CN107089652A - Narrow band gap distribution, the preparation method of high-purity semi-conductive single-walled carbon nanotubes - Google Patents

Abstract

The invention relates to the field of controllable preparation of semiconducting single-wall carbon nanotubes, in particular to a method for preparing semiconducting single-wall carbon nanotubes with narrow band gap distribution and high purity by partially carbon-coating metal catalysts. A block copolymer self-assembly method was used to prepare copolymer film-coated metal anion nanoclusters with uniform size; by controlling solvent annealing, oxidation, and reduction conditions, monodisperse, partially carbon-coated metal catalyst nanoparticles were obtained; and then Hydrogen is an in-situ etching gas to directly grow narrow band gap distribution and high-purity semiconducting single-walled carbon nanotubes. Wherein the content of semiconducting single-walled carbon nanotubes is greater than 98%, and the band gap difference is at least 0.05eV and adjustable. The invention realizes the direct and controllable growth of narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes, breaks through the bottleneck of controlled preparation of high-purity and narrow-bandgap semiconducting single-walled carbon nanotubes at the present stage, and proves that it is the construction of thin film field effect Ideal channel material for transistors.

Description

Preparation method of narrow bandgap distribution, high-purity semiconducting single-walled carbon nanotubes

technical field

The invention relates to the field of controllable preparation of semiconducting single-walled carbon nanotubes, specifically a method for preparing semiconducting single-walled carbon nanotubes with narrow bandgap distribution and high purity by partially carbon-coated metal catalysts. Assembly process and post-treatment conditions to prepare monodisperse, narrow particle size distribution, partially carbon-coated metal catalyst nanoparticles; then use hydrogen as a carrier gas and etching gas to remove highly active metallic single-walled carbon nanotubes in situ , to directly realize the controlled growth of semiconducting single-walled carbon nanotubes with narrow bandgap distribution and tunable bandgap.

Background technique

Single-walled carbon nanotubes can be regarded as one-dimensional hollow tubular structures rolled from single-layer graphene, which have metallic or semiconducting properties related to diameter and helix angle. Semiconducting single-walled carbon nanotubes have very high electron mobility and adjustable band gap. They are ideal materials for constructing field-effect transistor channels, and are expected to replace single crystal silicon in the construction of next-generation nanoelectronic devices in the future. Therefore, directly obtaining high-purity semiconducting single-walled carbon nanotubes is the key to promoting their application in nanoelectronic devices.

In recent years, great progress has been made in the controlled preparation of semiconducting single-walled carbon nanotubes, mainly using the high chemical reactivity of metallic carbon nanotubes to remove them by introducing etchant in situ. The characteristics can be attributed to the following three types: (1) Etching gases such as water vapor, oxygen, and hydrogen (document 1: Zhang, G.; Qi, P.; Dai, H. et al. Science 2006, 314, 5801; Document 2: Yu, B.; Liu, C.; Hou, P.X. et al. Journal of the American Chemical Society 20011, 133, 5232; Document 3: Li, W.S.; Hou, P.X.; Liu, C. et al. ACS Nano 2013,7,6831); (2) cerium oxide which can release oxygen slowly as catalyst carrier (Qin,X.; Peng,F.; Li,Y.et al.Nano Letter 2014,14,512); (3) can Alcohols decomposed from hydroxyl groups are carbon sources (Che, Y.C.; Wang, C.; Zhou, C.W.; et al.ACS Nano 2012,6,7454); the purity of the semiconducting single-walled carbon nanotubes prepared so far is ~95 %, and the bandgap distribution is wide, which will affect the uniformity of the device performance. Since the band gap of single-walled carbon nanotubes is inversely proportional to its diameter, the necessary condition for obtaining carbon nanotubes with narrow band gap distribution is to obtain carbon nanotubes with uniform diameter. At the same time, the reactivity of single-walled carbon nanotubes is not only dependent on the conductive property, but also related to the diameter. In order to obtain high-purity semiconducting single-walled carbon nanotubes, it is necessary to control the concentration of the diameter distribution of the carbon nanotubes. It can be seen that the diameter control of carbon nanotubes is not only the key to the preparation of narrow-bandgap semiconducting carbon nanotubes, but also the key to the preparation of high-purity semiconducting single-walled carbon nanotubes. However, due to the nanometer scale of single-walled carbon nanotubes, the nanoparticles that catalyze their growth are very easy to agglomerate at high temperatures (>600°C), so it is difficult to obtain nanocatalyst particles with uniform sizes. At the same time, the nucleation of single-walled carbon nanotubes from nanoparticles mainly follows two modes, one is the "tangential growth" mode in which the diameter of carbon nanotubes is consistent with the diameter of nanoparticles, and the other is that the diameter of carbon nanotubes is smaller than the size of nanoparticles "vertical growth" mode. (Fiawoo, M.F.C.; Bonnot, A.M.; Amara, H et al. Physical Review Letters 2012, 108) Therefore, even if a catalyst with uniform size is obtained, it is difficult to grow single-walled carbon nanotubes with uniform size.

The main problem at present is: how to obtain catalyst nanoparticles with uniform size, and control the nucleation and growth mode of single-walled carbon nanotubes at the same time; further, to break through the bottleneck of controlled preparation of narrow-bandgap, high-purity semiconducting single-walled carbon nanotubes.

Contents of the invention

The purpose of the present invention is to provide a method for preparing narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes by partially carbon-coating metal catalysts, which overcomes the problem of uncertain nucleation modes of existing single-walled carbon nanotubes on metal catalysts. The problem of wide diameter distribution of carbon nanotubes, while overcoming the problem of wide diameter distribution caused by the easy agglomeration of existing metallic catalysts at high temperatures, through the size control and structural design of the catalyst, combined with hydrogen in-situ etching, directly grow narrow band gap distribution, high Pure, high-quality semiconducting single-walled carbon nanotubes.

Technical scheme of the present invention is:

A preparation method of narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes, using the block copolymer self-assembly method to prepare nanoparticles with uniform size, by controlling solvent annealing, oxidation, and reduction conditions, uniform size, Monodisperse, partially carbon-coated metal nanoparticles; using it as a catalyst, taking advantage of the weak etching property of hydrogen and the high reactivity of metallic carbon nanotubes with the same diameter, to directly etch metallic carbon nanotubes in situ, High-purity semiconducting single-walled carbon nanotubes with narrow bandgap distribution were obtained.

In the preparation method of narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes, the catalyst structure is partially carbon-coated nanoparticles, and the particle size is 2.0-4.5nm; wherein, the catalyst component is one of transition metals or two or more; or, the catalyst component is one or two or more of the refractory metals.

In the preparation method of the narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes, the self-assembly method is used to prepare the block copolymer film, the solvent annealing time is 6 to 30 hours, and the block copolymer film is in air The treatment time in plasma is 20-60 minutes.

The preparation method of the narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes needs to reduce the partially carbon-coated catalyst before growing the carbon nanotubes. The reducing atmosphere is a mixed gas of hydrogen and argon. The temperature is 500-800°C, and the reduction time is 2-25 minutes; after the catalyst is reduced, the semiconductor single-walled carbon nanotubes with narrow band gap distribution are prepared by chemical vapor deposition at 700-900°C with hydrogen as the carrier gas.

According to the preparation method of narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes, the bandgap difference of the grown single-walled carbon nanotubes is only 0.05eV and adjustable, and the content of semiconducting carbon nanotubes is greater than 98%.

The preparation method of the narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes regulates the bandgap difference of the semiconducting carbon nanotubes by regulating the structure of the catalyst and the reduction process.

The preparation method of the described narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes utilizes multi-wavelength Raman spectroscopy to qualitatively estimate the content of semiconducting single-walled carbon nanotubes, and according to Katarula plots the breath excited by each wavelength laser The semiconducting and metallic carbon nanotubes are divided into semiconducting and metallic carbon nanotubes, and the number of breathing modes in the corresponding area is counted. The content of semiconducting carbon nanotubes is the ratio of the number of breathing modes excited in the semiconducting area and the number of all breathing modes. ratio.

In the preparation method of narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes, the content of semiconducting single-walled carbon nanotubes is qualitatively calculated by absorption spectrum, and the _S22 and The M ₁₁ peak area integral is calculated using the following formula:

M ₁₁ , M ₁₁ peak area of metallic single-walled carbon nanotubes;

S ₂₂ , the S ₂₂ peak area of semiconducting single-walled carbon nanotubes;

f, absorption coefficient.

According to the preparation method of narrow bandgap distribution and high-purity semiconducting single-wall carbon nanotubes, the thin film field-effect transistor constructed by using such high-purity, narrow-bandgap semiconducting single-wall carbon nanotubes has both high switching ratio and high loading Flow carrier mobility, demonstrating the potential application of this narrow-bandgap semiconducting single-walled carbon nanotube in nanoelectronic devices.

Design idea of the present invention is:

The invention provides a method for directly growing narrow-bandgap semiconducting single-walled carbon nanotubes, and designs and prepares a monodisperse, uniform-sized partially carbon-coated metal nanoparticle catalyst. The high-temperature agglomeration of metal particles controls the nucleation mode of single-walled carbon nanotubes to be vertical growth, so that single-walled carbon nanotubes with uniform size can be prepared; on this basis, hydrogen etchant is introduced in situ to remove metallic carbon Nanotubes may inhibit their growth, and then directly obtain narrow band gap distribution and high-purity semiconducting single-walled carbon nanotubes.

In the present invention, by designing the structure of the metal catalyst, combined with in-situ etching, the direct growth of narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes has the following advantages:

1. For the first time, the present invention has designed and prepared a partially carbon-coated metal nanoparticle structure with monodispersity and uniform size, which not only solves the problem of catalyst agglomeration at high temperature, but also solves the problem of controlling the nucleation and growth mode of carbon nanotubes, and then realizes Preparation of single-walled carbon nanotubes with uniform size.

2. On the basis of the preparation of single-walled carbon nanotubes with uniform size, the method of the present invention uses hydrogen as the carrier gas and etching gas, and realizes the narrow bandgap distribution for the first time (the minimum bandgap difference is only 0.05eV) and the bandgap is adjustable. Controlled preparation of high-purity (above 98%) semiconducting single-walled carbon nanotubes.

In a word, the present invention starts from controlling the catalyst structure on which the nucleation stage of single-walled carbon nanotubes depends, realizes the direct growth of narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes, and breaks through the present stage of high-purity, narrow-bandgap The bottleneck of controlled preparation of distributed semiconducting single-walled carbon nanotubes provides a new understanding of the nucleation mechanism of semiconducting single-walled carbon nanotubes with specific structures, and confirms that it is an ideal channel material for the construction of thin film field effect transistors.

Description of drawings

Figure 1. Schematic diagram of the preparation of partially carbon-coated cobalt nanoparticles and the process of growing semiconducting single-walled carbon nanotubes with narrow bandgap distribution.

Figure 2. Morphology of partially carbon-coated cobalt nanoparticles. (a) Atomic force micrograph of part of carbon-coated cobalt nanoparticles; (b) transmission electron micrograph of part of carbon-coated cobalt nanoparticles; (c) histogram of particle size distribution of TEM statistics.

Figure 3. Morphology of carbon nanotubes prepared with partially carbon-coated cobalt nanoparticles as catalysts. (a) SEM image of carbon nanotube network on silicon substrate; (b) TEM image of single-walled carbon nanotubes; (c) TEM image of single-walled carbon nanotubes grown vertically on partially carbon-coated cobalt nanoparticles Photo; (d) Histogram of diameter distribution of carbon nanotubes using transmission electron microscopy.

Figure 4. Raman spectrum D and G modes of single-walled carbon nanotubes prepared with partially carbon-coated cobalt nanoparticles as catalysts.

Figure 5. Multi-wavelength Raman spectrum RBM mode of single-walled carbon nanotubes prepared with partially carbon-coated cobalt nanoparticles as catalysts. (a) 532nm wavelength laser; (b) 633nm wavelength laser; (c) 785nm wavelength laser; (d) 488nm wavelength laser.

Fig. 6. Absorption spectra of single-walled carbon nanotubes prepared with partially carbon-coated cobalt nanoparticles as catalysts.

Figure 7. Performance of thin-film field-effect transistors constructed with single-walled carbon nanotubes prepared using partially carbon-coated cobalt nanoparticle catalysts. (a) Output characteristic curves of a single FET at -1V to -5V; (b) Transfer characteristic curves of 10 TFTs.

Figure 8. Multi-wavelength Raman spectrum RBM mode of bandgap-tunable single-walled carbon nanotubes prepared with partially carbon-coated cobalt nanoparticles as catalysts. (a) 532nm wavelength laser; (b) 633nm wavelength laser; (c) 785nm wavelength laser.

Figure 9. Multi-wavelength Raman spectrum RBM modes of single-walled carbon nanotubes prepared with cobalt nanoparticles as catalysts. (a) Laser with a wavelength of 532nm; (b) Laser with a wavelength of 633nm; (c) Distribution map of the conductive properties of single-walled carbon nanotubes characterized by Raman spectroscopy.

detailed description

In the specific implementation process, the method for preparing a narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes with a partially carbon-coated metal catalyst of the present invention controls the structure and size of the catalyst, and utilizes the etching effect of hydrogen to directly selectively grow Narrow band gap distribution, high-purity semiconducting single-walled carbon nanotubes, the specific steps are as follows:

Using the method of chemical self-assembly of block copolymers, self-assembled block copolymer thin films on silicon substrates; after solvent annealing of the thin films in the mixed vapor of toluene and tetrahydrofuran, chemically adsorbed catalyst precursors, and then subjected to air Plasma (plasma) treatment can obtain metal oxide catalyst nanoclusters covered by part of organic matter, hydrogen reduction treatment at 500-800 ° C to obtain part of carbon-coated catalyst nanoparticles, at 700 ~ 900 ° C with hydrogen as Preparation of semiconducting single-walled carbon nanotubes with narrow bandgap distribution by carrier gas chemical vapor deposition. in:

(1) The self-assembled block copolymer is that the concentration is 0.2～0.5wt%PS-b-P4VP (PS-b-P4VP refers to poly-(styrene-block-4-vinylpyridine) block copolymer) toluene and A tetrahydrofuran mixed solution (the mass ratio of toluene to tetrahydrofuran is 1:1-5:1) is spin-coated at 3000-5000 rpm on the surface of the silicon wafer after hydrophilic treatment.

(2) The block copolymer film on the surface of the silicon wafer is placed in the mixed steam of toluene and tetrahydrofuran (volume ratio 1:2-1:6) for solvent annealing for 6-30 hours, and then immersed in the catalyst with a molar concentration of 0.1-1mM The precursor solution is 1 to 5 minutes, washed and dried with deionized water, and treated with air plasma for 20 to 60 minutes.

(3) The solution of block copolymer film chemical adsorption catalyst precursor is 41.5-166.2g/L hydrochloric acid solution, and its catalyst precursors are: K ₃ [Co(CN) ₆ ], K ₃ [Fe(CN) ₆ ], K ₂ RuCl ₅ , (NH ₄ ) ₁₀ W ₁₂ O ₄₁ , H ₂ [PtCl ₆ ], one or more of them, and must contain K ₃ [Co(CN) ₆ ], K ₂ RuCl ₅ , one of K ₃ [Fe(CN) ₆ ].

(4) Catalyst reduction conditions are 100-200 sccm hydrogen at 500-800° C. for 2-25 minutes.

(5) The carbon source used in chemical vapor deposition is organic small molecule alcohol vapor loaded with argon gas. The volume ratio of argon gas containing carbon source to carrier gas hydrogen gas is 1:1~1:5, and the total gas flow rate remains At 100-600 seem, the growth time is 1-15 minutes.

(6) The diameter of the obtained partial carbon-coated metal nanoparticles is distributed between 2.0 and 4.5 nm, and the catalyst can be Co, Fe, Ru, CoPt, CoRu, CoW, FeRu, FeW, FePt, CoPtW, FePtW, CoRuW , or FeRuW. In the present invention, the specific meaning and structure of partial carbon coating is that the outer surface of the metal particle is partially covered by a carbon layer to form a structure similar to an acorn. That is, the outer surface of the metal particle is partly exposed, and the other part is covered by the carbon layer.

The diameter distribution of the grown single-walled carbon nanotubes is concentrated, the band gap difference is at least 0.05eV and adjustable, the content of semiconducting carbon nanotubes is greater than 98%, and the content of semiconducting single-walled carbon nanotubes is determined by Raman spectroscopy and absorption spectroscopy Perform qualitative estimates and quantitative calculations.

The present invention is further described in detail below by way of examples.

Example 1. Preparation of partially carbon-coated cobalt nanoparticles and its catalytic growth of narrow bandgap distribution, high-purity semiconducting single-walled carbon nanotubes

The specific preparation and growth process is shown in Figure 1.

(1) Preparation of partially carbon-coated Co metal nanoparticles

The toluene and tetrahydrofuran solution (mass ratio of toluene and tetrahydrofuran 2:1) containing 0.3wt% block copolymer was spin-coated on the surface of the silicon wafer after hydrophilic treatment with 4000rpm, and then placed in toluene and tetrahydrofuran solution (volume ratio 1 :3) Solvent annealing in steam for 20 hours, and then place the silicon wafer in 1mM K ₃ [Co(CN) ₆ ] solution for 3 minutes to absorb [Co(CN) ₆ ] ^3- anion, take it out and use deionized Wash with water, dry at 60°C for 30 minutes, and finally place in air plsama (power 20W) for 20 minutes. Place the silicon wafers treated above in a tube furnace, evacuate to below 0.5 MPa, and then inject argon gas to restore the normal pressure, then switch the argon gas to 200 sccm hydrogen gas, and push the silicon wafers into the constant temperature zone, at 20°C Raise the temperature of the constant temperature zone from 500°C to 700°C at a heating rate of 1/min and keep it warm for 5 minutes. The atomic force microscope photo (Fig. 2(a)) shows that the nanoparticles are uniformly dispersed on the surface of the silicon substrate. The TEM pictures (Fig. 2(b)) show that all the nanoparticles are partially covered by the carbon layer, and the particle size is uniform. The diameters of 130 particles were randomly counted, and the result is shown in Figure 2(c), the particle size distribution of nanoparticles is between 2.0 and 4.5nm.

(2) Growth and characterization of narrow bandgap distribution, high-purity semiconducting single-walled carbon nanotubes

On the basis of step one, further pass into the argon gas containing ethanol vapor, its volume ratio to the carrier gas hydrogen is 1:2, the total gas flow rate is maintained at 300 sccm, and chemical vapor deposition is carried out to grow single-walled carbon nanotubes. The growth time is 10 minutes. After the growth was over, the carbon source was turned off, and the samples were taken out after falling to room temperature under the protection of argon. The scanning electron micrograph of the prepared single-walled carbon nanotubes is shown in Fig. 3(a), which is a uniform carbon nanotube network. Its transmission electron microscope photo is shown in Figure 3(b), which is a single high-quality single-walled carbon nanotube with uniform diameter. And the vertical relationship between single-walled carbon nanotubes and some carbon-coated nanoparticles can be directly observed, as shown in Figure 3(c), which indirectly proves its vertical growth mode. The diameters of 150 carbon nanotubes were randomly counted, and the diameter distribution is shown in Figure 3(d). It can be seen that the diameter distribution is very narrow, concentrated at 1.6-1.9nm. According to the corresponding relationship between the diameter of semiconducting single-walled carbon nanotubes and the band gap, the difference in band gap is only 0.08ev. The Raman spectrum of single-walled carbon nanotubes in the range of 1200-1800 wavenumbers is shown in Figure 4. Single-walled carbon nanotubes have a very strong G peak at 1590cm ^-1 , indicating that carbon nanotubes have good crystallinity. The multi-wavelength (532nm, 633nm, 785nm, 488nm laser) Raman RBM peaks are shown in Figure 5(a)-(d). According to the katarula plots and the number of RBM peaks in the corresponding interval, the qualitative estimation of the semiconductor single-walled carbon nanotube content is 98wt%. The absorption spectrum of single-walled carbon nanotubes is shown in Figure 6 (lower curve), and the content of semiconducting single-walled carbon nanotubes is 99wt by quantitative calculation of the integrated area of _S22 and _M11 peaks after deducting the background (upper curve). %.

(3) Construction and performance of thin-film transistor devices with narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes

Using the narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes prepared in step 2 as channel materials, a bottom-gate thin film field-effect transistor was constructed. The output characteristic curve of the field effect transistor is shown in Fig. 7(a), which shows that a good ohmic contact is formed between the carbon nanotubes and the electrodes. Figure 7(b) is the transfer characteristic curve of 10 devices with the same size. According to these curves, the switching ratio of the thin film field effect transistor is 3.1×10 ³ to 3.6×10 ⁶ , and the carrier mobility is 36 to 143 cm ² v ^-1 s ^-1 . Compared with the results reported in the existing literature, the performance of its thin film transistor is at the leading level.

Example 2. Preparation of partially carbon-coated iron nanoparticles and its catalytic growth of narrow bandgap distribution, high-purity semiconducting single-walled carbon nanotubes

(1) Preparation of partially carbon-coated iron metal nanoparticles

The catalyst preparation steps are the same as in Example 1, except that the catalyst precursor is 1 mM K ₃ [Fe(CN) ₆ ] solution. Atomic force microscopy characterization showed that the nanoparticles were uniformly dispersed on the surface of the silicon substrate. The transmission electron microscope observation shows that the surface of all the nanoparticles is partially covered by the carbon layer, and the particle size is uniform. The diameters of 125 particles randomly counted are distributed in the range of 2.5 to 4.0 nm.

(2) Growth and characterization of narrow bandgap distribution, high-purity semiconducting single-walled carbon nanotubes

The growth and characterization of single-walled carbon nanotubes are consistent with those in Example 1. The diameter of single-walled carbon nanotubes collected by transmission electron microscopy is concentrated in the range of 1.8-2.1 nm. According to the corresponding relationship between the diameter of semiconducting single-walled carbon nanotubes and the band gap, the difference in band gap is only 0.08ev. According to the qualitative estimation of multi-wavelength Raman RBM peaks, the content of semiconducting single-walled carbon nanotubes is 98wt%. The content of the semiconducting single-walled carbon nanotubes is 98wt% according to the quantitative calculation of the absorption spectrum after buckling the background.

(3) Construction and performance of thin-film transistor devices with narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes

The construction and performance testing process of the thin film field effect transistor device is the same as that in Example 1. The switching ratio of the constructed thin film field effect transistor is 4.0×10 ⁴ to 2.5×10 ⁵ , and the carrier mobility is 50 to 110 cm ² v ^-1 s ^-1 .

Example 3. Preparation of partially carbon-coated iron-tungsten nanoparticles and its catalytic growth of narrow bandgap distribution, high-purity semiconducting single-walled carbon nanotubes

(1) Preparation of partially carbon-coated iron-tungsten metal nanoparticles

The catalyst preparation steps are the same as in Example 1, except that the catalyst precursor is a mixed solution of 0.5 mM K ₃ [Fe(CN) ₆ ] and 0.5 mM (NH ₄ ) ₁₀ W ₁₂ O ₄₁ . Atomic force microscopy characterization showed that the nanoparticles were uniformly dispersed on the surface of the silicon substrate. The transmission electron microscope observation shows that the surface of all the nanoparticles is partially covered by the carbon layer, and the particle size is uniform. The diameters of 135 particles randomly counted are distributed in the range of 3.0-4.5nm.

(2) Growth and characterization of narrow bandgap distribution, high-purity semiconducting single-walled carbon nanotubes

The growth and characterization of single-walled carbon nanotubes are consistent with those in Example 1. The diameter of single-walled carbon nanotubes collected by transmission electron microscopy is concentrated in the range of 1.9-2.2nm. According to the corresponding relationship between the diameter of semiconducting single-walled carbon nanotubes and the band gap, the difference in band gap is only 0.06ev. According to the qualitative estimation of multi-wavelength Raman RBM peaks, the content of semiconducting single-walled carbon nanotubes is 98wt%. The content of the semiconducting single-walled carbon nanotubes is 99wt% according to the quantitative calculation of the absorption spectrum after buckling the background.

(3) Construction and performance of thin-film transistor devices with narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes

The construction and performance testing process of the thin film field effect transistor device is the same as that in Example 1. The switching ratio of the constructed thin film field effect transistor is 5.7×10 ⁴ to 7.3×10 ⁵ , and the carrier mobility is 45 to 131 cm ² v ^-1 s ^-1 .

Example 4. Preparation of partially carbon-coated cobalt-tungsten-ruthenium nanoparticles and its catalytic growth of narrow bandgap distribution, high-purity semiconducting single-walled carbon nanotubes

(1) Preparation of partially carbon-coated cobalt-tungsten-ruthenium metal nanoparticles

The catalyst was prepared using the method of Example 1, except that the catalyst precursor was a mixed solution of 0.3 mM K ₃ [Co(CN) ₆ ], 0.3 mM (NH ₄ ) ₁₀ W ₁₂ O ₄₁ and 0.3 mM K ₂ RuCl ₅ . Atomic force microscopy characterization showed that the nanoparticles were uniformly dispersed on the surface of the silicon substrate. The transmission electron microscope observation shows that the surface of all the nanoparticles is partially covered by the carbon layer, and the particle size is uniform. The diameters of 125 particles randomly counted are distributed in the range of 3.5 to 5.0 nm.

(2) Growth and characterization of narrow bandgap distribution, high-purity semiconducting single-walled carbon nanotubes

The growth and characterization of single-walled carbon nanotubes are consistent with those in Example 1. The diameter of single-walled carbon nanotubes collected by transmission electron microscopy is concentrated in the range of 1.9-2.2nm. According to the corresponding relationship between the diameter of semiconducting single-walled carbon nanotubes and the band gap, the difference in band gap is only 0.07ev. According to the qualitative estimation of multi-wavelength Raman RBM peaks, the content of semiconducting single-walled carbon nanotubes is 98wt%. The content of the semiconducting single-walled carbon nanotubes is 98wt% according to the quantitative calculation of the absorption spectrum after buckling the background.

(3) Construction and performance of thin-film transistor devices with narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes

The construction and performance testing process of the thin film field effect transistor device is the same as in Example 1. The switching ratio of the constructed thin film field effect transistor is 9.7×10 ³ to 8.1×10 ⁵ , and the carrier mobility is 51 to 124 cm ² v ^-1 s ^-1 .

Example 5. Preparation of partially carbon-coated cobalt nanoparticles and its catalytic growth of semiconducting single-walled carbon nanotubes with tunable bandgap

(1) Catalyst preparation

The steps are the same as in Example 1, except that the catalyst reduction process is 100 sccm hydrogen and 100 sccm Ar at 800° C. for 10 minutes. Atomic force microscopy characterization showed that the nanoparticles were uniformly dispersed on the surface of the silicon substrate. The transmission electron microscope observation shows that the surface of all the nanoparticles is partially covered by the carbon layer, and the particle size is uniform. The diameters of 140 particles randomly counted are distributed in the range of 2.5 to 4.5 nm.

(2) Growth and characterization of narrow bandgap distribution, high-purity semiconducting single-walled carbon nanotubes

The growth and characterization of single-walled carbon nanotubes are consistent with those in Example 1. The diameter of single-walled carbon nanotubes collected by transmission electron microscopy is concentrated in the range of 2.0-2.2 nm, and the difference in band gap is 0.05 eV. According to the multi-wavelength Raman RBM peaks (Fig. 8(a)-(c)), the qualitative estimation of semiconducting single-walled carbon nanotube content is 97wt%. The content of the semiconducting single-walled carbon nanotubes is 99wt% according to the quantitative calculation of the absorption spectrum after buckling the background.

(3) Construction and performance of thin-film transistor devices with narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes

The construction and performance testing process of the thin film field effect transistor device is the same as that in Example 1. The switching ratio of the constructed thin film field effect transistor is 5.9×10 ³ to 3.4×10 ⁵ , and the carrier mobility is 50 to 121 cm ² v ^-1 s ^-1 .

Comparative example. Preparation of ordinary cobalt nanoparticles and its catalytic growth of single-walled carbon nanotubes

(1) Catalyst preparation

The preparation steps are the same as in Example 1, except that there is no solvent-free annealing process in the block copolymer self-assembly process, and the "air plasmama treatment process" is replaced by "heat treatment at 700°C in air for 10 minutes" to obtain fully exposed metal nanoparticles . Atomic force microscopy characterization showed that the nanoparticles were uniformly dispersed on the surface of the silicon substrate. The transmission electron microscope observation shows that all the nanoparticles have no carbon coating on the surface. The diameters of 130 particles randomly counted are distributed in the range of 1.5 to 5.5 nm.

(2) Growth and characterization of single-walled carbon nanotubes

The growth and characterization of single-walled carbon nanotubes are consistent with those in Example 1. The diameter of single-walled carbon nanotubes collected by transmission electron microscopy is concentrated in the range of 1.1 to 2.2 nm, and the difference in band gap is 0.38 eV. According to the qualitative estimation of the multi-wavelength Raman RBM peak (Fig. 9(a)-(c)), the content of semiconducting single-walled carbon nanotubes is 67wt%. The content of the semiconducting single-walled carbon nanotubes is 69wt% according to the quantitative calculation of the absorption spectrum behind the background.

(3) Construction and performance of single-walled carbon nanotube thin film transistor devices

The construction and performance testing process of the thin film field effect transistor device is the same as that in Example 1. The switching ratio of the constructed thin film field effect transistor is 0.5×10 ² to 1.4×10 ² , and the carrier mobility is 10 to 21 cm ² v ^-1 s ^-1 .

The results of the examples show that the present invention can control the nucleation mode of carbon nanotubes through the design of the structure of the partially carbon-coated catalyst, which is a prerequisite for obtaining single-walled carbon nanotubes with narrow diameter distribution. Utilizing the in-situ etching effect of hydrogen, it can Direct growth of narrow bandgap distribution, high-purity semiconducting single-walled carbon nanotubes. Moreover, the bandgap difference of semiconducting single-walled carbon nanotubes can be regulated by adjusting the catalyst type, composition and reduction conditions, and the obtained narrow bandgap distribution and high-purity semiconducting single-walled carbon nanotubes have excellent performance of field effect transistors.

Claims (9)

1. a kind of narrow band gap distribution, the preparation method of high-purity semi-conductive single-walled carbon nanotubes, it is characterised in that The characteristics of can preparing size uniformity nano particle using Self-Assembling of Block Copolymer method, by control solvent anneal, Oxidation, reducing condition, obtain size uniformity, single dispersing, the metal nanoparticle of part carbon coating；Using its as Catalyst, using hydrogen weak etching and higher same diameter metallic carbon nanotubes reactivity the characteristics of, Direct in-situ etches metallic carbon nanotubes, obtains high-purity, narrow band gap distribution semi-conductive single-walled carbon nanotubes.

2. according to narrow band gap distribution, the preparation of high-purity semi-conductive single-walled carbon nanotubes described in claim 1 Method, it is characterised in that：Catalyst structure is the nano particle of part carbon coating, and particle size is 2.0~4.5 nm；Wherein, catalyst component is more than one or both of transition metal；Or, catalyst component is height It is more than one or both of melting point metals.

3. according to narrow band gap distribution, the preparation of high-purity semi-conductive single-walled carbon nanotubes described in claim 1 Method, it is characterised in that：During Block Copolymer Thin Film being prepared using self-assembly method, the solvent anneal time For 6~30 hours, the time that Block Copolymer Thin Film is handled in air plasma was 20~60 minutes.

4. according to narrow band gap distribution, the preparation of high-purity semi-conductive single-walled carbon nanotubes described in claim 1 Method, it is characterised in that：Need to carry out reduction treatment to the catalyst of part carbon coating before growth CNT, Reducing atmosphere is the mixed gas of hydrogen and argon gas, and reduction temperature is 500~800 DEG C, and the recovery time is 2~25 Minute；Catalyst is prepared after reduction treatment at 700~900 DEG C by carrier gas chemical vapor deposition of hydrogen Narrow band gap is distributed semi-conductive single-walled carbon nanotubes.

5. according to narrow band gap distribution, the preparation of high-purity semi-conductive single-walled carbon nanotubes described in claim 1 Method, it is characterised in that：The single-walled carbon nanotube difference in band gap grown is only 0.05eV and adjustable, semiconductor Property content of carbon nanotubes be more than 98%.

6. according to the narrow band gap distribution described in claim 1 or 5, high-purity semi-conductive single-walled carbon nanotubes Preparation method, it is characterised in that：Regulate and control semiconductive carbon nanometer by regulating and controlling the structure and reduction process of catalyst The difference in band gap of pipe.

7. according to narrow band gap distribution, the preparation of high-purity semi-conductive single-walled carbon nanotubes described in claim 5 Method, it is characterised in that：The content of semi-conductive single-walled carbon nanotubes is estimated using wavelength Raman qualitative spectrometric, The breathing mould excited according to Katarula plots to each wavelength laser carries out semiconductive and metallicity carbon nanometer The division of pipe, counts the number in respective regions internal respiration mould, the content of semiconductive carbon nano tube is semiconductor Property region in excited breathing mould number with it is all breathing mould numbers ratios.

8. according to narrow band gap distribution, the preparation of high-purity semi-conductive single-walled carbon nanotubes described in claim 5 Method, it is characterised in that：The content of semi-conductive single-walled carbon nanotubes is obtained using the qualitative calculating of absorption spectrum, The S corresponding to the absorption curve after back end will be deducted₂₂And M₁₁Integrating peak areas, is counted using equation below Calculate：

<mrow> <msub> <mi>R</mi> <mi>S</mi> </msub> <mo>=</mo> <mfrac> <msub> <mi>n</mi> <mi>S</mi> </msub> <mrow> <msub> <mi>n</mi> <mi>M</mi> </msub> <mo>+</mo> <msub> <mi>n</mi> <mi>S</mi> </msub> </mrow> </mfrac> <mo>=</mo> <mfrac> <mn>1</mn> <mrow> <mn>1</mn> <mo>+</mo> <mfrac> <msub> <mi>M</mi> <mn>11</mn> </msub> <mrow> <msub> <mi>S</mi> <mn>22</mn> </msub> <mi>f</mi> </mrow> </mfrac> </mrow> </mfrac> </mrow>

M₁₁, metallic single-wall carbon nano-tube M₁₁Peak area；

S₂₂, semi-conductive single-walled carbon nanotubes S₂₂Peak area；

F, absorption coefficient.

9. according to narrow band gap distribution, the preparation of high-purity semi-conductive single-walled carbon nanotubes described in claim 1 Method, it is characterised in that：Using thin constructed by this high-purity, narrow gap semiconductor single-walled carbon nanotube Film field-effect transistor has high on-off ratio and high carrier mobility concurrently, shows this narrow gap semiconductor single wall Potential application of the CNT in terms of nanometer electronic device.