A two-dimensional tin diselenide crystal, its preparation method and application

Abstract

This invention relates to the field of two-dimensional layered material fabrication technology, specifically to a two-dimensional tin diselenide crystal, its preparation method, and its applications. The invention provides a method for preparing a two-dimensional tin diselenide crystal. Inside a single-temperature zone tube furnace, a selenium source, a tin source, and a blank substrate are placed sequentially according to the gas flow direction. The axial direction of the gas inlet flange is adjusted to form an inclination angle of 1-7° relative to the horizontal direction of the inner tube of the single-temperature zone tube furnace. Under specific reaction conditions, a two-dimensional tin diselenide crystal is deposited on the blank substrate. This method can prepare two-dimensional tin diselenide crystals with a lateral dimension greater than or equal to 400 μm, a thickness less than or equal to 10 nm, and no obvious stacking. The obtained crystals are expected to meet the fabrication requirements of high-performance, large-area devices. This fabrication process has good versatility and high reproducibility, providing a new reference approach for the controllable growth of other layered two-dimensional materials.

Description

Technical Field

[0001] This application relates to the field of two-dimensional layered material preparation technology, and in particular to a two-dimensional tin diselenide crystal, its preparation method and application. Background Technology

[0002] Tin diselenide (SnSe2) is a layered IV-VI group semiconductor material that has attracted widespread attention from researchers in recent years due to its potential applications in optoelectronic and gas-sensitive devices. This material exhibits good chemical stability in air and its constituent elements are relatively abundant in nature, providing a solid foundation for its application in terms of raw material sourcing and cost control. In the research and fabrication of SnSe2-related devices, the lateral dimensions and thickness of the single-crystal wafers used for device construction are crucial structural parameters affecting device design and performance. Specifically: achieving larger-area two-dimensional single crystals facilitates compatibility with existing micro / nano fabrication processes, enabling parallel fabrication and statistical evaluation of multiple devices on the same wafer, thereby improving the repeatability and consistency of device fabrication and laying the foundation for arrayed devices and subsequent large-scale integrated applications; reduced thickness makes confinement and surface effects more pronounced and enhances the gate electric field's control over the channel, thus providing more favorable structural conditions for improving device performance control and parameter consistency. Furthermore, single, non-stacked single-crystal wafers can reduce the potential barrier introduced by overlapping interfaces and the transport losses caused by scattering, ensuring the uniformity and stability of device performance. In contrast, tin diselenide materials with smaller lateral dimensions, larger thickness, or multiple stacked layers are more prone to problems such as morphological inhomogeneity, local wrinkles, and interface contamination. This makes it difficult to obtain independent, complete, and stably processable single-crystal wafers, thereby increasing the uncertainty of subsequent device fabrication and performance evaluation, and making it difficult to meet the needs of high-performance devices and large-area array integration applications. Therefore, developing a method for controllable fabrication of large-size, thin, non-stacked two-dimensional SnSe2 single-crystal wafers has important practical application value (Zheng Tao, Lin Gaoxiang, Zhou Yinghui. Growth and structural study of large-size two-dimensional tin diselenide crystals [J]. Materials Science, 2020, 10(5): 348-354.).

[0003] Currently, existing technologies have been used to prepare two-dimensional SnSe2 flakes based on vapor deposition. For example, Chinese patent application CN104962990A discloses a method for preparing two-dimensional nano-SnSe2 crystals. The prepared SnSe2 flakes have a lateral dimension of approximately 40 μm and a thickness of 3-10 atomic layers, corresponding to approximately 1.5-3 nm. Although this method can obtain relatively thin samples, the lateral dimension of the flakes is still relatively small, which is difficult to meet the application requirements of high-performance devices. The technical solution disclosed by Fu et al. (Fu J, Zhao L, Zhou L, et al. Controllable Synthesis of Atomically Thin 1T‐SnSe2 Flakes and Its Linear Second Harmonic Generation with Layer Thickness[J]. Advanced Materials Interfaces, 2022, 9(11): 2102376.) can prepare SnSe2 flakes with a thickness of 0.9 nm, but its lateral dimension is less than or equal to 20 μm, which also has the technical limitation of a small lateral dimension. It is evident that existing vapor deposition methods for preparing two-dimensional tin diselenide crystals generally suffer from the problem of not being able to simultaneously achieve both large lateral dimensions and thin-film characteristics, making it impossible to obtain high-quality single-crystal thin films with both large lateral dimensions and low thickness.

[0004] Therefore, there is an urgent need in this field to develop a preparation technology that can simultaneously achieve large-size, low-thickness, single-crystal, non-stacked two-dimensional tin diselenide crystals, so as to promote the practical application and industrialization of high-quality tin diselenide single crystal materials in optoelectronic devices, gas-sensitive devices, and energy storage devices. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the existing technology that cannot simultaneously achieve the controllable preparation of large-size, low-thickness, single non-stacked tin diselenide single crystal thin films, and to provide a method for preparing two-dimensional tin diselenide crystals.

[0006] Another object of the present invention is to provide tin diselenide crystals prepared by the above preparation method.

[0007] Another object of the present invention is to provide the application of the above-mentioned tin diselenide crystal in the preparation of optoelectronic devices, gas-sensitive devices or energy storage devices.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution:

[0009] This invention protects a method for preparing a two-dimensional tin diselenide crystal, comprising the following steps:

[0010] Inside a single-zone tube furnace, a selenium source, a tin source, and a blank substrate are placed sequentially according to the airflow direction. The inlet flange of the single-zone tube furnace is adjusted so that the axial direction of the inlet flange forms an inclination angle of 1~7° relative to the horizontal direction of the inner tube of the single-zone tube furnace. The reaction is carried out for 3~7 h under the conditions of a carrier gas flow rate of 10~18 sccm and a temperature of 615~625 ℃. After cooling, two-dimensional tin diselenide crystals are deposited on the blank substrate.

[0011] The tin source is located in the heating center of the single-temperature zone tube furnace; the inner diameter of the inner tube of the single-temperature zone tube furnace is 20~30 mm; the molar ratio of tin in the tin source to selenium in the selenium source is 1:(30~60).

[0012] This invention alters the gas flow state during the reaction process by adjusting the tilt angle of the inlet flange relative to the horizontal direction of the inner tube of a single-zone tube furnace. This effectively reduces the nucleation density on the substrate surface, thereby promoting the lateral growth of two-dimensional tin diselenide crystals and achieving crystal size scaling. Simultaneously, by controlling the inner diameter of the inner tube, the reaction temperature, and the carrier gas conditions of the single-zone tube furnace, the lateral size of the crystal is increased while reducing crystal stacking and abnormal thickening. This results in controllable thickness tin diselenide single-crystal wafers with low impurity particle adhesion on the wafer surface. The preparation process of this invention is simple, the reaction conditions are easy to control, and the method has good reproducibility. It can stably produce large-size, low-thickness two-dimensional tin diselenide crystals without significant stacking. The resulting crystals are expected to meet the fabrication requirements of high-performance, large-area devices. This fabrication process has good universality and high reproducibility, providing a new reference approach for the controllable growth of other layered two-dimensional materials.

[0013] In this invention, single-temperature zone tubular furnaces from different manufacturers are all applicable to this application because they have the same structural design principle, all have a single heating center zone, and have no essential differences in function.

[0014] Furthermore, the parameters of the single-temperature zone tubular furnace include at least one of the following items (1) to (3):

[0015] (1) The inner diameter of the furnace tube of the single-temperature zone tubular furnace is 50~60 mm;

[0016] (2) The length of the furnace tube of the single-temperature zone tubular furnace is 100~105 cm;

[0017] (3) The wall thickness of the furnace tube of the single-temperature zone tube furnace is 3~5 mm.

[0018] In this invention, the inner tube of the single-temperature zone tubular furnace is an independent component installed inside the furnace tube.

[0019] Furthermore, the inner tube of the single-temperature zone tube furnace includes a quartz tube, a corundum tube, or a stainless steel tube.

[0020] Furthermore, the inner tube of the single-temperature zone tube furnace is a quartz tube.

[0021] Furthermore, the inner diameter of the inner tube of the single-temperature zone tubular furnace is 22~28 mm.

[0022] Furthermore, the inner diameter of the inner tube of the single-temperature zone tubular furnace is 24~26 mm.

[0023] Furthermore, the length of the inner tube of the single-temperature zone tubular furnace is 96~98 cm.

[0024] Furthermore, the wall thickness of the inner tube of the single-temperature zone tubular furnace is 1~3mm.

[0025] Furthermore, the inner tube of the single-temperature zone tubular furnace is fixed by setting shims on both sides of the inner wall of the single-temperature zone tubular furnace, using the shims to raise the inner tube of the single-temperature zone tubular furnace, so that the axial direction of the inner tube of the single-temperature zone tubular furnace coincides with the axial direction of the furnace tube of the single-temperature zone tubular furnace, thereby fixing it at the center position of the single-temperature zone tubular furnace.

[0026] Furthermore, the raised component includes any one of quartz products, corundum products, and zirconium oxide products.

[0027] Preferably, the shim is a quartz product.

[0028] Furthermore, the selenium source includes one or more of elemental selenium, inorganic selenium compounds, and organic selenium compounds.

[0029] Furthermore, the inorganic selenium compound is selenium tinide.

[0030] Furthermore, the organoselenium compound includes one or more of tetramethyltin, tetraethyltin, and dibutyltin oxide.

[0031] Preferably, the selenium source is elemental selenium.

[0032] Furthermore, the selenium source is placed inside the carrier.

[0033] Furthermore, the carrier includes a corundum boat, a quartz boat, a nickel boat, or a tungsten boat.

[0034] Furthermore, the tin source includes elemental tin and / or inorganic tin compounds.

[0035] Furthermore, the inorganic tin compound includes one or more of tin halides, tin selenides, and tin oxides.

[0036] Preferably, the tin halide includes one or more of tin diiodide, tin dichloride, and tin tetrachloride.

[0037] Preferably, the tin selenide is tin selenide.

[0038] Preferably, the tin oxide comprises tin monoxide and / or tin dioxide.

[0039] More preferably, the tin source is tin selenide.

[0040] Furthermore, the tin source is placed inside the carrier.

[0041] Furthermore, the carrier includes a corundum boat, a quartz boat, a nickel boat, or a tungsten boat.

[0042] Furthermore, the distance between the selenium source and the tin source is 19-24 cm. This distance is the horizontal distance between the center point of the bottom surface of the selenium source carrier and the center point of the bottom surface of the tin source carrier.

[0043] Furthermore, the molar ratio of tin in the tin source to selenium in the selenium source is 1:(40~50).

[0044] Furthermore, the molar ratio of tin in the tin source to selenium in the selenium source is 1:(41~45).

[0045] In this invention, the blank substrate refers to the original substrate material that has not undergone any pretreatment.

[0046] Furthermore, the blank substrate includes a mica substrate, a sapphire substrate, or a conductive glass substrate.

[0047] Furthermore, the blank substrate is placed on top of the carrier.

[0048] Furthermore, the carrier includes an inverted corundum boat, an inverted quartz boat, an inverted nickel boat, or an inverted tungsten boat.

[0049] Furthermore, the distance between the blank substrate and the tin source is 22-30 cm. Specifically, the distance between the blank substrate and the tin source is the horizontal distance between the center point of the top surface of the blank substrate carrier and the center point of the bottom surface of the tin source carrier.

[0050] Furthermore, the tilt angle is 2~6°.

[0051] Furthermore, the tilt angle is 2°, 4°, or 6°.

[0052] Preferably, the tilt angle is 4° or 6°.

[0053] More preferably, the tilt angle is 4°.

[0054] Furthermore, the carrier gas is hydrogen and / or argon.

[0055] Furthermore, the volume ratio of hydrogen to argon is 1:(8~10).

[0056] Preferably, the volume ratio of hydrogen to argon is 1:9.

[0057] Furthermore, the carrier gas flow rate is 10.5~15 sccm.

[0058] Furthermore, the carrier gas flow rate is 11~13 sccm.

[0059] Furthermore, the temperature is 618~622 ℃.

[0060] Preferably, the temperature rise rate is 5~20 °C / min.

[0061] More preferably, the temperature rise rate is 8~12 °C / min.

[0062] Furthermore, the reaction time is 4 to 6.5 hours.

[0063] Furthermore, the reaction time is 5-6 hours.

[0064] Furthermore, the cooling is natural cooling to room temperature.

[0065] This invention protects the two-dimensional tin diselenide crystals prepared by the aforementioned preparation method.

[0066] Furthermore, the lateral dimension of the two-dimensional tin diselenide crystal is greater than or equal to (≥) 400 μm, and the thickness is less than or equal to (≤) 10 nm.

[0067] Furthermore, the two-dimensional tin diselenide crystal has a lateral dimension ≥ 500 μm and a thickness ≤ 8 nm.

[0068] Furthermore, the two-dimensional tin diselenide crystal has a lateral dimension ≥800 μm and a thickness ≤3 nm.

[0069] This invention protects the application of the aforementioned two-dimensional tin diselenide crystal in the fabrication of optoelectronic devices, gas-sensitive devices, or energy storage devices.

[0070] Compared with the prior art, the present invention has the following beneficial effects:

[0071] This invention alters the gas flow state during the reaction process by adjusting the tilt angle of the inlet flange relative to the horizontal direction of the inner tube of a single-zone tube furnace. This effectively reduces the nucleation density on the substrate surface, thereby promoting the lateral growth of two-dimensional tin diselenide crystals and achieving crystal size scaling. Simultaneously, by controlling the inner diameter of the inner tube, the reaction temperature, and the carrier gas conditions of the single-zone tube furnace, the lateral size of the crystal is increased while reducing crystal stacking and abnormal thickening. This results in controllable thickness tin diselenide single-crystal wafers with low impurity particle adhesion on the wafer surface. The preparation process of this invention is simple, the reaction conditions are easy to control, and the method has good reproducibility. It can stably produce two-dimensional tin diselenide crystals with a lateral size ≥400 μm, a thickness ≤10 nm, and no obvious stacking. The obtained crystals are expected to meet the fabrication requirements of high-performance, large-area devices. Furthermore, the good versatility of this preparation process provides a new reference path for the controllable growth of other layered two-dimensional materials. Attached Figure Description

[0072] Figure 1 This is a schematic diagram of the chemical vapor deposition reactor in Example 1.

[0073] Figure 2 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Example 1.

[0074] Figure 3 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Example 2.

[0075] Figure 4 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Example 3.

[0076] Figure 5 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 1.

[0077] Figure 6 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 2.

[0078] Figure 7 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 3.

[0079] Figure 8 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 4.

[0080] Figure 9 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 5.

[0081] Figure 10 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 6.

[0082] Figure 11 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 7.

[0083] Figure 12 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 8.

[0084] Figure 13 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 9.

[0085] Figure 14 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 10.

[0086] Figure 15 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 11.

[0087] Figure 16 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 12.

[0088] Figure 17 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 13.

[0089] Figure 18 This is an optical microscope image of a two-dimensional tin diselenide crystal on a mica substrate in Comparative Example 14.

[0090] Figure 19 The image shows the Raman spectra of the two-dimensional tin diselenide crystal on the mica substrate and the mica substrate in Example 1.

[0091] Figure 20 The images show atomic force microscopy images of two-dimensional tin diselenide crystals on a mica substrate in different regions of Example 1. Detailed Implementation

[0092] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0093] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0094] Example 1: Preparation of a two-dimensional tin diselenide crystal

[0095] The preparation of two-dimensional tin diselenide crystals specifically includes the following steps:

[0096] S1. The deposition equipment uses a single-zone horizontal tube furnace (model GSL-1200X, manufactured by Hefei Kejing Materials Technology Co., Ltd.). The furnace tube parameters are as follows: furnace tube length 100 cm, furnace tube inner diameter 54 mm, furnace tube wall thickness 3 mm. A quartz tube is added as the inner tube of the single-zone tube furnace, with the following parameters: quartz tube length 98 cm, quartz tube inner diameter 25 mm, quartz tube wall thickness 2 mm. Quartz product shims are placed on both sides of the inner wall of the single-zone tube furnace to raise the quartz tube horizontally by 5 mm, ensuring that the axial direction of the quartz tube coincides with the axial direction of the furnace tube. It is then fixed at the center of the furnace tube. The inlet flange of the single-zone tube furnace is then adjusted so that the axial direction of the inlet flange forms a 4° angle with respect to the horizontal direction of the quartz tube. An angle of inclination of °, and the quartz tube is arranged on one side of the air intake end;

[0097] S2. Weigh 0.5 g of selenium powder (6.3 mmol) and place it in an alumina boat, positioning it upstream of the quartz tube. Weigh 0.03 g of tin selenide powder (0.15 mmol) and place it in another alumina boat, ensuring the center of the bottom surface of this alumina boat coincides with the heating center of the single-zone tube furnace (i.e., the midpoint of the furnace tube). The horizontal distance between the center of the bottom surface of this alumina boat and the center of the bottom surface of the alumina boat containing the selenium powder is 21 cm. Place a mica substrate on the inverted alumina boat as a blank substrate for product collection, positioning it downstream of the quartz tube. The horizontal distance between the center of the top surface of this inverted alumina boat and the center of the bottom surface of the alumina boat containing the tin selenide powder is 26 cm. After sealing the reaction system, use a mechanical pump to evacuate the inside of the single-zone tube furnace. Then, introduce a hydrogen-argon mixture with a volume ratio of 1:9 as the carrier gas at a flow rate of 12. After the furnace tube is filled to atmospheric pressure, the outlet valve is opened, and the single-temperature zone tube furnace is heated to 620 ℃ at a heating rate of 10 ℃ / min. The reaction is kept at a constant temperature for 6 h, and then naturally cooled to room temperature. The product is collected on the mica substrate to obtain two-dimensional tin diselenide crystals.

[0098] The above-mentioned two-dimensional tin diselenide crystals were prepared using a chemical vapor deposition reactor, the schematic diagram of which is shown below. Figure 1 As shown.

[0099] Example 2: Preparation of a two-dimensional tin diselenide crystal

[0100] The difference from Example 1 is that in step S1, the tilt angle is replaced by 2° instead of 4°.

[0101] The other steps and conditions are the same as in Example 1.

[0102] Example 3: Preparation of a two-dimensional tin diselenide crystal

[0103] The difference from Example 1 is that in step S1, the tilt angle is replaced by 6° instead of 4°.

[0104] The other steps and conditions are the same as in Example 1.

[0105] Comparative Example 1: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0106] The difference from Example 1 is that in step S1, the tilt angle is replaced by 0° instead of 4°.

[0107] The other steps and conditions are the same as in Example 1.

[0108] Comparative Example 2: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0109] The difference from Example 1 is that in step S1, the tilt angle is replaced by 8° instead of 4°.

[0110] The other steps and conditions are the same as in Example 1.

[0111] Comparative Example 3: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0112] The difference from Comparative Example 1 is that, in step S2, the outlet side of the inverted corundum boat below the mica substrate is raised, so that the bottom of the mica substrate forms a 4° tilt angle relative to the horizontal direction of the quartz tube. The specific steps are as follows:

[0113] S1. The deposition equipment uses a single-zone horizontal tube furnace (model GSL-1200X, manufactured by Hefei Kejing Materials Technology Co., Ltd.). The furnace tube parameters are as follows: furnace tube length 100 cm, furnace tube inner diameter 54 mm, furnace tube wall thickness 3 mm. A quartz tube is added as the inner tube of the single-zone tube furnace, with the following parameters: quartz tube length 98 cm, quartz tube inner diameter 25 mm, quartz tube wall thickness 2 mm. Quartz product shims are placed on both sides of the inner wall of the single-zone tube furnace to raise the quartz tube horizontally by 5 mm, ensuring that the axial direction of the quartz tube coincides with the axial direction of the furnace tube. It is then fixed at the center of the furnace tube. The inlet flange of the single-zone tube furnace is then adjusted so that the axial direction of the inlet flange forms a 0° angle with the horizontal direction of the quartz tube. An angle of inclination of °, and the quartz tube is arranged on one side of the air intake end;

[0114] S2. Weigh 0.5 g of selenium powder (6.3 mmol) and place it in an alumina boat, positioning the alumina boat upstream of the quartz tube. Weigh 0.03 g of tin selenide powder (0.15 mmol) and place it in another alumina boat, aligning the center of the bottom surface of this alumina boat with the heating center of the single-zone tube furnace (i.e., the midpoint of the furnace tube). The horizontal distance between the center of the bottom surface of this alumina boat and the center of the bottom surface of the alumina boat containing the selenium powder is 21 cm. Place a mica substrate on the inverted alumina boat as a blank substrate for product collection. Elevate the outlet side of the alumina boat so that the bottom of the mica substrate forms a 4° tilt angle with the horizontal direction of the quartz tube. Place this substrate downstream of the quartz tube, with the horizontal distance between the center of the bottom of the inverted alumina boat containing the blank substrate and the center of the bottom of the alumina boat containing the tin selenide powder being 26 cm. cm; After sealing the reaction system, a mechanical pump was used to evacuate the inside of the single-temperature zone tube furnace. Then, a hydrogen-argon mixture with a volume ratio of 1:9 was introduced as a carrier gas at a flow rate of 12 sccm. After the furnace tube was filled to atmospheric pressure, the outlet valve was opened, and the single-temperature zone tube furnace was heated to 620 ℃ at a heating rate of 10 ℃ / min. The reaction was carried out at a constant temperature for 6 h, and then naturally cooled to room temperature. The product was collected on a mica substrate to obtain two-dimensional tin diselenide crystals.

[0115] Comparative Example 4: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0116] The difference from Comparative Example 3 is that, in step S2, the tilt angle formed by the bottom of the mica substrate relative to the horizontal direction of the quartz tube is replaced by 6° instead of 4°.

[0117] The other steps and conditions are the same as in Comparative Example 3.

[0118] Comparative Example 5: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0119] The difference from Example 1 is that in step S1, the inner diameter of the quartz tube is replaced with 15 mm instead of 25 mm.

[0120] The other steps and conditions are the same as in Example 1.

[0121] Comparative Example 6: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0122] The difference from Example 1 is that in step S1, the inner diameter of the quartz tube is replaced with 35 mm instead of 25 mm.

[0123] The other steps and conditions are the same as in Example 1.

[0124] Comparative Example 7: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0125] The difference from Example 1 is that in step S2, the amount of selenium powder is replaced from 0.5 g to 0.3 g, that is, the molar ratio of tin element in tin selenide to selenium element in selenium powder is replaced from 1:42 to 1:25.

[0126] The other steps and conditions are the same as in Example 1.

[0127] Comparative Example 8: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0128] The difference from Example 1 is that in step S2, the amount of selenium powder is replaced from 0.5 g to 0.8 g, that is, the molar ratio of tin element in tin selenide to selenium element in selenium powder is replaced from 1:42 to 1:67.

[0129] The other steps and conditions are the same as in Example 1.

[0130] Comparative Example 9: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0131] The difference from Example 1 is that in step S2, the reaction time is changed from 6 h to 1 h.

[0132] The other steps and conditions are the same as in Example 1.

[0133] Comparative Example 10: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0134] The difference from Example 1 is that in step S2, the reaction time is changed from 6 h to 8 h.

[0135] The other steps and conditions are the same as in Example 1.

[0136] Comparative Example 11: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0137] The difference from Example 1 is that in step S2, the carrier gas flow rate is replaced by 8 sccm instead of 12 sccm.

[0138] The other steps and conditions are the same as in Example 1.

[0139] Comparative Example 12: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0140] The difference from Example 1 is that in step S2, the carrier gas flow rate is replaced by 20 sccm instead of 12 sccm.

[0141] The other steps and conditions are the same as in Example 1.

[0142] Comparative Example 13: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0143] The difference from Example 1 is that in step S2, the reaction temperature is replaced by 610 °C instead of 620 °C.

[0144] The other steps and conditions are the same as in Example 1.

[0145] Comparative Example 14: Preparation of a Two-Dimensional Tin Diselenide Crystal

[0146] The difference from Example 1 is that in step S2, the reaction temperature is changed from 620 °C to 630 °C.

[0147] The other steps and conditions are the same as in Example 1.

[0148] Experimental Example 1: Structural Characterization of Two-Dimensional Tin Diselenide Crystals

[0149] 1. Optical Microscope Testing

[0150] The morphology of two-dimensional tin diselenide crystals on mica substrates obtained in Examples 1-3 and Comparative Examples 1-14 was characterized using an optical microscope (model M70, manufactured by Guangzhou Daoyi Science & Technology Co., Ltd., China). The apparent color of the tin diselenide crystal is closely related to its thickness; a lighter color corresponds to a thinner tin diselenide crystal, while a darker color corresponds to a thicker tin diselenide crystal. The test results are shown below. Figures 2-18 As shown. Figure 2 As shown, the two-dimensional tin diselenide crystal prepared in Example 1 is attached to the surface of a mica substrate. The crystal's lateral dimension reaches 1.1 mm, and its thickness is 1.6 nm. The crystal quality is excellent (the bubbles and scratches near the crystal in the figure are the morphology of the mica substrate itself, not other crystal structures); Figure 3 As shown, the two-dimensional tin diselenide crystal in Example 2 also possesses the characteristics of large size, low thickness, and no stacking, with a lateral dimension of approximately 480 μm and a thickness of approximately 6 nm; Figure 4 As shown, the lateral dimension of the two-dimensional tin diselenide crystal in Example 3 can reach 550 μm, and the thickness is about 7.5 nm, both of which meet the requirements. Although the lateral dimension and thickness of the crystals in Examples 2 and 3 are slightly inferior to those in Example 1, the lateral dimension is significantly greater than 300 μm and the thickness is less than 10 nm, which fully meets the core requirements of large size, low thickness, and single non-stacked two-dimensional materials.

[0151] In contrast, the two-dimensional tin diselenide crystals prepared in Comparative Examples 1 to 14 failed to simultaneously meet the comprehensive requirements of large size, low thickness, and single, non-stacked crystals, showing a significant quality difference compared to the two-dimensional tin diselenide crystals of Examples 1 to 3. The specific analysis is as follows: Figure 5As shown, the lateral dimensions of the two-dimensional tin diselenide crystals prepared in Comparative Example 1 are all less than 70 μm, and the color is significantly darker, indicating that the thickness of the tin diselenide crystals has increased significantly to about 100 nm. At the same time, there is also a relatively obvious stacking phenomenon, which does not meet the requirements of large size, low thickness, and single, non-stacked two-dimensional tin diselenide crystals. Figure 6 As shown, the size and thickness of the two-dimensional tin diselenide crystals prepared in Comparative Example 2 are relatively controllable, but they exhibit significant stacking on the mica substrate, making it impossible to obtain independent, single crystal sheet structures; as Figure 7 As shown, the lateral dimensions of the two-dimensional tin diselenide crystals prepared in Comparative Example 3 are all less than 150 μm, which is relatively small, and the thickness is all greater than 30 nm. Furthermore, there is significant stacking, which fails to meet the comprehensive requirements of large size, low thickness, and a single, non-stacked two-dimensional tin diselenide crystal. Figure 8 As shown, the lateral dimensions of the two-dimensional tin diselenide crystals in Comparative Example 4 are all less than 150 μm, which is relatively small, and the thickness is all greater than 50 nm. Furthermore, severe stacking occurs, making it difficult to obtain large-size, low-thickness, and single-crystal tin diselenide flakes without stacking. Figure 9 As shown, the lateral dimensions of the tin diselenide crystals in Comparative Example 5 are all less than 250 μm, and their thicknesses are all greater than 15 nm, indicating poor controllability of large-size, low-thickness crystals; Figure 10 As shown, the lateral dimension of the two-dimensional tin diselenide crystal in Comparative Example 6 is only about 50 μm, which is relatively small and the thickness is significantly increased, far from reaching the level of the large-size, low-thickness two-dimensional tin diselenide crystals in Examples 1 to 3; Figure 11 As shown, the lateral dimension of the two-dimensional tin diselenide crystal in Comparative Example 7 is approximately 180 μm, significantly smaller than the large size range of 480 μm to 1.1 mm in Examples 1 to 3, indicating no significant size advantage; Figure 12 As shown, although the lateral dimension of the two-dimensional tin diselenide crystal in Comparative Example 8 can reach about 800 μm, the thickness is significantly increased to about 15 nm, and there is severe stacking, making it difficult to obtain a single crystal sheet and thus difficult to achieve the controllable preparation of low-thickness, single, non-stacked two-dimensional tin diselenide crystals; Figure 13 As shown, the thickness of the two-dimensional tin diselenide crystal in Comparative Example 9 is controllable, but its lateral dimension is approximately 290 μm, which is still far lower than the lateral dimension range of 480 μm to 1.1 mm in Examples 1 to 3, failing to highlight its large size advantage; Figure 14 As shown, the size of the two-dimensional tin diselenide crystal in Comparative Example 10 is controllable, but the thickness is greater than 40 nm, and the crystal layers are severely stacked, making it difficult to obtain a single, unstacked single-crystal sheet, which is not conducive to subsequent device applications; such as Figure 15As shown, the lateral dimension of the two-dimensional tin diselenide crystal in Comparative Example 11 is approximately 200 μm, but its thickness is greater than 20 nm, significantly exceeding the thickness range of Examples 1-3. Furthermore, it exhibits obvious stacking, making it difficult to meet the requirements for a low-thickness, single, non-stacked two-dimensional tin diselenide crystal. Figure 16 As shown, in Comparative Example 12, the sample has an excessively high distribution density on the substrate, resulting in a significantly reduced size of the obtained two-dimensional tin diselenide crystal. The interlayer stacking phenomenon is prominent, and it lacks the characteristics of large size and single, non-stacked crystals. Figure 17 As shown, Comparative Example 13 only produced crystals with a thickness greater than 50 nm, which completely fails to meet the requirements for large-size, low-thickness, single-crystal, non-stacked two-dimensional tin diselenide crystals; as Figure 18 As shown, although the lateral dimension of the two-dimensional tin diselenide crystal in Comparative Example 14 can reach about 800 μm, the thickness of the crystal is greater than 20 nm and there is some stacking, which cannot meet the requirements for the controllable preparation of large-size, low-thickness, single non-stacked two-dimensional tin diselenide crystals.

[0152] 2. Raman spectroscopy test

[0153] The phase structure of the two-dimensional tin diselenide crystal on the mica substrate obtained in Example 1 was characterized using a Raman spectrometer (LabRAM HR Evolution, manufactured by HORIBA Jobin Yvon, France). The results are as follows: Figure 19 As shown. This two-dimensional tin diselenide crystal is approximately 105 cm⁻¹. -1 and 185 cm -1 Characteristic Raman peaks appear at these locations, corresponding to the E values ​​of two-dimensional tin diselenide crystals. g Vibrational (coupled vibrations between the stretching vibrations of one atom and the bending vibrations of another atom in a molecule) modes and A 1g The vibrational (stretching vibration between two atoms in a molecule) mode, with characteristic peak positions perfectly matching the standard spectrum; at approximately 198 cm⁻¹ -1 The characteristic peaks appearing at the location are attributed to the mica substrate. The above results indicate that the two-dimensional tin diselenide crystal obtained in Example 1 is a pure-phase tin diselenide crystal.

[0154] 3. Atomic force microscopy test

[0155] The surface morphology of the two-dimensional tin diselenide crystal on the mica substrate obtained in Example 1 was characterized using an atomic force microscope (Dimension FastScan, manufactured by Bruker, USA). The results are as follows: Figure 20 As shown in the figure. The test results show that the thickness of the two-dimensional tin diselenide crystal is about 1.6 nm; the crystal surface has high flatness and no obvious impurity particles or defects attached, further confirming that the method of this application can prepare high-quality, large-size, low-thickness, single-crystal, non-stacked two-dimensional tin diselenide crystals.

[0156] The Raman spectra and atomic force microscopy images of the two-dimensional tin diselenide crystals in Examples 2 and 3 are basically the same as those in Example 1, and will not be described again here.

[0157] In summary, the characterization results from combined optical microscopy, Raman spectroscopy, and atomic force microscopy indicate that this application successfully prepared pure-phase two-dimensional tin diselenide crystals with large lateral dimensions, low thickness, and no obvious stacking under specific single-temperature tube furnace deposition conditions. Both the crystal structure and phase structure of this crystal meet the standards for high-quality two-dimensional tin diselenide materials. Compared with comparative examples, the preparation method of this application has significant advantages in crystal size control and thickness regulation, making it more suitable for the large-scale preparation and subsequent application research of high-quality two-dimensional tin diselenide materials.

[0158] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a two-dimensional tin diselenide crystal, characterized in that, Includes the following steps: Inside a single-zone tube furnace, a selenium source, a tin source, and a blank substrate are placed sequentially according to the airflow direction. The inlet flange of the single-zone tube furnace is adjusted so that the axial direction of the inlet flange forms an inclination angle of 1~7° relative to the horizontal direction of the inner tube of the single-zone tube furnace. The reaction is carried out for 3~7 h under the conditions of a carrier gas flow rate of 10~18 sccm and a temperature of 615~625 ℃. After cooling, two-dimensional tin diselenide crystals are deposited on the blank substrate. The tin source is located in the heating center of the single-temperature zone tube furnace; the inner diameter of the inner tube of the single-temperature zone tube furnace is 20~30 mm; the molar ratio of tin in the tin source to selenium in the selenium source is 1:(30~60).

2. The preparation method according to claim 1, characterized in that, The tilt angle is 2~6°.

3. The preparation method according to claim 1, characterized in that, The inner diameter of the inner tube of the single-temperature zone tubular furnace is 22~28 mm.

4. The preparation method according to claim 1, characterized in that, The temperature is 618~622 ℃.

5. The preparation method according to claim 1, characterized in that, The reaction time is 4 to 6.5 hours.

6. The preparation method according to claim 1, characterized in that, The distance between the selenium source and the tin source is 19-24 cm.

7. The preparation method according to claim 1, characterized in that, The distance between the blank substrate and the tin source is 22~30cm.

8. The two-dimensional tin diselenide crystal prepared by the preparation method according to any one of claims 1 to 7.

9. The two-dimensional tin diselenide crystal according to claim 8, characterized in that, The two-dimensional tin diselenide crystal has a lateral dimension greater than or equal to 400 μm and a thickness less than or equal to 10 nm.

10. The application of the two-dimensional tin diselenide crystal according to claim 8 or 9 in the preparation of optoelectronic devices, gas-sensitive devices or energy storage devices.

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