A method for removing polymers from the surface of carbon nanotubes and carbon nanotubes

Abstract

The present application relates to a kind of methods for removing polymer on the surface of carbon nanotube and carbon nanotube, belong to semiconductor technical field, solve the problem that the method for removing polymer on the surface of carbon nanotube in prior art can introduce more defects.The method comprises: step 1: using thermal mode atomic layer deposition method to grow a layer of yttrium oxide film on the carbon nanotube film on the surface of substrate;Step 2: using dilute hydrochloric acid to etch the yttrium oxide film grown in step 1.The method of the present application reduces the introduction of defects, improves the interface electrical characteristics of carbon nanotube field effect transistor.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more particularly to a method for removing polymers from the surface of carbon nanotubes and carbon nanotubes. Background Technology

[0002] The development of the microelectronics industry is the foundation of the modern information industry. As the feature size of devices continues to shrink according to Moore's Law, the impact of the short-channel effect on the performance of traditional silicon-based electronic devices will become increasingly significant. Furthermore, the manufacturing cost of advanced technology nodes is also rapidly increasing with the reduction in feature size, pushing the physical limits of silicon-based devices step by step. Currently, carbon-based nanoelectronics has received widespread attention in the industry, especially field-effect transistors using carbon nanotubes as channel materials. Due to their advantages such as high mobility, near-ballistic transport, large current density, and good manufacturing process compatibility, they have the potential to replace traditional silicon-based devices.

[0003] In the solution-based fabrication of carbon nanotube films, polymers are required for assisted growth. Consequently, a certain amount of organic polymers remain around the formed carbon nanotubes. The presence of these organic polymers degrades device performance, making polymer removal a primary objective. Current methods involve high-temperature annealing of the carbon nanotube film, which decomposes the polymers, thus removing them. However, high temperatures introduce numerous defects, further reducing the performance of the carbon nanotubes. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a method for removing polymers from the surface of carbon nanotubes and carbon nanotubes, in order to solve the problem that existing methods for removing polymers from the surface of carbon nanotubes introduce many defects.

[0005] On one hand, embodiments of the present invention provide a method for removing polymers from the surface of carbon nanotubes, the method comprising:

[0006] Step 1: A yttrium oxide film is grown on the carbon nanotube film on the substrate surface using a thermal atomic layer deposition method;

[0007] Step 2: Use dilute hydrochloric acid to etch away the yttrium oxide film grown in Step 1.

[0008] Preferably, in step 1, a yttrium oxide film is grown on a carbon nanotube film on the substrate surface using a thermal mode atomic layer deposition method, which includes: placing a substrate containing carbon nanotubes on its surface in an atomic layer deposition reaction chamber, and then alternately introducing yttrium source vapor and oxygen source vapor into the reaction chamber to grow the yttrium oxide film.

[0009] Preferably, step 1 includes:

[0010] Step 1-1: Place the substrate containing carbon nanotubes on its surface in the atomic layer deposition reaction chamber;

[0011] Steps 1-2: Clean the reaction chamber and gas transmission pipeline with inert gas;

[0012] Steps 1-3: Use inert gas to transfer yttrium source vapor into the reaction chamber;

[0013] Steps 1-4: Clean the reaction chamber and gas transmission pipeline with inert gas;

[0014] Steps 1-5: Use inert gas to transfer oxygen vapor into the reaction chamber;

[0015] Steps 1-6: Clean the reaction chamber and gas transmission pipeline with inert gas;

[0016] Steps 1-7: Repeat steps 1-2 to 1-6 in a loop.

[0017] Preferably, the yttrium source is at least one selected from the following: tri(cyclopentadienyl)yttrium, tri(methylcyclopentadienyl)yttrium, tri(butylcyclopentadienyl)yttrium, tri(propylcyclopentadienyl)yttrium, tri(propylformamide)yttrium, tri(tetramethylheptanedionate)yttrium, hexafluoroacetylacetonate yttrium, and yttrium acetylacetonate hydrate.

[0018] Preferably, the oxygen source is water.

[0019] Preferably, the vacuum degree of the reaction chamber is 0.1-4 mbar, and the temperature of the reaction chamber is 90-400℃.

[0020] Preferably, the heat source temperature of the yttrium source is 50-200°C, and the liquid source temperature of the oxygen source is 15-30°C.

[0021] Preferably, the thickness of the yttrium oxide film is 0.3-100 nm.

[0022] On the other hand, the present invention also provides carbon nanotubes obtained by the above method.

[0023] Thirdly, the present invention also provides a method for preparing a carbon nanotube thin film, the method comprising: preparing a carbon nanotube thin film on a substrate by a solution method, and then removing the polymer on the surface of the carbon nanotube by the method described in any one of claims 1-8.

[0024] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0025] 1. This invention employs a thermal atomic layer deposition (TLD) method to grow a yttrium oxide (YTO) film on carbon nanotubes on a substrate surface. The grown YTO film is then etched away using dilute hydrochloric acid. Because the electrostatic force between YTO and the organic polymer on the carbon nanotube surface is greater than the electrostatic force between the organic polymer and the carbon nanotube and the substrate, the organic polymer is removed simultaneously with the YTO. The thermal ALD method offers the advantage of conformality; during YTO growth, the YTO molecules effectively encapsulate the carbon nanotubes. Compared to first growing metallic YTO and then subjecting it to high-temperature oxidation, this invention increases the contact area between the two. Furthermore, by utilizing the principle that the electrostatic force between YTO and the organic polymer on the carbon nanotube surface is greater than the electrostatic force between the organic polymer and the carbon nanotube and the substrate, the efficiency of removing the organic polymer is also improved.

[0026] 2. Compared with the prior art, the thermal mode atomic layer deposition method and the dilute hydrochloric acid etching step of the present invention can both remove organic polymers under low temperature conditions, reduce the introduction of defects (the G / D peak ratio of the treated carbon nanotubes can reach above 7.6, for example 7.6-7.7), thereby improving the interfacial electrical properties of carbon nanotube field-effect transistors.

[0027] 3. Thermal atomic layer deposition method has the advantages of high uniformity, good density, low temperature growth, good surface coverage, low deposition rate, self-limiting surface adsorption reaction and precise control of growth rate, which can effectively improve the surface treatment efficiency of carbon nanotubes.

[0028] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0029] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0030] Figure 1 This is a flowchart illustrating the process of removing polymers from the surface of carbon nanotubes according to the present invention;

[0031] Figure 2a This is a substrate ready for use after cleaning;

[0032] Figure 2b To prepare a thin film of carbon nanotubes on a substrate;

[0033] Figure 2c To grow a yttrium oxide film on the surface of carbon nanotube materials;

[0034] Figure 2d The surface of carbon nanotubes after being etched with dilute hydrochloric acid.

[0035] Figure 3 SEM image of the surface of untreated carbon nanotubes;

[0036] Figure 4 SEM image of carbon nanotube surface after treatment using the method of removing polymer from carbon nanotube surface according to the present invention;

[0037] Figure 5 Raman spectral scans of the surfaces of untreated carbon nanotubes and carbon nanotubes treated in Example 1;

[0038] Figure 6 This illustrates the effect of different nitrogen purging times on the uniformity of yttrium oxide films in Example 8.

[0039] Figure 7 This illustrates the effect of different reaction chamber temperatures on the uniformity of the yttrium oxide film in Example 9.

[0040] Figure 8 This is a Raman spectrum scan of the carbon nanotube surface treated in Comparative Example 1.

[0041] Figure label:

[0042] 01-Substrate; 02-Carbon nanotube film; 03-Yttrium oxide film; 04-Cleaned carbon nanotube film. Detailed Implementation

[0043] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0044] On the one hand, the present invention provides a method for removing polymers from the surface of carbon nanotubes, such as... Figure 1 and Figures 2a-2d As shown, the method includes:

[0045] Step 1: A yttrium oxide film 03 is grown on the carbon nanotube film 02 on the surface of substrate 01 using a thermal mode atomic layer deposition method;

[0046] Step 2: Use dilute hydrochloric acid to etch away the yttrium oxide film grown in Step 1 to obtain the cleaned carbon nanotube film 04.

[0047] Compared to existing technologies, this invention employs a thermal mode atomic layer deposition (TMD) method to grow a yttrium oxide (YO) film on carbon nanotubes on a substrate surface. This YO film is then etched away using dilute hydrochloric acid. Because the electrostatic force between YO and the organic polymer on the carbon nanotube surface is greater than the electrostatic force between the organic polymer and the carbon nanotube and the substrate, the organic polymer is removed simultaneously with the YO. The thermal mode AMD method offers the advantage of conformality; during YO growth, the YO molecules can effectively encapsulate the carbon nanotubes. Compared to first growing metallic YO and then performing high-temperature oxidation, this invention increases the contact area between the two. Furthermore, by utilizing the principle that the electrostatic force between YO and the organic polymer on the carbon nanotube surface is greater than the electrostatic force between the organic polymer and the carbon nanotube and the substrate, the efficiency of removing the organic polymer is also improved. Compared to existing technologies, both the thermal mode AMD method and the dilute hydrochloric acid etching step of this invention remove the organic polymer under low-temperature conditions, reducing the introduction of defects and thus improving the interfacial electrical properties of the carbon nanotube field-effect transistor. The thermal mode atomic layer deposition method of the present invention has the advantages of high uniformity, good density, low temperature growth, good surface coverage, low deposition rate, self-limiting surface adsorption reaction, and precise control of growth rate.

[0048] For example, the polymer on the surface of the carbon nanotube is poly[9-(1-octylnonyl)-9H-carbazole](PCz).

[0049] For example, in step 1, the method of growing a yttrium oxide film on a carbon nanotube film on a substrate surface using thermal mode atomic layer deposition includes: placing a substrate containing carbon nanotubes on its surface in an atomic layer deposition reaction chamber, and then alternately introducing yttrium source vapor and oxygen source vapor into the reaction chamber to grow a yttrium oxide film.

[0050] Specifically, step 1 includes:

[0051] Step 1-1: Place the substrate containing carbon nanotubes on its surface in the atomic layer deposition reaction chamber;

[0052] Steps 1-2: Clean the reaction chamber and gas transmission pipeline with inert gas;

[0053] Steps 1-3: Use inert gas to transfer yttrium source vapor into the reaction chamber;

[0054] Steps 1-4: Clean the reaction chamber and gas transmission pipeline with inert gas;

[0055] Steps 1-5: Use inert gas to transfer oxygen vapor into the reaction chamber;

[0056] Steps 1-6: Clean the reaction chamber and gas transmission pipeline with inert gas;

[0057] Steps 1-7: Repeat steps 1-2 to 1-6 in a loop.

[0058] For example, in steps 1-3, the pulse time of the yttrium source vapor is 1 millisecond to 5 minutes, more preferably 1-60 seconds, such as 10 seconds, 20 seconds, 30 seconds, 40 seconds, or 50 seconds. If the pulse time of the yttrium source vapor is too short, the quality of the grown film will be deteriorated; if it is too long, it will result in material waste.

[0059] For example, in steps 1-5, the pulse time of the oxygen source vapor is 1 millisecond to 5 minutes, more preferably 1-60 seconds, such as 10 seconds, 20 seconds, 30 seconds, 40 seconds, or 50 seconds. If the pulse time of the oxygen source vapor is too short, the quality of the grown film will be deteriorated; if it is too long, it will result in material waste.

[0060] For example, in steps 1-2, 1-4, and 1-6, the cleaning time is 1 millisecond to 30 minutes, more preferably 1-60 seconds, such as 10 seconds, 20 seconds, 30 seconds, 40 seconds, or 50 seconds, and most preferably 10 seconds. Too short a cleaning time will result in incomplete cleaning of the cavity and deterioration of the membrane quality, while too long a cleaning time will lead to waste of both material and time.

[0061] For example, the yttrium source is at least one of tri(cyclopentadienyl)yttrium, tri(methylcyclopentadienyl)yttrium, tri(butylcyclopentadienyl)yttrium, tri(propylcyclopentadienyl)yttrium, tri(propylformamide)yttrium, tri(tetramethylheptanedionate)yttrium, hexafluoroacetylacetonate yttrium, and yttrium acetylacetonate hydrate.

[0062] For example, the oxygen source is water.

[0063] For example, the vacuum level of the reaction chamber is 0.1-4 mbar, such as 1 mbar, 2 mbar, or 3 mbar.

[0064] For example, the temperature of the reaction chamber is 90-400°C, such as 100°C, 150°C, 200°C, 250°C, 300°C, or 350°C. More preferably, it is 200°C or 250°C. The temperature of the reaction chamber must be at least higher than the temperature of the heat source, and the maximum temperature is the annealing temperature, to minimize the introduction of defects. If the temperature of the reaction chamber is too low, the quality of the formed film will be poor; if the temperature of the reaction chamber is too high, defects are easily introduced, and the growth rate of yttrium oxide will be affected.

[0065] For example, the heat source temperature of the yttrium source is 50-200°C, such as 70°C, 100°C, 120°C, 140°C, 160°C, or 180°C. The heat source temperature of the yttrium source is determined by the physical properties of the source; if it is too low, it will affect the growth rate or even prevent film formation.

[0066] The heat source temperature of the oxygen source is determined by the physical properties of the source. For example, the liquid source temperature of the oxygen source is 15-30℃, such as 17℃, 20℃, 23℃, and 27℃.

[0067] For example, the thickness of the yttrium oxide film is 0.3-100 nm, more preferably 2-20 nm, such as 3 nm, 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, and 17 nm. The thickness of the yttrium oxide film is sufficient to encapsulate the carbon nanotubes; if the thickness is too small, the nanotubes will not be encapsulated, and the polymer will not be completely removed.

[0068] For example, in step 2, the volume ratio of hydrochloric acid to water in the dilute hydrochloric acid is 1:1-30, such as 1:5, 1:10, 1:15, 1:20, or 1:25. If the dilute hydrochloric acid is too dilute, the removal will be incomplete.

[0069] For example, in step 2, the etching time is from 10 seconds to 1 hour. If the time is too short, the removal will not be complete.

[0070] Secondly, the present invention also provides carbon nanotubes obtained by the above method. These nanotubes have fewer defects and exhibit higher interfacial electrical properties compared to carbon nanotube field-effect transistors.

[0071] For example, the carbon nanotubes have a G / D peak ratio of 7.6 or higher, such as 7.6-7.7.

[0072] Thirdly, the present invention provides a method for preparing a carbon nanotube thin film, the method comprising: preparing a carbon nanotube thin film on a substrate using a solution method, and then removing the polymer on the surface of the carbon nanotube using the above method.

[0073] Exemplarily, the preparation of a carbon nanotube film on a substrate includes: preparing a carbon nanotube film using a solution method, the process of which includes: dissolving carbon nanotube powder and poly[9-(1-octylnonyl)-9H-carbazole] (PCz) solution in toluene, then dispersing, centrifuging, filtering, rinsing, redispersing, and purifying to obtain a highly dispersed carbon nanotube solution (CNT solution). At this point, the carbon nanotubes are coated with PCz molecules. The substrate is then immersed in the prepared CNT solution, 2-buten-1,4-diol is added dropwise, and then the substrate is removed, repeatedly washed, and heated to obtain the carbon nanotube film.

[0074] For example, the substrate is a group IV material, a group III-V compound semiconductor material, or a group II-VI compound semiconductor material.

[0075] The following specific embodiments further illustrate the method for removing polymers from the surface of carbon nanotubes and the method for preparing carbon nanotube films according to the present invention.

[0076] Example 1

[0077] This embodiment provides a method for removing polymers from the surface of carbon nanotubes.

[0078] Step 1: A yttrium oxide film is grown on a carbon nanotube film on a substrate surface using a thermal atomic layer deposition method.

[0079] Step 1-1: Place the prepared silicon-based carbon nanotube substrate in the atomic layer deposition reaction chamber; evacuate the reaction chamber to a vacuum level of 2 mbar; control the nitrogen flow rate at 200 sccm; control the temperature of the commercial liquid water source at 20℃, the heat source temperature of the yttrium source at 140℃, and heat the reaction chamber to 250℃. At this temperature, the growth rate of yttrium oxide is 0.14 nm / cycle.

[0080] Step 1-2: Clean the reaction chamber and gas transmission pipeline with nitrogen for 0.5 seconds;

[0081] Steps 1-3: Use nitrogen gas to transmit yttrium source (yttrium tri(cyclopentadiene)ide) vapor with a pulse duration of 0.5s into the reaction chamber;

[0082] Steps 1-4: Clean the reaction chamber and gas transmission pipeline with nitrogen for 10 seconds;

[0083] Steps 1-5: Use nitrogen gas to transmit water vapor with a pulse duration of 0.2s into the reaction chamber;

[0084] Steps 1-6: Clean the reaction chamber and gas transmission pipeline with nitrogen for 10 seconds;

[0085] Steps 1-7: Repeat steps 1-2 to 1-6 60 times to obtain a yttrium oxide film with a thickness of 8 nm.

[0086] Step 2: Use dilute hydrochloric acid to etch away the yttrium oxide film grown in Step 1 to obtain the cleaned carbon nanotube film 04.

[0087] Step 2-1: Pour 200ml of deionized water into a beaker;

[0088] Step 2-2: Add 10ml of hydrochloric acid to the deionized water in the beaker;

[0089] Steps 2-3: Place the wafer grown in step 1 into a beaker for 10 minutes to remove the yttrium oxide film.

[0090] Figure 3 This is a SEM scan image of the carbon nanotube film surface before treatment in this embodiment. Figure 4 This is a SEM scan of the surface of the carbon nanotube film after treatment in this embodiment. Figure 3 and Figure 4It is evident that the gaps between the carbon nanotubes after treatment in this embodiment are larger, indicating that the organic matter attached to the carbon nanotubes has been effectively removed, and the surface quality of the carbon nanotubes after yttrium oxide growth and dilute hydrochloric acid corrosion is higher.

[0091] Figure 5 The images show Raman spectra of untreated carbon nanotubes and carbon nanotubes treated in Example 1. As can be seen from the images, the Raman shift is around 1620 cm⁻¹. -1 The significant decrease in the peak value represented by nearby PCz molecules indicates that Example 1 effectively removed the polymer PCz from the surface of the carbon nanotubes; furthermore, while maintaining the Raman shift at 1590 cm⁻¹... -1 Under constant conditions near the (G peak), the Raman shift is at 1350 cm⁻¹. -1 The G / D peak value was significantly reduced. The G / D peak value ratio of the untreated carbon nanotube was 5.2, while that of the carbon nanotube treated in Example 1 was 7.7. This indicates that the ratio of the peak value of the G peak to the peak value of the D peak of the carbon nanotube was significantly improved after the treatment in Example 1. This also indicates that the defects of the carbon nanotube were significantly reduced, thereby improving the performance of the carbon nanotube (the larger the ratio of the G peak to the D peak, the better the quality of the carbon nanotube and the fewer the defects).

[0092] Example 2

[0093] This embodiment provides a method for preparing carbon nanotube thin films, including:

[0094] The process includes: dissolving carbon nanotube powder and poly[9-(1-octylnonyl)-9H-carbazole] (PCz) solution in toluene, followed by dispersion, centrifugation, filtration, rinsing, and redispersion, and then purification to obtain a highly dispersed carbon nanotube solution (CNT solution). At this point, the carbon nanotubes are coated with PCz molecules. A substrate is immersed in the prepared CNT solution, and 2-buten-1,4-diol is added dropwise. The substrate is then removed, repeatedly washed, and heated to obtain a carbon nanotube film. The polymer on the carbon nanotube surface is then removed according to the method in Example 1.

[0095] Example 3

[0096] This embodiment provides a method for removing polymers from the surface of carbon nanotubes that is the same as in Example 1, except that the reaction chamber temperature is 200°C.

[0097] At this point, the growth rate of yttrium oxide was 0.12 nm / cycle, indicating that increasing the reaction chamber temperature would decrease the growth rate of yttrium oxide. The peak G / D ratio of the carbon nanotubes was 7.6.

[0098] Example 4

[0099] This embodiment provides a method for removing polymers from the surface of carbon nanotubes that is the same as in Example 1, except that the thickness of the yttrium oxide film is 1 nm.

[0100] Compared to Example 1, the carbon nanotubes obtained in this example have a small amount of polymer remaining around them. This is because the yttrium oxide film is thinner and does not completely encapsulate the carbon nanotubes.

[0101] Example 5

[0102] This embodiment provides a method for removing polymers from the surface of carbon nanotubes that is the same as in Example 1, except that the heat source temperature of the yttrium source is 120°C.

[0103] In this embodiment, due to the low yttrium source temperature, the growth rate of yttrium oxide is low, at 0.08 nm / cycle.

[0104] Example 6

[0105] This embodiment provides a method for removing polymers from the surface of carbon nanotubes that is the same as in Example 1, except that the pulse duration of the yttrium source vapor is 0.1 s.

[0106] Compared to Example 1, a small amount of polymer remained around the carbon nanotubes obtained in this example. This is because the pulse time of the yttrium source vapor was shorter, which affected the quality of the grown yttrium oxide film.

[0107] Example 7

[0108] This embodiment provides a method for removing polymers from the surface of carbon nanotubes that is the same as in Example 1, except that the pulse duration of the oxygen source vapor is 0.1 s.

[0109] Compared to Example 1, a small amount of polymer remained around the carbon nanotubes obtained in this example because the pulse time of the oxygen source vapor was shorter, which affected the quality of the yttrium oxide film.

[0110] Example 8

[0111] This embodiment provides the effect of nitrogen purging times of 2s and 10s on the uniformity of yttrium oxide films when the reaction chamber temperature is 250°C.

[0112] The effect of different nitrogen purging times on the uniformity of yttrium oxide films is as follows: Figure 6 As shown, when the nitrogen purging time is 2 s, the standard deviation of the yttrium oxide film thickness is 6.692, and when the nitrogen purging time is 10 s, the standard deviation is 4.685. It can be seen that the standard deviation of the yttrium oxide film thickness with a nitrogen purging time of 10 s is less than that with a nitrogen purging time of 2 s. Therefore, the optimal nitrogen purging time is 10 s.

[0113] Example 9

[0114] In this embodiment, yttrium oxide films were grown at different reaction chamber temperatures (160℃, 180℃, 200℃, 250℃, 275℃) to obtain the effect of different reaction chamber temperatures on the uniformity of yttrium oxide films.

[0115] The results are as follows Figure 7 As shown, the standard deviation of the yttrium oxide film thickness at 160℃ is 17.267, at 180℃ it is 11.145, at 200℃ it is 2.392, at 250℃ it is 4.685, and at 160℃ it is 5.820. Therefore, the preferred temperature for the reaction chamber is 200℃ or 250℃.

[0116] Comparative Example 1

[0117] Comparative Example 1 describes an existing high-temperature annealing method for removing polymers from the surface of carbon nanotubes, comprising: annealing a substrate containing a carbon nanotube film at 600°C using argon gas at a flow rate of 350 sccm and hydrogen gas at a flow rate of 50 sccm for 3 hours; heating process: heating to 600°C in half an hour; cooling process: naturally cooling to room temperature, and the annealing process is completed.

[0118] Figure 8 The image shows the Raman spectrum of the carbon nanotube surface treated in this comparative example. The G / D peak ratio of the carbon nanotube obtained in this comparative example is 4.5.

[0119] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for removing polymers from the surface of carbon nanotubes, characterized in that, The method includes: Step 1: A yttrium oxide film is grown on a carbon nanotube film on a substrate surface using a thermal atomic layer deposition method, including: placing the substrate containing carbon nanotubes on its surface in an atomic layer deposition reaction chamber, and then alternately introducing yttrium source vapor and oxygen source vapor into the reaction chamber to grow the yttrium oxide film, including: Step 1-1: Place the substrate containing carbon nanotubes on its surface in the atomic layer deposition reaction chamber; Steps 1-2: Clean the reaction chamber and gas transmission pipeline with inert gas; Steps 1-3: Yttrium source vapor is transferred to the reaction chamber using an inert gas; the pulse duration of the yttrium source vapor is 0.5s-50s; Steps 1-4: Clean the reaction chamber and gas transmission pipeline with inert gas; Steps 1-5: Use an inert gas to transfer oxygen source vapor into the reaction chamber; the pulse time of the oxygen source vapor is 0.2s-50s; Steps 1-6: Clean the reaction chamber and gas transmission pipeline with inert gas; Steps 1-7: Repeat steps 1-2 to 1-6 in a loop; In steps 1-2, 1-4 and 1-6, the cleaning time is 10s-60s. The temperature of the reaction chamber is 150-200℃ or 275-350℃; The thickness of the yttrium oxide film is 5-20 nm; Step 2: Use dilute hydrochloric acid to etch away the yttrium oxide film grown in Step 1; In the dilute hydrochloric acid, the volume ratio of hydrochloric acid to water is 1:1-20; The carbon nanotubes obtained by the method have a G / D peak ratio of over 7.6, and the defects of the carbon nanotubes are reduced.

2. The method according to claim 1, characterized in that, The yttrium source is at least one of tri(cyclopentadienyl)yttrium, tri(methylcyclopentadienyl)yttrium, tri(butylcyclopentadienyl)yttrium, tri(propylcyclopentadienyl)yttrium, tri(propylformamide)yttrium, tri(tetramethylheptanedionate)yttrium, hexafluoroacetylacetonate yttrium, and acetylacetonate yttrium hydrate.

3. The method according to claim 1, characterized in that, The oxygen source is water.

4. The method according to claim 1, characterized in that, The vacuum degree of the reaction chamber is 0.1-4 mbar, and the temperature of the reaction chamber is 160-200℃ or 275-300℃.

5. The method according to claim 1, characterized in that, The heat source temperature of the yttrium source is 50-200℃, and the liquid source temperature of the oxygen source is 15-30℃.

6. The method according to claim 1, characterized in that, The thickness of the yttrium oxide film is 5-17 nm.

7. Carbon nanotubes obtained by the method according to any one of claims 1-6.

8. A method for preparing a carbon nanotube thin film, characterized in that, The preparation method includes: preparing a carbon nanotube film on a substrate using a solution method, and then removing the polymer on the surface of the carbon nanotubes using the method described in any one of claims 1-6.

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