Preparation method for thinning multilayer tungsten disulfide nanosheet and application

Abstract

The invention belongs to the field of semiconductor film preparation, and particularly relates to a preparation method for thinning a multilayer tungsten disulfide nanosheet and application. One purpose of the invention is to provide a preparation method for thinning a multilayer tungsten disulfide nanosheet. The preparation method comprises the following steps: irradiating the multilayer tungsten disulfide nanosheet with neutrons. The irradiation condition is set as follows: the total neutron fluence is 1 * 10 < 12 >-5 * 10 < 13 > n / cm < 2 > / s. According to the method, the thin and uniform multilayer tungsten disulfide (WS2) nanosheets can be prepared by adopting a neutron irradiation method with different doses, the method has the advantages of simple operation process, high yield, high efficiency, no pollution and the like, and meanwhile, the physicochemical properties of the nanosheet material are reserved in the preparation process.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor film preparation, and in particular relates to a preparation method and application for thinning multi-layer tungsten disulfide nanosheets. Background Art

[0002] Tungsten disulfide (WS2) nanosheets, a two-dimensional graphene-like material with a non-zero band gap, have attracted considerable attention due to their unique "sandwich" layered structure (three layers of XMX covalently bonded and tightly packed). In this structure, the layers are connected by weak van der Waals forces, allowing foreign reactants to be inserted into the interlayer gaps, thus endowing the material with excellent optoelectronic and mechanical properties. It is considered a new functional material with great development potential in the field of optoelectronic devices. At the same time, multilayer disulfide nanosheets, with their unique two-dimensional layered structure, exhibit rich properties that are closely related to the number of layers, and have important application value in the fields of electronics, energy, catalysis, etc.

[0003] The physicochemical properties of WS2 nanosheets are closely related to their number of layers. In the multilayer state (interlayer spacing of about 0.7nm), the material behaves as an indirect bandgap semiconductor (~1.3eV) with bipolar electron transport properties. As the number of layers decreases, its band structure changes significantly: when the thickness is reduced to a single layer, it transforms into a direct bandgap semiconductor (~1.905eV). This transformation makes it have important application value in the fields of photodetectors, sensors and solar cells. It is worth noting that the quantum confinement effect is particularly significant in the few-layer state. When the number of layers is reduced from 10 layers to 1 layer, the carrier mobility can be reduced from tens of cm 2 / (V·s) increased to hundreds of cm 2 / (V·s), opening up the possibility of developing high-performance, low-power electronic devices. Furthermore, regulating the number of layers can optimize the material's lubrication properties and catalytic activity: a moderate number of layers is conducive to the formation of a stable lubricating film, while a few-layer structure can significantly improve photocatalytic efficiency due to its unique energy band structure and surface activity.

[0004] Currently, the thinning methods for WS2 nanosheets mainly include mechanical grinding, ultrasonic exfoliation, chemical etching, intercalation-exfoliation, and physical and chemical synergistic thinning. However, these methods all have obvious limitations, as follows:

[0005] Mechanical grinding method: low efficiency, easily leading to nanosheet breakage and agglomeration;

[0006] Ultrasonic peeling method: limited solvent selection, prone to structural damage and uneven thickness;

[0007] Chemical etching: may introduce impurities and change the intrinsic properties of the material;

[0008] Intercalation-stripping method: The process is complex and the residual intercalant affects the material properties;

[0009] Physical and chemical synergistic method: high cost and poor process controllability.

[0010] Therefore, developing a thinning technology that can precisely control the number of layers, maintain the intrinsic properties of the material, and achieve good repeatability has become a key scientific issue in promoting the practical application of WS2 nanosheets. This technological breakthrough will significantly enhance the material's performance in applications such as electronics, energy, and catalysis, and has important scientific and engineering value.

[0011] In addition, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the inventor studied a large number of documents and patents when making the present invention, but due to space limitations, not all details and contents are listed in detail. However, this does not mean that the present invention does not have the characteristics of these prior arts. On the contrary, the present invention already has all the characteristics of the prior art, and the applicant reserves the right to add relevant prior art to the background art. Summary of the Invention

[0012] The present invention belongs to the field of semiconductor film preparation, and in particular relates to a preparation method and application for thinning multi-layer tungsten disulfide nanosheets.

[0013] Based on the above technical problems, one of the objectives of the present invention is to provide a preparation method for thinning multilayer tungsten disulfide nanosheets, which comprises the following steps: neutron irradiation of the multilayer tungsten disulfide nanosheets.

[0014] According to a preferred embodiment, the irradiation conditions are set as follows: the total neutron injection is 1×10 12 ~5×10 13 n / cm 2 / s.

[0015] According to a preferred embodiment, the number of layers of the multilayer tungsten disulfide nanosheets before thinning ranges from 3 to 19 layers.

[0016] According to a preferred embodiment, the number of layers of the multilayer tungsten disulfide nanosheet after thinning can be reduced by 10-30% compared to the number of layers of the multilayer tungsten disulfide nanosheet before thinning. Preferably, for a multilayer tungsten disulfide nanosheet having 19 layers before thinning, the number of layers of the thinned multilayer tungsten disulfide nanosheet after neutron irradiation can be 17, 15, or 14.

[0017] According to a preferred embodiment, the neutron yield of the irradiation is 8.0×10 11 n / s.

[0018] According to a preferred embodiment, the multilayer tungsten disulfide nanosheet material is prepared based on a hydrothermal reaction method, a liquid phase exfoliation method, or a chemical vapor deposition method. Preferably, the multilayer tungsten disulfide nanosheet is prepared using a chemical vapor deposition (CVD) method with sapphire (Al2O3) as the substrate.

[0019] According to a preferred embodiment, the parameters of the irradiation are selected from one or more of the following groups:

[0020] The distance between the multilayer tungsten disulfide nanosheets and the neutron source is 100 cm, and the neutron flux rate of the sample is 6.37×10 6 n / cm 2 / s; the total neutron injection of the sample is 1×10 12 n / cm 2 ;

[0021] The distance between the multilayer tungsten disulfide nanosheets and the neutron source is 31.6 cm, and the neutron flux rate is 6.37×10 7 n / cm 2 / s; the total neutron injection of the sample is 1×10 13 n / cm 2 ;

[0022] The distance between the multilayer tungsten disulfide nanosheets and the neutron source is 14.1 cm, and the neutron flux rate of the sample is 3.2×10 8 n / cm 2 / s; the total neutron injection of the sample is 5×10 13 n / cm 2 .

[0023] According to a preferred embodiment, the irradiation time is 43.6 hours.

[0024] One of the objectives of the present invention is to provide the use of the multilayer tungsten disulfide nanosheets or the multilayer tungsten disulfide nanosheets obtained based on the above preparation method in semiconductor devices.

[0025] One of the objectives of the present invention is to provide a device for thinning multi-layer tungsten disulfide nanosheets, which can implement the above-mentioned irradiation conditions to irradiate the multi-layer tungsten disulfide nanosheets.

[0026] The beneficial effects of this technical solution are as follows:

[0027] The ideal preparation method should avoid the use of toxic reagents or the production of harmful byproducts, while ensuring the structural integrity and surface cleanliness of the nanosheets to maximize the preservation of their intrinsic physicochemical properties, such as excellent carrier mobility, tunable band structure, and stable lubrication and catalytic performance. Furthermore, the nanosheets prepared by this technical solution possess good scalability, enabling the large-scale production of high-quality nanosheets to meet the specific material performance requirements of various application areas (such as electronic devices, energy storage, and catalytic degradation).

[0028] The present invention adopts a neutron irradiation method with different doses to prepare thin and uniform multilayer tungsten disulfide (WS2) nanosheets, which has the advantages of simple operation process, high output, high efficiency, and no pollution. At the same time, the physical and chemical properties of the nanosheet material are retained during the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 These are high-resolution transmission electron micrographs of the cross-section of multilayer tungsten disulfide (WS2) nanosheets after irradiation with different neutron doses (C1-4). The inner figure in the lower right corner of each image is a selected area electron diffraction pattern of the cross-section of the multilayer tungsten disulfide (WS2) nanosheets after irradiation.

[0030] Figure 2 is the optical absorption spectrum of multilayer tungsten disulfide (WS2) nanosheets at different neutron fluences obtained in Example 1;

[0031] Figure 3 1 is the Raman spectrum of multilayer tungsten disulfide (WS2) nanosheets at different neutron fluences obtained in Example 1;

[0032] Figure 4 This is a rocking curve diagram of multilayer tungsten disulfide (WS2) nanosheets under different neutron fluences obtained in Example 1. DETAILED DESCRIPTION

[0033] In the description of the present invention, terms are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly indicate the number of technical features indicated. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0034] The present invention is further described below with reference to specific examples. Experimental methods in the following examples, where specific conditions are not specified, generally follow conventional conditions or the conditions recommended by the manufacturer. Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to professionals in the field. In addition, any methods and materials similar or equivalent to those described herein can be applied to the present invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0035] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0036] Those skilled in the art will appreciate that the apparatus and its modules for irradiating materials can be implemented in a variety of ways. In certain embodiments, the apparatus and its modules can be implemented using hardware (e.g., a neutron collider), software, or a combination of hardware and software. Specifically, the hardware portion can be implemented using dedicated logic; the software portion can be stored in memory and executed by an appropriate instruction execution system (e.g., a microprocessor or specially designed hardware). Furthermore, the apparatus and its modules of the present invention can be implemented using hardware circuits such as very large-scale integrated circuits, gate arrays, logic chips, transistors, field programmable gate arrays, programmable logic devices, or software executed by various types of processors, or a combination of hardware circuits and software (e.g., firmware). These methods and apparatus can be implemented using computer-executable instructions and / or contained in processor control code. For example, such code can be placed on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier.

[0037] In the following examples, the multilayer tungsten disulfide nanosheets before thinning were prepared using a chemical vapor deposition (CVD) method with sapphire (Al2O3) as a substrate.

[0038] Before thinning, the tungsten disulfide nanosheets had 19 layers with an interlayer spacing of 0.618 nm. After thinning, the tungsten disulfide nanosheets of Example 1 had 17 layers with an interlayer spacing of 0.693 nm; the tungsten disulfide nanosheets of Example 2 had 15 layers with an interlayer spacing of 0.644 nm; and the tungsten disulfide nanosheets of Example 3 had 14 layers with an interlayer spacing of 0.651 nm.

[0039] After neutron irradiation, the interlayer spacing initially decreases and then slightly increases as the irradiation dose increases. This is related to lattice distortion, defect accumulation, or changes in interlayer stress caused by irradiation. The number of tungsten disulfide nanosheets decreases with increasing irradiation dose. This is because high-energy particle irradiation causes damage to the material's internal structure, atomic rearrangement, or disruption of interlayer bonds, reducing the number of observable intact layers.

[0040] Example 1

[0041] A method for thinning and preparing multilayer tungsten disulfide (WS2) nanosheet materials, comprising the following steps:

[0042] (1) The sample box is ultrasonically cleaned with acetone and alcohol and rinsed with deionized water. The prepared multilayer tungsten disulfide (WS2) nanosheet material is placed in the sample box, and the sample box is placed in a packaging container;

[0043] (2) Evaluate and optimize the neutron source yield, irradiation time, and sample location based on the neutron fluence to be irradiated;

[0044] (3) Use a dedicated sample loading tool to accurately place the packaged sample in the designated position of the neutron irradiation device, that is, the distance from the neutron source is 100 cm, and the corresponding neutron yield is 8.0×10 11 n / s; the neutron injection rate of the sample is 6.37×10 6 n / cm 2 / s; the total neutron injection of the sample is 1×10 12 n / cm 2 ;

[0045] (4) Start the neutron source according to the predetermined parameters and run it for 43.6 hours;

[0046] (5) After the irradiation is completed, the sample is taken out to obtain thinned multilayer tungsten disulfide (WS2) nanosheets.

[0047] Example 2

[0048] A method for thinning and preparing multilayer tungsten disulfide (WS2) nanosheet materials, comprising the following steps:

[0049] (1) The sample box is ultrasonically cleaned with acetone and alcohol and rinsed with deionized water. The prepared multilayer tungsten disulfide (WS2) nanosheet material is placed in the sample box, and the sample box is placed in a packaging container;

[0050] (2) Evaluate and optimize the neutron source yield, irradiation time, and sample location based on the neutron fluence to be irradiated;

[0051] (3) Using a dedicated sample loading tool, the packaged sample was accurately placed in the designated position of the neutron irradiation device, i.e., the distance from the neutron source was 31.6 cm, and the corresponding neutron yield was 8.0×10 11 n / s; the neutron injection rate of the sample is 6.37×10 7 n / cm 2 / s; the total neutron injection of the sample is 1×10 13 n / cm 2 ;

[0052] (4) Start the neutron source according to the predetermined parameters and run it for 43.6 hours.

[0053] (5) After the irradiation is completed, the sample is taken out to obtain thinned multilayer tungsten disulfide (WS2) nanosheets.

[0054] Example 3

[0055] A method for thinning and preparing multilayer tungsten disulfide (WS2) nanosheet materials, comprising the following steps:

[0056] (1) The sample box is ultrasonically cleaned with acetone and alcohol and rinsed with deionized water. The prepared multilayer tungsten disulfide (WS2) nanosheet material is placed in the sample box, and the sample box is placed in a packaging container;

[0057] (2) Evaluate and optimize the neutron source yield, irradiation time, and sample location based on the neutron fluence to be irradiated;

[0058] (3) Using a dedicated sample loading tool, the packaged sample was accurately placed in the designated position of the neutron irradiation device, i.e., the distance from the neutron source was 14.1 cm, and the corresponding neutron yield was 8.0×10 11 n / s; the neutron injection rate of the sample is 3.2×10 8 n / cm 2 / s; the total neutron injection of the sample is 5×10 13 n / cm 2 ;

[0059] (4) Start the neutron source according to the predetermined parameters and run it for 43.6 hours;

[0060] (5) After the irradiation is completed, the sample is taken out to obtain thinned multilayer tungsten disulfide (WS2) nanosheets.

[0061] Example 4

[0062] This embodiment relates to a multilayer tungsten disulfide (WS2) nanosheet material that has not been irradiated.

[0063] The irradiation condition parameters of the multilayer tungsten disulfide (WS2) nanosheet materials of Examples 1 to 4 are shown in Table 1.

[0064] Table 1

[0065]

[0066]

[0067] like Figure 1 As shown in the figure, with the increase of neutron irradiation dose, the number of nanosheets and the interlayer spacing of the multilayer tungsten disulfide nanosheet film sample decreases. Neutron irradiation transfers energy to the atoms (W and S) in the WS2 lattice through elastic collision. For the layered structure of tungsten disulfide, sulfur atoms (S) are more likely to be sputtered or displaced due to their light mass, resulting in a local increase in the atomic density within the layer, and then attracting adjacent layers through Coulomb force, compressing the interlayer spacing.

[0068] like Figure 2As shown, taking the material of Example 1 as an example, after neutron irradiation, the position of the absorption peak does not change, and the light absorption rate decreases with the increase of irradiation dose. High-dose neutron irradiation causes surface atomic sputtering or interlayer separation, reduces the effective optical thickness of the film, shortens the light absorption path, and reduces the macroscopic absorption rate.

[0069] like Figure 3 As shown in Figure 2, after neutron irradiation, the number of Raman peaks does not change. As the neutron irradiation dose increases, The peak continues to move toward high frequency, A 1g The peak shifts toward lower frequencies, which is mainly due to the suppression of out-of-plane vibrations by interlayer interactions, the increase in vibrational freedom as the number of layers decreases, and the weakening of the constraints of interlayer van der Waals forces on phonon vibrations.

[0070] like Figure 4 As shown in Figure 2, with the increase of neutron irradiation dose, the full width at half maximum (FWHM) of the 002 diffraction peak increases and redshifts to the direction of small angles. 12 n / cm 2 ) Under the condition of high neutron bombardment, a small amount of neutrons causes point defects (such as S vacancies) inside the nanosheets, and the local distortion of the crystal lattice increases. At this time, the size effect (thickness reduction) dominates, and the FWHM may increase slightly. Increasing the irradiation dose, high-energy neutrons induce interlayer cleavage or fragmentation, and the nanosheets split into thinner sheets along the c-axis (perpendicular to the layer plane), and the defect density increases significantly. However, at this time, the integrity of the layered structure is destroyed, the stacking order of WS2 decreases, and a few-layer structure is formed, resulting in a decrease in the intrinsic width of the diffraction peak. Under high-dose irradiation, the internal stress of the nanosheet is released through fragmentation, and the lattice relaxes and expands in the c-axis direction, resulting in a decrease in the diffraction angle. In summary, the thinning of multilayer tungsten disulfide nanosheet materials can be achieved by regulating the neutron irradiation dose.

[0071] It should be noted that the above-described specific embodiments are illustrative only. Those skilled in the art may devise various solutions based on the disclosure of the present invention, and such solutions fall within the scope of the present invention and are intended to be protected by the present invention. Those skilled in the art should understand that the present description and its accompanying drawings are intended to be illustrative only and are not intended to limit the scope of the claims. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A method for thinning multilayer tungsten disulfide nanosheets, characterized in that: The method comprises the following steps: neutron irradiating multilayer tungsten disulfide nanosheets.

2. The method for thinning multilayer tungsten disulfide nanosheets according to claim 1, characterized in that: The irradiation conditions are set as follows: the total neutron injection is 1×10 12 ~5×10 13 n / cm 2 / s.

3. The method for thinning multi-layer tungsten disulfide nanosheets according to claim 1, characterized in that: The number of layers of the multilayer tungsten disulfide nanosheets before thinning ranges from 3 to 19 layers.

4. The method for thinning multilayer tungsten disulfide nanosheets according to claim 1, characterized in that: The number of layers of the multilayer tungsten disulfide nanosheet after thinning can be reduced by 10-30% compared with the number of layers of the multilayer tungsten disulfide nanosheet before thinning.

5. The method for thinning multi-layer tungsten disulfide nanosheets according to claim 1, characterized in that: The neutron yield of the irradiation is 8.0×10 11 n / s.

6. The method for thinning multi-layer tungsten disulfide nanosheets according to claim 1, characterized in that: The multilayer tungsten disulfide nanosheets before thinning are prepared by a CVD method using sapphire as a substrate.

7. A multilayer tungsten disulfide nanosheet, characterized in that: The multilayer tungsten disulfide nanosheet is thinned based on the preparation method according to claims 1 to 6.

8. The multilayer tungsten disulfide nanosheet according to claim 7, characterized in that: The interlayer spacing of the multilayer tungsten disulfide nanosheets is no greater than 0.693 nm.

9. Use of the multilayer tungsten disulfide nanosheet according to any one of claims 1 to 4 or the multilayer tungsten disulfide nanosheet obtained by the preparation method according to any one of claims 5 to 9 in a semiconductor device.

10. A device for thinning multilayer tungsten disulfide nanosheets, characterized in that: The device can implement the irradiation conditions involved in the preparation method according to any one of claims 5 to 9 to irradiate multilayer tungsten disulfide nanosheets.

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