Metal chalcogenide monocrystalline thin film and preparation method therefor

Abstract

A metal chalcogenide monocrystalline thin film and a preparation method therefor, belonging to the field of materials. The metal chalcogenide single-crystal thin film comprises multiple layers of rhombohedral or hexagonal metal chalcogenide monocrystalline grains stacked sequentially, the metal chalcogenide single-crystal grains in each layer being unidirectionally oriented, and the unidirectional orientation directions of any two adjacent layers of metal chalcogenide single-crystal grains being parallel. By means of cooperation of the described multiple layers of unidirectional phase-structured metal chalcogenide single-crystal grains stacked in parallel, the metal chalcogenide monocrystalline thin film combines advantages such as high uniformity, high quality, wafer scale, phase purity and controllable thickness.

Description

Metal chalcogenide single crystal thin film and preparation method thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority and benefits of Chinese patent application number 202410325437.6, filed with the State Intellectual Property Office of China on March 21, 2024, entitled “Metal Chalcogenide Compound Single Crystal Thin Film and Preparation Method Thereof,” and incorporates the entire text of the patent application into this disclosure by reference. Technical Field

[0003] The present disclosure relates to the field of materials, and in particular to a metal chalcogenide single crystal thin film and a preparation method thereof. Background Art

[0004] Two-dimensional metal chalcogenides, especially two-dimensional transition metal chalcogenides, have been indispensable throughout the 20th century and are promising materials for a range of modern chemical, optical, electronic, and optoelectronic applications.

[0005] Currently, surface-mode chemical vapor deposition (CVD) is considered an effective method for preparing two-dimensional metal chalcogenides. However, large-scale production of wafer-scale, phase-pure metal chalcogenide single crystal thin films remains elusive.

[0006] Summary of the Invention

[0007] The present disclosure provides a metal chalcogenide single crystal thin film and a preparation method thereof, which can be mass-produced to obtain a wafer-level, pure-phase, and controllable-thickness metal chalcogenide single crystal thin film.

[0008] The embodiments of the present disclosure are implemented as follows:

[0009] In a first aspect, the present disclosure provides a metal chalcogenide single crystal film, which comprises a plurality of layers of rhombohedral or hexagonal metal chalcogenide single crystal grains stacked in sequence, wherein each layer of metal chalcogenide single crystal grains is unidirectionally oriented, and the unidirectional orientation directions of any two adjacent layers of metal chalcogenide single crystal grains are parallel.

[0010] The metal chalcogenide single crystal thin film provided by the present disclosure has the advantages of high uniformity, high quality, wafer-level, pure phase and controllable thickness through the above-mentioned parallel stacking of multiple layers of metal chalcogenide single crystal grains with the same unidirectional phase structure.

[0011] In a second aspect, the present disclosure further provides a method for preparing the above-mentioned metal chalcogenide single crystal thin film, which comprises:

[0012] Using a single crystal substrate doped with a target metal (e.g., single crystal nickel foil) as a growth substrate, laminating the growth substrate with a metal chalcogenide sheet to obtain a growth module, wherein the target metal includes a transition metal;

[0013] Placing the growth module in an inert atmosphere, exposing the side of the growth substrate facing away from the metal sulfide sheet to the inert atmosphere, heating the substrate to a preset temperature and maintaining the temperature for 1 minute to 1000 hours, and obtaining a metal chalcogenide single crystal thin film generated by the reaction of the target metal with the chalcogen element in the metal chalcogenide sheet;

[0014] Among them, the preset temperature is 500℃-1500℃.

[0015] The preparation method provided by the present disclosure has a simple and easy process flow and can realize the batch preparation of metal chalcogenide single crystal thin films. The prepared metal chalcogenide single crystal thin films have the advantages of large size, high quality, phase purity, high uniformity and controllable thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0017] FIG1 is a schematic flow chart of a method for preparing a metal chalcogenide single crystal thin film provided by the present disclosure;

[0018] FIG2 is a photograph of the MoS2 single crystal thin film obtained in Example 1;

[0019] FIG3 is an optical microscope image of the MoS2 single crystal thin film obtained in Example 1;

[0020] FIG4 is a characterization diagram of the single crystal and stacking mode of the MoS2 single crystal film prepared in Example 1;

[0021] FIG5 is an electron diffraction pattern and corresponding atomic structure characterization diagram of each metal chalcogenide single crystal thin film prepared in Examples 2-7;

[0022] FIG6 is an optical microscope image of each metal chalcogenide single crystal thin film prepared in Examples 2-7;

[0023] FIG7 is a performance characterization diagram of the WSe2 single crystal thin film prepared in Example 8;

[0024] FIG8 is a physical comparison diagram of MoS2 prepared using ZnS and sulfur in Comparative Example 1. DETAILED DESCRIPTION

[0025] The embodiments of the present disclosure will be described in detail below with reference to the examples. However, those skilled in the art will appreciate that the following examples are intended only to illustrate the present disclosure and should not be construed as limiting the scope of the present disclosure. Where specific conditions are not specified in the examples, the experiments were performed under conventional conditions or the conditions recommended by the manufacturer. Where the manufacturer of the reagents or instruments is not specified, all are commercially available conventional products.

[0026] Currently, surface-modified chemical vapor deposition (CVD) is considered an effective method for preparing two-dimensional metal chalcogenides. However, large-scale production of single-crystalline thin films of metal chalcogenides remains elusive. This is primarily due to the limitations of the currently popular epitaxial growth mechanism, where new layers grow on top of existing ones, resulting in very weak interlayer interactions and the inability to precisely control the number of layers or stacking phase.

[0027] This paper attempts to use interfacial epitaxy technology to fully dissolve target metal atoms and chalcogenide atoms into a nickel single crystal substrate, followed by epitaxial precipitation of a new layer at the interface between the nickel single crystal substrate and the existing layer. By continuously lifting the formed new layer, the activity of the nickel-metal chalcogenide interface is maintained, thereby driving the continuous epitaxy of multiple layers. Simultaneously, the morphology of the metal step surface is maintained during the growth process, confirming the unidirectional orientation of each layer, thereby forming a parallel stack of multiple layers of rhombohedral or hexagonal metal chalcogenide single crystal grains, achieving the universal preparation of wafer-scale, phase-pure, and thickness-controlled metal chalcogenide single crystal thin films.

[0028] The following is a detailed description of the metal chalcogenide single crystal thin film and its preparation method according to the embodiment of the present disclosure:

[0029] Some embodiments of the present disclosure provide a metal chalcogenide single crystal film, which includes multiple layers of rhombohedral or hexagonal metal chalcogenide single crystal grains stacked in sequence, each layer of metal chalcogenide single crystal grains is unidirectionally oriented, and the unidirectional orientation directions of any two adjacent layers of metal chalcogenide single crystal grains are parallel.

[0030] It should be noted that multilayer refers to 2 layers or more, such as 2 layers, 5 layers, 10 layers, 50 layers, etc., wherein the specific number of layers can be limited according to actual needs to accurately control the thickness of the metal chalcogenide single crystal film.

[0031] Both the rhombohedral phase and the hexagonal phase refer to the phase structures of metal chalcogenides, wherein the rhombohedral phase is also a trigonal structure, also known as the 3R phase; the hexagonal phase is also a hexagonal structure, also known as the 2H phase.

[0032] The sequentially stacked multilayer rhombohedral or hexagonal metal chalcogenide compound single crystal grains refer to: the metal chalcogenide compound single crystal film includes sequentially stacked multilayer metal chalcogenide compound single crystal grains, wherein the phase structure of each layer of metal chalcogenide compound is rhombohedral or hexagonal, and the phase structure of any two adjacent layers of metal chalcogenide compound single crystal grains is the same, thereby controlling the final single crystal film to be a pure phase.

[0033] The metal chalcogenide single crystal thin film provided by the present disclosure has the advantages of high uniformity, high quality, wafer-level, pure phase and controllable thickness through the above-mentioned parallel stacking of multiple layers of metal chalcogenide single crystal grains with the same unidirectional phase structure.

[0034] The metal in the metal chalcogenide single crystal film includes at least one of a transition metal and a non-transition metal, any one of which can be selected, wherein the non-transition metal includes but is not limited to at least one of indium, gallium, germanium, tin, antimony, lead, bismuth, magnesium, calcium, etc., and the transition metal includes but is not limited to at least one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, cobalt, rhodium, iridium, palladium, platinum, chromium, manganese, iron, etc.

[0035] In some optional embodiments, the metal chalcogenide includes at least one of a transition metal chalcogenide and its derivatives, that is, the metal chalcogenide may be a transition metal chalcogenide alone or a derivative of a transition metal chalcogenide, or a combination of the two, wherein the transition metal chalcogenide includes at least one of the sulfides, selenides, and tellurides corresponding to titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, cobalt, rhodium, iridium, palladium, platinum, chromium, manganese, and iron.

[0036] Derivatives of transition metal chalcogenides include, but are not limited to, multi-component alloys and heterojunction structures containing transition metal chalcogenides.

[0037] For example, the transition metal chalcogenide is MX2, wherein M represents a transition metal element, including at least one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, cobalt, rhodium, iridium, palladium, platinum, chromium, manganese, iron, etc., and X represents at least one of chalcogenide atoms such as sulfur, selenium, and tellurium. For example, the transition metal chalcogenide includes but is not limited to at least one of titanium disulfide, zirconium disulfide, hafnium disulfide, vanadium sulfide, niobium disulfide, tantalum disulfide, molybdenum disulfide, tungsten disulfide, technetium disulfide, rhenium disulfide, cobalt disulfide, rhodium sulfide, iridium disulfide, and corresponding alloys. The alloy includes but is not limited to MoS 2-2x Se 2x , WS 2-2x Se 2x 、NbS 2-2x Se 2x 、Mo 1-x Nbx S2 or Mo 1-x W x S2. These single-crystal thin films composed of transition metal chalcogenides can be applied to cutting-edge technologies in post-Moore's Law nanoelectronics, non-volatile memory, neuromorphic computing, solar energy harvesting, on-chip nonlinear optical devices, and quantum light sources, bringing more possibilities to the development of high-performance devices and product manufacturing.

[0038] Among them, when the transition metal chalcogenide is a rhombohedral transition metal chalcogenide, the final rhombohedral transition metal chalcogenide single crystal film has high current density and high carrier mobility. The rhombohedral transition metal chalcogenide has in-plane inversion and out-of-plane mirror symmetry based on its unique stacking arrangement, realizing switchable interface ferroelectricity, and has advantages such as energy-saving bulk photovoltaic effect and super-strong nonlinear optical enhancement. These advantages have greatly promoted the frontiers of post-Moore's Law nanoelectronics, non-volatile memory, neuromorphic computing, solar energy collection, on-chip nonlinear optical devices and quantum light sources.

[0039] Optionally, the transition metal chalcogenide comprises MoS2, MoSe2, WS2, WSe2, NbS2, NbSe2, MoS 2-2x Se 2x , WS 2-2x Se 2x 、NbS 2-2x Se 2x 、Mo 1-x Nb x S2、Mo 1-x W x At least one of S2, where 0<x<1.

[0040] The above transition metal chalcogenides have both good current density and good carrier mobility and have a wide range of applications.

[0041] In some optional embodiments, the metal chalcogenide single crystal thin film has a thickness of 0.65 nm-1 cm and a size of 1 μm-1 m.

[0042] The size here refers to the size of the orthographic projection of the metal chalcogenide single crystal film along the thickness direction. For example, when the orthographic projection is a circle, the size here is the diameter of the circle; when the orthographic projection is a rectangle, the size refers to the side length of the rectangle.

[0043] That is, the thickness of the above-mentioned metal chalcogenide single crystal film is adjustable and the size can be as high as 1m, breaking through the difficulties that traditional methods cannot prepare, and at the same time, having a wide range of applications.

[0044] Illustratively, the thickness of the metal chalcogenide single crystal film is any value among 0.65nm, 1nm, 50nm, 100nm, 500nm, 1μm, 10μm, 20μm, 30μm, 50μm, 100μm, 500μm, 1cm, or between any two values, and the size is any value among 1μm, 10μm, 100μm, 500μm, 1mm, 1cm, 5cm, 10cm, 50cm, 1m, or between any two values.

[0045] As shown in FIG1 , some embodiments of the present disclosure further provide a method for preparing the above-mentioned metal chalcogenide compound single crystal thin film, which comprises:

[0046] A single crystal substrate doped with a target metal (illustratively, M represents the target metal in FIG1 , and Ni-M alloy represents the single crystal nickel foil doped with the target metal) is used as a growth substrate, and the growth substrate is laminated with a metal chalcogenide sheet (ZnX sheet represents the metal chalcogenide sheet in FIG1 , where X represents a chalcogen element, such as at least one of S, Se, and Te) to obtain a growth module, wherein the target metal includes a transition metal;

[0047] Placing the growth module in an inert atmosphere, exposing the side of the growth substrate facing away from the metal chalcogenide sheet to the inert atmosphere, heating the substrate to a preset temperature and maintaining the temperature for 1 minute to 1000 hours, to obtain a metal chalcogenide single crystal thin film generated by the reaction of the target metal with the chalcogenide element in the metal chalcogenide sheet;

[0048] Among them, the preset temperature is 500℃-1500℃.

[0049] It should be noted that the single crystal nickel foil doped with the target metal means that the nickel foil is doped with the target metal element and maintains single crystallinity. Using the single crystal nickel foil doped with the target as the growth substrate is, on the one hand, conducive to the subsequent slow release of the doped target metal element at a preset temperature to generate metal sulfide compounds with sulfide elements. On the other hand, the single crystal nature of the growth substrate is conducive to inducing a single orientation of the crystal nucleus of the metal sulfide compound and suppressing the effects of other orientations, thereby forming single crystal grains of metal sulfide compounds with consistent orientation.

[0050] The target metal includes at least one of a non-transition metal and a transition metal. The target metal can be a non-transition metal or a transition metal, wherein the non-transition metal includes at least one of indium, gallium, germanium, tin, antimony, lead, bismuth, magnesium, and calcium, and the transition metal includes but is not limited to at least one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, cobalt, rhodium, iridium, palladium, platinum, chromium, manganese or iron. It can be understood that since the single crystal nickel foil is doped, the composition of the target metal is different from that of the nickel foil, that is, the target metal cannot be nickel.

[0051] A metal chalcogenide sheet is a sheet of metal chalcogenide material. Using the metal chalcogenide sheet as a source of chalcogen elements, compared to a single chalcogenide sheet, when heated to a preset temperature, the chalcogen elements in the metal chalcogenide sheet are slowly released and fully dissolved into the growth substrate, epitaxially precipitating a wafer-scale, phase-pure, and thickness-controlled metal chalcogenide single crystal thin film at the interface between the nickel single crystal substrate and the existing layer. In other words, the metal chalcogenide single crystal thin film is epitaxially grown at the interface between the nickel single crystal substrate and the existing layer, resulting from the reaction of the target metal with the chalcogen elements in the metal chalcogenide sheet.

[0052] The growth substrate is bonded to a metal chalcogenide sheet and placed in an inert atmosphere, with the side of the growth substrate facing away from the metal chalcogenide sheet exposed to the inert atmosphere. The temperature is raised to 500°C-1500°C and maintained for 1 minute to 1000 hours. By controlling the preset temperature, on the one hand, the target metal atoms and chalcogenide atoms can be fully dissolved into the nickel single crystal substrate, and then a new layer is epitaxially precipitated on the side of the growth substrate facing away from the metal chalcogenide sheet. The activity of the nickel-metal chalcogenide interface is maintained by continuously raising the formed new layer, thereby driving the continuous epitaxy of multiple layers. At the same time, the morphology of the metal step surface is maintained during the growth process, thereby forming parallel stacked multilayer metal chalcogenide single crystal grains. On the other hand, the phase structure of the generated metal chalcogenide single crystal grains can be controlled to be rhombohedral or hexagonal by adjusting the temperature according to actual needs to meet usage requirements.

[0053] Since the growth substrate is bonded to the metal chalcogenide compound sheet and the film is formed by epitaxial growth, the size of the metal chalcogenide compound single crystal film can be controlled by controlling the size of the single crystal nickel foil and the metal chalcogenide compound sheet, which can realize the preparation of large-area wafer-level single crystal films. At the same time, the thickness can also be precisely controlled by adjusting the holding time.

[0054] An inert atmosphere is used as a protective atmosphere to prevent the process of generating the metal chalcogenide single crystal grains from being disturbed, wherein the inert atmosphere includes a nitrogen atmosphere and / or an argon atmosphere.

[0055] The preparation method of the metal sulfide compound single crystal thin film provided by the present invention has a simple and easy process flow, and can realize the batch preparation of the metal sulfide compound single crystal thin film. The prepared metal sulfide compound single crystal thin film has the advantages of large size, high quality, phase purity, high uniformity and controllable thickness.

[0056] Exemplarily, the preset temperature is any value of 500°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1500°C, or between any two values.

[0057] Illustratively, the holding time is any value among 1 min, 5 min, 10 min, 50 min, 100 min, 300 min, 1000 min, 20 h, 100 h, 1000 h, or between any two values.

[0058] Optionally, the holding time is 1 min-1000 min.

[0059] In some optional embodiments, the holding time is 2 min to 10 min.

[0060] The growth module can be placed in a tube furnace for heating and holding operations, and the atmosphere within the tube furnace can be controlled to maintain an inert atmosphere at normal pressure. It is understood that the preparation method also includes maintaining natural cooling in the inert atmosphere at normal pressure after holding at the preset temperature. In other words, there is no need to intervene in the cooling process, thereby effectively reducing the preparation difficulty.

[0061] In some optional embodiments, the preset temperature satisfies any one of (a1)-(a5):

[0062] (a1) The metal chalcogenide in the metal chalcogenide single crystal thin film is rhombohedral molybdenum disulfide and / or rhombohedral molybdenum diselenide, and the preset temperature is 650° C.-900° C.

[0063] Exemplarily, the metal chalcogenide in the metal chalcogenide single crystal film is rhombohedral molybdenum disulfide and / or rhombohedral molybdenum diselenide, and the preset temperature is any value of 650°C, 700°C, 800°C, 820°C, 850°C, 870°C, 900°C or between any two values.

[0064] (a2) The metal chalcogenide compound in the metal chalcogenide single crystal film is rhombohedral tungsten disulfide and / or rhombohedral tungsten diselenide, and the preset temperature is 700° C.-950° C.

[0065] Exemplarily, the metal chalcogenide in the metal chalcogenide single crystal film is rhombohedral tungsten disulfide and / or rhombohedral tungsten diselenide, and the preset temperature is any value of 700°C, 800°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, 930°C, 940°C, and 950°C, or between any two values.

[0066] (a3) The metal chalcogenide compound in the metal chalcogenide single crystal film is rhombohedral niobium disulfide and / or rhombohedral niobium diselenide, and the preset temperature is 500° C.-850° C.

[0067] Illustratively, the metal chalcogenide in the metal chalcogenide single crystal film is rhombohedral niobium disulfide and / or rhombohedral niobium diselenide, and the temperature is any one of 500°C, 610°C, 720°C, 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, 800°C, 810°C, 820°C, 830°C, 840°C, and 850°C, or between any two values.

[0068] (a4) The metal chalcogenide compound in the metal chalcogenide single crystal film is at least one of hexagonal molybdenum disulfide, hexagonal molybdenum diselenide, hexagonal tungsten disulfide and hexagonal tungsten diselenide, and the preset temperature is greater than 900° C. and less than or equal to 1500° C.

[0069] Exemplarily, the metal chalcogenide in the metal chalcogenide single crystal film is at least one of hexagonal molybdenum disulfide, hexagonal molybdenum diselenide, hexagonal tungsten disulfide and hexagonal tungsten diselenide, and the preset temperature is any one of 905°C, 920°C, 950°C, 970°C, 980°C, 1500°C or between any two values.

[0070] (a5) The metal chalcogenide compound in the metal chalcogenide single crystal film is hexagonal niobium disulfide and / or hexagonal niobium diselenide, and the preset temperature is greater than 850° C. and less than or equal to 1200° C.

[0071] Exemplarily, the metal chalcogenide in the metal chalcogenide single crystal film is hexagonal niobium disulfide and / or hexagonal niobium diselenide, and the preset temperature is any value among 855°C, 890°C, 900°C, 920°C, 950°C, 980°C, 1200°C or between any two values.

[0072] That is, different preset temperatures can be accurately selected for different phase structures and different metal chalcogenides, which is conducive to the preparation of metal chalcogenide single crystal films with high uniformity, high quality, wafer level, pure phase, and controllable thickness.

[0073] In some optional embodiments, the heating rate is 5°C / min-100°C / min.

[0074] The above-mentioned heating rate range is conducive to controlling the release rate of the target metal in the growth substrate during the heating process.

[0075] Illustratively, the heating rate is any value of 5°C / min, 10°C / min, 30°C / min, 50°C / min, 70°C / min, 100°C / min, or between any two values.

[0076] It should be noted that the growth substrate can be purchased directly from the market or prepared by oneself.

[0077] In some optional embodiments, as shown in FIG1 , the growth substrate is prepared by the following steps:

[0078] A target metal foil (denoted as M foil in FIG1 ) made of a target metal is laminated to a single crystal nickel foil and annealed at 1100° C. to 2000° C. for 2 h to 50 h in an inert atmosphere;

[0079] The thickness of the single crystal nickel foil is greater than the thickness of the target metal foil.

[0080] The inert atmosphere includes a nitrogen atmosphere and / or an argon atmosphere.

[0081] Since the thickness of the single crystal nickel foil is greater than that of the target metal foil, the two are controlled to be annealed at 1100℃-2000℃ for 2h-50h after bonding, which is beneficial for diffusing the transition metal elements in the target metal foil, such as the transition metal foil, into the single crystal nickel foil to dope it, and is also beneficial for maintaining the single crystal nature of the doped single crystal nickel foil.

[0082] Illustratively, in the step of preparing the growth substrate, the annealing temperature is any one of 1100° C., 1225° C., 1250° C., 1750° C., 1200° C., 1225° C., 1250° C., 1275° C., 1300° C., 1325° C., 1350° C., 1375° C., 1400° C., 1450° C., 1500° C., and 2000° C., or between any two values. Illustratively, the annealing time is any one of 2 h, 6 h, 7 h, 8 h, 9 h, 10 h, 13 h, 15 h, 40 h, and 50 h, or between any two values.

[0083] Optionally, the annealing temperature used in the step of preparing the growth substrate is 1100-1500°C.

[0084] Optionally, the thickness of the single crystal nickel foil is 10 μm-10 cm, and the thickness of the target metal foil is 500 nm-5 cm.

[0085] Controlling the thickness of the single crystal nickel foil and the target metal foil within the above range is beneficial to fully diffuse the target metal in the target metal foil into the single crystal nickel foil to dope it within the above annealing temperature and time, and is also beneficial to maintaining the single crystal nature of the doped single crystal nickel foil.

[0086] Illustratively, the thickness of the single crystal nickel foil is any value of 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 5 cm, 10 cm, or between any two values.

[0087] Illustratively, the target metal foil has a thickness of any value of 500 nm, 700 nm, 1 μm, 10 μm, 30 μm, 50 μm, 80 μm, 100 μm, 130 μm, 150 μm, 180 μm, or 5 cm, or between any two values.

[0088] It should be noted that in the preparation process of the growth substrate, single crystal nickel foil can be purchased directly from the market, or polycrystalline nickel foil can be obtained by high-temperature heat treatment. The temperature and time of the high-temperature heat treatment can refer to relevant technologies and are not limited here.

[0089] It can be understood that the preparation process of the growth substrate also includes a supporting substrate, wherein the single crystal nickel foil and the target metal foil are bonded, and the supporting substrate can be bonded to the side of the single crystal nickel foil facing away from the target metal foil, or the supporting substrate can be bonded to the side of the target metal foil facing away from the single crystal nickel foil, wherein the supporting substrate is a refractory material, and the refractoriness of the supporting substrate is greater than the annealing temperature. The supporting substrate includes but is not limited to a corundum substrate or a quartz substrate. The choice of the substrate can be selected according to the annealing temperature. Exemplarily, the supporting substrate is a corundum substrate.

[0090] In some optional embodiments, the target metal foil is Mo foil or W foil, and the annealing temperature is 1100° C.-2000° C.; or,

[0091] The target metal foil is Nb foil, and the annealing temperature is 1100°C-1600°C.

[0092] That is, different annealing temperatures can be accurately selected for different target metal foils, which is conducive to the target metal fully diffusing into the single crystal nickel foil for doping, and is also conducive to maintaining the single crystal nature of the doped single crystal nickel foil.

[0093] Illustratively, the target metal foil is Mo foil or W foil, and the annealing temperature is any one of 1100° C., 1300° C., 1325° C., 1350° C., 1375° C., 1400° C., 1500° C., and 2000° C., or between any two values.

[0094] Illustratively, the target metal foil is Nb foil, and the annealing temperature is any one of 1100° C., 1200° C., 1225° C., 1250° C., 1275° C., 1300° C., 1325° C., 1350° C., 1375° C., and 1600° C., or between any two values.

[0095] The metal chalcogenide sheet refers to a material prepared from a metal chalcogenide compound and having a macroscopically flake-like shape.

[0096] The metal chalcogenide sheet includes a metal sulfide sheet, a metal selenide sheet, a metal telluride sheet, or a mixed pressed sheet of at least two of the two. The metal sulfide sheet includes, but is not limited to, a ZnS sheet, and may also be a CdS sheet. The metal selenide sheet includes, but is not limited to, a ZnSe sheet, and may also be a CdSe sheet. The metal telluride sheet includes, but is not limited to, a ZnTe sheet, and may also be a CdTe sheet.

[0097] In some optional embodiments, the metal chalcogenide sheet includes a ZnS sheet, a ZnSe sheet, a ZnTe sheet, a CdS sheet, a CdSe sheet, a CdTe sheet, or a mixed pressed sheet of at least two of the above.

[0098] The above-mentioned metal sulfide sheets are easy to obtain and can slowly release chalcogenides at a preset temperature to react with the target metal element and continuously produce multi-layer stacked metal chalcogenide single crystal grains, which is conducive to obtaining metal chalcogenide single crystal films with high uniformity, high quality, wafer level, pure phase and controllable thickness.

[0099] In some optional embodiments, the growth module further includes a high temperature resistant substrate, which is bonded to a side of the metal chalcogenide compound sheet facing away from the growth substrate, and the refractoriness of the high temperature resistant substrate is greater than a preset temperature.

[0100] Since the refractoriness of the high-temperature substrate is greater than the preset temperature, the high-temperature resistant substrate is bonded to the side of the metal chalcogenide compound sheet facing away from the growth substrate. On the one hand, this can support the metal chalcogenide compound sheet so that the side of the growth substrate facing away from the metal chalcogenide compound sheet can be exposed to an inert atmosphere. On the other hand, the bonding method, that is, the face-to-face contact method, is also conducive to uniform heating of the metal chalcogenide compound sheet, which is conducive to the preparation of metal chalcogenide compound single crystal thin films with high uniformity, high quality, wafer level, pure phase, and controllable thickness.

[0101] It should be noted that the high temperature resistant substrate includes but is not limited to a corundum substrate or a quartz substrate. The choice of substrate can be selected according to the annealing temperature. For example, a quartz substrate or a corundum substrate is selected when the temperature is 700-1150°C, and a corundum substrate is selected when the annealing temperature is 1150-1450°C.

[0102] Some embodiments of the present disclosure further provide a field effect transistor comprising the metal chalcogenide single crystal thin film provided by the above embodiments.

[0103] Some embodiments of the present disclosure further provide an optoelectronic device or a micro-nanoelectronic device, which includes the metal chalcogenide single crystal thin film provided by the above embodiments.

[0104] The metal chalcogenide single crystal thin film and its preparation method disclosed in the present invention are further described in detail below with reference to the examples.

[0105] Example 1

[0106] This embodiment provides a method for preparing a metal chalcogenide single crystal thin film, which includes the following steps:

[0107] 1. A single crystal Ni foil with a thickness of 100 μm and a Mo foil with a thickness of 10 μm were laminated and annealed at 1300 °C for 8 h to obtain a Mo-doped single crystal Ni foil, wherein the Mo-doped single crystal Ni foil was a square foil with a side length of 4 cm.

[0108] 2. The Mo-doped single crystal Ni foil, ZnS sheet, and corundum substrate are laminated in sequence to obtain a growth module.

[0109] 3. Place the growth module in a tubular furnace with the Mo-doped single-crystalline Ni foil located above the ZnS sheet. The surface of the Mo-doped single-crystalline Ni foil facing away from the ZnS sheet is not blocked and exposed to the tubular furnace. Maintain a normal-pressure nitrogen atmosphere in the tubular furnace, raise the temperature to 800°C at a rate of 20°C / min and keep it warm for 10 minutes. Stop heating and maintain a normal-pressure nitrogen atmosphere in the tubular furnace for natural cooling to obtain a MoS2 single-crystalline thin film on the single-crystalline Ni foil.

[0110] FIG2 is a physical photograph of the directly prepared MoS2 single crystal film. It can be seen from FIG2 that the size of the MoS2 single crystal film reaches 4 cm.

[0111] Figure 3 is an optical microscope image of the prepared MoS2 single crystal film. Parts a, b, c, and d in Figure 3 represent optical microscope images of the MoS2 single crystal film at different positions. It can be seen that the MoS2 single crystal film has no impurity phase and a pure MoS2 single crystal material is obtained.

[0112] FIG4 is a characterization diagram of the single crystal and stacking mode of the MoS2 single crystal film, wherein part a in FIG4 is the electron backscattered diffraction pattern (EBSD) of the MoS2 single crystal film in the y direction and the z direction, wherein IPFY represents the electron backscattered diffraction pattern of the MoS2 single crystal film in the y direction, and IPFZ represents the electron backscattered diffraction pattern of the MoS2 single crystal film in the z direction. According to part a in FIG4, it can be shown that the MoS2 prepared in Example 1 is a single crystal in the z direction, has no crystal plane rotation in the plane, and has good single crystallinity. Part b in FIG4 is the selected area electron diffraction pattern of the MoS2 single crystal film, part c in FIG4 is the planar atomic structure diagram of the MoS2 single crystal film, and part d in FIG4 is the cross-sectional atomic structure diagram of the MoS2 single crystal film. Combined with parts b, c, and d in FIG4, it can be shown that the MoS2 prepared in Example 1 is a pure rhombohedral phase.

[0113] Example 2

[0114] This embodiment provides a method for preparing a metal chalcogenide single crystal thin film, which differs from the embodiment 1 only in that:

[0115] 2. The Mo-doped single crystal Ni foil, ZnSe sheet, and corundum substrate are laminated in sequence to obtain a growth module.

[0116] 3. Place the growth module in a tubular furnace with the Mo-doped single-crystalline Ni foil located above the ZnSe sheet. The surface of the Mo-doped single-crystalline Ni foil facing away from the ZnSe sheet is not blocked and exposed to the tubular furnace. Maintain a normal-pressure nitrogen atmosphere in the tubular furnace, raise the temperature to 800°C at a rate of 20°C / min and keep it there for 10 minutes. Stop heating and maintain a normal-pressure nitrogen atmosphere in the tubular furnace for natural cooling to obtain a MoSe2 single-crystalline thin film on the single-crystalline Ni foil.

[0117] Example 3

[0118] This embodiment provides a method for preparing a metal chalcogenide single crystal thin film, which includes the following steps:

[0119] 1. A single crystal Ni foil with a thickness of 100 μm and a W foil with a thickness of 10 μm were bonded and annealed at 1300 °C for 8 h to obtain a W-doped single crystal Ni foil, wherein the W-doped single crystal Ni foil was a square foil with a side length of 4 cm.

[0120] 2. Lay the W-doped single crystal Ni foil, ZnS sheet, and corundum substrate together in sequence to obtain a growth module.

[0121] 3. Place the growth module in a tubular furnace, with the W-doped single-crystalline Ni foil located above the ZnS sheet. The surface of the W-doped single-crystalline Ni foil facing away from the ZnS sheet is not blocked and exposed to the tubular furnace. Maintain a normal-pressure nitrogen atmosphere in the tubular furnace, raise the temperature to 900°C at a rate of 20°C / min and keep warm for 10 minutes. Stop heating and maintain a normal-pressure nitrogen atmosphere in the tubular furnace for natural cooling to obtain a WS2 single-crystalline thin film on the single-crystalline Ni foil.

[0122] Example 4

[0123] This embodiment provides a method for preparing a metal chalcogenide single crystal thin film, which differs from embodiment 3 only in that:

[0124] 2. Lay the W-doped single crystal Ni foil, ZnSe sheet, and corundum substrate together in sequence to obtain a growth module.

[0125] 3. Place the growth module in a tubular furnace, with the W-doped single-crystalline Ni foil located above the ZnSe sheet. The surface of the W-doped single-crystalline Ni foil facing away from the ZnSe sheet is not blocked and exposed to the tubular furnace. Maintain a normal-pressure nitrogen atmosphere in the tubular furnace, raise the temperature to 900°C at a rate of 20°C / min and keep it warm for 5 minutes. Stop heating and maintain a normal-pressure nitrogen atmosphere in the tubular furnace for natural cooling to obtain a WSe2 single-crystalline thin film on the single-crystalline Ni foil.

[0126] Example 5

[0127] This embodiment provides a method for preparing a metal chalcogenide single crystal thin film, which includes the following steps:

[0128] 1. A single crystal Ni foil with a thickness of 100 μm and a Nb foil with a thickness of 10 μm were laminated and annealed at 1350°C for 8 h to obtain a Nb-doped single crystal Ni foil, wherein the Nb-doped single crystal Ni foil was a square foil with a side length of 4 cm.

[0129] 2. Lay Nb-doped single crystal Ni foil, ZnS sheet, and corundum substrate together in sequence to obtain a growth module.

[0130] 3. Place the growth module in a tubular furnace with the Nb-doped single-crystalline Ni foil located above the ZnS sheet. The surface of the Nb-doped single-crystalline Ni foil facing away from the ZnS sheet is not blocked and exposed to the tubular furnace. Maintain a normal-pressure nitrogen atmosphere in the tubular furnace, raise the temperature to 800°C at a rate of 20°C / min and keep it there for 2 minutes. Stop heating and maintain a normal-pressure nitrogen atmosphere in the tubular furnace for natural cooling to obtain a NbS2 single crystal thin film on the single-crystalline Ni foil.

[0131] Example 6

[0132] This embodiment provides a method for preparing a metal chalcogenide single crystal thin film, which differs from embodiment 5 only in that:

[0133] 2. Lay Nb-doped single crystal Ni foil, ZnSe sheet, and corundum substrate together in sequence to obtain a growth module.

[0134] 3. Place the growth module in a tubular furnace with the Nb-doped single-crystalline Ni foil located above the ZnSe sheet. The surface of the Nb-doped single-crystalline Ni foil facing away from the ZnSe sheet is not blocked and exposed to the tubular furnace. Maintain a normal-pressure nitrogen atmosphere in the tubular furnace, raise the temperature to 800°C at a rate of 20°C / min and keep it there for 2 minutes. Stop heating and maintain a normal-pressure nitrogen atmosphere in the tubular furnace for natural cooling to obtain a NbSe2 single-crystalline thin film on the single-crystalline Ni foil.

[0135] Example 7

[0136] This embodiment provides a method for preparing a metal chalcogenide single crystal thin film, which differs from the embodiment 1 only in that:

[0137] 2. The Mo-doped single crystal Ni foil, ZnS / ZnSe mixed pressed sheet, and corundum substrate are laminated in sequence to obtain a growth module.

[0138] 3. Place the growth module in a tube furnace, with the Mo-doped single crystal Ni foil located above the ZnS / ZnSe mixed pressed sheet. The surface of the Mo-doped single crystal Ni foil facing away from the ZnS / ZnSe mixed pressed sheet is not blocked and exposed to the tube furnace. Maintain the tube furnace in a normal pressure nitrogen atmosphere, heat it to 800°C at a rate of 20°C / min and hold it for 10 minutes. Stop heating and keep the tube furnace in a normal pressure nitrogen atmosphere for natural cooling to obtain MoS on the single crystal Ni foil. 2(1-x) Se 2x Single crystal thin film.

[0139] FIG5 is an electron diffraction pattern and a corresponding atomic structure characterization diagram of each metal chalcogenide single crystal thin film prepared in Examples 2-7. According to FIG5 , it can be seen that each metal chalcogenide single crystal thin film is a pure rhombohedral phase single crystal thin film.

[0140] FIG6 is an optical microscope image of each metal sulfide compound single crystal thin film prepared in Examples 2-7. It can be seen that the surface of each metal sulfide compound single crystal thin film is clean and free of impurities. Combining FIG5 and FIG6, it can be seen that Examples 2-7 produced highly uniform, high-quality, wafer-level, pure-phase rhombohedral transition metal sulfide compound single crystal thin films.

[0141] Example 8

[0142] This embodiment provides a method for preparing a metal chalcogenide single crystal thin film, which differs from embodiment 4 only in that:

[0143] 3. Place the growth module in a tubular furnace, with the W-doped single-crystalline Ni foil located above the ZnSe sheet. The surface of the W-doped single-crystalline Ni foil facing away from the ZnSe sheet is not blocked and exposed to the tubular furnace. Maintain the tubular furnace at a normal pressure nitrogen atmosphere, raise the temperature to 950°C at a rate of 20°C / min and keep warm for 5 minutes. Stop heating and maintain the tubular furnace at a normal pressure nitrogen atmosphere for natural cooling to obtain a WSe2 single crystal thin film located on the single-crystalline Ni foil.

[0144] Figure 7 is a performance characterization diagram of the WSe2 single crystal film obtained in Example 8, wherein part a in Figure 7 represents the SEM image of the WSe2 single crystal film, part b in Figure 7 represents the planar atomic structure, and part c in Figure 7 represents the electron diffraction pattern. It can be seen from Figure 7 that the phase structure of the WSe2 single crystal is a hexagonal phase.

[0145] Comparative Example 1

[0146] For the convenience of comparison, two Mo-doped single-crystal Ni foils of the same specifications were used. One foil was used with a ZnS sheet to prepare MoS2 single crystals according to the preparation method of Example 1, and the other foil was used with an elemental sulfur sheet to prepare MoS2 single crystals according to the preparation method of Example 1, as Comparative Example 1.

[0147] The results are shown in Figure 8. Figure 8 is a physical comparison of MoS2 prepared using ZnS and elemental sulfur in Comparative Example 1, wherein part a in Figure 8 shows a physical picture of the Mo-doped single-crystalline Ni foil used and its specifications, part b in Figure 8 shows a physical picture of the MoS2 single crystal grown using a ZnS sheet, and part c in Figure 8 shows a physical picture of the MoS2 grown using an elemental sulfur sheet. It can be seen from Figure 8 that using an elemental sulfur sheet to grow MoS2 will cause the Mo-doped single-crystalline Ni foil to be severely damaged, making it impossible to prepare a MoS2 single crystal.

[0148] In summary, the preparation method provided by the present disclosure has a simple and easy process flow and can realize the batch preparation of metal sulfide compound single crystal films. The prepared metal sulfide compound single crystal films have the advantages of large size, high quality, phase purity, high uniformity and controllable thickness.

[0149] The foregoing description is merely a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Those skilled in the art will readily appreciate that the present disclosure may be modified and varied in various ways. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present disclosure shall be included within the scope of protection of the present disclosure. Industrial Applicability

[0150] The present disclosure provides a metal chalcogenide single crystal thin film and a preparation method thereof, which can be mass-produced to obtain wafer-level, phase-pure, and thickness-controllable metal chalcogenide single crystal thin films. This preparation method has a simple and easy process flow and enables the mass production of metal chalcogenide single crystal thin films. Furthermore, the prepared metal chalcogenide single crystal thin films exhibit the advantages of large size, high quality, phase purity, high uniformity, and controllable thickness, and have promising industrial application prospects.

Claims

1. A metal chalcogenide single crystal thin film, characterized in that: The invention comprises multiple layers of rhombohedral or hexagonal metal chalcogenide compound single crystal grains stacked in sequence, wherein the metal chalcogenide compound single crystal grains in each layer are unidirectionally oriented, and the unidirectional orientation directions of any two adjacent layers of the metal chalcogenide compound single crystal grains are parallel.

2. The metal chalcogenide single crystal thin film according to claim 1, characterized in that The metal chalcogenide compound includes at least one of a transition metal chalcogenide compound and a derivative thereof.

3. The metal chalcogenide single crystal thin film according to claim 1 or 2, characterized in that: The transition metal chalcogenide comprises at least one of sulfides, selenides and tellurides corresponding to titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, cobalt, rhodium, iridium, palladium, platinum, chromium, manganese and iron; derivatives of the transition metal chalcogenide comprise multi-component alloys and / or heterojunction structures containing the transition metal chalcogenide.

4. The metal chalcogenide single crystal thin film according to any one of claims 1 to 3, characterized in that: The transition metal chalcogenides include MoS2, MoSe2, WS2, WSe2, NbS2, NbSe2, MoS 2-2x Se 2x , WS 2-2x Se 2x 、NbS 2-2x Se 2x 、Mo 1-x Nb x S2、Mo 1-x W x At least one of S2, where 0<x<1.

5. The metal chalcogenide single crystal thin film according to any one of claims 1 to 4, characterized in that: The phase structure of each layer of the metal chalcogenide single crystal grains is a rhombohedral phase.

6. The metal chalcogenide single crystal thin film according to any one of claims 1 to 5, characterized in that: The thickness of the metal chalcogenide single crystal thin film is 0.65 nm to 1 cm, and the size is 1 μm to 1 m.

7. The method for preparing a metal chalcogenide single crystal thin film according to any one of claims 1 to 6, wherein: include: Using a single crystal substrate doped with a target metal as a growth substrate, laminating the growth substrate to a metal chalcogenide sheet to obtain a growth module, wherein the target metal includes a transition metal; Placing the growth module in an inert atmosphere, exposing the side of the growth substrate facing away from the metal chalcogenide compound sheet to the inert atmosphere, heating the substrate to a preset temperature and maintaining the temperature for 1 minute to 1000 hours, to obtain the metal chalcogenide compound single crystal thin film formed by the target metal and the chalcogen element in the metal chalcogenide compound sheet precipitating from the single crystal substrate and reacting on the substrate surface; Wherein, the preset temperature is 500°C-1500°C.

8. The preparation method according to claim 7, characterized in that The preset temperature satisfies any one of (a1) to (a5): (a1) the metal chalcogenide in the metal chalcogenide single crystal thin film is rhombohedral molybdenum disulfide and / or rhombohedral molybdenum diselenide, and the preset temperature is 650° C.-900° C.; (a2) the metal chalcogenide compound in the metal chalcogenide compound single crystal thin film is rhombohedral tungsten disulfide and / or rhombohedral tungsten diselenide, and the preset temperature is 700° C.-950° C.; (a3) the metal chalcogenide compound in the metal chalcogenide single crystal thin film is rhombohedral niobium disulfide and / or rhombohedral niobium diselenide, and the preset temperature is 500° C.-850° C.; (a4) the metal chalcogenide compound in the metal chalcogenide single crystal thin film is at least one of hexagonal molybdenum disulfide, hexagonal molybdenum diselenide, hexagonal tungsten disulfide, and hexagonal tungsten diselenide, and the preset temperature is greater than 900° C. and less than or equal to 1500° C.; (a5) The metal chalcogenide compound in the metal chalcogenide single crystal thin film is hexagonal niobium disulfide and / or hexagonal niobium diselenide, and the preset temperature is greater than 850° C. and less than or equal to 1200° C.

9. The preparation method according to claim 7 or 8, characterized in that The heating rate is 5°C / min-100°C / min.

10. The preparation method according to any one of claims 7 to 9, characterized in that: The heating rate is 10°C / min-30°C / min.

11. The preparation method according to any one of claims 7 to 10, characterized in that: The holding time after heating to the preset temperature is 2 minutes to 10 minutes.

12. The preparation method according to any one of claims 7 to 11, characterized in that: The growth substrate is prepared by the following steps: laminating a target metal foil composed of the target metal to a single crystal nickel foil, and annealing them in an inert atmosphere; Wherein, the thickness of the single crystal nickel foil is greater than the thickness of the target metal foil.

13. The preparation method according to any one of claims 7 to 12, characterized in that: The thickness of the single crystal nickel foil is 10 μm-10 cm, and the thickness of the target metal foil is 500 nm-5 cm.

14. The preparation method according to any one of claims 7 to 13, characterized in that: The annealing temperature is 1100°C-2000°C, and the annealing time is 2h-50h.

15. The preparation method according to claim 14, characterized in that The target metal foil is Mo foil or W foil, and the annealing temperature is 1100° C.-2000° C.; or, The target metal foil is Nb foil, and the annealing temperature is 1100° C.-1600° C.

16. The preparation method according to any one of claims 7 to 15, characterized in that: The metal chalcogenide sheet includes a ZnS sheet, a ZnSe sheet, a ZnTe sheet, a CdS sheet, a CdSe sheet, a CdTe sheet, or a mixed pressed sheet of at least two of them.

17. The preparation method according to any one of claims 7 to 16, characterized in that: The growth module further includes a high temperature resistant substrate, which is bonded to a side of the metal chalcogenide compound sheet facing away from the growth substrate, and the refractoriness of the high temperature resistant substrate is greater than the preset temperature.

18. A field effect transistor, characterized in that: The invention comprises the metal chalcogenide single crystal thin film according to any one of claims 1 to 6.

19. A photoelectric device, characterized in that: The invention comprises the metal chalcogenide single crystal thin film according to any one of claims 1 to 6.

20. A micro-nanoelectronic device, characterized in that: The invention comprises the metal chalcogenide single crystal thin film according to any one of claims 1 to 6.

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