Preparation method of single-walled carbon tube film, single-walled carbon tube film and Hall device

Abstract

The invention provides a preparation method of a single-walled carbon tube film, the single-walled carbon tube film and a Hall device, and the preparation method comprises the following steps: providing chemical vapor deposition equipment, the chemical vapor deposition equipment is provided with a first temperature zone, a second temperature zone and a third temperature zone which are communicated, the temperature of the first temperature zone is lower than that of the second temperature zone, and the temperature of the third temperature zone is lower than that of the first temperature zone; the temperature of the second temperature zone is higher than that of the third temperature zone; the method comprises the following steps: placing a catalyst in a first temperature zone for heating treatment, volatilizing the catalyst, introducing a carrier gas and a gas carbon source into the first temperature zone, and forming a mixed gas from the volatilized catalyst, the carrier gas and the gas carbon source; the mixed gas flows to a second temperature zone, and the catalyst and the gas carbon source in the mixed gas react in the second temperature zone to generate a single-walled carbon tube; the bottom lining is placed in a third temperature zone, the generated single-walled carbon tube flows to the third temperature zone along with the gas flow of the carrier gas, and the single-walled carbon tube film is deposited on the surface of the bottom lining. And the three temperature zones are arranged to prepare the single-wall carbon tube film, so that the quality of the single-wall carbon tube film can be effectively improved.

Description

Technical Field

[0001] The present application belongs to the technical field of carbon nanotubes, and more specifically, relates to a method for preparing a single-walled carbon tube film, a single-walled carbon tube film and a Hall device. Background Art

[0002] Carbon nanotubes have excellent electrical properties, high mobility and nanometer-scale diameter. They are competitive materials in the post-Moore era and have great application potential in the field of microelectronics. At the same time, due to the relatively weak hyperfine interaction and spin-orbit coupling effect of carbon nanotubes, carbon nanotubes can achieve longer spin relaxation lifetime and spin diffusion length compared with traditional metal or semiconductor materials. The giant magnetic moment effect at the top or radial opening of carbon nanotubes lays the foundation for the construction of carbon-based spin electronic devices.

[0003] The single-walled carbon tube film produced by the existing single-walled carbon tube film preparation method has residual impurities, which affects the electrical properties and further affects its application in electronic devices such as Hall devices. Summary of the invention

[0004] Based on this, the purpose of the present application is to provide a method for preparing a single-walled carbon tube film, a single-walled carbon tube film and a Hall device, so as to solve the technical problem in the prior art that the single-walled carbon tube film generated in the existing method for preparing the single-walled carbon tube film has residual impurities, which affects the electrical performance.

[0005] In order to achieve the above-mentioned invention object, the technical solution of this application is as follows:

[0006] In a first aspect, a method for preparing a single-walled carbon tube film is provided, comprising the following steps:

[0007] A chemical vapor deposition device is provided, wherein the chemical vapor deposition device is provided with a first temperature zone, a second temperature zone and a third temperature zone which are connected to each other, wherein the temperature of the first temperature zone is lower than the temperature of the second temperature zone, and the temperature of the second temperature zone is higher than the temperature of the third temperature zone;

[0008] The catalyst is placed in the first temperature zone for heating treatment, the catalyst is volatilized, and at the same time, a carrier gas and a gaseous carbon source are introduced into the first temperature zone, and the volatilized catalyst, the carrier gas and the gaseous carbon source form a mixed gas;

[0009] The mixed gas flows to the second temperature zone, and the catalyst and the gaseous carbon source in the mixed gas react in the second temperature zone to generate single-walled carbon tubes;

[0010] The substrate is placed in the third temperature zone, and the generated single-walled carbon tubes flow to the third temperature zone along with the flow of carrier gas, and are deposited on the surface of the substrate to form a single-walled carbon tube film.

[0011] Optionally, the catalyst comprises ferrocene and sulfur; and / or,

[0012] The heating temperature in the first temperature zone is 80°C-95°C, preferably 85°C-92°C.

[0013] Optionally, the catalyst comprises ferrocene and sulfur in a mass ratio of 15-17:1.

[0014] Optionally, the gaseous carbon source is methane; and / or,

[0015] The flow rate of the carrier gas is 900 sccm-1100 sccm, and the flow rate of the gaseous carbon source is 9 sccm-12 sccm.

[0016] Optionally, the molar ratio of the carrier gas to the gaseous carbon source is 95-105:1.

[0017] Optionally, the temperature of the second temperature zone is 1050°C-1200°C.

[0018] Optionally, the temperature of the third temperature zone is 50° C.-200° C., and the temperature gradually decreases from the side close to the second temperature zone to the side away from the second temperature zone; and / or,

[0019] The deposition time of single-walled carbon nanotubes in the third temperature zone is ≥3 min.

[0020] In a second aspect, a single-walled carbon tube film produced by the above-mentioned preparation method is provided.

[0021] Optionally, the length of the single-walled carbon tubes in the single-walled carbon tube film is 90 nm-200 nm.

[0022] Optionally, the diameter of the single-walled carbon tube in the single-walled carbon tube film is 0.8 nm-3 nm.

[0023] In a third aspect, a Hall device is provided, comprising an electrode, a substrate, and a carbon tube film made of the above-mentioned single-walled carbon tube film, wherein the carbon tube film is bonded to the substrate, and the electrode comprises N groups of relatively arranged current input electrodes and M groups of relatively arranged voltage test electrodes, where N is an integer ≥ 1 and M is an integer ≥ 1. The electrode is bonded to the surface of the carbon tube film, and the carbon tube film is exposed between each group of current input electrodes, and the carbon tube film is exposed between each group of voltage test electrodes, and the straight line where each group of current input electrodes is located intersects with the straight line where each group of voltage test electrodes is located.

[0024] Optionally, the straight line where each group of current input electrodes is located is perpendicular to the straight line where each group of voltage test electrodes is located; and / or,

[0025] N=1, M=2, the carbon tube film exposed between each group of current input electrodes and the carbon tube film exposed between each group of voltage test electrodes form a "double-ten connected shape", and each current input electrode and each of the voltage test electrodes are electrically connected to one end of the double-ten connected shape.

[0026] The beneficial effects of this application are:

[0027] 1. The preparation method of the single-walled carbon tube film provided in the application sets the chemical vapor deposition equipment to three temperature zones. The catalyst is heated and volatilized in the first temperature zone, and initially mixed with the carrier gas and the gas carbon source, and then flows to the second temperature zone for further mixing and reaction to generate single-walled carbon tubes. The generated single-walled carbon tubes flow to the third temperature zone and are deposited on the surface of the substrate to form a single-walled carbon tube film. On the one hand, the first temperature zone and the second temperature zone form two mixing areas, so that the catalyst and the gas carbon source can be fully mixed, thereby improving the uniformity of the reaction. On the other hand, the area where the catalyst is heated and volatilized is separated from the area where the single-walled carbon tube is generated by the reaction. The volatilization rate of the catalyst can be controlled by controlling the heating temperature of the first temperature zone, thereby controlling the amount of catalyst added and the reaction rate of the catalyst and the gas carbon source, reducing impurities caused by excess catalyst due to the excessive volatilization rate of the catalyst, improving the quality of the single-walled carbon tube film, and thereby improving the electrical properties of the single-walled carbon tube film. The preparation method of the present application adopts a floating chemical vapor deposition method to prepare the single-walled carbon tube film, and the process is simple, clear, and easy to control, which can effectively improve the quality of the single-walled carbon tube film and has a good prospect for industrial promotion.

[0028] 2. The single-walled carbon tube film provided in this application reduces impurities and improves electrical properties;

[0029] 3. The Hall device provided in the present application, which is made of the above-mentioned single-walled carbon tube film, has improved electrical properties of the Hall device due to the improved electrical properties of the single-walled carbon tube film. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

[0031] Figure 1 This is a schematic diagram of the structure of the Hall device in the embodiment of the present application;

[0032] Figure 2 A cross-sectional schematic diagram of the locations of a group of current input electrodes of the Hall device according to an embodiment of the present application;

[0033] Figure 3 This is a flow chart of a method for preparing a single-walled carbon tube film and a method for preparing a Hall device according to an embodiment of the present application;

[0034] Figure 4 This is a scanning electron microscope characterization image of the single-walled carbon tube film of Example 1 of the present application;

[0035] Figure 5 This is a scanning electron microscope characterization image of the single-walled carbon tube film of Example 2 of the present application;

[0036] Figure 6This is a scanning electron microscope characterization image of the single-walled carbon tube film of Example 3 of the present application;

[0037] Figure 7 This is a scanning electron microscope characterization image of the single-walled carbon tube film of Example 4 of the present application;

[0038] Figure 8 This is a scanning electron microscope characterization image of the single-walled carbon tube film of Example 5 of the present application;

[0039] Fig. 9 This is a schematic diagram of the structure of a Hall device made of the single-walled carbon tube film of Example 1 of the present application;

[0040] Fig.10 This is a test connection diagram of a Hall device made of a single-walled carbon tube film according to an embodiment of the present application;

[0041] Fig.11 This is a graph showing the electrical performance of a Hall device made of the single-walled carbon tube film of Example 1 of the present application;

[0042] Fig.12 This is a graph showing the electrical performance of a Hall device made of the single-walled carbon tube film of Example 2 of the present application;

[0043] Fig.13 This is a graph showing the electrical performance of a Hall device made of the single-walled carbon tube film of Example 3 of the present application;

[0044] Fig.14 This is a graph showing the electrical performance of a Hall device made using the single-walled carbon tube film of Example 5 of the present application.

[0045] Description of reference numerals:

[0046] 10. Hall device; 11. Substrate; 12. Carbon tube film; 13. Electrode; 131. Current input electrode; 132. Voltage test electrode. DETAILED DESCRIPTION

[0047] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0048] In the existing single-walled carbon tube film preparation method, the generated single-walled carbon tube film has residual impurities, which affects the electrical properties of the single-walled carbon tube film, and further affects its application in electronic devices such as Hall devices. During the study, it was found that the reason for the residual impurities in the single-walled carbon tube film is that during the reaction process, the volatilization rate of the catalyst is too fast, and it is difficult to control the reaction. After the single-walled carbon tube is generated, the excess catalyst flows with the single-walled carbon tube to the deposition area and co-deposits to form impurities.

[0049] In order to solve the above problems, the present invention provides a method for preparing a single-walled carbon tube film, comprising the following steps:

[0050] S01: Provide a chemical vapor deposition device, wherein the chemical vapor deposition device is provided with a first temperature zone, a second temperature zone and a third temperature zone which are interconnected, wherein the temperature of the first temperature zone is lower than the temperature of the second temperature zone, and the temperature of the second temperature zone is higher than the temperature of the third temperature zone.

[0051] The first temperature zone is mainly used to provide a temperature zone for heating and volatilizing the catalyst, the second temperature zone is mainly used to provide a temperature zone for reacting to generate single-walled carbon tubes, and the third temperature zone is mainly used to provide a temperature zone for depositing single-walled carbon tubes to form a single-walled carbon tube film. Among them, the first temperature zone is selected according to the volatilization temperature of the catalyst. Generally, the temperature of the first temperature zone is lower than that of the second temperature zone, so that while the catalyst is volatilized, the carbon source will not react in the first temperature zone to generate carbon tubes. Since the carbon source is cracked at a high temperature in the second temperature zone, the temperature of the second temperature zone is the highest, which is conducive to the cracking of the carbon source. The temperature of the third temperature zone is lower than that of the second temperature zone, so that the generated single-walled carbon tubes can settle and deposit into a film.

[0052] Multiple temperature zones serve as multiple working areas, which are beneficial for separately controlling the reaction conditions of each process, so that each process can achieve better reaction effects.

[0053] S02: placing the catalyst in the first temperature zone for heating treatment, the catalyst volatilizes, and a carrier gas and a gaseous carbon source are introduced into the first temperature zone, and the volatilized catalyst, the carrier gas and the gaseous carbon source form a mixed gas.

[0054] The gaseous carbon source in the embodiment of the present application refers to a carbon source in a gaseous state under normal temperature conditions. The use of a gaseous carbon source can avoid the step of heating and gasifying the carbon source, simplify the process, and facilitate the control of the amount of carbon source added.

[0055] The gaseous carbon source is the reactant, and the carrier gas is mainly used to drive the catalyst volatile gas and the gaseous carbon source to flow, and to give the catalyst volatile gas and the gaseous carbon source a certain impact force to disperse and mix the two, and adjust the concentration of the two to avoid excessive local concentration of the catalyst volatile gas and / or the gaseous carbon source, resulting in uneven reaction, generation of impurities or difficulty in controlling the progress of the reaction.

[0056] The catalyst is heated and volatilized in the first temperature zone, and preliminarily mixed with the carrier gas and the gas carbon source to prepare for the next process. The catalyst volatilization rate, carrier gas flow rate and gas carbon source flow rate can be adjusted in the first temperature zone according to the actual reaction conditions, so that the input of each component and the reaction rate of the next process can achieve a better balance effect, improve material utilization, and reduce the generation of impurity particles. Moreover, due to the improved utilization rate of catalyst materials, the amount of catalyst can be reduced, saving materials.

[0057] In some embodiments, the catalyst includes ferrocene and sulfur, that is, a mixture of ferrocene and sulfur as the catalyst. In some preferred embodiments, the catalyst includes ferrocene and sulfur in a mass ratio of 15-17:1.

[0058] The volatilization rate of the catalyst is mainly controlled by the heating temperature of the first temperature zone. The higher the heating temperature, the faster the volatilization rate of the catalyst; and the lower the heating temperature, the lower the volatilization rate of the catalyst.

[0059] In some embodiments, when the catalyst is a mixture of ferrocene and sulfur, the heating temperature of the first temperature zone can be selected as 80°C-95°C, so that the mixture of ferrocene and sulfur volatilizes, and at the same time, the gaseous carbon source does not crack. Moreover, according to experimental results, the heating temperature of the first temperature zone also affects the subsequent reaction of the catalyst with the gaseous carbon source. When the heating temperature of the first temperature zone is too low, for example, <80°C, it may be difficult to grow single-walled carbon tubes, resulting in experimental failure; when the heating temperature of the first temperature zone is too high, for example, >95°C, it may cause the generated single-walled carbon tubes to be relatively fine, and the problem of catalyst particles will appear on the surface of the single-walled carbon tubes. Therefore, in some preferred embodiments, the heating temperature of the first temperature zone is selected as 80°C-95°C, preferably 85°C-92°C.

[0060] At this time, the flow rate of the carrier gas can be selected as 900sccm-1100sccm, the flow rate of the gas carbon source can be selected as 9sccm-12sccm, the volatilization rate of the catalyst, the input rate of the gas carbon source and the reaction rate are relatively balanced, and the raw material utilization rate is high.

[0061] Most existing chemical vapor deposition methods use at least one of alcohol, acetone, benzene, toluene and other substances as a carbon source for cracking to prepare carbon nanotubes. The structures of these substances are relatively complex, and the breaking of the carbon chain is difficult to control, or amorphous carbon is formed, which affects the quality of the carbon nanotubes.

[0062] The embodiments of the present application use gaseous carbon sources, especially small molecule alkanes, such as methane, ethane, propane, etc. as carbon sources. These small molecule alkanes have relatively simple structures, relatively uniform carbon chain breaks, and do not contain heteroatoms, so no impurities will be generated. In particular, when methane is used as the carbon source, the uniformity and electrical properties of the generated single-walled carbon tubes are better.

[0063] In some embodiments, the molar ratio of the carrier gas to the gaseous carbon source is 95-105:1, so as to dilute and disperse the catalyst volatile gas and the gaseous carbon source to reach a suitable concentration and adjust the subsequent reaction rate and reaction degree.

[0064] In some embodiments, the carrier gas is an inert gas, including argon, etc. Argon does not participate in the reaction between the catalyst and the small molecule alkane, and can drive the catalyst volatile gas and the gaseous carbon source to flow along a preset process direction.

[0065] S03: The mixed gas flows to the second temperature zone, and the gaseous carbon source in the mixed gas reacts in the second temperature zone to generate single-walled carbon nanotubes.

[0066] The mixed gas of the catalyst, carrier gas and gaseous carbon source flows to the second temperature zone for further mixing and reaction to generate single-walled carbon tubes. The mixed gas has been heated in the first temperature zone, which has a preheating effect. The temperature of the mixed gas rises naturally in the process from the first temperature zone to the second temperature zone, avoiding the problem of sudden temperature rise, too fast reaction, and catalyst decomposition to produce impurities.

[0067] The single-walled carbon tubes prepared by the existing single-walled carbon tube preparation method have a length of about 20nm-30nm, which is relatively short, and the formed carbon tube film has poor flexibility.

[0068] The embodiment of the present application uses a mixture of ferrocene and sulfur as a catalyst and methane as a carbon source. By using the preparation method of the present application, single-walled carbon tubes with a length of 90nm-200nm can be prepared, and a typical value is 100nm-160nm. The carbon tubes in the prepared single-walled carbon tube film are arranged in a disordered manner. The formed single-walled carbon tube film has good flexibility and can be used to prepare flexible electrodes or other flexible electronic products. It also has good electrical properties and greatly improved electron mobility. When applied to Hall devices, it can improve the electrical properties of the Hall devices.

[0069] The typical value of the embodiments of the present application refers to the average value or normal value of a certain performance of the product, which is a representative parameter that can characterize the characteristics of a group (or the characteristics of a certain subgroup).

[0070] In some embodiments, the molar ratio of the catalyst to the small molecule alkane is 95-105:1, which ensures that longer single-walled carbon tubes can be generated. At the same time, the catalyst will not form excess impurities attached to the single-walled carbon tubes, effectively improving the electrical properties of the single-walled carbon tubes.

[0071] In some embodiments, the temperature of the second temperature zone is 1050° C.-1200° C., which provides sufficient energy for the reaction between the catalyst and the small molecule alkane to make the reaction proceed in the positive direction.

[0072] S04: placing the substrate in the third temperature zone, and the generated single-walled carbon tubes flow to the third temperature zone along with the flow of the carrier gas, and are deposited on the surface of the substrate to form a single-walled carbon tube film.

[0073] After the single-walled carbon tube reaction is completed, the flowing gas includes a carrier gas, or a carrier gas and an incompletely reacted small molecule alkane. The single-walled carbon tube flows to the third temperature zone with the flowing gas. The temperature of the third temperature zone is lower than that of the second temperature zone, so that the single-walled carbon tube can settle and deposit on the surface of the substrate to form a single-walled carbon tube film. The thickness of the single-walled carbon tube film increases with time.

[0074] The deposition time can be adjusted according to the actual thickness requirement of the single-walled carbon tube film. For example, in some embodiments, the single-walled carbon tube is deposited in the third temperature zone for ≥3 minutes.

[0075] It can be understood that the temperatures of the first temperature zone and the third temperature zone may be the same or different. The temperature of the first temperature zone is mainly selected according to the volatilization temperature of the catalyst, and the temperature of the third temperature zone is mainly selected according to the sedimentation of the single-walled carbon tubes.

[0076] In some embodiments, the temperature of the third temperature zone is 50°C-200°C, and the temperature gradually decreases from the side close to the second temperature zone to the side away from the second temperature zone, that is, along the flow direction of the gas, the temperature gradually decreases. According to the experimental results, the deposition sparseness and fineness of the single-walled carbon tube film are different in each temperature zone of the third temperature zone. As the temperature decreases, the deposition of the single-walled carbon tube film becomes sparser, while the single-walled carbon tube film is more finely divided in the higher temperature area.

[0077] In some embodiments, the substrate is cleaned before being placed in the third temperature zone to remove impurities such as dust and grease on the surface of the substrate to prevent the impurities from affecting the deposition of the single-walled carbon tubes and the adhesion of the single-walled carbon tube film.

[0078] Optionally, the cleaning agent is acetone and isopropanol, the substrate is placed in an ultrasonic cleaning machine loaded with acetone and isopropanol, and cleaned under an ultrasonic power of 100 W. After cleaning, it is blown dry with a nitrogen gun to obtain a cleaned substrate.

[0079] In some embodiments, the substrate is a SiO2 / Si P-type silicon wafer substrate, which is a semiconductor material with better electrical properties and is less prone to problems such as warping, fragmentation, and oxygen precipitation, which is beneficial to improving the yield of electronic devices.

[0080] The preparation method of the single-walled carbon tube film provided in the embodiment of the present application sets three temperature zones in the chemical vapor deposition equipment, the catalyst is heated and volatilized in the first temperature zone, and is initially mixed with the carrier gas and the gas carbon source, and then flows to the second temperature zone for further mixing and reaction to generate single-walled carbon tubes, and the generated single-walled carbon tubes flow to the third temperature zone and are deposited on the surface of the substrate to form a single-walled carbon tube film.

[0081] On the one hand, the first temperature zone and the second temperature zone form two mixing zones, so that the catalyst and the small molecule alkane can be fully mixed, thereby improving the uniformity of the reaction. On the other hand, the zone for heating and volatilizing the catalyst is separated from the zone for generating single-walled carbon tubes by reaction, and the volatilization rate of the catalyst can be controlled by controlling the heating temperature of the first temperature zone, thereby controlling the amount of catalyst added and the reaction rate of the catalyst and the small molecule alkane, reducing the impurities generated by the excess catalyst due to the excessive volatilization rate of the catalyst, improving the quality of the single-walled carbon tube film, and thereby improving the electrical properties of the single-walled carbon tube film.

[0082] The preparation method of the embodiment of the present application adopts a floating chemical vapor deposition method to prepare a single-walled carbon tube film, which has a simple, clear and easy-to-control process, can effectively improve the quality of the single-walled carbon tube film, and has a good prospect for industrial promotion.

[0083] The embodiment of the present application also provides a single-walled carbon tube film prepared by the above-mentioned preparation method. The single-walled carbon tube film has reduced impurities, better uniformity, and improved electrical properties.

[0084] The diameter of the single-walled carbon tube in the single-walled carbon tube film is 0.8nm-3nm, the diameter of each single-walled carbon tube is uniform, the diameter of most single-walled carbon tubes is 1nm-2nm, the number of single-walled carbon tubes with a diameter in the range of 1nm-2nm accounts for more than 90% of the total, and the single-walled carbon tubes are uniform.

[0085] The tube diameter in the embodiment of the present application refers to the outer diameter of the single-walled carbon tube.

[0086] The present application embodiment also provides a Hall device 10, such as Figure 1 and Figure 2 As shown, it includes a substrate 11, an electrode 13 and a carbon tube film 12 made of the above-mentioned single-walled carbon tube film, the carbon tube film 12 is bonded to the substrate 11, the electrode 13 includes N groups of current input electrodes 131 arranged oppositely and M groups of voltage test electrodes 132 arranged oppositely, N is an integer ≥ 1, M is an integer ≥ 1, the electrode 13 is bonded to the surface of the carbon tube film 12, and the carbon tube film 12 is exposed between each group of current input electrodes 131, and the carbon tube film 12 is exposed between each group of voltage test electrodes 132, and the straight line where each group of current input electrodes 131 is located intersects with the straight line where each group of voltage test electrodes 131 is located.

[0087] Each group of relatively arranged current input electrodes 131 forms an injection current loop with the carbon tube film 12 and the current input device. The current input electrode 131 is the current connection end of the current input device. The current is input from the current input electrode 131 at one end, passes through the carbon tube film 12 connected to the current input electrode 131, and flows to the current input electrode 131 at the other end, injecting electrons into the Hall device 10, generating an electric field, and then generating a Hall voltage. Each group of relatively arranged voltage test electrodes 132 forms a detection loop with the carbon tube film 12 and the voltage test device to measure the Hall voltage generated by the Hall device 10.

[0088] The carbon tube film 12 of the embodiment of the present application is combined with the substrate 11, which means that the single-walled carbon tubes are deposited on the surface of the substrate 11 and attached to the surface of the substrate 11; the electrode 13 is combined with the carbon tube film 12, which means that the electrode 13 is deposited on the surface of the carbon tube film 12 and attached to the surface of the carbon tube film 12.

[0089] In some embodiments, the straight line where each group of current input electrodes 131 is located is perpendicular to the straight line where each group of voltage test electrodes 132 is located.

[0090] In some embodiments, N=1, M=2, the carbon tube film 12 exposed between each group of current input electrodes 131 and the carbon tube film 12 exposed between each group of voltage test electrodes 132 form a "double-ten connected shape", and each current input electrode 131 and each voltage test electrode 132 are respectively electrically connected to one end of the double-ten connected shape to form a Hall bar shape.

[0091] In some embodiments, the substrate 11 is a P-type silicon wafer substrate of SiO 2 / Si.

[0092] The embodiment of the present application provides a Hall device made of the above-mentioned single-walled carbon tube film. Due to the improvement of the electrical properties of the single-walled carbon tube film, the electrical properties of the Hall device are further improved.

[0093] The present application also provides a method for preparing a Hall device, the process flow is as follows: Figure 3 As shown, steps S01-S04 in the process flow chart are the preparation process of the single-walled carbon tube film, and steps S11-S16 are the preparation process of the Hall device. The preparation method of the Hall device of the embodiment of the present application includes the following steps:

[0094] S11: coating the surface of the single-walled carbon tube film with electron beam glue for the first time, drying, forming a first electron beam glue layer, and obtaining a first-stage primary product.

[0095] In some embodiments, PMMA 950K may be used as the electron beam glue, and the coating method may be spin coating, the process parameters of the spin coating are 3000r / 60s, and then the coating is baked and dried at 180°C-185°C for about 2 minutes.

[0096] S12: According to the first preset pattern, the first electron beam gelatin layer of the first-stage preliminary product is subjected to the first electron beam exposure, then developed with a developer, fixed with a fixer, and dried with a nitrogen gun to form a first development pattern on the first electron beam gelatin layer to obtain a second-stage preliminary product.

[0097] The first preset pattern can be designed using L-edit software.

[0098] Isopropyl alcohol may be used as the fixing solution.

[0099] S13: using a magnetron sputtering method, metal deposition is performed on the surface of the single-walled carbon tube film corresponding to the first developed pattern in the second-stage preliminary product to obtain a third-stage preliminary product having a metal electrode.

[0100] The deposited metal may be molybdenum, or other metals having good electrical conductivity and which can be deposited by magnetron sputtering.

[0101] Optionally, the magnetron sputtering method uses a direct current process (DC), and its process parameters are: the magnetron sputtering power is 200W, and the metal electrode thickness is about 60nm. After the deposition is completed, the sample is placed in a water bath heated with acetone, the water bath temperature is 60°C, and the temperature is kept for about 30 minutes, and then the electrode structure is peeled off by a lift-off process, that is, the first electron beam glue layer outside the electrode structure is removed to obtain the third-stage primary product.

[0102] S14: coating the surface of the third-stage primary product where the metal electrode is located with electron beam glue for the second time to cover the area outside the metal electrode, and then drying to form a second electron beam glue layer to obtain a fourth-stage primary product.

[0103] The electron beam glue coated for the second time may be PMMA 950K, and the coating method may be spin coating, and the process parameters of the spin coating are 3000r / 60s.

[0104] The drying temperature is 180°C-185°C. The drying time can be selected according to the actual drying conditions.

[0105] S15: According to the second preset pattern, the second electron beam gel layer of the fourth-stage primary product is subjected to a second electron beam exposure, and then developed and fixed, and blown dry with a nitrogen gun to obtain a second developed pattern, and the single-walled carbon tube film is exposed in the area corresponding to the second developed pattern to obtain a fifth-stage primary product.

[0106] S16: using reactive ion etching to etch away excess single-walled carbon tube film, that is, the single-walled carbon tube film in areas other than the metal electrode and the second development pattern, the single-walled carbon tube film forms a carbon tube film, and a target product Hall device is obtained.

[0107] In some embodiments, the process parameters of reactive ion etching are: etching gas oxygen, gas flow rate 20 sccm, etching power 100 W, and etching time 5 s.

[0108] The following examples are used to illustrate.

[0109] Example 1

[0110] The length of the single-walled carbon tube film of this embodiment is 90nm-150nm, the diameter of the single-walled carbon tubes in the single-walled carbon tube film is 0.8-3nm, and the diameter of 90% of the single-walled carbon tubes is 1-2nm.

[0111] The method for preparing the single-walled carbon tube film of this embodiment comprises the following steps:

[0112] S1: Provide a chemical vapor deposition device, wherein the chemical vapor deposition device is provided with a first temperature zone, a second temperature zone and a third temperature zone which are interconnected, wherein the temperature of the first temperature zone is 80°C, the temperature of the second temperature zone is 1100°C, and the temperature of the third temperature zone is 50°C-200°C.

[0113] S2: Ferrocene and sulfur in a catalyst mass ratio of 15:1 are placed in the first temperature zone for heat treatment. The catalyst volatilizes, and argon and methane in a molar ratio of 105:1 are introduced into the first temperature zone. The flow rate of argon is 900 sccm, and the flow rate of methane is 9.5 sccm. The volatilized catalyst, argon and methane form a mixed gas.

[0114] S3: The mixed gas flows to the second temperature zone, and the methane in the mixed gas reacts in the second temperature zone to generate single-walled carbon tubes with a length of 90nm-150nm and a tube diameter of 0.8nm-3nm.

[0115] S4: placing a SiO2 / Si P-type silicon wafer substrate in a third temperature zone, and the generated single-walled carbon tubes flow to the third temperature zone along with the argon gas flow, and are deposited on the surface of the substrate to form a single-walled carbon tube film.

[0116] Example 2

[0117] The length of the single-walled carbon tube film of this embodiment is 100nm-160nm, the diameter of the single-walled carbon tubes in the single-walled carbon tube film is 0.8-3nm, and the diameter of 93% of the single-walled carbon tubes is 1-2nm.

[0118] The method for preparing the single-walled carbon tube film of this embodiment comprises the following steps:

[0119] S1: Provide a chemical vapor deposition device, wherein the chemical vapor deposition device is provided with a first temperature zone, a second temperature zone and a third temperature zone which are interconnected, wherein the temperature of the first temperature zone is 85°C, the temperature of the second temperature zone is 1200°C, and the temperature of the third temperature zone is 50°C-200°C.

[0120] S2: ferrocene and sulfur in a catalyst mass ratio of 16:1 are placed in the first temperature zone for heat treatment. The catalyst volatilizes, and argon and methane in a molar ratio of 100:1 are introduced into the first temperature zone. The flow rate of argon is 1100 sccm, and the flow rate of methane is 11 sccm. The volatilized catalyst, argon and methane form a mixed gas.

[0121] S3: The mixed gas flows to the second temperature zone, and the methane in the mixed gas reacts in the second temperature zone to generate single-walled carbon tubes with a length of 100nm-160nm and a tube diameter of 0.8nm-3nm.

[0122] S4: placing a SiO2 / Si P-type silicon wafer substrate in a third temperature zone, and the generated single-walled carbon tubes flow to the third temperature zone along with the argon gas flow, and are deposited on the surface of the substrate to form a single-walled carbon tube film.

[0123] Example 3

[0124] The length of the single-walled carbon tube film of this embodiment is 100nm-200nm, the diameter of the single-walled carbon tubes in the single-walled carbon tube film is 0.8-3nm, and the diameter of 95% of the single-walled carbon tubes is 1-2nm.

[0125] The method for preparing the single-walled carbon tube film of this embodiment comprises the following steps:

[0126] S1: Provide a chemical vapor deposition device, which is provided with a first temperature zone, a second temperature zone and a third temperature zone which are connected to each other. The temperature of the first temperature zone is 90°C, the temperature of the second temperature zone is 1050°C, and the temperature of the third temperature zone is 50°C-200°C.

[0127] S2: Ferrocene and sulfur in a catalyst mass ratio of 17:1 are placed in the first temperature zone for heat treatment. The catalyst volatilizes, and argon and methane in a molar ratio of 105:1 are introduced into the first temperature zone. The flow rate of argon is 900 sccm, and the flow rate of methane is 12 sccm. The volatilized catalyst, argon and methane form a mixed gas.

[0128] S3: The mixed gas flows to the second temperature zone, and the methane in the mixed gas reacts in the second temperature zone to generate single-walled carbon tubes with a length of 100nm-200nm and a tube diameter of 0.8nm-3nm.

[0129] S4: placing a SiO2 / Si P-type silicon wafer substrate in a third temperature zone, and the generated single-walled carbon tubes flow to the third temperature zone along with the argon gas flow, and are deposited on the surface of the substrate to form a single-walled carbon tube film.

[0130] Example 4

[0131] The length of the single-walled carbon tube film of this embodiment is 100nm-200nm, the diameter of the single-walled carbon tubes in the single-walled carbon tube film is 0.8-3nm, and the diameter of 90% of the single-walled carbon tubes is 1-2nm.

[0132] The method for preparing the single-walled carbon tube film of this embodiment comprises the following steps:

[0133] S1: Provide chemical vapor deposition equipment, which is provided with a first temperature zone, a second temperature zone and a third temperature zone which are connected to each other. The temperature of the first temperature zone is 92°C, the temperature of the second temperature zone is 1100°C, and the temperature of the third temperature zone is 50°C-200°C.

[0134] S2: Ferrocene and sulfur in a catalyst mass ratio of 16:1 are placed in the first temperature zone for heat treatment. The catalyst volatilizes, and argon and methane in a molar ratio of 105:1 are introduced into the first temperature zone. The flow rate of argon is 905 sccm, and the flow rate of methane is 12 sccm. The volatilized catalyst, argon and methane form a mixed gas.

[0135] S3: The mixed gas flows to the second temperature zone, and the methane in the mixed gas reacts in the second temperature zone to generate single-walled carbon tubes with a length of 100nm-200nm and a tube diameter of 0.8nm-3nm.

[0136] S4: placing a SiO2 / Si P-type silicon wafer substrate in a third temperature zone, and the generated single-walled carbon tubes flow to the third temperature zone along with the argon gas flow, and are deposited on the surface of the substrate to form a single-walled carbon tube film.

[0137] Example 5

[0138] The length of the single-walled carbon tube film of this embodiment is 100nm-200nm, the diameter of the single-walled carbon tubes in the single-walled carbon tube film is 0.8-3nm, and the diameter of 85% of the single-walled carbon tubes is 1-2nm.

[0139] The method for preparing the single-walled carbon tube film of this embodiment comprises the following steps:

[0140] S1: Provide a chemical vapor deposition device, which is provided with a first temperature zone, a second temperature zone and a third temperature zone which are connected to each other. The temperature of the first temperature zone is 95°C, the temperature of the second temperature zone is 1050°C, and the temperature of the third temperature zone is 50°C-200°C.

[0141] S2: Ferrocene and sulfur in a catalyst mass ratio of 17:1 are placed in the first temperature zone for heat treatment. The catalyst volatilizes, and argon and methane in a molar ratio of 95:1 are introduced into the first temperature zone. The flow rate of argon is 1000 sccm, and the flow rate of methane is 12 sccm. The volatilized catalyst, argon and methane form a mixed gas.

[0142] S3: The mixed gas flows to the second temperature zone, and the methane in the mixed gas reacts in the second temperature zone to generate single-walled carbon tubes with a length of 100nm-200nm and a tube diameter of 0.8nm-3nm.

[0143] S4: placing a SiO2 / Si P-type silicon wafer substrate in a third temperature zone, and the generated single-walled carbon tubes flow to the third temperature zone along with the argon gas flow, and are deposited on the surface of the substrate to form a single-walled carbon tube film.

[0144] The single-walled carbon tube films of Examples 1 to 4 were scanned by SEM images, and the scanning results were as follows: Figures 4 to 7 In the attached figure, the white lines are single-walled carbon tubes, and the white dots are the cross-knotting points of the single-walled carbon tubes.

[0145] in, Figure 4 For the single-walled carbon tube film of Example 1, the temperature of the first temperature zone is 80° C. The generated single-walled carbon tubes are relatively sparse and have knots. Therefore, when the temperature of the first temperature zone is 80° C., it is difficult to deposit a uniform and compact single-walled carbon tube film.

[0146] Figure 5 For the single-walled carbon tube film of Example 2, the temperature of the first temperature zone is 85° C. The single-walled carbon tube film grows well, the single-walled carbon tubes are evenly distributed, and there are fewer cross-knots.

[0147] Figure 6 For the single-walled carbon tube film of Example 3, the temperature of the first temperature zone is 90° C., the single-walled carbon tube film grows well, the single-walled carbon tubes are evenly distributed, and there are fewer cross-knots.

[0148] Figure 7 For the single-walled carbon tube film of Example 4, the temperature of the first temperature zone is 92° C. The single-walled carbon tube film grows well, the single-walled carbon tubes are evenly distributed, and there are fewer cross-knots.

[0149] Figure 8 For the single-walled carbon tube film of Example 5, the temperature of the first temperature zone is 95° C. The distribution of the single-walled carbon tubes is uneven, and the number of catalyst particles on the surface is significantly increased. The distribution of the single-walled carbon tubes is a bit messy, and there are many cross-knots.

[0150] The single-walled carbon tube films of Examples 1, 2, 3, 5 and Comparative Example 1 are applied to a Hall device. The preparation method of the Hall device comprises the following steps:

[0151] S11: The surface of the single-walled carbon tube film is first coated with electron beam glue PMMA 950K, the process parameters of the spin coating are 3000r / 60s, and then baked and dried at 180℃-185℃ for about 2 minutes to form a first electron beam glue layer to obtain a first-stage primary product.

[0152] S12: L-edit software is used to design a first preset pattern. According to the first preset pattern, the first electron beam adhesive layer of the first-stage preliminary product is subjected to the first electron beam exposure, and then developed with a developer, and then fixed with a fixing solution of isopropyl alcohol, and dried with a nitrogen gun to form a first development pattern on the first electron beam adhesive layer to obtain a second-stage preliminary product.

[0153] S13: Using magnetron sputtering method, metal molybdenum is deposited on the surface of the single-walled carbon tube film corresponding to the first development pattern in the second-stage primary product, and its process parameters are: magnetron sputtering power is 200W, and the thickness of the metal electrode is about 60nm. After the deposition is completed, the sample is placed in a water bath heated with acetone, the water bath temperature is 60℃, and the temperature is kept for about 30 minutes, and then the lift-off process is used to peel off the electrode structure, that is, the first electron beam glue layer outside the electrode structure is removed to obtain the third-stage primary product.

[0154] S14: The electron beam glue PMMA950K is coated for the second time on the side where the metal electrode is located in the third-stage primary product. The coating method can be spin coating. The process parameters of spin coating are 3000r / 60s, covering the area outside the metal electrode, and then drying at a temperature of 180℃-185℃ to form a second electron beam glue layer to obtain the fourth-stage primary product.

[0155] S15: According to the second preset pattern, the second electron beam gel layer of the fourth-stage primary product is subjected to a second electron beam exposure, and then developed and fixed, and blown dry with a nitrogen gun to obtain a second developed pattern, and the single-walled carbon tube film is exposed in the area corresponding to the second developed pattern to obtain a fifth-stage primary product.

[0156] S16: Reactive ion etching is used to etch away the excess single-walled carbon tube film, that is, the single-walled carbon tube film in the area other than the metal electrode and the second developing pattern. The process parameters of the reactive ion etching are: etching gas oxygen, gas flow rate 20sccm, etching power 100W, etching time 5s, and the single-walled carbon tube film forms a carbon tube film to obtain the target product Hall device. The structure of the Hall device is as follows Figure 6 shown.

[0157] Among them, the Hall device made of the single-walled carbon tube film of Example 1 is as follows Fig. 9 shown.

[0158] The Hall voltage test was performed on the Hall devices made of the single-walled carbon tube films of Examples 1, 2, 3, and 5. The test connection was as follows: Fig.10 As shown, the test results are distributed as Figures 11 to 14 shown.

[0159] like Fig.11 As shown, the Hall voltage detected by the Hall device made of the single-walled carbon tube film of Example 1 is low, the signal-to-noise ratio is poor, and the Hall phenomenon is not obvious.

[0160] like Fig.12 As shown, the Hall device made of the single-walled carbon tube film in Example 2 has a higher Hall voltage magnitude and significantly improved Hall phenomenon than the Hall device made of the single-walled carbon tube film in Example 1, but the values ​​obtained by scanning back and forth do not overlap enough and have not yet reached the ideal state.

[0161] like Fig.13 As shown, the Hall voltage of the Hall device made of the single-walled carbon tube film of Example 3 is relatively large, the round-trip scanning lines overlap, and the Hall phenomenon is obvious.

[0162] like Fig.14 As shown, the Hall voltage of the Hall device made of the single-walled carbon tube film of Example 5 is low, the round-trip scanning lines are dispersed, and the Hall phenomenon is weak.

[0163] Therefore, the Hall voltage of the Hall devices made of the single-walled carbon tube film of Example 2 and Example 3 is larger and the Hall phenomenon is better. Among them, the Hall device made of the single-walled carbon tube film of Example 3 is the best.

[0164] In summary, when the catalyst is a mixture of ferrocene and sulfur, and the temperature of the first temperature zone is 85°C or 90°C, the generated single-walled carbon tube film is better and the manufactured Hall device is better. When the temperature of the first temperature zone is less than or equal to 80°C, or greater than or equal to 95°C, the generated single-walled carbon tube film is worse, and the corresponding Hall effect of the manufactured Hall device is very small.

[0165] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a single-walled carbon tube film, characterized in that: The following steps are involved: A chemical vapor deposition device is provided, wherein the chemical vapor deposition device is provided with a first temperature zone, a second temperature zone and a third temperature zone which are interconnected, wherein the temperature of the first temperature zone is lower than the temperature of the second temperature zone, and the temperature of the second temperature zone is higher than the temperature of the third temperature zone; Placing the catalyst in a first temperature zone for heating treatment, the catalyst volatilizes, and a carrier gas and a gaseous carbon source are introduced into the first temperature zone, so that the volatilized catalyst, the carrier gas and the gaseous carbon source form a mixed gas; The mixed gas flows to the second temperature zone to generate single-walled carbon tubes; The substrate is placed in the third temperature zone to deposit a single-walled carbon tube film on the surface of the substrate.

2. The method for preparing a single-walled carbon tube film according to claim 1, wherein: The catalyst comprises ferrocene and sulfur; and / or, The heating temperature in the first temperature zone is 80°C-95°C, preferably 85°C-92°C.

3. The method for preparing a single-walled carbon tube film according to claim 2, characterized in that: The catalyst comprises ferrocene and sulfur in a mass ratio of 15-17:

1.

4. The method for preparing a single-walled carbon tube film according to any one of claims 1 to 3, characterized in that: The gaseous carbon source is methane; and / or, The flow rate of the carrier gas is 900 sccm-1100 sccm, and the flow rate of the gaseous carbon source is 9 sccm-12 sccm.

5. The method for preparing a single-walled carbon tube film according to claim 4, characterized in that: The molar ratio of the carrier gas to the gaseous carbon source is 95-105:

1.

6. The method for preparing a single-walled carbon tube film according to claim 4, characterized in that: The temperature of the second temperature zone is 1050°C-1200°C.

7. The method for preparing a single-walled carbon tube film according to claim 1, characterized in that: The temperature of the third temperature zone is 50° C.-200° C., and the temperature gradually decreases from the side close to the second temperature zone to the side far away from the second temperature zone; and / or, The single-walled carbon tube is deposited in the third temperature zone for ≥3 minutes.

8. A single-walled carbon tube film, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 7.

9. The single-walled carbon tube film according to claim 8, characterized in that: The length of the single-walled carbon tube in the single-walled carbon tube film is 90nm-200nm.

10. The single-walled carbon tube film according to claim 8, characterized in that: The diameter of the single-walled carbon tube in the single-walled carbon tube film is 0.8nm-3nm.

11. A Hall device, characterized in that: It comprises electrodes, a substrate and a carbon tube film made of the single-walled carbon tube film as claimed in claim 9 or 10, wherein the carbon tube film is bonded to the substrate, the electrodes comprise N groups of relatively arranged current input electrodes and M groups of relatively arranged voltage test electrodes, wherein N is an integer greater than or equal to 1 and M is an integer greater than or equal to 1, the electrodes are bonded to the surface of the carbon tube film, and the carbon tube film is exposed between each group of the current input electrodes, and the carbon tube film is exposed between each group of the voltage test electrodes, and the straight line where each group of the current input electrodes is located intersects with the straight line where each group of the voltage test electrodes is located.

12. The Hall device according to claim 11, characterized in that: The straight line where each group of current input electrodes is located is perpendicular to the straight line where each group of voltage test electrodes is located; and / or, N=1, M=2, the carbon tube film exposed between each group of the current input electrodes and the carbon tube film exposed between each group of the voltage test electrodes form a "double-ten connected shape", and each of the current input electrodes and each of the voltage test electrodes are electrically connected to one end of the double-ten connected shape respectively.

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