| 研究課題/領域番号 |
14J11197
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| 研究機関 | 名古屋大学 |
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研究代表者 |
THENDIE BOANERGES 名古屋大学, 理学研究科, 特別研究員(DC1)
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| 研究期間 (年度) |
2014-04-25 – 2017-03-31
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| キーワード | Carbon nanotubes / Separation / Gel Filtration / Semiconducting / Large diameter |
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| 研究実績の概要 |
Single-wall carbon nanotubes (SWCNTs) has potential application for high performance electronic devices. However, due to the vast variety in structures and electrical properties of SWCNTs, purification process hereby required prior to the device fabrication. Here, we utilize gel filtration method to purify large diameter semiconducting SWCNTs (s-SWCNTs) for thin film transistor application.
Gel filtration (gel column chromatography) has been widely known as one of the most powerful purification method of s-SWCNTs with diameter of less than 1.6 nm. However, for larger diameter s-SWCNTs, there was difficulty in which large diameter s-SWCNTs were not adsorbed into the gel column. To solve this problem, we used high temperature column chromatography, using a jacketed column which is heated by hot water flow, for the purification of large diameter s-SWCNTs. As estimated by thermodynamic approach, not only large diameter s-SWCNTs has been successfully adsorbed into the gel, the yield of purification has also been successfully increased by 10-fold.
However, high temperature column chromatography have a drawback as metallic SWCNTs (m-SWCNTs) were also began adsorbed into the gel column. To negate this trade-off, we utilized gradient elution system which were developed in previous year to increase the elution selectivity of the adsorbed s-SWCNTs. By using gradient elution system, as high as 99% purity of s-SWCNTs with average diameter of 1.9 nm has been successfully purified as confirmed by optical absorption measurement and Raman measurement at 3 different excitation wavelength.
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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
In this research, we aim to obtain semiconducting single-wall carbon nanotubes (s-SWCNTs) which has highest possible performance characteristic for electronic devices fabrication. We have already proposed that ultra-long and high purity s-SWCNTs are necessary for high performance device application. In addition to length and purity, diameter of s-SWCNTs was also expected to affect the device performance. With increasing diameter of s-SWCNTs, the bandgap become smaller thus the carrier mobility (the easiness of switching) become larger which means better device performance. Thus, not only ultra-long and high purity s-SWCNTs, we also aim to separate large diameter s-SWCNTs to obtain the best possible s-SWCNTs for devices fabrication.
Due to its known difficulties of purifying large diameter s-SWCNTs, at first we were not expecting to separate large diameter s-SWCNTs in high purity. However, by combining thermodynamic approach with our previously developed elution method, we have successfully separated large diameter s-SWCNTs in purity near to 99% with average diameter of 1.9 nm, which is highest purity of large diameter s-SWCNTs purification reported so far. In addition, utilizing high temperature to purify large diameter s-SWCNTs also increase the total yield of separation, which is not included in our main targets. Therefore, since we are able to overcome the seemingly difficult task of purifying large diameter s-SWCNTs and increasing the yield at the same time, we can say that this year our progress are higher than what we have expected.
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| 今後の研究の推進方策 |
As the last year of this project has been started, we are aiming to finish the remaining works: obtaining ultra-long s-SWCNTs and fabricate devices such as thin film transistor from the separated s-SWCNTs.
To obtain ultra-long s-SWCNTs, not only we need to search the longest possible s-SWCNTs from the available s-SWCNTs sample, we are also need to keep the length intact during the dispersion process. From our works so far with more than 3 types of SWCNTs sample, we found the length differences of the sample are insignificant even with different diameter distribution. On the hand, the dispersion process affects the diameter distribution of same sample significantly. Thus, to obtain ultra-long s-SWCNTs, we will focus on minimalizing the SWCNTs breakdown during the dispersion process by using weaker power and shorter time. Since weaker power and shorter time dispersion will reduce the dispersion yield of the SWCNTs sample, we will also apply recycling dispersion method to avoid further breakdown of already dispersed SWCNTs while continuing the dispersion for the undispersed SWCNTs.
For the final task, we will fabricate thin film transistor from the ultra-long, large diameter, high purity s-SWCNTs. First, a film fabrication method will be developed to obtain high density, high alignment single layer film of s-SWCNTs. Then, electrode will be developed by vapor deposition method, patterned using metal mask or electron beam lithograpy patterns. Finally, device measurement will be conducted to evaluate the quality of the separated s-SWCNTs.
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