Preparation method of two-dimensional cobalt antimonide

Abstract

The invention belongs to the technical field of inorganic two-dimensional materials, and particularly relates to a preparation method of two-dimensional cobaltous antimonide, which comprises the following steps: placing a precursor in a heating area of a tubular furnace, placing a substrate above the precursor, introducing gas, heating to 560-580 DEG C, keeping the temperature, and cooling to obtain the two-dimensional cobaltous antimonide; the precursor is cobalt dichloride powder and antimony powder which are arranged adjacently, and both the cobalt dichloride powder and the antimony powder contain ammonium salt; the preparation method is simple, low in cost and convenient to operate, and the obtained two-dimensional cobalt antimonide is large in size.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic two-dimensional materials, and particularly relates to a preparation method of two-dimensional cobalt antimonide. Background Art

[0002] With the development of two-dimensional (2D) materials, they have gradually become preferred candidates for numerous optoelectronic applications. Compared with traditional bulk-structured narrow-bandgap materials, 2D narrow-bandgap semiconductors have the advantages of small size, relatively simple preparation process, high-quality surface without dangling bonds, strong light-matter interaction, wide photoelectric detection range, high light responsivity, good flexibility, easy construction of heterojunction structures, excellent mechanical properties, and good compatibility with CMOS devices. These advantages help to overcome the deficiencies of traditional bulk-structured narrow-bandgap materials, and also make 2D narrow-bandgap semiconductor materials particularly important in modern optoelectronics, especially in infrared detection and optoelectronic detector applications that require wide spectral response. However, existing 2D narrow-bandgap semiconductors still have limitations in practical applications. For example, graphene has a low intrinsic sensitivity, transition metal dichalcogenides have a large bandgap width, and black phosphorus is unstable in air and difficult to produce on a large scale. Therefore, there is an urgent need to find new 2D narrow-bandgap semiconductor materials with both excellent stability and excellent optoelectronic properties. CoSb is a narrow-bandgap non-layered material with advantages such as a wide photoelectric detection range and high light responsivity, but its non-layered structure limits the preparation of two-dimensional materials and also limits its application in the field of photoelectric detection.

[0003] Non-layered materials, as the name implies, are tightly bonded together by chemical bonds in all three dimensions and usually exhibit a specific three-dimensional morphology. At the same time, because of their closely connected chemical bonds, when grown to the nanoscale, they tend to form structures that can display their symmetry and grow isotropically thermodynamically. Therefore, it is necessary to break the thermodynamic equilibrium state and artificially introduce controllable kinetics to stimulate the anisotropic growth of non-layered materials. Currently, chemical vapor deposition and wet chemical methods are commonly used to synthesize two-dimensional non-layered materials. In the wet chemical synthesis method, due to the participation of polymers or organic substances, the obtained two-dimensional products usually have the characteristics of poor crystal quality, small size (less than 1 micron), and many residual impurities, which is not conducive to the exploration of properties and the characterization of device performance, bringing great resistance and challenges to the further application of two-dimensional non-layered materials. Due to the structural characteristics of non-layered materials, the CVD method for preparing two-dimensional non-layered materials is different from the traditional CVD method. In this method, usually the following two conditions need to be met: 1) Achieve kinetic control by precisely regulating growth parameters, constructing a confined space or introducing foreign elements, and finally complete the anisotropic growth of non-layered materials; 2) Use a substrate without dangling bonds to provide a passivated growth surface, such as layered two-dimensional materials or mica, which can promote the two-dimensional planar growth of non-layered materials and effectively avoid the problem of lattice mismatch. Thus, the researchers proposed three types of optimized chemical vapor deposition methods, namely: van der Waals epitaxial growth method (vdWE), spatially confined CVD method, and self-limiting epitaxial growth method. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a preparation method of two-dimensional cobalt antimonide, which has a simple preparation method, low cost, convenient operation, and the obtained two-dimensional cobalt antimonide has a large size.

[0005] An embodiment of the present invention provides a preparation method of two-dimensional cobalt antimonide. Place the precursor in the heating zone of a tube furnace, place the substrate above the precursor, introduce gas, heat to 560 - 580 °C, keep warm, and then cool down to obtain two-dimensional cobalt antimonide; The precursor is cobalt dichloride powder and antimony powder arranged adjacent to each other, and both the cobalt dichloride powder and the antimony powder contain ammonium salts.

[0006] Preferably, the weight ratio of cobalt dichloride to antimony is 0.9 - 1.1:0.9 - 1.1.

[0007] Preferably, the weight ratio of cobalt dichloride to antimony is 1:1.

[0008] Preferably, the ammonium salt is ammonium chloride.

[0009] Preferably, the cobalt dichloride powder contains an ammonium salt, and the weight ratio of cobalt dichloride to the ammonium salt is 0.9 - 1.1:0.9 - 1.1; the antimony powder contains an ammonium salt, and the weight ratio of antimony to the ammonium salt is 0.9 - 1.1:0.9 - 1.1.

[0010] Preferably, after heating to 570 °C, keep the temperature constant.

[0011] Preferably, the precursor is placed in a glass boat; the material of the substrate is fluorophlogopite mica, the distance between the substrate and the precursor is 2 - 5 mm, preferably 3 mm, the glass boat is boat-shaped, including a concave bottom and protruding edges around, the substrate is a flat plate, and both ends of the flat plate are set on the protruding edges, and there is a certain distance between the precursor located at the concave bottom and the substrate, so as to achieve the purpose of placing the substrate above the precursor.

[0012] Directly relying on its own weight, the substrate can also be fixed on the glass boat. In order to better fix the substrate, the substrate can be placed in ultrapure water for 1 - 2 s, and then both ends of the substrate are set on the protruding edges of the glass boat. The substrate fits tightly with the glass boat to prevent the substrate from falling off the glass boat.

[0013] Preferably, the distance between the cobalt dichloride powder and the antimony powder is 2 - 4 mm.

[0014] Preferably, the air flow direction for ventilation is from the cobalt dichloride powder to the antimony powder. Before heating, the air flow rate for ventilation is above 600 sccm, and after the heating starts, the air flow rate for ventilation is 80 - 120 sccm; The heating rate is 20 - 25 °C·min -1 。

[0015] Preferably, the heat preservation time is 10 - 30 min, then stop heating and naturally cool to room temperature.

[0016] The beneficial effect of the present invention is that the present invention synthesizes a thin-layer two-dimensional cobalt antimonide sample by the CVD method, which has excellent optoelectronic properties.

[0017] The present invention provides a preparation method for CVD growth of CoSb, using CoCl2 and antimony powder as precursors, and preparing through a tube furnace (preferably a single-temperature zone tube furnace). The prepared CoSb shows high crystallization characteristics and has excellent optical properties; the present invention overcomes the difficulty that CoSb, as a non-layered material, is difficult to be two-dimensionalized, provides a new growth strategy for synthesizing CoSb, and promotes the application of CoSb in optoelectronic detection devices.

[0018] The present invention regulates the Co / Sb ratio of the precursor during the growth process through a tube furnace. Compared with the traditional growth method (sputtering deposition method), it has the advantages of low cost and convenient operation. CoSb of about 20 μm has been successfully prepared. The prepared CoSb exhibits high crystallization characteristics and excellent optical properties.

[0019] In the present invention, the required Co / Sb ratio of the precursor is first determined, and then the corresponding masses of CoCl2 and Sb powder are weighed using an electronic scale. The CoCl2 powder and Sb powder are arranged adjacent to each other, and the substrate is placed above them. The device (preferably a glass boat) with the precursor placed is pushed into the center of the tube furnace, and then the temperature is raised to 560 - 580 °C, held for a certain time, and then the heating is stopped and it is naturally cooled to room temperature. A CoSb sample can be obtained on the substrate. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the experimental equipment for growing CoSb using CoCl2 and Sb powder as raw materials.

[0021] Figure 2 It is a physical picture of the experiment.

[0022] Figure 3 It is an optical photograph of CoSb grown using CoCl2 and Sb powder as raw materials (mass ratio 1:1).

[0023] Figure 4 It is a Raman scan of CoSb grown using CoCl2 and Sb powder as raw materials.

[0024] Figure 5 It is a SEM scan of CoSb grown using CoCl2 and Sb powder as raw materials.

[0025] Figure 6 It is an EDS spectrum of CoSb grown using CoCl2 and Sb powder as raw materials. Among them, Figure 6 (A) is the EDS spectrum of CoSb at a certain position, Figure 6 (B) is the EDS spectrum of CoSb at another position.

[0026] Figure 7 It is an optical photograph of CoSb grown using CoCl2 and Sb powder as raw materials transferred to a silicon wafer.

[0027] Figure 8 It is an optical photograph and EDS spectrum of CoSb2 grown in Comparative Example 1. Among them, Figure 8 (A) is the optical photograph, Figure 8 (B) is the EDS spectrum test diagram.

[0028] Figure 9Optical photograph and EDS spectrum of CoSb grown as Comparative Example 2. Among them, Figure 9 (A) is the optical photograph, Figure 9 and (B) is the EDS spectrum test chart.

[0029] Figure 10 Optical photograph of the sample obtained in Comparative Example 3.

[0030] Figure 11 Optical photograph of the sample obtained in Comparative Example 4.

[0031] Figure 12 Optical photograph of the sample obtained in Comparative Example 5. Specific Embodiments

[0032] The present invention will be further described in detail below through specific examples, where the raw materials are all industrial products. The examples are only used to explain the present invention and should not be construed as a limitation of the present invention. Modifications or alterations of equivalent forms of the present invention by those skilled in the art also fall within the scope defined by the appended claims of this application.

[0033] Example 1 The present invention provides a method for preparing two-dimensional CoSb. Experiments on CoSb with various morphologies are carried out in a single-temperature-zone tube furnace, and the experimental device is as Figure 1-2 shown.

[0034] The single-temperature-zone tube furnace includes a heating zone and an air flow regulating device. Other supporting equipment includes an argon gas cylinder, a three-way pipe, a flange, a switch, a quartz boat, a quartz tube, and a silicon wafer, etc. These all belong to the known supporting equipment of the single-temperature-zone tube furnace.

[0035] Specifically, it includes the following steps: 1) Substrate: Fluorphlogopite is selected as the substrate for preparing CoSb. A thick mica sheet needs to be peeled into a thin mica sheet with a blade or tweezers, and then the dust on the mica surface is blown off with a small gas cylinder; 2) Weigh 30 mg of the precursor CoCl2 powder and mix it evenly with 30 mg of NH4Cl powder (to obtain precursor A), and mix 30 mg of Sb powder evenly with 30 mg of NH4Cl powder (to obtain precursor B). Then spread the two evenly on the bottom of the glass boat (the glass boat is 11 cm long and 1.5 cm wide). Precursor A is located in the upwind area of the air flow direction, and precursor B is located in the downwind area of the air flow direction. The two are 3 mm apart. The two ends of the single-temperature-zone tube furnace are sealed by asbestos furnace plugs, and the mica is placed above the middle of the two precursors; 3) Place the glass boat with the precursors and the substrate in the middle of the heating zone of the tube furnace; 4) Wrap the asbestos furnace plugs at both ends of the single-temperature-zone tube furnace around the quartz tube and assemble the flange components at both ends; 5) Turn on the argon flowmeter purge switch. At this time, argon gas is blown from precursor A to precursor B into the tube. High-purity argon gas is sent into the quartz tube at a flow rate of 600 sccm to expel the impurity gas in the tube. Continue for 5 minutes (the argon gas does not need to change direction and is always in the positive direction, from CoCl2 to Sb); 6) After the purge is completed, the argon gas flow is increased to 100 sccm, and the temperature is raised and kept in the tube furnace until the growth is completed and then naturally cooled to room temperature, maintaining the 100 sccm flow; 7) At 22.8℃·min -1 The temperature was raised to 570°C at a heating rate of 100 °C and maintained at 570°C for ten minutes (growth 10 minutes), and then the heating was stopped and naturally cooled to room temperature. CoSb samples were obtained on mica.

[0036] 8) The growth substrate is removed to complete the preparation, and a two-dimensional CoSb with a hexagonal morphology can be obtained.

[0037] The performance of CoSb obtained in Example 1 was tested and the results were as follows: Figure 3-7 Performance table shown.

[0038] Figure 3 This is an optical photograph of the prepared CoSb.

[0039] Figure 4 This is the Raman spectrum test image of CoSb. It can be seen that its Raman peak is mainly located at 145.91cm -1 .

[0040] Figure 5 The SEM scan of CoSb is shown in Figure 2. Figure 5 It can be seen that the middle area is thinner.

[0041] Figure 6 This is the EDS spectrum test diagram of CoSb. In order to avoid errors in one test, two positions were measured. The results are as follows Figure 6 (A) and Figure 6 (B). Figure 6 It can be found that the Co / Sb atomic ratio of the two spectra is close to 1:1.

[0042] Figure 7 This is an optical photograph of CoSb transferred from mica to silicon wafer. It can be found that its state has hardly changed after the transfer.

[0043] Example 2 On the basis of Example 1, in this Example 2, the composition of precursor A was adjusted, and the following substances were selected to replace CoCl2, while the others remained unchanged. The raw materials replacing CoCl2 were: Co, CoCl2, Co3O4, Sb, SbCl3, Sb2O3. In Example 2, ammonium chloride was still added to precursor A and precursor B, and the addition amount was the same as that in Example 1.

[0044] Through experiments, it was found that the experimental effects of CoCl2 and Sb were better. They could react at a certain temperature to form samples with a certain shape, while no samples with a fixed shape were obtained for other types of precursors. For example, after the reaction of Co and Sb, Co basically did not evaporate, and no samples were obtained on mica; both Co3O4 and SbCl3 evaporated during the reaction, but the samples obtained on mica were black unknown substances. For the experimental samples of CoCl2 and Sb, after testing, it was found that they were indeed CoSb, as Figure 6 shown.

[0045] Comparative Example 1 Compared with Example 1, the difference in Comparative Example 1 was that the growth temperature in Comparative Example 1 was 500 °C, and the others were the same as in Example 1.

[0046] By measuring the samples grown at 500 °C, the light microscope pictures and EDS energy spectrum diagrams as shown in Figure 8 could be obtained. It was found that the Co / Sb atomic ratios in the spectra were all close to 2:1, which was significantly different from the ratio of the samples grown with a precursor mass ratio of 1:1.

[0047] Comparative Example 2 Compared with Example 1, the difference was that the growth temperature in Example 1 was 570 °C, and the growth temperature in Comparative Example 2 was 550 °C, and the others were the same as in Example 1.

[0048] By measuring the samples grown at 550 °C, the light microscope pictures and EDS energy spectrum diagrams as shown in Figure 9 could be obtained. It was found that the Co / Sb atomic ratios in the spectra were all close to 3:1, which was significantly different from the ratio of the samples grown with a precursor mass ratio of 1:1.

[0049] Comparative Example 3 Compared with Example 1, the difference was that the catalyst in Example 1 was NH4Cl, and no catalyst was used in Comparative Example 3, and the others were the same as in Example 1.

[0050] Experiments found that without using the catalyst NH4Cl, very few samples were obtained on mica, and the samples were small and thick, as shown in Figure 10 shown. It shows that NH4Cl can reduce the binding energy required for the reaction, promote the evaporation reaction of CoCl2 and Sb, increase the number of generated samples and improve the quality of the samples.

[0051] Comparative Example 4 Compared with Example 1, the difference in Comparative Example 4 is that the catalyst in Example 1 is NH4Cl, while the catalyst in Comparative Example 4 is NaCl, and the others are the same as in Example 1.

[0052] Experiments found that when using the catalyst NaCl, small-scale sputtering occurred to the samples during the experiment, and the mica was all covered with black substances, without any sample generated, as Figure 11 shown. This indicates that NaCl cannot catalyze the reaction between CoCl2 and Sb, but instead will block the reaction.

[0053] Comparative Example 5 Compared with Example 1, the difference in Comparative Example 5 is that the catalyst in Example 1 is NH4Cl, while the catalyst in Comparative Example 5 is BiOCl, and the others are the same as in Example 1.

[0054] Experiments found that when using the catalyst BiOCl, the mica was all covered with black substances, and no sample similar to that in Example 1 was generated, as Figure 12 shown. This indicates that BiOCl also cannot catalyze the reaction between CoCl2 and Sb, but instead will block the occurrence of the reaction.

[0055] Those of ordinary skill in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; under the concept of this application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of one or more embodiments of this application as described above, and they are not provided in detail for the sake of brevity.

[0056] One or more embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this application shall be included within the scope of protection of this application.

Claims

1. A preparation method of two-dimensional cobalt antimonide, characterized in that, Place the precursor in the heating zone of a tubular furnace, place the substrate above the precursor, introduce gas, heat up to 560 - 580 °C, keep the temperature, and then cool down to obtain two-dimensional cobalt antimonide; The precursor is cobalt dichloride powder and antimony powder arranged adjacent to each other, and both the cobalt dichloride powder and the antimony powder contain ammonium salts.

2. The preparation method according to claim 1, characterized in that, The weight ratio of cobalt dichloride to antimony is 0.9 - 1.1:0.9 - 1.

1.

3. The preparation method according to claim 2, characterized in that, The weight ratio of cobalt dichloride to antimony is 1:

1.

4. The preparation method according to claim 1, characterized in that, The ammonium salt is ammonium chloride.

5. The preparation method according to claim 1, characterized in that, The cobalt dichloride powder contains an ammonium salt, and the weight ratio of cobalt dichloride to the ammonium salt is 0.9 - 1.1:0.9 - 1.1; the antimony powder contains an ammonium salt, and the weight ratio of antimony to the ammonium salt is 0.9 - 1.1:0.9 - 1.

1.

6. The preparation method according to claim 1, characterized in that, Keep the temperature after heating up to 570 °C.

7. The preparation method according to claim 1, characterized in that, The precursor is placed in a glass boat; the material of the substrate is fluorophlogopite mica, and the distance between the substrate and the precursor is 2 - 5 mm.

8. The preparation method according to claim 1, characterized in that, The distance between the cobalt dichloride powder and the antimony powder is 2 - 4 mm.

9. The preparation method according to claim 1, characterized in that, The gas flow direction of introducing gas is from the cobalt dichloride powder to the antimony powder direction. Before heating up, the gas flow rate of introducing gas is above 600 sccm, and after heating starts, the gas flow rate of introducing gas is 80 - 120 sccm; The heating rate is 20 - 25 °C·min -1 .

10. The preparation method according to claim 1, characterized in that, The time for keeping the temperature is 10 - 30 min, then stop heating and cool down naturally to room temperature.

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