviewed
• [Presentation] Flexible ferromagnetic Co2FeSi films on flexible Ge(111) (2019)
  • Author(s): S. Yamada, H. Higashi, T. Kanashima, and K. Hamaya
  • Organizer: 8th International Symposium on Control of Semiconductor Interfaces (ISCSI-8), Tohoku University, Sendai
  • Int'l Joint Research
• [Presentation] 金誘起層交換成長法で作製したGe薄膜を用いた薄膜トランジスタ特性 (2019)
  • Author(s): 東英実, 笠原健司, 山本圭介, 工藤康平, 山田晋也, 金島岳, 中島寛, 浜屋宏平
  • Organizer: 第66回応用物理学会春季学術講演大会、東京工業大学 大岡山キャンパス
• [Presentation] 金誘起層交換成長法で作製したGe薄膜における電気伝導特性の理解 (2019)
  • Author(s): 東英実, 笠原健司, 工藤康平, 山田晋也, 金島岳, 角田功, 中島寛, 浜屋宏平
  • Organizer: 第66回応用物理学会春季学術講演大会、東京工業大学 大岡山キャンパス
• [Presentation] Flexible thin-film transistors with crystalline germanium layers (2018)
  • Author(s): H. Higashi, K. Kudo, S. Yamada, T. Kanashima, I. Tsunoda, H. Nakashima, and K. Hamaya
  • Organizer: The 9th International SiGe Technology and Device Meeting (ISTDM), Seminaris Seehotel Potsdam, Germany
  • Int'l Joint Research