| 研究実績の概要 |
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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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
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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