2020 Fiscal Year Annual Research Report
| Project/Area Number |
19H02543
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| Research Institution | The University of Tokyo |
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Principal Investigator |
項 栄 東京大学, 大学院工学系研究科(工学部), 准教授 (20740096)
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| Co-Investigator(Kenkyū-buntansha) |
井ノ上 泰輝 大阪大学, 工学研究科, 助教 (00748949)
熊本 明仁 東京大学, 大学院工学系研究科(工学部), 客員共同研究員 (70724590)
宮田 耕充 東京都立大学, 理学研究科, 准教授 (80547555)
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | 一次元ファンデルワールスヘテロ構造 / カーボンナノチューブ |
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| Outline of Annual Research Achievements |
1. One-dimensional (1D) van der Waals heterostructure is successfully synthesized by chemical vapor deposition (CVD). We demonstrated the growth of single-crystal layers of hexagonal boron nitride (BN) and molybdenum disulfide (MoS2) crystals on single-walled carbon nanotubes (SWCNTs). This work suggests that a plethora of function-designable 1D heterostructures could be realized. This year we also succeeded in the synthesis of other crystal nanotube on SWCNT. WSe2, WS2, and NbS2 nanotubes are prepared by chemical vapor deposition.
2. To understand the growth mechanism of BN nanotubes on SWCNTs, we demonstrated the heteroepitaxial growth of aligned monolayer h-BN single crystals on exfoliated graphite by CVD without a metal catalyst. This year, we further used a transmission electron microscopy (TEM) to used the edge structure and growth mechanism of this heteronanotube. The edge of a BNNT is found to have different shapes depending on the chirality angle of the BNNT.
3. We also used a SWCNT-BNNT-MoS2NT to fabricate a heterojunction. This is so far the smallest diode achieved by a co-axial structure. When opposite potential
polarity was applied on a semiconducting single-walled carbon nanotube and molybdenum disulfide nanotube, respectively,
the rectifying effect was materialized.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
Growth method of one-dimensional (1D) van der Waals (vdW) heterostructures are greatly improved this year. Besides conventional powder chemical vapor deposition (CVD) metal organic CVD, molecular beam epitaxy is also found to be able to synthesize 1D vdW heterostructures.
For device application, various structure may be constructed using a 1D vdW heterostructure. (R. Xiang, S. Maruyama, Small Science, 2021, invited perspective) We demonstrate a one-dimensional heterostructure nanotube, 11 nm wide, with the coaxial assembly of a semiconducting single-walled carbon nanotube, insulating boron nitride nanotube, and semiconducting molybdenum
disulfide nanotube, which induces a radial semiconductor－insulator-semiconductor heterojunction (ACS Nano 2021). This work has attract global attention, and was highlighted in many media.
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| Strategy for Future Research Activity |
Future work will be focused on the next two parts.
1. To further understand the growth mechanism and the crystal epitaxial relationship of 1D van der Waals heterostructures. TEM will be used to
characterize the handedness relationship between different walls.
2. To further investigate the new phenomena and properties in this new structure. We also expect to investigate the optoelectronic response of SWCNT-BNNT-MoS2NT heterojunction.
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