| 研究課題/領域番号 |
20K15120
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| 研究機関 | 国立研究開発法人理化学研究所 |
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研究代表者 |
Fang Nan 国立研究開発法人理化学研究所, 開拓研究本部, 基礎科学特別研究員 (50850509)
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| 研究期間 (年度) |
2020-04-01 – 2022-03-31
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| キーワード | carbon nanotubes / 2D materials / dielectric screening / cavity |
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| 研究実績の概要 |
1 The interaction between h-BN substrate and CNTs has been clarified. The paper regarding h-BN/CNTs heterostructures has been published. Exciton life of CNTs on top of the h-BN substrate has been studied, which is comparable with that of suspended CNTs.
2 The 2D transfer system has been set up, and a new transfer method based on anthracene crystals has been developed to form suspended 2D structures. Interaction between anthracene crystals and 2D materials has been investigated, indicating that 2D materials with many mobile carriers are more difficult to be picked up. The selectivity of anthracene pick-up process has been observed for studying more than 5 types of 2D materials. The strain is largely suppressed in our method.
3 The 2D nanoribbon/CNT heterostructures have been prepared by using the anthracene transfer method. The new sub-peak around the E11 exciton has been observed by forming this 2D nanoribbon/CNT heterostructures, indicating the local dielectric effect on CNTs.
4 WSe2 and CNT interaction has been studied by using the new transfer method. Exciton energy shift is saturated around 3 layers. The activation of k-momentum states in CNTs by WSe2 has been observed, which also shows strong thickness dependence of WSe2. The quenching effect is enhanced by increasing the WSe2 thickness from monolayer to trilayer. Also lower energy new peaks have been observed in some samples, which might come from the interaction between excitons in CNT and defects in WSe2. The flick noise has been observed in some new peaks, indicating the instant trapping and emission process.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
The research project has been going well as expected in this fiscal year. The new transfer method of 2D materials based on anthracene crystals has been developed, and makes is possible to prepare many new suspended 2D heterostructures. This transfer method brings out more interesting experiments in two main projects. The first one is the interaction between 2D materials and CNTs. Thickness dependence of 2D materials help clarify the origin of quenching effect. The second one is 2D materials/cavity interaction. Large mode modulation has been observed by transferring 2D materials on top of the cavity. I got trained in AFM and SSDM. I also studied the fundamentals of optics and cavities, which enables me to set up and change the optical system for different research purposes.
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| 今後の研究の推進方策 |
The following two main research projects will be focused on in the next fiscal year.
1) 2D/CNT heterostructures. The thickness dependence of WSe2 (from monolayer to bulk) will be investigated in WSe2/(9,7) CNT heterostructures. Clarity dependence of CNTs will also be studied. The diameter of the exciton will be experimentally clarified. Time-resolved PL will be performed to study the exciton dynamics further. The split of the main peak to two subpeaks are expected in the WSe2 nanoribbon/CNT heterostructures. The single photon emission is expected in this structure by decreasing WSe2 nanoribbon width.
2) 2D/cavity heterostructures. The thickness dependence of h-BN as well as WSe2 (from monolayer to bulk) will be investigated. Multi-transfer of WSe2 and h-BN will be performed on the cavity.
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| 次年度使用額が生じた理由 |
Many conferences such as SSDM (International conference on solid state devices and materials) and APS march meeting have been changed to online due to COVID-19. In order to increase the remote work and decrease the infection risk, more optical measurements has been done at home remotely instead of sample preparation in the laboratory. Also the nano-fabrication process is reduced because it is done at Takeda cleanroom in the University of Tokyo. The development of new transfer 2D materials decreases the usage of 2D materials, which also decreases the usage for the amount.
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