2Dヘテロ界面特性の理解に基づく2DトンネルFETの構築

2019 Fiscal Year Annual Research Report

• Project/Area Number: 19H00755
• Research Institution: The University of Tokyo
• Principal Investigator: 長汐 晃輔 東京大学, 大学院工学系研究科(工学部), 准教授 (20373441)
• Co-Investigator(Kenkyū-buntansha): 吾郷 浩樹 九州大学, グローバルイノベーションセンター, 教授 (10356355)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: トンネルFET / MoS2 / WSe2 / h-BN

Outline of Annual Research Achievements

二次元トンネルFET(2D-TFET)において，低消費電力動作かつ高い駆動電流の両立が期待されている．我々はバンド間トンネル(BTBT)電流向上に適したtype IIIのバンドアライメント取得を目指しcharge transfer(CT)型p+-WSe2及びNb置換型p+-MoS2の2種類のソースに対してMoS2チャネルとのヘテロ構造においてBTBTを観測してきた．しかしながら，依然としてS.S.は60 mV/dec以上であった．本年度は，完全縮退のため安定なp+を示すp+-MoS2/ n-MoS2ヘテロ構造及び，界面準位を低減できるh-BNをゲートに選択し，チャネルのバンドギャップの層数依存性に着目してS.S.をMOSFETの理論限界値である60 mV/dec以下に低減することを試みた．S.S.を広い電流範囲で小さくするためには，チャネルのバンドギャップを小さくしトンネル確率を上げることが有効である．チャネルをバンドギャップの小さい3層に変えた3層-MoS2/BN-TGデバイスでは，広い電流範囲でS.S.がさらに低減しており，最小で51 mV/decと60 mV/dec以下のS.S.を得ることができた．リーク電流存在時においてはS.S.は見かけ上小さくなるため，精緻なリーク電流計測から測定限界に到達していること，ISとIDが常に一致していることを確認している．以上より，2次元系の特徴である2次元界面での極低界面準位及びバンドギャップの層数依存を最適化することで60 mV/dec以下のS.S.を達成した．

Current Status of Research Progress

1: Research has progressed more than it was originally planned.

Reason

これまで2次元ヘテロトンネルFETによりBTBTは確認できていたが，今回さらにMOSFETの理論限界の60mV/decを切るSSを得ることに成功している．以上の結果は，当初の計画以上である．

Strategy for Future Research Activity

2次元トンネルFETにおける理論計算では，20mV/decを切るSSの値が報告されている．2次元界面には積層時にバブルが形成されることが良く知られている．SSの値を向上するためには，理想に近い2次元界面を形成することが重要である．今後は，これまでに研究室において独自に研究してきたバブルフリー積層技術をトンネルFET構造作製時に適応し，清浄界面でのSS測定を行う．

Research Products

• [Int'l Joint Research] National Chiao Tung University(その他の国・地域)
  • Country Name: その他の国・地域
  • Counterpart Institution: National Chiao Tung University
• [Journal Article] Uniform and ultrathin high-κ gate dielectrics for two-dimensional electronic devices (2019)
  • Author(s): Li Weisheng、Zhou Jian、Cai Songhua、Yu Zhihao、Zhang Jialin、Fang Nan、Li Taotao、Wu Yun、Chen Tangsheng、Xie Xiaoyu、Ma Haibo、Yan Ke、Dai Ningxuan、Wu Xiangjin、Zhao Huijuan、Wang Zixuan、He Daowei、Pan Lijia、Shi Yi、Wang Peng、Chen Wei、Nagashio Kosuke、Duan Xiangfeng、Wang Xinran
  • Journal Title: Nature Electronics Volume: 2 Pages: 563～571
  • DOI: 10.1038/s41928-019-0334-y
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Full Energy Spectra of Interface State Densities for n ‐ and p ‐type MoS 2 Field‐Effect Transistors (2019)
  • Author(s): Fang Nan、Toyoda Satoshi、Taniguchi Takashi、Watanabe Kenji、Nagashio Kosuke
  • Journal Title: Advanced Functional Materials Volume: 29 Pages: 1904465～1904465
  • DOI: 10.1002/adfm.201904465
  • Peer Reviewed
• [Journal Article] Influence of interface dipole layers on the performance of graphene field effect transistors (2019)
  • Author(s): Nagamura Naoka、Fukidome Hirokazu、Nagashio Kosuke、Horiba Koji、Ide Takayuki、Funakubo Kazutoshi、Tashima Keiichiro、Toriumi Akira、Suemitsu Maki、Horn Karsten、Oshima Masaharu
  • Journal Title: Carbon Volume: 152 Pages: 680～687
  • DOI: 10.1016/j.carbon.2019.06.038
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Detection of both optical polarization and coherence transfers to excitonic valley states in CVD-grown monolayer MoS2 (2019)
  • Author(s): Asakura Eito、Suzuki Masaki、Karube Shutaro、Nitta Junsaku、Nagashio Kosuke、Kohda Makoto
  • Journal Title: Applied Physics Express Volume: 12 Pages: 063005～063005
  • DOI: 10.7567/1882-0786/ab21a8
  • Peer Reviewed
• [Journal Article] Pinpoint pick-up and bubble-free assembly of 2D materials using PDMS/PMMA polymers with lens shapes (2019)
  • Author(s): Toyoda Satoshi、Uwanno Teerayut、Taniguchi Takashi、Watanabe Kenji、Nagashio Kosuke
  • Journal Title: Applied Physics Express Volume: 12 Pages: 055008～055008
  • DOI: 10.7567/1882-0786/ab176b
  • Peer Reviewed
• [Journal Article] Expansion of the Graphdiyne Family: A Triphenylene-Cored Analogue (2019)
  • Author(s): Matsuoka Ryota、Toyoda Ryojun、Shiotsuki Ryo、Fukui Naoya、Wada Keisuke、Maeda Hiroaki、Sakamoto Ryota、Sasaki Sono、Masunaga Hiroyasu、Nagashio Kosuke、Nishihara Hiroshi
  • Journal Title: ACS Applied Materials & Interfaces Volume: 11 Pages: 2730～2733
  • DOI: 10.1021/acsami.8b00743
  • Peer Reviewed
• [Presentation] "Understanding interface properties in 2D heterostructure FETs" (2019)
  • Author(s): K. Nagashio,
  • Organizer: 2019 Int. Workshop on Dielectric thin films for future electron devices -science and technology -, (Nov. 19, 2019, Tokyo Tech. Tokyo, Japan)
  • Int'l Joint Research / Invited
• [Presentation] "Full energy spectra of interface states density for n- and p-type MoS2 field effect transistors (2019)
  • Author(s): K. Nagashio,
  • Organizer: Recent Progress in Graphene Research(RPGR), (October10, 2019, Kunibiki Messe, Matsue, Shimane, Japan).
  • Int'l Joint Research / Invited
• [Presentation] "2D heterostructure FETs", (2019)
  • Author(s): K. Nagashio,
  • Organizer: PKU-UTokyo Nanocarbon summer camp, (Aug. 2, 2019, UTokyo, Tokyo).
  • Int'l Joint Research / Invited
• [Presentation] "2D layered semiconductors", (2019)
  • Author(s): K. Nagashio,
  • Organizer: 7th International symposium on organic and inorganic electronic materials and related nanotechnology, (June 19-22, 2019, Shinshu Univ. Nagano, Japan).
  • Int'l Joint Research / Invited
• [Presentation] "How to understand interface properties in 2D heterostructure FETs", (2019)
  • Author(s): K. Nagashio,
  • Organizer: 2019 Symposia on VLSI Technology and Circuits, (June 19-14, 2019, RIHGA Royal Hotel, Kyoto, Japan).
  • Int'l Joint Research / Invited
• [Presentation] "2次元層状トランジスタの界面の理解と制御", (2019)
  • Author(s): 長汐 晃輔,
  • Organizer: 2019年電子情報通信学会シリコン材料・デバイス研究会 ,（2019年10月7日, 機械振興会館 (東京)).
  • Invited
• [Presentation] "2次元層状SnSの圧電・強誘電特性", (2019)
  • Author(s): 長汐 晃輔,
  • Organizer: 第23回VBLシンポジウム ,（2019年10月6日, 名古屋大学 (愛知)).
  • Invited
• [Presentation] ”Direct observation of electron capture & emission processes by the time domain charge pumping measurement of MoS2 FET”, (2019)
  • Author(s): K. Nagashio, K. Taniguchi, and N. Fang,
  • Organizer: Materials Research Meeting 2019, (Dec. 13, 2019, Yokohama Symposia, Yokohama).
  • Int'l Joint Research
• [Presentation] ”Photoresponse in h-BN encapsulated bilayer graphene field-effect phototransistor”, (2019)
  • Author(s): T. Uwanno, T. Taniguchi, K. Watanabe, K. Nagashio,
  • Organizer: Materials Research Meeting 2019, (Dec. 13, 2019, Yokohama Symposia, Yokohama
  • Int'l Joint Research
• [Presentation] "Ferroelectricity in monolayer SnS", (2019)
  • Author(s): K. Nagashio,
  • Organizer: JSPS/EPSRC C2C meeting, (Nov. 22, 2019, Tohoku univ., Sendai)
  • Int'l Joint Research
• [Presentation] "All-2D Flexible Device with Piezoelectric Layered Materials for Highly Sensitive Sensor and Generator Applications", (2019)
  • Author(s): N. Higashitarumizu,
  • Organizer: Recent Progress in Graphene Research(RPGR), (October8, 2019, Kunibiki Messe, Matsue, Shimane, Japan).（Oral）
  • Int'l Joint Research
• [Presentation] "High Temperature Retention Study of MoS2/h-BN/MoS2 Hetero-Stack Based Non-Volatile Memory", (2019)
  • Author(s): T. Sasaki,
  • Organizer: Recent Progress in Graphene Research(RPGR), (October9, 2019, Kunibiki Messe, Matsue, Shimane, Japan).（Poster）
  • Int'l Joint Research
• [Presentation] "Growth and Characterization of High Quality Monolayer SnS", (2019)
  • Author(s): H. Kawamoto,
  • Organizer: Recent Progress in Graphene Research(RPGR), (October7, 2019, Kunibiki Messe, Matsue, Shimane, Japan).（Poster）
  • Int'l Joint Research
• [Presentation] "Selection Mechanism of Band Alignment in 2D p+/n Tunnel FET", (2019)
  • Author(s): K. Nakamura,
  • Organizer: Recent Progress in Graphene Research(RPGR), (October8, 2019, Kunibiki Messe, Matsue, Shimane, Japan).（Oral）
  • Int'l Joint Research
• [Presentation] "Demonstration of Electromechanical Device Based on 2D Piezoelectric Materials for Nanogenerator Applications", (2019)
  • Author(s): N. Higashitarumizu, H. Kawamoto, K. Nagashio,
  • Organizer: International Conference on Solid State Devices and Materials (SSDM), (September. 5, 2019, Nagoya University, Nagoya).
  • Int'l Joint Research
• [Presentation] "388 K High Temperature Retention Study of 2D Hetero-stack Based Non- Volatile Memory", (2019)
  • Author(s): T. Sasaki, T. Taniguchi, K. Watanabe, K. Nagashio,
  • Organizer: International Conference on Solid State Devices and Materials (SSDM), (September. 5, 2019, Nagoya University, Nagoya).
  • Int'l Joint Research
• [Presentation] "Band Alignment in Charge- Transfer-Type p+-WSe2/MoS2 Tunnel FET", (2019)
  • Author(s): K. Nakamura, N. Nagamura, K. Ueno, T. Taniguchi, K. Watanabe, K. Nagashio,
  • Organizer: International Conference on Solid State Devices and Materials (SSDM), (September. 4, 2019, Nagoya University, Nagoya).
  • Int'l Joint Research
• [Presentation] "PVD growth of monolayer SnS under S-rich condition toward piezoelectric application", (2019)
  • Author(s): H. Kawamoto, N. Higashitarumizu, M. Nakamura, I. Yonemori, K. Wakabayashi, K. Nagashio,
  • Organizer: International Conference on Solid State Devices and Materials (SSDM), (September. 4, 2019, Nagoya University, Nagoya).
  • Int'l Joint Research
• [Presentation] "All solid-state 2D tunnel FET", (2019)
  • Author(s): K. Nagashio,
  • Organizer: Compound semiconductor week 2019 (CSW2019), (May 19-23, 2019, Kasugano International Forum, Nara, Japan).
  • Int'l Joint Research
• [Presentation] "Electromechanical Response of Few-to-monolayer SnS PVD-grown on Flexible Mica", (2019)
  • Author(s): N. Higashitarumizu, H. Kawamoto, K. Nagashio,
  • Organizer: 2019 MRS Spring Meeting, (April, 26, 2019, Phoenix Convention Center, Phoenix, USA).
  • Int'l Joint Research
• [Presentation] "Photoresponse in h-BN encapsulated bilayer graphene field-effect phototransistor", (2019)
  • Author(s): Uwanno, T. Taniguchi, K. Watanabe, & K. Nagashio,
  • Organizer: 2019 MRS Spring Meeting, (April, 26, 2019, Phoenix Convention Center, Phoenix, USA).
  • Int'l Joint Research
• [Presentation] ”2次元層状SnSの室温強誘電特性", (2019)
  • Author(s): 東垂水 直樹, 川元 颯巳, 西村 知紀, 張 文豪, 長汐 晃輔",
  • Organizer: 2019年第80回応用物理学会秋季学術講演会,（2019年9月19日, 北海道大学(札幌市)).
• [Presentation] "中心対称性の破れた2次元層状物質の圧電特性", (2019)
  • Author(s): 東垂水 直樹, 川元 颯巳, 梅田 雅也, 北浦 良, 長汐 晃輔,
  • Organizer: 2019年第80回応用物理学会秋季学術講演会,（2019年9月19日, 北海道大学(札幌市)).
• [Presentation] "MoS2/h-BN/Graphite積層構造による不揮発性メモリデバイスの動作解析", (2019)
  • Author(s): 佐々木 太郎, 谷口 尚, 渡邊 賢司, 西村 知紀, 長汐 晃輔,
  • Organizer: 2019年第80回応用物理学会秋季学術講演会,（2019年9月20日, 北海道大学(札幌市)).
• [Presentation] "PtS2/WSe2によるp型2D-TFETにおけるBTBT電流の観測", (2019)
  • Author(s): 佐藤 雄一朗，中村 圭吾，上野 啓司，長汐 晃輔,
  • Organizer: 2019年第80回応用物理学会秋季学術講演会,（2019年9月19日, 北海道大学(札幌市)).
• [Book] ”hBNの絶縁性破壊強さの異方性とその起源” (2019)
  • Author(s): 服部吉晃，長汐晃輔，
  • Total Pages: 5
  • Publisher: NEW DIAMOND，2019, 35
• [Remarks] 東大マテリアル・長汐研
  • URL: http://webpark1753.sakura.ne.jp/nagashio_lab/