Controllable preparation method of bubbles in two-dimensional material based on ionizing radiation

Abstract

The invention discloses a controllable preparation method of two-dimensional material bubbles based on ionizing radiation. The method comprises the following steps: firstly, preparing a single-layer two-dimensional material sample through a mechanical stripping and dry transfer process, then irradiating the sample by using a low-energy alpha source, subsequently putting the sample into a temperature control console, and carrying out annealing treatment according to a preset program. Tiny bubbles can appear on the surface of the irradiated two-dimensional material, and after annealing treatment, the tiny bubbles in the material are gradually combined into larger bubbles under the thermal action and are finally stabilized. Through an atomic force microscope and a photoluminescence spectrum, the treated sample can be characterized, and the size, shape and distribution of the bubbles and the influence of local strain introduced by the bubbles on the spectral property of the two-dimensional material are analyzed. According to the novel method for introducing the strain into the two-dimensional material, the two-dimensional material is treated through the ionizing radiation technology and annealing, accurate regulation and control of the size and the form of the bubbles are achieved, and the optical property of the material is remarkably changed.

Description

Technical Field

[0001] The present invention belongs to the field of materials science and nanotechnology, and relates to a method for preparing controllable bubbles in two-dimensional materials by combining irradiation technology with annealing process, which is particularly suitable for two-dimensional semiconductor materials such as atomically thin TMDCs. Background Art

[0002] In recent years, monolayer two-dimensional transition metal dichalcogenides (TMDCs) have attracted significant attention due to their unique electrical, mechanical, and optical properties. These properties hold significant practical significance for manipulating the properties of two-dimensional materials, expanding their applications, and opening up new areas of exploration in materials science and engineering. However, achieving these goals requires overcoming numerous practical challenges, including achieving optimal mechanical, optical, and electromagnetic properties in these two-dimensional materials.

[0003] Research has shown that the thermal, electrical, mechanical, and optical properties of TMDCs can be effectively manipulated through intrinsic structural factors such as the number of layers and stacking order, as well as through external means such as voltage, strain, defects, and doping. However, existing manipulation methods remain limited due to difficulties in achieving active control and the introduction of contaminants, hindering the development and application of TMDCs in optoelectronic devices. To further meet the application needs of two-dimensional TMDC materials and expand their application areas, finding effective means to manipulate their physical properties has become a key scientific issue that urgently needs to be addressed.

[0004] Traditional control methods, such as doping and setting fixed pattern substrates, have disadvantages such as introducing contamination or being unable to be controlled in real time, which limits their application in the field of controlling the physical properties of two-dimensional materials. As a widely used irradiation method, ionizing radiation (IR) has been widely used to control the properties of various nanomaterials. It has the advantages of no chemical doping, no contact, controllable and reversible. It is crucial to study the mechanism of action between radiation and two-dimensional materials and its application in physical property control. At present, most studies focus on the impact of defects on two-dimensional materials after high-energy particle irradiation, but lack research on non-destructive control of the physical properties of two-dimensional materials by ionizing radiation. At the same time, optoelectronic devices based on two-dimensional TMDCs have broad application prospects in the aerospace field due to their advantages such as small size, light weight and low power consumption. Exploring the changes or damage to the physical properties of two-dimensional materials caused by radiation conditions is also of great application value for evaluating the working performance of related devices under working conditions. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem of introducing contamination or being unable to control in real time in traditional methods for regulating the physical properties of two-dimensional materials, and to provide a method for the controllable preparation of bubbles in two-dimensional materials based on ionizing radiation. The method prepares a monolayer of TMDCs, then uses a 5MeV exempted α-plane source for twelve days of irradiation treatment, and finally further realizes the controllable growth of bubbles through annealing treatment. The stress field generated by these bubbles can significantly change the exciton luminescence intensity distribution and emission energy in the monolayer TMDCs, while reducing the local roughness of the material. The method of the present invention is applicable to a variety of two-dimensional materials, has the advantages of high efficiency and high applicability, and provides a new approach for the application of high-performance devices.

[0006] The technical solutions of the present invention are as follows:

[0007] A controllable preparation method for bubbles in two-dimensional materials based on ionizing radiation, the apparatus used in the method includes an exempted-level α-plane source, a temperature control console, and a computer; the preparation method comprises:

[0008] Step 1: Prepare a monolayer of transition metal dichalcogenides (TMDCs) on a reflective substrate by mechanical exfoliation and dry transfer;

[0009] Step 2: Place the prepared single-layer sample on an exempted α-plane source for irradiation treatment. After irradiation treatment, tiny bubbles are generated on the surface of the material. These tiny bubbles serve as seed sources to control its morphology through annealing operation.

[0010] Step 3: Place the irradiated sample in a computer-controlled temperature control console and perform annealing according to the preset temperature and time program. After annealing, the tiny bubbles on the surface of the material converge into larger bubbles under the action of heat.

[0011] Step 4: The irradiated samples can be characterized by atomic force microscopy and photoluminescence spectroscopy. The local strain introduced by bubbles can change the photoluminescence spectrum of monolayer TMDCs.

[0012] In the above method, the mechanical exfoliation step includes repeatedly sticking and exfoliating the bulk crystal material using tape until a single layer of TMDCs is obtained.

[0013] In the above method, the single-layer TMDCs is a single-layer WSe2, MoS2, WS2 or MoSe2.

[0014] In the above method, the dry transfer step is to transfer a single layer of TMDCs thin layer onto a reflective substrate.

[0015] In the above method, the reflective substrate is a silicon dioxide / silicon substrate.

[0016] In the above method, the specific parameters of the exempted-level α plane source are: energy 5MeV, surface emissivity in the 2π direction: 5.71×10 4 / min.

[0017] In the above method, the temperature control console is controlled by a computer, and its functions include:

[0018] (1) a heating unit for providing the required heat;

[0019] (2) a cooling unit for controlling the cooling process;

[0020] (3) a temperature sensor for real-time temperature monitoring;

[0021] (4) A controller for controlling the heating and cooling units according to a preset temperature and time program.

[0022] In the above method, the temperature and time program of the annealing treatment specifically includes:

[0023] (1) Gradually increase the temperature from room temperature to 400 K at a heating rate of 40 K / min;

[0024] (2) Maintain at 400K for 3 minutes;

[0025] (3) Cooling at a rate of 30 K / min and stabilizing for 3 minutes every time the temperature drops by 20 K until it reaches 80 K;

[0026] (4) After stabilizing at 80 K for 3 minutes, the temperature was restored to room temperature at a rate of 40 K / min, completing one cycle.

[0027] In the above method, after the irradiated sample is annealed, the initial microbubbles present in the monolayer gradually merge into larger bubbles under the action of heat, and eventually stabilize to form controllable bubbles.

[0028] In the above method, the characteristics of the bubbles include:

[0029] (1) The bottom radius is 0.1 to 2 μm and the height is 10 to 100 nm;

[0030] (2) The shape is spherical crown;

[0031] (3) Random distribution;

[0032] In the above method, the size, morphology and distribution of bubbles in the two-dimensional material can be accurately measured using an atomic force microscope, and the photoluminescence signal of the material sample before and after irradiation is measured using photoluminescence spectroscopy, specifically including:

[0033] (1) Atomic force microscopy is used to measure the height, radius, and distribution of bubbles;

[0034] (2) Photoluminescence spectroscopy is used to analyze the effect of local strain introduced by bubbles on the photoluminescence properties of the material.

[0035] Advantages and beneficial effects of the present invention:

[0036] The method for preparing bubbles in controllable two-dimensional materials based on ionizing radiation described in the present invention provides a new method for introducing strain in two-dimensional materials, realizes effective regulation of the size and morphology of bubbles, and can also improve the quality of two-dimensional material crystals and reduce defects through annealing operations. Compared with the traditional method of introducing stress, the method of the present invention does not require the preparation of substrate patterns and cumbersome steps in advance. It can achieve precise control of bubble growth through simple irradiation treatment and annealing process, and solves the shortcomings of the traditional method that the stress cannot be regulated due to the inability to change the substrate, reduces the preparation cost, improves the preparation efficiency, is suitable for large-scale production and application, and has the advantages of non-contact, no doping, reversible and controllable. The method also significantly changes the optical properties of the material. In addition, the method is applicable to a variety of two-dimensional materials, has wide applicability and versatility, provides a new way to develop new high-performance devices, and has the advantages of high efficiency and high applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of an irradiation and annealing treatment device in a specific embodiment of the present invention is shown, wherein: 1 is a computer, 2 is a temperature control console, 3 is a two-dimensional material single-layer sample, 4 is α particles, and 5 is an exemption-level α standard source.

[0038] Figure 2 The left figure shows the motion trajectory of 5MeV α particles irradiating a single layer using SRIM simulation software, and the right figure shows the generation of sample defects. It is found that every 10 5 It takes one alpha particle bombardment to create one vacancy.

[0039] Figure 3 Schematic diagram of bubble generation before and after irradiation of the present invention is shown, wherein (a) is a single-layer sample that has not been irradiated, and (b) is a schematic diagram of a single-layer sample that generates bubbles after irradiation. After irradiation, helium is generated between the sample and the silicon substrate.

[0040] Figure 4 The atomic force microscope scanning images of the two-dimensional material before and after irradiation in a specific embodiment of the present invention are shown, where (a) is the two-dimensional atomic force microscope scanning image of the two-dimensional material before irradiation, and (b) is the atomic force microscope scanning image after irradiation. It can be clearly observed that a large number of tiny protrusions are generated on the sample surface at the same position after irradiation.

[0041] Figure 5 Shows Figure 4 Bubble contour diagram of the white area in the middle, where (a) and (b) are statistical diagrams of the height and width of different bubbles in the area. It can be seen that the bubbles are approximately semicircular, and (c) is the fitting curve of the bubble height and width in Figure (b). It can be found that the bubble height and width are linearly related.

[0042] Figure 6 Atomic force microscope scanning images of the two-dimensional material before and after annealing are shown, where (a) and (b) are the atomic force images before and after annealing, respectively, and (c) is the contour map of the bubbles before and after annealing.

[0043] Figure 7 The photoluminescence spectra of the sample before and after irradiation measured in Example 1 of the present invention are shown. (b) is the peak position of the photoluminescence spectrum in (a) extracted to better observe the red shift phenomenon of the spectrum. DETAILED DESCRIPTION

[0044] The present invention will be described in further detail below through embodiments in conjunction with the accompanying drawings so that those skilled in the art can understand the present invention more clearly.

[0045] The present invention proposes a technology that generates seed source bubbles through ionizing radiation technology and combines it with annealing treatment to reorganize tiny bubbles to prepare controllable bubbles. This method performs the original accumulation of tiny bubbles through multiple irradiations, and then through annealing operations, it realizes the re-regulation of the size and morphology of the bubbles, providing a new way for the performance optimization and device application of two-dimensional materials. Specifically, in theory, the present invention proves through SRIM simulation that this technology is a non-destructive irradiation technology. In the experiment, tiny bubbles can be generated through ionizing irradiation, and then through annealing treatment, the initial tiny bubbles in the single-layer two-dimensional material are gradually merged into larger bubbles, and finally stabilized, thereby forming a controllable artificial potential field on the surface of the two-dimensional material, thereby realizing the effective regulation of the two-dimensional exciton flow. This method not only improves the crystallization quality of the material, but also provides a new means for modulating the electronic and optical properties of two-dimensional materials.

[0046] The present invention proposes a controllable method for preparing bubbles in two-dimensional materials based on ionizing radiation, and the schematic diagram of the preparation device used is as follows: Figure 1 As shown in the figure, 1 is a computer, 2 is a temperature control console, 3 is a two-dimensional material single layer sample, 4 is an α particle, and 5 is an exemption-level α standard source. The preparation method includes the following steps:

[0047] Step 1: Mechanically peel off a single layer of TMDCs (such as WSe2) from the bulk crystal, and use tape to repeatedly stick and peel until a single layer of TMDCs material is obtained.

[0048] Step 2: Transfer the peeled monolayer TMDCs to a polydimethylsiloxane (PDMS) substrate.

[0049] Step 3: Transfer the monolayer TMDCs on the PDMS substrate to the silica / silicon substrate.

[0050] Step 4: Place the transferred monolayer TMDCs on an exempted-level α-plane source with an energy of 5 MeV for irradiation treatment for a period of twelve days.

[0051] Step 5: Place the prepared TMDCs thin layer sample in a computer-controlled temperature control console (such as Figure 1 As shown), the temperature control console includes a heating unit, a cooling unit, a temperature sensor and a controller.

[0052] Step 6: Perform multiple annealing treatments according to the preset temperature and time program. The specific steps include:

[0053] (1) Gradually increase the temperature from room temperature to 400 K at a heating rate of 40 K / min;

[0054] (2) Maintain at 400K for 3 minutes;

[0055] (3) Cooling at a rate of 30 K / min and stabilizing for 3 minutes every time the temperature drops by 20 K until it reaches 80 K;

[0056] (4) After stabilizing at 80 K for 3 minutes, the temperature was restored to room temperature at a rate of 40 K / min, completing one cycle.

[0057] Finally, we get a two-dimensional material bubble sample, such as Figure 4 Atomic force microscopy scanning imaging shown.

[0058] The characterization method of the controllable two-dimensional material bubbles based on ionizing radiation technology and annealing treatment is given below: In the present invention, the height and radius of the controllable two-dimensional material bubbles based on ionizing radiation are measured by atomic force microscopy, and the changes in the size and morphology of the bubbles are analyzed, such as Figure 5 and Figure 6 As shown; the photoluminescence spectrum of the sample before and after irradiation is measured by spectrometer to analyze the effect of local strain introduced by bubbles on the spectral characteristics of the material, as shown in Figure 7 shown.

[0059] Example 1

[0060] First, SRIM software was used to simulate the 5MeV α-particle irradiation of a two-dimensional material monolayer. It was found that every 10 5 Only one vacancy will be created by bombarding with alpha particles, which proves that this technology is a non-destructive irradiation method.

[0061] Then, a single-layer WSe2 sample was prepared according to the above steps, including a silicon dioxide / silicon substrate, a single-layer WSe2, as shown in FIG. Figure 3 As shown in (a).

[0062] The prepared WSe2 monolayer sample was first placed on an exempted-grade α-plane source for multiple irradiation, and the photoluminescence spectrum was measured by a spectrometer after each irradiation. The specific parameters of the exempted-grade α-plane source used here are energy 5MeV, surface emissivity in the 2π direction: 5.71×10 4 / min.

[0063] After the irradiation experiment, place it in a computer-controlled temperature control console (such as Figure 1 As shown), the temperature control console used here is Linkam THMS600, which includes a heating unit, a cooling unit, a temperature sensor and a controller.

[0064] Annealing is performed according to the preset temperature and time program. The specific steps include:

[0065] (1) Gradually increase the temperature from room temperature to 400 K at a heating rate of 40 K / min;

[0066] (2) Maintain at 400K for 3 minutes;

[0067] (3) Cooling at a rate of 30 K / min and stabilizing for 3 minutes every time the temperature drops by 20 K until it reaches 80 K;

[0068] (4) After stabilizing at 80 K for 3 minutes, the temperature was restored to room temperature at a rate of 40 K / min, completing one cycle.

[0069] Finally, a two-dimensional material bubble sample was obtained. Figure 3 (a) and 3(b) record the atomic force microscopy scanning images of the monolayer WSe2 sample before and after irradiation, respectively.

[0070] Sample area ( Figure 3 The white dotted box in the middle shows a significant change. By comparing the AFM scans before and after irradiation, it can be found that a large number of tiny bubbles are generated after irradiation. The height and radius of the bubbles are measured by AFM, and the size and morphology of the bubbles in the monolayer WSe2 sample before and after annealing are analyzed, as shown in the figure below. Figure 4 As shown in the figure, the fitting of bubble height and width shows that there is a linear relationship between them. By comparing the AFM scans before and after annealing, it can be found that the initial microbubbles gradually merge into larger bubbles under the action of heat, as shown in the figure. Figure 5 (a) and 5(b), Figure 5 (c) This phenomenon can be observed more intuitively.

[0071] The photoluminescence spectra of the samples before and after irradiation were measured by a spectrometer, such as Figure 6 As shown, it can be seen that with the increase of irradiation time, the spectral intensity first increases and then tends to be stable, and the spectrum shows a red shift of about 0.7meV, indicating that the controllable two-dimensional material bubbles based on ionizing radiation treatment significantly changed the luminescence intensity and photoluminescence spectral position of the sample, which is due to the change in the band structure of the single-layer TMDCs caused by strain engineering.

[0072] This invention proposes for the first time a method for preparing controllable bubbles in two-dimensional materials using ionizing radiation. This method generates initial bubbles through a single layer of ionizing radiation. Repeated irradiation allows for continuous modification of the optical properties of the two-dimensional material. Annealing further allows for the manipulation of bubble size and morphology. This method provides a novel approach for introducing strain into two-dimensional materials, significantly altering their electronic and optical properties. Specifically, ionizing radiation generates helium, followed by annealing. The initial microbubbles gradually merge into larger bubbles under the influence of heat and eventually stabilize, forming a controllable artificial potential field, thereby enabling active manipulation of exciton flow. This method offers the advantages of being contactless, doping-free, reversible, and controllable, making it applicable to a variety of two-dimensional materials, such as WSe2, MoS2, WS2, and MoSe2. In addition to modulating exciton flow, this method is also suitable for optimizing other material properties, such as in electronic devices, optoelectronic devices, and quantum information processing. The demand for high-performance two-dimensional materials in materials science and nanotechnology is increasing, and this invention provides strong support and valuable insights for the development of these fields.

[0073] Finally, it should be noted that the purpose of disclosing the embodiments is to facilitate a further understanding of the present invention. Those skilled in the art should understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the contents disclosed in the embodiments; the scope of protection claimed by the present invention shall be determined by the scope defined in the claims.

Claims

1. A method for controllable preparation of bubbles in two-dimensional materials based on ionizing radiation, characterized in that: include Step 1: Prepare a monolayer of transition metal dichalcogenides (TMDCs) on a reflective substrate by mechanical exfoliation and dry transfer; Step 2: Place the prepared single-layer sample on an exempted α-plane source for irradiation treatment. After irradiation treatment, tiny bubbles are generated on the surface of the material. These tiny bubbles serve as seed sources to control its morphology through annealing operation. Step 3: Place the irradiated sample in a computer-controlled temperature control console and perform annealing treatment according to the preset temperature and time program. After annealing, the tiny bubbles on the surface of the material converge into larger bubbles under the action of heat.

2. The method according to claim 1, wherein: The single-layer TMDCs are single-layer tungsten diselenide (WSe2), single-layer molybdenum disulfide (MoS2), single-layer tungsten disulfide (WS2) or single-layer molybdenum diselenide (MoSe2).

3. The method according to claim 1, wherein: The reflective substrate is a silicon dioxide / silicon substrate.

4. The method according to claim 1, wherein: The specific parameters of the exempted-level α plane source are energy 5MeV, surface emissivity in the 2π direction: 5.71×10 4 / min.

5. The method according to claim 1, wherein: After the monolayer sample is annealed, the initial tiny bubbles present in the sample gradually merge into larger bubbles under the action of heat, and eventually stabilize to form controllable bubbles; The characteristics of the bubbles include: (1) The bottom radius is 0.1 to 2 μm and the height is 10 to 100 nm; (2) The shape is spherical crown; (3) Random distribution.

6. The method according to claim 1, wherein: The size, morphology and distribution of bubbles in the two-dimensional material can be accurately measured using an atomic force microscope, and the photoluminescence signal of the material sample before and after irradiation can be measured using photoluminescence spectroscopy, specifically including: (1) Atomic force microscopy is used to measure the height and radius of bubbles; (2) Photoluminescence spectroscopy is used to analyze the effect of local strain introduced by bubbles on the photoluminescence properties of the material.

7. The method according to claim 1, wherein: The local strain introduced by the bubbles after irradiation can change the photoluminescence spectrum of TMDCs, mainly because the local stress distribution induced by the bubbles changes the band structure of the monolayer TMDCs, thereby changing its emission energy.

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