Nanotube array manufacturing method, nanotube array and device

Abstract

The present invention provides a nanotube array manufacturing method, a nanotube array, and a device, the method comprising the steps of: manufacturing a bilayer two-dimensional material having a relative include angle of lattice orientation on a substrate as a template; determining a chiral parameter of the nanotubes to be manufactured corresponding to the relative include angle of the lattice orientation of the bilayer two-dimensional material; determining a nanoribbon orientation and nanoribbon width based on the determined chiral parameter; determining a pitch between nanoribbons based on the density and nanoribbon width of the nanotubes to be manufactured; etching the bilayer two-dimensional material based on the determined nanoribbon orientation, nanoribbon width, and pitch between nanoribbons to obtain a nanoribbon array of the bilayer two-dimensional material; and thermally exciting the obtained nanotube array made of the bilayer two-dimensional material to obtain a nanotube array. The present invention can manufacture a nanotube array with controllable density, orientation, and chirality.

Description

[Technical Field]

[0001] The present invention relates to the technical fields of nanomaterial production and semiconductors, and more particularly to a method for producing a nanotube array, a nanotube array, and a device. [Background technology]

[0002] Single-walled carbon nanotubes (hereinafter referred to as carbon tubes) can be regarded as quasi-one-dimensional structures of curled graphene. Depending on the curling pattern (chirality), single-walled carbon tubes can be described as metallic or semiconducting. Fully semiconducting, high-density (more than 125 tubes per micron) parallel arrays of semiconducting single-walled carbon tubes are the core materials for building high-performance carbon-based transistors and integrated circuits.

[0003] Currently, the manufacturing methods used for single-walled carbon tubes can be divided into two main categories. The first is catalyst-assisted chemical vapor deposition (see, for example, Reference 1: Zhang S et al., Nature, 2017, 543:234-238; Reference 2: Wang J et al., NatureCatalysis, 2018, 1:326-331). This method can directly grow all-semiconductor or single-chiral single-walled carbon tube arrays. However, the drawbacks of this method are that the synthesis temperature is too high, making it incompatible with integrated circuit processing, and the array density is low. The second method is the solution separation + assembly and array method, which typically involves obtaining a single-walled carbon tube solution using polymer dispersion and then combining it with density gradient centrifugation to separate metallic-semiconducting single-walled carbon tubes, which then self-assemble into carbon nanotube array wafers (see, for example, Ref. 3: Liu L et al., Science, 2020, 368:850-856; Ref. 4: Jinkins KR et al., Science Advances, 2021, 7(37):eabh0640). While this method can meet the performance indicators of advanced technology nodes in terms of the purity and density of semiconducting carbon tubes, it can result in difficult-to-control polymer residues and uneven carbon tube arrays, such as localized aggregation and stacking. At the same time, this method currently lacks effective control over the chirality of the carbon tubes, meaning that the chirality of the carbon tubes is randomly distributed.

[0004] In general, current carbon tube array manufacturing technology still faces many difficulties and challenges, and it is difficult to simultaneously ensure the density, orientation, chiral control, and cleanliness of carbon tube arrays. As a result, the requirements of high orientation, high density, full semiconductor properties, and high cleanliness cannot be simultaneously met when using carbon nanotube arrays to construct high-performance carbon-based transistors and integrated circuits, which affects the realization of high-performance carbon-based transistors and integrated circuits. Summary of the Invention

[0005] SUMMARY OF THE INVENTION In light of this, embodiments of the present invention provide methods for fabricating nanotube arrays, nanotube arrays, and devices to overcome or ameliorate one or more deficiencies present in the prior art.

[0006] One aspect of the present invention provides a method for producing a nanotube array, the method comprising: a template fabrication step of fabricating a two-layer two-dimensional material having a relative included angle of lattice orientation on a substrate as a template; a nanoribbon array etching step of determining a chiral parameter of the nanotubes to be manufactured, which corresponds to the relative included angle of the lattice orientation of the two-layer two-dimensional material; determining a nanoribbon orientation and a nanoribbon width based on the determined chiral parameter; determining a pitch between the nanoribbons based on the density of the nanotubes to be manufactured and the nanoribbon width; and etching the two-layer two-dimensional material based on the determined nanoribbon orientation, nanoribbon width, and pitch between the nanoribbons to obtain a nanoribbon array of the two-layer two-dimensional material; and a nanotube array generating step of subjecting the obtained nanotube array of the two-layer two-dimensional material to thermal excitation treatment to obtain a nanotube array.

[0007] In some embodiments of the present invention, the step of fabricating a two-layer two-dimensional material on the substrate with a relative include angle of lattice orientation comprises: combining mechanical exfoliation with an angle-controllable transfer method, or combining liquid-phase transfer with an angle-controllable transfer method to fabricate a two-layer two-dimensional material on the substrate with a relative include angle of lattice orientation; or obtaining a one-layer two-dimensional material using mechanical exfoliation or liquid-phase transfer and folding the obtained one-layer two-dimensional material into a predetermined orientation to obtain a two-layer two-dimensional material with a relative include angle of lattice orientation; or directly growing a two-layer two-dimensional material with a relative include angle of lattice orientation by a growth method including any of chemical vapor deposition, molecular beam epitaxy, or physical vapor deposition.

[0008] In some embodiments of the present invention, the step of etching the two-layer two-dimensional material based on the determined nanoribbon orientation, nanoribbon width, and pitch between nanoribbons includes etching the two-layer two-dimensional material using an etching technique such as laser lithography, electron beam lithography, focused ion beam, high-energy electron beam, masking, or chemical etching based on the determined nanoribbon orientation, nanoribbon width, and pitch between nanoribbons.

[0009] In some embodiments of the present invention, the thermal excitation treatment comprises one or more of the following treatments: annealing, laser excitation, Joule heating, and high-energy radiation.

[0010] In some embodiments of the present invention, at least one of the two-layer two-dimensional materials is a p-type doped or n-type doped two-dimensional material.

[0011] In some embodiments of the present invention, at least one of the two-layer two-dimensional materials is a two-dimensional material having grain boundaries, different regions of the same two-layer two-dimensional material produced in the template production step have relative included angles of different lattice orientations, and / or different longitudinal segments of nanoribbons of the same two-layer two-dimensional material in the nanoribbon array etching step correspond to different nanoribbon widths, and the nanotube array obtained in the nanotube array generation step is an array of interlinked nanotubes of different chiralities.

[0012] In some embodiments of the present invention, the nanoribbon array generating step further includes determining the length of the nanoribbons based on the length of the nanotubes to be produced, and the step of etching the two-layer two-dimensional material based on the determined nanoribbon orientation, nanoribbon width, and pitch between nanoribbons includes etching the two-layer two-dimensional material based on the determined nanoribbon orientation, nanoribbon width, pitch between nanoribbons, and length of the nanoribbons.

[0013] In some embodiments of the present invention, the bilayer two-dimensional material is bilayer graphene, and the resulting nanotube array is a carbon nanotube array.

[0014] In some embodiments of the present invention, the two-layer two-dimensional material is a two-layer boron nitride two-dimensional material, a two-layer molybdenum sulfide two-dimensional material, a two-layer molybdenum selenide two-dimensional material, or a two-layer tungsten sulfide two-dimensional material, and the resulting nanotube array is a boron nitride nanotube array, a molybdenum sulfide nanotube array, a molybdenum selenide nanotube array, or a tungsten sulfide nanotube array.

[0015] In some embodiments of the present invention, the nanoribbon orientation is obtained based on the following orientation equation:

number

number

[0016] Another aspect of the present invention further provides a nanotube array produced by the above-described method.

[0017] Another aspect of the present invention further provides semiconductor devices (eg, carbon nanotube transistors) fabricated using the nanotube arrays described above.

[0018] The nanotube array manufacturing method provided by the present invention can manufacture nanotube arrays with controllable density, orientation, and chirality.

[0019] Furthermore, in some embodiments, high-density, highly oriented, fully semiconducting, single-walled carbon nanotube arrays with controllable chirality can be fabricated. The controllable density ensures uniform distribution of carbon nanotubes, without aggregation or stacking.

[0020] Additional advantages, objects, and features of the present invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by the practice of the invention. The objectives and other advantages of the present invention will be realized and attained by the structure particularly pointed out in the description and drawings.

[0021] As will be understood by those skilled in the art, the objects and advantages that can be achieved by the present invention are not limited to those specifically described above, and the above and other objects that can be achieved by the present invention will be more clearly understood from the following detailed description. [Brief explanation of the drawings]

[0022] The drawings described herein are provided to provide a further understanding of the invention, constitute a part of this application, and are not to be construed as limiting the invention.

[0023] [Figure 1] 1 is a schematic chiral diagram of a carbon nanotube. [Figure 2A] 1 is a schematic diagram of the geometric relationship between bilayer graphene nanoribbons and carbon tube chirality in one embodiment of the present invention. FIG. [Figure 2B] 1 is a schematic diagram of the geometric relationship between bilayer graphene nanoribbons and carbon tube chirality in one embodiment of the present invention. FIG. [Figure 2C] 1 is a schematic diagram of the geometric relationship between bilayer graphene nanoribbons and carbon tube chirality in one embodiment of the present invention. FIG. [Figure 3] 1 is a flowchart of a method for manufacturing a nanotube array according to an embodiment of the present invention. [Figure 4] 1 is a schematic diagram of a carbon nanotube array manufacturing process according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in more detail below with reference to embodiments and drawings, wherein the exemplary embodiments of the present invention and the description thereof are for illustrating the present invention but not for limiting the present invention.

[0025] It should be noted that in order to avoid obscuring the present invention with unnecessary details, only structures and / or processing steps closely related to the solution according to the present invention are shown in the drawings, and other details that are not closely related to the present invention are omitted.

[0026] It must be emphasized that the term "comprises" when used in the present text refers to the presence of a feature, element, step or component and does not exclude the presence or addition of one or more other features, elements, steps or components.

[0027] It should be explained here that the term "connection" in this context may represent not only a direct connection but also an indirect connection where an intermediate exists, unless otherwise specified.

[0028] Hereinafter, embodiments of the present invention will be described with reference to the drawings, in which the same reference numerals represent the same or similar parts or steps.

[0029] It should be understood that the symbols assigned to each step mentioned below do not limit the order of each step, and that the steps may be performed in the order mentioned in the example, or may be performed in a different order from that in the example, or multiple steps may be performed simultaneously.

[0030] The present invention addresses the difficulties inherent in simultaneously controlling the density, orientation, and chirality of conventional carbon nanotube arrays, resulting in problems such as uneven array orientation, localized aggregation, and stacking, as well as uneven chirality. This paper proposes a new method for fabricating chiral-controllable single-walled carbon nanotube arrays based on bilayer graphene. The method provides a novel means for top-down selection and control of the chirality of carbon nanotubes (or simply carbon tubes). This method allows for the tuning of the density (ρ) of single-walled carbon nanotube arrays within the range of 0 < ρ ≦ 350 tubes / μm, while maintaining a consistent alignment height of the single-walled carbon nanotubes in the array. Furthermore, it also allows for further control of the chirality of the carbon nanotubes, i.e., single-walled carbon nanotubes with specific chiralities. Furthermore, metal-semiconductor junctions or chiral junctions with different bandgaps can be introduced as needed to meet the demand for channel materials for high-performance carbon nanotube transistors and integrated circuits.

[0031] Hereinafter, the principle of the nanotube array manufacturing method according to the present invention will be explained first by taking the example of manufacturing single-walled carbon tubes using double-layer graphene, and then the nanotube array manufacturing method according to the present invention will be described in detail.

[0032] As shown in Figure 1, the geometric structure of a single-walled carbon nanotube can be viewed as a single layer of graphene curled along a chiral vector Ch. Depending on the direction and magnitude of the chiral vector Ch, the curled carbon nanotube has a different chirality, which can also be represented by Ch. The vectors a1 and a2 indicated by arrows in Figure 1 represent basis vectors of a single-layer graphene crystal. In this invention, the geometric relationships according to the present invention are described using the two zigzag edges of graphene as basis vectors, and include, but are not limited to, angular relationships and length relationships. The principle that different geometric descriptions are structurally equivalent depending on the basis vector selection is also within the scope of protection of the present invention.

[0033] The chiral vector Ch of a carbon nanotube can be expressed in terms of the basis vector quantities a1 and a2. When Ch = na1 + ma2, the chirality of the carbon nanotube is (n, m). The electronic structure of a carbon nanotube correlates with its chiral index; when nm is divisible by 3, the carbon nanotube is described as metallic; when nm is not divisible by 3, the carbon nanotube is described as semiconducting. At the same time, the band gap of the carbon nanotube is also affected by the size of Ch; the larger Ch, the smaller the band gap. Therefore, controlling the chirality of the carbon nanotube allows us to control its electronic structure. In Figure 1, θ denotes the angle between the chiral vector and the graphene basis vector, and T denotes the radial direction of the carbon nanotube.

[0034] As shown in Figure 2A, folding a single-layer graphene nanoribbon at 1 / 2 Ch results in a bilayer graphene nanoribbon, as shown in Figure 2B. The geometric topology of the bilayer graphene nanoribbon remains unchanged. By connecting the carbon atoms in the upper and lower layers at both edges of the bilayer graphene nanoribbon and expanding the entire planar bilayer structure into a cylindrical shape, a carbon nanotube with a chiral vector of Ch is obtained. The inventors discovered that the edges of bilayer graphene form a bulged, closed structure under annealing conditions. Based on this phenomenon, the inventors innovatively employed bilayer graphene as a template for fabricating parallel carbon tube arrays. The bilayer graphene was then converted by etching into bilayer graphene nanoribbon arrays whose orientation and width matched the carbon tube chiral parameters. The bilayer graphene nanoribbon arrays were then transformed into single-walled carbon nanotube arrays by thermal excitation, such as annealing. Therefore, the present invention proposes a method for producing bilayer graphene nanoribbons with a specific relative angle and a specific width, and then obtaining carbon nanotubes with a determined target chirality through thermal excitation treatment (e.g., annealing).

[0035] The chirality of a carbon nanotube is determined by the relative included angle θ of the lattice orientation between the two graphene layers and the nanoribbon width w. Referring to Figures 2A to 2C, when the target chiral vector is C h , direction is θ, size is │C h For a carbon nanotube with a θ = ∑ n ⁢ ⁢ m ⁢ ...

number

[0036] Here, the relative included angle θ0 of the lattice orientation between the two graphene layers determines the direction of the carbon nanotube chiral vector Ch (i.e., the included angle θ between the chiral vector and the graphene basis vector), and the width w of the bilayer nanoribbon determines the magnitude |Ch| of the carbon nanotube chiral vector Ch. The relationship between the chiral index (n, m) and the direction and magnitude of the chiral vector is given by (Equation 2):

number

[0037] where α is the lattice constant of graphene and d t is the diameter of the target carbon tube. Substituting θ and |Ch| into Equation Group 1, we obtain the relationship between the bilayer graphene nanoribbon width w, the relative included angle θ0 of the interlayer lattice orientation, and the target carbon tube chiral index (n, m) (Equation Group 3):

number

[0038] Based on the relationship in the above formula, the present invention designs a bilayer graphene nanoribbon having a specific relative included angle θ0 and a specific width w, and then obtains the corresponding chiral carbon nanotube by subjecting the bilayer graphene nanoribbon to a heat treatment such as annealing.

[0039] The method of the present invention is not limited to the fabrication of single-walled carbon nanotube arrays. Because the edges of double-layered 2D nanoribbons typically close after annealing, the method can also be applied to the fabrication and processing of other 1D nanotubes and their arrays by replacing double-layered graphene with other 2D material templates. For example, other nanotube arrays, such as boron nitride nanotube arrays, molybdenum sulfide nanotube arrays, molybdenum selenide nanotube arrays, and tungsten sulfide nanotube arrays, can be fabricated based on double-layered boron nitride 2D materials, molybdenum sulfide 2D materials, molybdenum selenide 2D materials, and tungsten sulfide 2D materials, respectively. When calculating the nanoribbon orientation and nanoribbon width to be etched, the graphene lattice constant α in the preceding formula must be replaced with the lattice constant of the corresponding crystal. These new 1D nanotube arrays also have the advantage of precise control of array density, orientation, and chirality. The nanotube arrays listed here are merely examples, and the present invention is not limited thereto.

[0040] 3 is a flowchart showing a method for manufacturing a nanotube array according to an embodiment of the present invention. As shown in FIG. 3, the method includes the following steps S110 to S130.

[0041] In the template fabrication step S110, a two-layer two-dimensional material having lattice orientations with a relative included angle is fabricated on a substrate as a template.

[0042] When the two-dimensional material is graphene, the method corresponds to the production of single-walled carbon nanotubes. In the present embodiment, there is no special requirement for the rotation of the substrate; in principle, it is sufficient if the substrate can withstand the annealing temperature. However, since the nanotubes produced by the method of the present invention have high purity and can be used for the production of high-performance semiconductor devices, the substrate may be a surface-insulating substrate such as a surface-insulating silicon substrate, and more specifically, a silicon wafer coated with silica, but the present invention is not limited thereto.

[0043] In the nanoribbon array etching step S120, the chiral parameters of the nanotubes to be produced, which correspond to the relative included angles of the lattice orientations of the two-layer two-dimensional material, are determined, the nanoribbon orientation and nanoribbon width are determined based on the determined chiral parameters, the pitch between nanoribbons is determined based on the density of the nanotubes to be produced and the nanoribbon width, and the two-layer two-dimensional material is etched based on the determined nanoribbon orientation, nanoribbon width and pitch between nanoribbons to obtain a nanoribbon array of the two-layer two-dimensional material.

[0044] In the nanotube array generating step S130, the nanotube array of the obtained two-layer two-dimensional material is subjected to a thermal excitation process to obtain a nanotube array.

[0045] Through the above steps, a nanotube array with a determined chirality can be obtained.

[0046] In step S110, a two-layer two-dimensional material having a relative included angle of lattice orientation is fabricated on a substrate as a template. When the fabrication method is used to fabricate single-walled carbon nanotubes, the two-layer two-dimensional material used as the template is bilayer graphene.

[0047] For a carbon nanotube array with a specified chirality (n, m), it is first necessary to manufacture bilayer graphene having an interlayer relative include angle θ0 based on the relationship between the relative include angle θ0 of bilayer graphene and the chiral index (n, m) in Equation Group 3. The manufacturing method for bilayer graphene having an interlayer relative include angle θ0 may include multiple methods, such as (1) a method combining mechanical peeling with an angle-controllable transfer method (mechanical peeling + angle-controllable transfer method), (2) a method combining liquid-phase transfer with an angle-controllable transfer method (liquid-phase transfer + angle-controllable transfer method), or (3) a single-layer graphene folding method.

[0048] (1) Mechanical peeling + angle-controllable transfer method The production of bilayer graphene using mechanical exfoliation + angle-controllable transfer refers to first obtaining two sheets of single-layer graphene by two mechanical exfoliations using the mechanical exfoliation method, and then transferring the two sheets of single-layer graphene obtained by the two mechanical exfoliations onto a substrate using the angle-controllable transfer technique to obtain bilayer graphene.

[0049] Here, obtaining single-layer graphene using a mechanical exfoliation method involves applying a mechanical force (e.g., frictional force and / or tensile force) to the graphite crystal to separate the graphene sheet layer from the graphite crystal. Obtaining single-layer graphene using a mechanical exfoliation method is an existing, mature technology, so a detailed description will be omitted here.

[0050] The process of obtaining bilayer graphene using angle-controllable transfer technology is specifically as follows:

[0051] After obtaining two sheets of single-layer graphene by mechanical peeling, they may be subsequently held on a transparent substrate such as PDMS (polydimethylsiloxane) or PMMA (polymethyl methacrylate) to control the relative overlapping angle of the two sheets of single-layer graphene using an optical corner console. Here, the material used for the transparent substrate is merely an example, and the present invention is not limited thereto.

[0052] In a process of controlling the relative overlap angle of two single-layer graphene sheets using an optical corner console, the lattice orientation of the two single-layer graphene sheets is determined and marked using means such as angle-resolved Raman, crystallographic structure (e.g., edge included angle) measurement, or low-energy electron diffraction, and the two single-layer graphene sheets whose crystallographic orientation has been determined are then bonded together at a specific relative included angle using the optical corner console at a controllable angle, thereby producing bilayer graphene sheets having a specific lattice orientation and relative included angle.

[0053] The resulting bilayer graphene with a specific lattice orientation and relative included angle can then be transferred onto a substrate using a dry or wet transfer technique.

[0054] (2) Liquid phase transfer + angle controllable transfer method The production of bilayer graphene using liquid-phase transfer + angle-controllable transfer refers to obtaining two sheets of single-layer graphene by using liquid-phase transfer twice, and then using angle-controllable transfer technology to transfer the two sheets of single-layer graphene obtained by the two liquid-phase transfers onto a substrate to obtain bilayer graphene.

[0055] Obtaining single-layer graphene using liquid phase transfer involves the following:

[0056] Two single-layer graphene sheets are obtained by liquid-phase transfer on a substrate with two single-layer graphene sheets grown by methods such as chemical vapor deposition (CVD), molecular beam epitaxy (MBE), or chemical vapor transport (CVT).Then, the two single-layer graphene sheets are held on a transparent substrate such as PDMS or PMMA using an angle console to control the relative overlap angle.

[0057] In a process of controlling the relative overlap angle of two single-layer graphene sheets using an optical corner console, the lattice orientation of the two single-layer graphene sheets is determined and marked using means such as angle-resolved Raman, crystallographic structure (e.g., edge included angle) measurement, or low-energy electron diffraction, and the two single-layer graphene sheets whose crystallographic orientation has been determined are then bonded together at a specific relative included angle using the optical corner console at a controllable angle, thereby producing bilayer graphene sheets having a specific lattice orientation and relative included angle.

[0058] The resulting bilayer graphene with a specific lattice orientation and relative included angle can then be transferred onto a substrate using a dry or wet transfer technique.

[0059] (3) Single-layer graphene folding method Single-layer graphene can be obtained using mechanical exfoliation or liquid-phase transfer, and then folded into a predetermined orientation to obtain a two-layer 2D material with a relative included angle between the lattice orientations.

[0060] Two-layer two-dimensional materials with a relative included angle of lattice orientation can also be directly grown using growth methods such as chemical vapor deposition, molecular beam epitaxy, or physical vapor deposition. Some of the above methods can be used to replace graphene with other two-dimensional materials, similarly producing two-layer two-dimensional materials with a relative included angle of lattice orientation on a substrate. Therefore, in step S110, two layers of two-dimensional materials such as boron nitride, molybdenum sulfide, molybdenum selenide, and tungsten sulfide can be similarly obtained on a substrate, and the relative included angle between each layer can be controlled.

[0061] Furthermore, in the examples of the present invention, even for bilayer graphene having any interlayer relative include angle θ, such as bilayer graphene obtained by a direct growth method, it is possible to back-calculate processable chiral indices (n, m) that satisfy the requirements for the electronic structure when the interlayer relative include angle is θ, depending on the electronic structure of the carbon nanotube that is actually required, such as semiconductivity.

[0062] In step S120, before etching the nanoribbon array, first, the chiral parameters such as the chiral index (n, m) of the nanotube to be produced are determined, and then, based on the determined chiral parameters of the nanotube, the orientation of the nanoribbon array obtained by etching, i.e., the lattice orientation included angle Ψ0 of the nanoribbon array obtained by etching relative to the lattice orientation of the two-layer two-dimensional material, is determined, and further, the nanoribbon width and the pitch between nanoribbons are determined.

[0063] Taking the case of etching a bilayer graphene nanoribbon array as an example, before etching the bilayer graphene nanoribbon array, it is necessary to determine the included angle Ψ0 of the nanoribbon array obtained by etching with respect to the bilayer graphene lattice. Due to the symmetry of the structure, the orientation of the nanoribbons should satisfy the same included angle Ψ with the basis vector direction of the bilayer graphene. Based on the geometric relationship shown in Figures 2A to 2C, if the included angle between the chiral vector Ch and the graphene basis vector quantity a1 is θ, then

number

[0064] The crystallographic orientation of bilayer graphene can be determined in various ways, including, but not limited to, one or a combination of several methods, such as optical microscopy, scanning electron microscopy, low-energy electron diffraction, electron diffraction, angular-resolved photoemission spectroscopy, Raman spectroscopy, and high-resolution transmission electron microscopy. Based on the determined crystallographic orientation of bilayer graphene, the included angle Ψ of the orientation of the nanoribbon array obtained by etching relative to the bilayer graphene lattice can be determined, i.e., the orientation of the bilayer graphene nanoribbon array can be determined.

[0065] After determining the orientation of the bilayer graphene nanoribbon array, the width of each nanoribbon is determined by w in Equation Group 3, and the pitch Δx between nanoribbons is determined by the required carbon nanotube density ρ (the number of carbon nanotubes per unit length),

number

[0066] From the above equation, we can see that the density ρ of the carbon nanotube array can be controlled by adjusting the gap Δx between the bilayer graphene nanoribbons (the width of the gap between the nanoribbons). Furthermore, when Δx is 0, the carbon nanotube density ρ reaches its maximum value ρ max reaches a maximum density ρ max is the tube diameter d of the target chiral carbon tube. t Because it is also related to

number

[0067] In the present invention, the range of controlling the carbon nanotube density in the carbon tube array is 0<ρ<ρ max The length of the carbon nanotube formed after annealing is determined by the length L of the graphene nanoribbon, and the length L of the nanoribbon can be selected according to the actual experimental needs.

[0068] After determining the nanoribbon orientation, nanoribbon width, inter-nanoribbon pitch, and nanoribbon length, the nanoribbon array can be etched based on these determined parameters. There are various etching methods for bilayer graphene nanoribbon arrays, including, but not limited to, laser lithography, electron beam lithography, focused ion beam, high-energy electron beam, masking, chemical etching, etc., and one of these etching methods can be selected to etch the nanoribbons.

[0069] Similar to the etching of graphene nanoribbon arrays, nanoribbon arrays of two-dimensional materials such as bilayer boron nitride nanoribbon arrays, bilayer molybdenum sulfide nanoribbon arrays, bilayer molybdenum selenide nanoribbon arrays, or bilayer tungsten sulfide nanoribbon arrays can be fabricated, although these materials are merely examples and the present invention is not limited thereto.

[0070] Similarly, step S130 will be described using a thermal excitation treatment for a bilayer graphene nanoribbon array as an example. The thermal excitation treatment in this step can be performed in various ways as long as it can provide sufficient excitation for the bilayer graphene nanoribbon to be reconstructed into an edge-off state. For example, the thermal excitation treatment can include one or more of annealing, laser excitation, Joule heating, and high-energy ray irradiation, but the present invention is not limited thereto.

[0071] Taking annealing as an example, in some embodiments of the present invention, the annealing temperature for the bilayer graphene nanoribbon array may be, for example, 250°C to 1300°C, and the annealing time may be, for example, 0.1 s to 600 s depending on the heating temperature. Annealing may be performed at different temperatures over different time periods, but the present invention is not limited thereto. The annealing of the bilayer graphene nanoribbon array may be performed under vacuum conditions or in an inert gas atmosphere.

[0072] When other thermal excitation treatment methods such as laser excitation, Joule heating, or high-energy ray irradiation are used instead of annealing the bilayer graphene nanoribbon arrays, the heating temperature range by these other thermal excitation treatment methods may be 250°C to 1300°C, and the heating time range may be, for example, 0.1 s to 600 s depending on the heating temperature.

[0073] After etching, the bilayer graphene nanoribbons have the same orientation Ψ, nanoribbon spacing Δx, interlayer relative included angle θ0, and nanoribbon width w. The process of generating single-walled carbon nanotubes by thermal excitation involves only the reorganization of unsaturated carbon atoms on both edges of the bilayer graphene nanoribbons by thermal excitation. Therefore, the carbon nanotubes after thermal excitation have the same orientation Ψ and intertube spacing Δx as the graphene nanoribbons. tube After forming the tube, the structure changes from a flat surface to a tubular structure.

number

[0074] At the same time, because the method of the present invention does not require means for growing, selecting, or aligning carbon nanotubes, such as catalytic growth or polymer centrifugal pulling, the impurity level is determined solely by the purity of the graphene and residues from typical semiconductor processes, so the produced carbon nanotube arrays are clean enough to be directly used in the fabrication of high-performance devices.

[0075] Similar to the process for bilayer graphene nanoribbon arrays, if the product obtained in step S120 is a bilayer nanoribbon array of another two-dimensional material (e.g., a boron nitride nanoribbon array, a molybdenum sulfide nanoribbon array, a molybdenum selenide nanoribbon array, or a tungsten sulfide nanoribbon array), the thermal excitation process is similarly performed in the temperature range of 250°C to 1300°C. Since the temperature at which the material becomes a tube varies depending on the material, the thermal excitation process temperature can be adaptively adjusted to similarly obtain nanotube arrays such as boron nitride nanoribbon arrays, molybdenum sulfide nanoribbon arrays, molybdenum selenide nanoribbon arrays, or tungsten sulfide nanoribbon arrays.

[0076] From the above, it can be seen that the method of the present invention can produce highly oriented, high-density, chiral, tunable, pitch-adjustable, uniformly distributed, and highly clean carbon nanotube arrays using bilayer graphene as a template. Nanotube arrays of other materials can also be produced in the same way.

[0077] In some embodiments of the present invention, one or both layers of the bilayer graphene used to produce single-walled carbon nanotubes can be replaced with p-type doped graphene or n-type doped graphene. When both layers are doped, the bilayer graphene can have the same or different doping types. If the doping types of the two layers are the same, the carbon nanotubes that can be produced using this as a template are p-type or n-type carbon nanotube arrays. If one layer is replaced with p-type doped graphene and the other layer is replaced with n-type doped graphene, the carbon nanotube array produced using this as a template will have a radial pn junction.

[0078] In some embodiments of the present invention, the chirality (n, m) of the fabricated carbon nanotubes is adjusted and controlled by the interlayer relative include angle θ0 and the nanoribbon width w of the bilayer graphene nanoribbon. Therefore, different interlayer relative include angles θ0 and / or widths w can be introduced into the same bilayer graphene nanoribbon, thereby forming carbon nanotubes with different chiralities, and carbon tubes with different chiralities are connected by chiral junctions. The interlayer relative include angle θ0 can be changed by introducing grain boundaries. The nanoribbon width w is relatively easier to adjust and control, and can be adjusted and controlled by changing the etching template. More specifically, by converting one or two layers of bilayer graphene into polycrystalline graphene, graphene nanoribbons on both sides of the grain boundary can have different interlayer relative include angles θ0. To achieve different widths w, different nanoribbon widths w can be achieved by controlling the nanoribbon widths retained during etching, so that different longitudinal segments of the same bilayer graphene nanoribbon correspond to different nanoribbon widths w.

[0079] Extending to two-layer two-dimensional materials, where at least one of the two-layer two-dimensional materials may be a two-dimensional material having grain boundaries, different regions of the same two-layer two-dimensional material produced in the template production step will have different relative included angles of lattice orientation, and correspondingly, the nanotube array obtained in the nanotube array production step will be an array of intertwined nanotubes of different chiralities.

[0080] Similar processes also apply to two-dimensional materials such as bilayer boron nitride, molybdenum sulfide, molybdenum selenide, and tungsten sulfide.

[0081] FIG. 4 shows a schematic flow of manufacturing a single-walled carbon nanotube array on a substrate.

[0082] As shown in FIG. 4(a), bilayer graphene 20 and 30 are fabricated on a surface-insulating substrate (e.g., a silica-coated silicon wafer) 10, with their lattice orientations exhibiting an interlayer relative include angle θ. For example, a single-layer graphene 20 is mechanically peeled off from the surface of a graphite crystal, and the exfoliated single-layer graphene 20 is transferred onto the substrate 10 in a predetermined orientation. The mechanical peeling and transfer steps are then repeated to place the second exfoliated single-layer graphene 30 on the first exfoliated single-layer graphene 20. The stacked bilayer graphene serves as a template, and the interlayer relative include angle of the lattice orientation between the two graphene layers is controlled to θ during the transfer process. In some embodiments of the present invention, θ may be any value between 0° and 360°. In another embodiment of the present invention, the bilayer graphene is placed on the substrate 10 at a desired angle during the transfer step. After the bilayer graphene is formed, the crystallographic relative include angle may be determined using a scanning electron microscope, a transmission electron microscope, or other means.

[0083] Figure 4(b) shows a bilayer graphene nanoribbon array obtained by etching the bilayer graphene obtained in (a) with a mask 40. First, the nanoribbon orientation (e.g., the included angle Ψ between the nanoribbon orientation and the graphene lattice orientation) and nanoribbon width are determined based on the chiral parameter corresponding to the interlayer relative included angle θ. The pitch between nanoribbons is then determined based on the carbon tube density and nanoribbon width to be manufactured. The bilayer graphene is then etched based on the determined nanoribbon orientation, nanoribbon width, and inter-nanoribbon pitch, resulting in a bilayer graphene nanoribbon array 50 as shown in Figure 4(c). The bilayer graphene nanoribbon array is then annealed at an annealing temperature of 250°C to 1300°C for an annealing time of 0.1 s to 600 s depending on the annealing temperature, resulting in a carbon nanotube array 60 as shown in Figure 4(d).

[0084] During the carbon nanotube array fabrication process of the present invention, if there are errors in the processing of graphene nanoribbons—for example, errors in the nanoribbons' width Δw, orientation ΔΨ, and relative interlayer included angle Δθ0—the nanoribbons cannot maintain a perfect geometrical connection, resulting in topological defects such as 5-8 rings and 5-7-7-5 rings in the resulting carbon nanotubes. As the errors increase, the mismatch density of the bilayer graphene nanoribbon edges increases, and the defect density in the resulting carbon tubes also increases. However, under high temperature conditions, bilayer graphene nanoribbon edges tend to form closed structures, lowering their energy, and therefore always forming carbon tube structures. In the case of extreme degradation, if w, Ψ0, and θ0 are not determined strictly in accordance with the aforementioned geometric relationships, carbon nanotube arrays can be fabricated. While these arrays offer advantages such as uniformity, high density, high purity, and adjustable pitch, they also suffer from a loss of chiral control and the introduction of a large number of topological defects into the carbon nanotubes. However, methods for fabricating carbon nanotube arrays using such degradation techniques are also within the scope of protection of the present invention.

[0085] By utilizing the geometric relationship of w, Ψ0, and θ0 in the above formula, the present invention can also construct carbon nanotubes having a metal-semiconductor junction and a chiral junction. In this case, the bilayer graphene has a grain boundary in at least one layer, and different regions between the bilayer graphene have different relative includeness angles. Furthermore, in the nanoribbon array etching step, different chiral parameters of the carbon nanotubes to be manufactured using bilayer graphene with different relative includeness angles can be determined. Furthermore, based on the determined different chiral parameters, different nanoribbon orientations and nanoribbon widths corresponding to the different chiral parameters of different segments in the nanoribbon longitudinal direction can be determined. Hereinafter, as an example, the same bilayer graphene nanoribbon can be fabricated with different interlayer relative includeness angles θ. 0A、 θ 0B and width w A and w BHere, different interlayer relative angles arise from the grain boundaries during graphene growth, and different widths can be set by adjusting the etching parameters during exposure etching. After annealing such bilayer graphene nanoribbons to form carbon nanotubes, θ 0A , w A The chiral index of the segment (n A ,m A ) and θ 0B , w B The chiral index of the segment (n B ,m B ) is obtained from the above formula, and at this time, a chiral junction carbon nanotube with a chiral difference is formed. Conversely, the present invention provides a pre-designed chiral index (n A ,m A ) and (n B ,m B ) based on the formula, the processing parameter θ 0A、 θ 0B and w A , w B The chiral index determines whether a carbon nanotube is metallic or semiconducting. Therefore, when one side of the carbon nanotube is metallic and the other side is semiconducting, a carbon nanotube with a metal-semiconductor junction is formed. The number of chiral junctions and metal-semiconductor junctions is determined by the number of different combinations of the processing parameters w, Ψ0, and θ0 introduced into the same bilayer graphene stripe.

[0086] Current technology cannot simultaneously satisfy the requirements of high orientation, high density, fully semiconducting properties, tunable pitch, and uniform distribution (meaning that the carbon tubes have a uniform pitch and are not aggregated or stacked). Consequently, there is a lack of effective means for controlling the chirality of carbon tubes. Conventional CVD carbon nanotube array growth methods result in low and uncontrollable density, broad and non-uniform chiral distribution (i.e., uncontrollable chirality), and residual catalyst. Conventional liquid-phase pulling carbon nanotubes result in high and uncontrollable density, only semiconducting chirality (i.e., uncontrollable chirality), complex nanotube orientation, stacking, and the presence of polymer contamination. In contrast, the carbon nanotubes produced by the method of the present application have controllable density and chirality, can produce not only semiconducting carbon nanotubes but also metallic carbon nanotubes, and have uniform intertube spacing and clean surfaces. Therefore, the method of the present invention can provide single-walled carbon nanotube arrays that meet the needs for controllable density, orientation, and chirality, and the cleanliness of the produced single-walled carbon nanotube arrays meets the needs for carbon nanotube materials in carbon nanotube (CNT) transistors and their integrated circuits.

[0087] By constructing a carbon nanotube transistor using the higher performance carbon nanotube array manufactured by the above method, it is possible to avoid loss of device performance due to carbon nanotube stacking, surface contamination, and tube diameter distribution, and to obtain a carbon nanotube transistor with higher performance.

[0088] It should be clear that the present invention is not limited to the specific configurations and processes described above and illustrated in the drawings. For the sake of brevity, detailed descriptions of known methods are omitted herein. In the above embodiments, some specific steps are described and illustrated as examples. However, the method process of the present invention is not limited to the specific steps described and illustrated, and those skilled in the art can make various changes, corrections, additions, and changes in the order of steps after understanding the spirit of the present invention.

[0089] In the present invention, features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments and / or may be combined with or substituted for features of other embodiments.

[0090] The above-described preferred embodiments of the present invention are not intended to limit the present invention, and those skilled in the art may make various modifications and changes to the embodiments of the present invention. Any amendments, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the scope of protection of the present invention.

Claims

1. a template fabrication step of fabricating a two-layer two-dimensional material having a relative included angle of lattice orientation on a substrate as a template; a nanoribbon array etching step of determining a chiral parameter of the nanotubes to be manufactured, which corresponds to the relative included angle of the lattice orientation of the two-layer two-dimensional material; determining a nanoribbon orientation and a nanoribbon width based on the determined chiral parameter; determining a pitch between nanoribbons based on the density of the nanotubes to be manufactured and the nanoribbon width; and etching the two-layer two-dimensional material based on the determined nanoribbon orientation, nanoribbon width, and pitch between nanoribbons to obtain a nanoribbon array of the two-layer two-dimensional material; and a nanotube array generation step of thermally exciting the obtained nanoribbon array of the two-layer two-dimensional material to obtain a nanotube array. A nanotube array manufacturing method comprising:

2. 2. The method of claim 1, further comprising the steps of: Fabricating a two-layer two-dimensional material with a relative included angle of lattice orientation on the substrate using mechanical peeling in combination with angle-controllable transfer methods or liquid-phase transfer in combination with angle-controllable transfer methods; or Obtaining a one-layer two-dimensional material using mechanical peeling or liquid phase transfer, and folding the obtained one-layer two-dimensional material in a predetermined orientation to obtain a two-layer two-dimensional material having a relative included angle of the lattice orientation; or and directly growing a two-layer two-dimensional material having a relative included angle of lattice orientation by a growth method including one of chemical vapor deposition, molecular beam epitaxy, or physical vapor deposition.

2. The method of claim 1 .

3. Etching the bilayer two-dimensional material based on the determined nanoribbon orientation, nanoribbon width, and pitch between nanoribbons includes: Etching the bilayer two-dimensional material using an etching technique such as laser lithography, electron beam lithography, focused ion beam, high energy electron beam, masking, or chemical etching based on the determined nanoribbon orientation, nanoribbon width, and pitch between nanoribbons.

2. The method of claim 1 .

4. The thermal excitation treatment includes one or more of the following treatments: annealing, laser excitation, Joule heating, and high-energy radiation.

2. The method of claim 1 .

5. At least one of the two-layer two-dimensional materials is a p-type doped or n-type doped two-dimensional material.

2. The method of claim 1 .

6. At least one layer of the two-dimensional material is a two-dimensional material having grain boundaries, different regions of the same two-layer two-dimensional material fabricated in the template fabrication step have different relative included angles of lattice orientation, and / or different longitudinal segments of nanoribbons of the same two-layer two-dimensional material in the nanoribbon array etching step correspond to different nanoribbon widths; The nanotube array obtained in the nanotube array generating step is an array of nanotubes connected together with different chiralities.

2. The method of claim 1 .

7. The nanoribbon array generating step includes: determining the length of the nanoribbon based on the length of the nanotube to be produced; The step of etching the two-layer two-dimensional material based on the determined nanoribbon orientation, nanoribbon width, and pitch between nanoribbons includes etching the two-layer two-dimensional material based on the determined nanoribbon orientation, nanoribbon width, pitch between nanoribbons, and length of the nanoribbons.

2. The method of claim 1 .

8. The bilayer two-dimensional material is bilayer graphene, and the resulting nanotube array is a carbon nanotube array. The method according to any one of claims 1 to 7.

9. the bilayer two-dimensional material having a relative include angle of lattice orientation is bilayer graphene having a grain boundary in at least one layer, and different regions between the bilayer graphene have different relative include angles; In the nanoribbon array etching step, different chiral parameters of carbon nanotubes to be manufactured using bilayer graphene with different relative included angles are determined, and based on the determined different chiral parameters, different nanoribbon orientations and different nanoribbon widths of different segments in the nanoribbon longitudinal direction, corresponding to the different chiral parameters, are determined.

9. The method of claim 8.

10. the two-layer two-dimensional material is a two-layer boron nitride two-dimensional material, a two-layer molybdenum sulfide two-dimensional material, a two-layer molybdenum selenide two-dimensional material, or a two-layer tungsten sulfide two-dimensional material; The resulting nanotube arrays are boron nitride nanotube arrays, molybdenum sulfide nanotube arrays, molybdenum selenide nanotube arrays, or tungsten sulfide nanotube arrays. The method according to any one of claims 1 to 7.

11. The nanoribbon orientation is obtained based on the following orientation equation: [Equation 1] The nanoribbon width is obtained based on the width formula: [Equation 2] where Ψ 0 denotes the nanoribbon orientation, w denotes the nanoribbon width, α is the lattice constant of the two-dimensional material, and n and m are the chiral indices of the nanotube, or The nanoribbon orientation and the nanoribbon width are obtained by introducing deviations into the orientation equation and the width equation, respectively.

9. The method of claim 8.

12. A nanotube array manufactured by the method for manufacturing a nanotube array according to any one of claims 1 to 11. A nanotube array characterized by:

13. In a carbon nanotube transistor manufactured using a carbon nanotube array, The carbon nanotube array is manufactured by the method according to claim 8 or 9. A carbon nanotube transistor.

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