Preparation method of metal chalcogenide crystal film

Abstract

The invention discloses a preparation method of a metal chalcogenide crystal film, and belongs to the field of semiconductors. According to the preparation method of the metal chalcogenide crystal thin film, the liquid metal is placed in the reaction tank, so that trace metal atoms generated by the surrounding liquid metal can be additionally introduced into the reaction tank where the metal chalcogenide amorphous thin film is located during annealing; the metal-rich liquid interface can be formed on the metal chalcogenide amorphous film, the metal chalcogenide amorphous film can be promoted to be recrystallized into a crystal structure with high crystallinity on the metal-rich liquid interface by reducing surface energy and enhancing atomic diffusion, and then under the driving of solid-liquid-solid growth, the metal chalcogenide amorphous film can be formed into a crystal structure with high crystallinity. And finally, the wafer-level, pure-phase and thickness-controllable metal chalcogenide crystal film is obtained.

Description

Technical Field

[0001] This application relates to the field of semiconductors, and more particularly, to a method for preparing a metal chalcogenide crystal thin film. Background Art

[0002] The rapid development of artificial intelligence technology has brought about an unprecedented demand for computing power. Especially in the fields of deep learning, data processing, and automation, the dependence on high-performance computing hardware is increasing day by day. However, with the continuous progress of technology, silicon-based transistor technology has gradually approached its physical limit at nodes below 10 nanometers. Traditional silicon materials have encountered bottlenecks in further improving chip performance, power efficiency, and integration density. This situation not only limits the development potential of future integrated circuits but also urgently requires exploring innovative materials that can break through the silicon limit. In this context, it is particularly crucial to search for and develop new semiconductor channel materials to support the continuous growth and evolution of transistor density in future integrated circuit nodes.

[0003] Indium selenide (InSe), as a two-dimensional semiconductor material, has become a strong candidate for breaking through the silicon technology limit due to its excellent electronic and optoelectronic properties. InSe not only has excellent bandgap tuning ability and carrier mobility but also has great potential for wide applications in the fields of electronics and optoelectronics under future advanced processes. However, despite its excellent theoretical performance, there are still many technical challenges in realizing large-scale and high-quality InSe thin film production, and this bottleneck has not been broken through yet.

[0004] Currently, the quality of most prepared InSe thin films cannot meet the theoretical requirements and lags far behind other mainstream two-dimensional semiconductor materials. To achieve the production of high-quality InSe thin films, a series of problems in material growth need to be solved first. Specifically, the main challenges faced include: (i) the complex phase segregation problem in the In-Se system. InSe and its related compounds (such as In2Se3, In4Se3, and In6Se7) have at least four stable phases under different growth conditions. Even a slight change in composition or temperature fluctuation may lead to a phase change, thus affecting the crystal structure and electronic properties of the material, and further causing instability or significant degradation of performance; (ii) due to the extremely large difference in vapor pressure between selenium (Se) and indium (In) at a growth temperature of about 500 °C, the vapor pressure of selenium is about 7 orders of magnitude higher than that of indium, which makes it difficult to maintain the chemical stoichiometric balance between In and Se, thereby affecting the crystallization quality of the InSe thin film. Due to these technical problems, the existing methods have not been able to achieve large-scale production of high-quality InSe thin films. Summary of the Invention

[0005] The present application provides a method for preparing a metal chalcogenide crystal thin film, which can achieve large-scale production of wafer-level metal chalcogenide crystal thin films with high crystal quality.

[0006] The embodiments of the present application are implemented as follows:

[0007] The present application provides a method for preparing a metal chalcogenide crystal thin film, wherein the preparation of the metal chalcogenide crystal thin film is carried out in a container, the container includes a bearing part and a cover plate, the bearing part includes a bearing surface, the bearing surface is provided with a reaction groove and a groove surrounding the circumference of the reaction groove, and the cover plate is used to contact the bearing surface to seal the reaction groove and the groove.

[0008] The preparation method includes:

[0009] Obtain a composite substrate, the composite substrate includes a single crystal substrate and a metal chalcogenide amorphous thin film formed on the surface of the single crystal substrate.

[0010] Place the composite substrate in the reaction groove, make the metal chalcogenide amorphous thin film face and be lower than the opening of the reaction groove, and place liquid metal in the groove. The liquid metal has the same metal composition as the metal component in the metal chalcogenide amorphous thin film, and the melting point of the liquid metal is lower than the growth temperature of the metal chalcogenide amorphous thin film.

[0011] Use the cover plate to seal the reaction groove and the groove, and the liquid metal contacts the cover plate to achieve liquid sealing, obtaining a plug.

[0012] Heat the plug to a preset temperature and keep it warm for annealing in an inert atmosphere to recrystallize the metal chalcogenide amorphous thin film to form a metal chalcogenide crystal thin film.

[0013] In the method for preparing a metal chalcogenide crystal thin film provided by the present application, since the metal chalcogenide amorphous thin film is placed in the reaction groove, and liquid metal with the same metal composition as the metal component in the metal chalcogenide amorphous thin film is placed in the groove, and the reaction groove and the groove are sealed with a cover plate, at this time, the liquid metal contacts the cover plate to form liquid sealing. At this time, the obtained plug is annealed, and trace metal atoms generated by the surrounding liquid metal can be additionally introduced into the reaction groove, which helps to form a metal-rich liquid interface on the metal chalcogenide amorphous thin film, is conducive to promoting the recrystallization of the metal chalcogenide amorphous thin film into a crystal structure with high crystallinity by reducing the surface energy and enhancing atomic diffusion, and then, under the driving of solid-liquid-solid growth, finally obtain a wafer-level, pure-phase, and controllable-thickness metal chalcogenide crystal thin film.

[0014] In some alternative embodiments, the bearing surface has a bearing area located between the groove and the reaction groove, and the bearing area is used to contact the cover plate;

[0015] The bearing area has a first edge close to the groove and a second edge close to the reaction tank, and the distance between the first edge and the second edge is 0.1 cm - 5 cm.

[0016] In some alternative embodiments, the bearing surface has a bearing area located between the groove and the reaction tank;

[0017] An excessive amount of liquid metal is placed in the groove so that when the cover plate seals the reaction tank and the groove, there is liquid metal between the bearing area and the cover plate that does not enter the reaction tank.

[0018] In some alternative embodiments, the material of the bearing part includes at least one of diamond, alumina, and steel; and / or,

[0019] The material of the cover plate includes glass.

[0020] In some alternative embodiments, the material of the metal chalcogenide crystal film includes at least one of indium selenide, diindium triselenide, indium sulfide, indium telluride, gallium selenide, gallium sulfide, gallium telluride, bismuth selenide, bismuth sulfide, and bismuth telluride.

[0021] In some alternative embodiments, the material of the metal chalcogenide crystal film is InSe;

[0022] Wherein, the preset temperature is 300 °C - 600 °C, optionally 500 °C - 600 °C, and / or;

[0023] The time for holding and annealing is 5 min - 200 min; optionally 120 min - 200 min.

[0024] In some alternative embodiments, the heating rate is 5 °C / min - 100 °C / min, optionally 5 °C / min - 20 °C / min.

[0025] In some alternative embodiments, a metal chalcogenide amorphous film is grown on the surface of a single crystal substrate by magnetron sputtering.

[0026] In some alternative embodiments, the single crystal substrate includes a single crystal sapphire substrate.

[0027] Optionally, the preparation method includes: heat-treating the sapphire substrate at 900 °C - 1300 °C before forming a metal chalcogenide amorphous film on the surface of the single crystal sapphire substrate.

[0028] In some alternative embodiments, the orthographic projection of the metal chalcogenide crystal film on the cover plate is circular, the radial dimension of the metal chalcogenide crystal film is 1 cm - 20 cm, and the longitudinal thickness is 0.8 nm - 30 nm.

[0029] Optionally, the metal chalcogenide crystal thin film is a single crystal metal chalcogenide thin film. Description of the Drawings

[0030] To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0031] Figure 1 Schematic flowchart of the preparation method of the InSe crystal thin film for Embodiment 1 of the present application;

[0032] Figure 2 Photo of the InSe crystal thin film prepared in Embodiment 1 of the present application and Raman characterizations at different positions corresponding thereto;

[0033] Figure 3 Monocrystallinity characterization of the InSe crystal thin film prepared in Embodiment 1 of the present application;

[0034] Figure 4 Structure characterization of the InSe crystal thin film prepared in Embodiment 1 of the present application;

[0035] Figure 5 Optical microscope photos of the InSe crystal thin films prepared in Embodiment 1 and Comparative Example 1. Detailed Embodiments

[0036] The implementation schemes of the present application will be described in detail below in combination with the embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those where specific conditions are not indicated in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments where the manufacturer is not indicated, they are all conventional products that can be obtained through commercial purchase.

[0037] The following specifically describes the preparation method of the metal chalcogenide crystal thin film for the embodiments of the present application:

[0038] In the preparation method of the metal chalcogenide crystal thin film provided by the present application, the preparation of the metal chalcogenide crystal thin film is carried out in a container. The container includes a bearing part and a cover plate. The bearing part includes a bearing surface. The bearing surface is provided with a reaction groove and a groove surrounding the circumference of the reaction groove. The cover plate is used to contact the bearing surface to close the reaction groove and the groove.

[0039] The preparation method of the metal chalcogenide crystal thin film includes:

[0040] S1. Obtain a composite substrate, where the composite substrate includes a single-crystal substrate and a chalcogenide amorphous thin film formed on the surface of the single-crystal substrate.

[0041] S2. Place the composite substrate in a reaction tank such that the chalcogenide amorphous thin film faces and is lower than the opening of the reaction tank, and place a liquid metal in the trench. The liquid metal is the same as the metal component in the chalcogenide amorphous thin film, and the melting point of the liquid metal is lower than the growth temperature of the chalcogenide amorphous thin film.

[0042] S3. Seal the reaction tank and the trench with a cover plate. The liquid metal contacts the cover plate to achieve liquid sealing, and a plug is obtained.

[0043] S4. Heat the plug to a preset temperature in an inert atmosphere and hold for annealing so that the chalcogenide amorphous thin film recrystallizes to form a chalcogenide crystal thin film.

[0044] It can be understood that sealing the reaction tank and the trench with the cover plate means: covering the cover plate on the bearing surface. At this time, the two are not absolutely sealed. Therefore, by placing a liquid metal in the trench, when the cover plate seals the reaction tank and the trench, the liquid metal contacts the cover plate to achieve liquid sealing. This can not only improve the sealing between the trench and the cover plate and avoid the introduction of impurities, but also during annealing, a trace amount of metal atoms generated by the liquid metal can be additionally introduced into the reaction tank to form a metal-rich liquid interface on the chalcogenide amorphous thin film. It can be understood that there is no liquid metal in the reaction tank.

[0045] Among them, for the convenience of setting, the bearing surface can be a plane, that is, the opening of the reaction tank and the opening of the trench are flush. At this time, the surface of the cover plate in contact with the bearing surface is also a plane.

[0046] It can be understood that the chalcogenide amorphous thin film faces and is lower than the opening of the reaction tank, that is, after the cover plate seals the opening of the reaction tank, the chalcogenide amorphous thin film does not contact the cover plate.

[0047] It can be understood that the melting point of the liquid metal is lower than the temperature of the annealing for holding, so that when the chalcogenide amorphous thin film recrystallizes, it can ensure that the metal in the trench is in a liquid state, achieving liquid sealing and being beneficial to the formation of a metal liquid interface.

[0048] The inert atmosphere includes at least one of argon and nitrogen.

[0049] The step of holding the single-crystal substrate, i.e., the single-crystal sapphire substrate, for annealing in an inert atmosphere can be carried out in a tube furnace. It should be noted that there is a substrate carrier in the tube furnace. The single-crystal substrate is placed on the substrate carrier for annealing. Among them, when the annealing temperature is less than 1150 °C, a quartz substrate carrier is selected, and at this time, the tube furnace is a quartz furnace; when the annealing temperature is 1150 °C - 1450 °C, a corundum substrate carrier can be selected, and the tube furnace is a corundum furnace.

[0050] In summary, in the method for preparing the metal chalcogenide crystal film provided by the present application, since the metal chalcogenide amorphous film is placed in the reaction tank, and the liquid metal with the same metal component as that in the metal chalcogenide amorphous film is placed in the groove, the reaction tank and the groove are sealed with a cover plate. At this time, the liquid metal contacts the cover plate to form a liquid seal. Then, the obtained plug is annealed. Trace metal atoms generated by the surrounding liquid metal can be additionally introduced into the reaction tank, which helps to form a metal-rich liquid interface on the metal chalcogenide amorphous film, is conducive to promoting the recrystallization of the metal chalcogenide amorphous film into a crystal structure with high crystallinity by reducing the surface energy and enhancing atomic diffusion, and finally, under the driving of the solid-liquid-solid growth, a wafer-level, pure-phase, and controllable-thickness metal chalcogenide crystal film is obtained.

[0051] In some alternative embodiments, the bearing surface has a bearing area located between the groove and the reaction tank, and the bearing area is used to contact the cover plate;

[0052] The bearing area has a first edge close to the groove and a second edge close to the reaction tank, and the distance between the first edge and the second edge is 0.1 cm - 5 cm.

[0053] The distance between the first edge and the second edge refers to the shortest straight-line distance between the two.

[0054] Controlling the distance between the first edge and the second edge to be 0.1 cm - 5 cm is conducive to enabling the metal atoms generated by the liquid metal in the groove to smoothly and quickly enter the reaction tank during annealing.

[0055] Exemplarily, the distance between the first edge and the second edge is any value among 0.1 cm, 0.5 cm, 1.0 cm, 1.5 cm, 2.0 cm, 2.5 cm, 3.0 cm, 3.5 cm, 4.0 cm, 4.5 cm, 5.0 cm or between any two values.

[0056] In some alternative embodiments, the bearing surface has a bearing area located between the groove and the reaction tank;

[0057] An excessive amount of liquid metal is placed in the groove so that when the cover plate seals the reaction tank and the groove, there is liquid metal that has not entered the reaction tank between the bearing area and the cover plate.

[0058] It is understandable that the liquid metal between the carrier area and the cover plate that does not enter the reaction tank means that the excessive liquid metal overflows from the groove, but the overflow part is located between the carrier area and the cover plate and does not enter the reaction tank. That is, the liquid metal in the groove only enters the reaction tank in the form of generated metal atoms.

[0059] Through the above limitations, it is beneficial that during annealing, the metal atoms generated by the liquid metal in the groove can smoothly and quickly enter the reaction tank, which helps to form a metal-rich liquid interface on the chalcogenide amorphous thin film.

[0060] It is understandable that the container is a high-temperature resistant container made of high-temperature resistant materials, so that during annealing, the container itself will not react or soften due to high temperature, affecting the preparation of the chalcogenide crystal thin film.

[0061] In some alternative embodiments, the material of the bearing part includes at least one of diamond, alumina, and steel; and / or,

[0062] The material of the cover plate includes glass.

[0063] Among them, the glass includes but is not limited to high-temperature resistant fused silica glass.

[0064] Through the above settings, the high-temperature resistance of the container can be guaranteed, and the introduction of glass is beneficial to observing the changes of the chalcogenide thin film in the container.

[0065] In some alternative embodiments, the material of the chalcogenide crystal thin film includes at least one of indium selenide, diindium triselenide, indium sulfide, indium telluride, gallium selenide, gallium sulfide, gallium telluride, bismuth selenide, bismuth sulfide, and bismuth telluride.

[0066] It should be noted that the material of the chalcogenide crystal thin film includes but is not limited to the above, and can also be chalcogenides of other metals, as long as the melting point of the liquid metal is lower than the temperature of the heat preservation annealing, and no exhaustive list is given here.

[0067] It should be noted that the time of heat preservation annealing can be selected according to the actual composition of the chalcogenide.

[0068] In some alternative embodiments, the material of the chalcogenide crystal thin film is InSe;

[0069] Among them, the preset temperature is 300°C - 600°C, and can be selected as 500°C - 600°C, and / or;

[0070] The time of heat preservation annealing is 5 min - 200 min; it can be selected as 100 min - 200 min.

[0071] By controlling the preset temperature and the holding annealing time within the above ranges, it is beneficial for the amorphous indium selenide thin film to recrystallize into a crystalline indium selenide thin film.

[0072] Exemplarily, when the material of the metal chalcogenide crystal thin film is indium selenide, the preset temperature is any value among 300 °C, 325 °C, 350 °C, 375 °C, 400 °C, 425 °C, 450 °C, 475 °C, 500 °C, 525 °C, 550 °C, 575 °C, 600 °C or between any two values.

[0073] Exemplarily, the time for holding annealing is any value among 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, 180 min, 190 min, 200 min or between any two values.

[0074] In some optional embodiments, the heating rate is 5 °C / min - 100 °C / min.

[0075] Exemplarily, the heating rate is any value among 5 °C / min, 10 °C / min, 15 °C / min, 20 °C / min, 30 °C / min, 40 °C / min, 50 °C / min, 60 °C / min, 70 °C / min, 80 °C / min, 90 °C / min, 100 °C / min or between any two values.

[0076] Optionally, the heating rate is 5 °C / min - 20 °C / min.

[0077] Controlling the heating rate within the above range is beneficial for slow crystallization and improving the crystallization quality.

[0078] Among them, a metal chalcogenide amorphous thin film can be grown on the surface of a single crystal substrate by a method including but not limited to chemical vapor deposition, physical vapor deposition, or molecular beam epitaxy.

[0079] In some optional embodiments, a metal chalcogenide amorphous thin film is grown on the surface of a single crystal substrate by magnetron sputtering.

[0080] The above method is simple to operate and is beneficial for obtaining a high-purity metal chalcogenide amorphous thin film.

[0081] It is understandable that the specific parameters of magnetron sputtering can refer to related technologies and are not limited here. At the same time, in order to avoid the introduction of impurities, the raw materials used in magnetron sputtering should be of high purity, such as raw materials with a purity greater than 99.9%.

[0082] In some optional embodiments, the single-crystal substrate includes a single-crystal sapphire substrate.

[0083] The introduction of the single-crystal sapphire substrate is beneficial to forming a high-purity chalcogenide metal amorphous thin film on its surface by magnetron sputtering.

[0084] Optionally, the preparation method includes: before forming the chalcogenide metal amorphous thin film on the surface of the single-crystal sapphire substrate, heat-treating the single-crystal sapphire substrate at 900°C - 1300°C.

[0085] By the above heat treatment, impurities on the surface of the single-crystal sapphire substrate are removed to avoid introducing impurities into the formed chalcogenide metal amorphous thin film.

[0086] Optionally, the single-crystal sapphire substrate is heat-treated at 900°C - 1300°C for 120 min - 360 min.

[0087] In some optional embodiments, the orthographic projection of the chalcogenide metal crystal thin film on the cover plate is circular, the radial dimension of the chalcogenide metal crystal thin film is 1 cm - 30 cm, and the longitudinal thickness is 0.8 nm - 30 nm.

[0088] That is, through the above preparation method, a chalcogenide metal crystal thin film with large size and controllable thickness can be prepared.

[0089] Optionally, the chalcogenide metal crystal thin film is a single-crystal chalcogenide metal thin film.

[0090] The following further describes in detail the preparation method of the chalcogenide metal crystal thin film of the present application in combination with embodiments.

[0091] Example 1

[0092] Figure 1 It is a schematic flow chart of the preparation method of the InSe crystal thin film of the present application.

[0093] As Figure 1 shown, the preparation method of the InSe crystal thin film includes:

[0094] First, as Figure 1 shown in part a, grow the InSe amorphous thin film by magnetron sputtering:

[0095] The single-crystal sapphire substrate was heat-treated at 1150 °C for 300 min, and then an InSe amorphous film was grown on the surface of the single-crystal sapphire substrate by magnetron sputtering to obtain a composite substrate. Among them, InSe was used as the magnetron sputtering target, and the corresponding power of magnetron sputtering was 50 W, and the working pressure was 3 Pa.

[0096] Secondly, as Figure 1 shown in part b of

[0097] : The composite substrate was assembled with the container. The container includes a steel substrate as the bearing part and fused quartz glass as the cover plate. The steel substrate includes a bearing surface. The bearing surface is provided with a reaction groove and a groove surrounding the circumference of the reaction groove. The bearing surface has a bearing area located between the groove and the reaction groove, and the bearing area is used to contact the fused quartz glass; the bearing area has a first edge close to the groove and a second edge close to the reaction groove, and the distance between the first edge and the second edge is 0.5 cm. The fused quartz glass is in a flat plate shape and is used to contact the bearing surface to seal the reaction groove and the groove.

[0098] The composite substrate was placed in the reaction groove so that the InSe amorphous film faced and was lower than the opening of the reaction groove, and liquid indium equal to the volume of the groove was placed in the groove. Then, the reaction groove and the groove were sealed with fused quartz glass. Among them, the liquid indium contacted the cover plate to achieve liquid sealing, and a plug was obtained.

[0099] Finally, as Figure 1 shown in part c of

[0100] : The plug was annealed in a tube furnace. The plug was placed on a quartz bearing substrate in the tube furnace, argon was introduced, and the argon flow rate was maintained at 300 sccm. It was heated to 550 °C at a rate of 10 °C / min and annealed for 120 min, and then cooled with the furnace while keeping the argon flow rate unchanged. After opening the furnace, an InSe crystal film was obtained.

[0101] Among them, Figure 2 are the photos of the prepared InSe crystal film and the corresponding Raman characterizations at different positions. Among them Figure 2 part a is the photo of the InSe crystal film. The InSe crystal film is circular, with a radial size of 2 inches and a longitudinal thickness of about 0.8 nm - 30 nm; Figure 2 part b is 12 positions selected on the InSe crystal film for Raman characterization; Figure 2 part c is the Raman spectrum comparison diagram of the above 12 positions. It can be seen that the Raman spectra at each position are basically the same, indicating that the wafer-level InSe crystal film has high uniformity.

[0102] Figure 3For the characterization of the single-crystallinity of the prepared InSe crystal thin film, where Figure 3 In part a of Figure 3 is the SEM photo of the InSe crystal domain. It can be seen that there are oriented triangular domains, proving that the InSe crystal thin film has a single crystal domain orientation and good single-crystallinity; Figure 3 In part b of Figure 3 is the SHG characterization. It can be seen that the SHG characterization at the corresponding position proves that its crystal orientation is consistent; Figure 3 In part c of Figure 3 is the Laue diffraction characterization, indicating that the InSe crystal thin film has large-area single-crystallinity. In summary, Figure 3 it shows that the two-inch InSe crystal thin film prepared in this example has good single-crystallinity.

[0103] Figure 4 For the structural characterization of the prepared InSe crystal thin film. Figure 4 In part a of Figure 4 is the selected area electron diffraction of the InSe crystal thin film, indicating the crystal orientation of the InSe prepared by the present invention. Figure 4 In part b of Figure 4 is the planar atomic structure of the InSe crystal thin film, Figure 4 In part c of Figure 4 is the cross-sectional atomic structure diagram of the InSe crystal thin film. According to Figure 4 parts b and c, it shows that the InSe prepared in this example is a pure rhombohedral phase and has no obvious lattice defects.

[0104] Example 2

[0105] The difference between it and Example 1 is only that:

[0106] Excessive liquid In is placed in the trench. When the cover plate seals the reaction tank and the trench, there is In that has not entered the reaction tank between the bearing area and the cover plate.

[0107] Through the above preparation method, an InSe crystal thin film with a pure rhombohedral phase, no obvious lattice defects and good single-crystallinity is obtained.

[0108] Example 3

[0109] The difference between it and Example 1 is only that:

[0110] The plugging material is placed on the quartz bearing substrate in the tubular furnace, nitrogen is introduced, the argon flow rate is maintained at 300 sccm, heated to 600 °C at a rate of 10 °C / min and annealed for 120 min, and cooled with the furnace while keeping the argon flow rate unchanged. Open the furnace to obtain the InSe crystal thin film.

[0111] Example 4

[0112] The difference between it and Example 1 is only that:

[0113] Place the plugging material on the quartz carrier substrate in the tube furnace, introduce nitrogen gas, keep the argon gas flow rate at 300 sccm, heat it to 300 °C at a rate of 10 °C / min, hold for annealing for 200 min, and cool it in the furnace while keeping the argon gas flow rate unchanged. Open the furnace to obtain the InSe crystal thin film.

[0114] Comparative Example 1

[0115] The difference between it and Example 1 is only that:

[0116] No liquid In is placed in the groove, and the material shows non-uniformity and poor quality.

[0117] Figure 5 Figure 13 is an optical microscope photograph of the InSe crystal thin films prepared in Example 1 and Comparative Example 1, where Figure 5 Part a in it is the optical microscope photograph of placing liquid In in the groove. It can be seen that the InSe crystal thin film is very uniform and has high crystallization quality. Figure 5 In part b in it, since no liquid In is placed in the groove, the material is very non-uniform and has poor crystallization quality. According to the comparison, it can be shown that the role of liquid In is to provide In atoms and promote the recrystallization of the metal-rich liquid interface into a crystal structure with high crystallinity.

[0118] Comparative Example 2

[0119] The difference between it and Example 1 is only that:

[0120] 1 / 2 of the volume of liquid In is placed in the groove. That is, after the cover plate closes the reaction tank and the groove, the liquid In does not contact the cover plate, and liquid sealing cannot be achieved.

[0121] The result is the same as that of Comparative Example 1, and its crystallization quality is poor. It shows that the role of liquid sealing is to prevent the evaporation of In atoms and Se atoms in the amorphous InSe thin film due to the large difference in vapor pressure, and form other heterogeneous phase materials.

[0122] In summary, in the method for preparing the metal chalcogenide crystal thin film provided in this application, since an amorphous metal chalcogenide thin film is placed in the reaction tank, a liquid metal with the same metal component as that in the amorphous metal chalcogenide thin film is placed in the groove, and the reaction tank and the groove are closed by a cover plate. At this time, the liquid metal contacts the cover plate to form liquid sealing. At this time, the obtained plugging material is annealed, and trace metal atoms generated by the surrounding liquid metal can be additionally introduced into the reaction tank, which helps to form a metal-rich liquid interface on the amorphous metal chalcogenide thin film, is conducive to promoting the recrystallization of the amorphous metal chalcogenide thin film into a crystal structure with high crystallinity by reducing the surface energy and enhancing atomic diffusion, and then, under the driving of solid-liquid-solid growth, finally obtain a wafer-level, pure-phase, and controllable-thickness metal chalcogenide crystal thin film.

[0123] The above are only specific embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various modifications and variations can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for preparing a metal chalcogenide crystal thin film, characterized in that: The preparation of the metal chalcogenide crystal film is carried out in a container, the container comprising a bearing portion and a cover plate, the bearing portion comprising a bearing surface, the bearing surface being provided with a reaction groove and a groove surrounding the reaction groove, the cover plate being used to contact the bearing surface to close the reaction groove and the groove; The preparation method comprises: obtaining a composite substrate, the composite substrate comprising a single crystal substrate and a metal chalcogenide amorphous thin film formed on a surface of the single crystal substrate; Placing the composite substrate in the reaction tank so that the metal chalcogenide amorphous film faces and is lower than the opening of the reaction tank, and placing liquid metal in the groove, wherein the liquid metal has the same metal component as that in the metal chalcogenide amorphous film and the melting point of the liquid metal is lower than the growth temperature of the metal chalcogenide amorphous film; The reaction tank and the groove are sealed by using the cover plate, and the liquid metal contacts the cover plate to achieve liquid sealing, thereby obtaining a sealing object; The sealing material is heated to a preset temperature in an inert atmosphere for heat preservation annealing to recrystallize the metal chalcogenide amorphous film to form a metal chalcogenide crystalline film.

2. The preparation method according to claim 1, characterized in that: The bearing surface has a bearing area located between the groove and the reaction tank, and the bearing area is used to contact with the cover plate; The carrying area has a first edge close to the groove and a second edge close to the reaction groove, and the distance between the first edge and the second edge is 0.1 cm-5 cm.

3. The preparation method according to claim 1, characterized in that: The bearing surface has a bearing area located between the groove and the reaction tank; Excessive liquid metal is placed in the groove, so that when the cover plate closes the reaction groove and the groove, the liquid metal that has not entered the reaction groove exists between the carrying area and the cover plate.

4. The preparation method according to claim 1, characterized in that: The material of the bearing portion includes at least one of diamond, alumina and steel; and / or, The material of the cover plate includes glass.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The material of the metal chalcogenide crystal film includes at least one of indium selenide, indium triselenide, indium sulfide, indium telluride, gallium selenide, gallium sulfide, gallium telluride, bismuth selenide, bismuth sulfide and bismuth telluride.

6. The preparation method according to any one of claims 1 to 4, characterized in that: The material of the metal chalcogenide crystal film is InSe; Wherein, the preset temperature is 300°C-600°C, optionally 500°C-600°C, and / or; The heat preservation annealing time is 5min-200min; optionally 100min-200min.

7. The preparation method according to any one of claims 1 to 4, characterized in that: The heating rate is 5°C / min-100°C / min, and can be optionally 5°C / min-20°C / min.

8. The preparation method according to any one of claims 1 to 4, characterized in that: The metal chalcogenide amorphous film is grown on the surface of the single crystal substrate by magnetron sputtering.

9. The preparation method according to any one of claims 1 to 4, characterized in that: The single crystal substrate comprises a single crystal sapphire substrate; Optionally, the preparation method comprises: before forming the metal chalcogenide amorphous thin film on the surface of the single crystal sapphire substrate, heat treating the single crystal sapphire substrate at 900° C.-1300° C.

10. The preparation method according to any one of claims 1 to 4, characterized in that: The orthographic projection of the metal chalcogenide crystal film on the cover plate is circular, the radial dimension of the metal chalcogenide crystal film is 1 cm-20 cm, and the longitudinal thickness is 0.82 nm-30 nm; Optionally, the metal chalcogenide compound crystal film is a single crystal metal chalcogenide compound film.

Images