Luminescent device containing molybdenum disulfide (MoS2) heterojunction and preparation method thereof

Abstract

The invention provides a light-emitting device containing a molybdenum disulfide (MoS2) heterojunction and a preparation method of the MoS2 heterojunction. The MoS2 heterojunction comprises a substrate, a heterojunction bottom layer material layer and a single-layer and multi-layer combined MoS2 structure. The heterojunction bottom layer material layer is arranged on the surface of one side of the substrate; the combined MoS2 structure is arranged on the side, away from the substrate, of the heterojunction bottom layer material layer, and the combined MoS2 structure comprises a first single-layer MoS2 and multiple layers of MoS2 formed in a partial region of the first single-layer MoS2. By adopting the scheme, the inherent low fluorescence luminous intensity of the single-layer MoS2 in the luminescent device can be improved.

Description

Technical Field

[0001] This application relates to the field of light-emitting devices, and particularly to a light-emitting device including a molybdenum disulfide (MoS2) heterojunction and a preparation method of the MoS2 heterojunction. Background Art

[0002] Molybdenum disulfide (MoS2) is a representative of transition metal dichalcogenides, having excellent physical and chemical properties and broad application prospects in the fields of nanoelectronics and optoelectronics. Among them, monolayer MoS2 is a direct-bandgap semiconductor with a large exciton binding energy and is a good material for preparing light-emitting devices. However, the ultra-thin thickness and limited spectral modulation of monolayer MoS2 limit the light-matter interaction thereof, hindering light absorption and quantum emission. Moreover, restricted and affected by the preparation method and the substrate, the intrinsic defects of the material and the impurity scattering at the interface during the synthesis process hinder the radiative recombination of MoS2 excitons, and the resulting inherently low photoluminescence (PL) intensity limits its application in nanophotonic devices.

[0003] Currently, methods such as external doping, surface plasmon resonance effect, and interface engineering are used to enhance the photoluminescence intensity of MoS2. Among them, interface engineering in van der Waals heterostructures stands out as a stable, low-cost, and clean method. Taking MoS2 as an example, during the process of constructing a van der Waals heterojunction, good van der Waals interaction and interfacial charge transfer will be formed between MoS2 and the combined two-dimensional material at the interface. This charge transfer modulates the energy band structure of MoS2, making the radiative recombination of excitons dominant, thereby increasing the PL intensity.

[0004] For van der Waals heterostructures, vertical stacking and lateral stitching are two typical assembly modes, and the energy dissipation pathway in the heterostructure determines the performance threshold of the device. In the vertical stacking structure, although it has a large interface area, the long distance of the charge transfer channel and the high van der Waals energy barrier make it less efficient in increasing the PL intensity. At the same time, in the lateral heterojunction, thanks to the seamless atomic-level bonding interface, the spontaneous diffusion of electrons can effectively achieve Fermi level equilibrium, but the small interface area limits the effective transport of excitons. Therefore, the regulation of a single dimension has a regulation threshold limitation, which hinders the improvement of the photoluminescence intensity. Summary of the Invention

[0005] This application provides a light-emitting device including a MoS2 heterojunction and a preparation method of the MoS2 heterojunction to solve the above technical problems in the prior art.

[0006] According to the first aspect of this application, there is provided a light-emitting device including a MoS2 heterojunction, and the MoS2 heterojunction includes:

[0007] A substrate;

[0008] A heterojunction bottom material layer, the heterojunction bottom material layer is disposed on one surface of the substrate;

[0009] A combined MoS2 structure of monolayer and multilayer, the combined MoS2 structure is disposed on the side of the heterojunction bottom material layer facing away from the substrate, and the combined MoS2 structure includes a first monolayer MoS2 and a multilayer MoS2 formed in a partial region of the first monolayer MoS2.

[0010] In some embodiments, the heterojunction bottom material layer is a CrOCl thin film.

[0011] In some embodiments, the substrate is a P-type doped SiO2 / Si substrate.

[0012] In some embodiments, along the thickness direction of the substrate, the multilayer MoS2 is stacked on the first monolayer MoS2.

[0013] In some embodiments, the above-mentioned light-emitting device including the MoS2 heterojunction further includes: a second monolayer MoS2 and a conductive bridge;

[0014] The second monolayer MoS2 is disposed on the side of the heterojunction bottom material layer facing away from the substrate and is connected to the combined MoS2 structure through the conductive bridge.

[0015] In some embodiments, the material of the conductive bridge includes: Cr and Au.

[0016] In some embodiments, the conductive bridge includes: a Cr-containing layer of 5 nm to 7 nm and an Au-containing layer of 50 nm to 70 nm, wherein the Cr-containing layer is disposed on the lower layer of the conductive bridge, close to the substrate side, and the Au-containing layer is disposed on the upper layer of the conductive bridge, away from the substrate side.

[0017] According to the second aspect of the present application, there is provided a method for preparing a MoS2 heterojunction for preparing the MoS2 heterojunction of the above-mentioned light-emitting device, and the method includes the following steps:

[0018] MoS2 generation step: At least generate the combined MoS2 structure of monolayer and multilayer on a preset substrate by a surface deposition method using sulfur powder and MoO3;

[0019] Bottom layer setting step: Set the heterojunction bottom material layer on one surface of the substrate;

[0020] Transfer step: Separate the combined MoS2 structure of monolayer and multilayer from the preset substrate and transfer it to the side surface of the heterojunction bottom material layer facing away from the substrate, and complete the heterostructure manufacturing through thermal release.

[0021] In some embodiments, the MoS2 generation step is further used to generate a second monolayer MoS2;

[0022] The transfer step further includes: separating the second monolayer MoS2 from the preset substrate and transferring it to a surface of the heterojunction bottom layer material layer facing away from the substrate.

[0023] In some embodiments, the method further includes:

[0024] Preparing the conductive bridge by using electron beam lithography and electron beam evaporation procedures, and connecting the second monolayer MoS2 to the combined MoS2 structure through the conductive bridge.

[0025] In some embodiments, the MoS2 generation step includes:

[0026] Placing the preset substrate downstream of the deposition system and heating the temperature to a first preset temperature;

[0027] Carrying sulfur powder in the main pipe of the deposition system with argon at a second preset temperature;

[0028] When heating the microtube of the deposition system to a third preset temperature, carrying MoO3 in the microtube with argon, and continuing to heat the microtube to a fourth preset temperature;

[0029] Waiting for a preset reaction duration to obtain at least the combined MoS2 structure.

[0030] In some embodiments, the carrying of sulfur powder in the main pipe of the deposition system with argon at a second preset temperature includes:

[0031] Carrying sulfur powder in the main pipe of the deposition system with argon at a rate of 100 standard cubic centimeters per minute at a second preset temperature.

[0032] In some embodiments, the preset duration is 10 minutes.

[0033] In some embodiments, the surface deposition method uses chemical vapor deposition.

[0034] In summary, the light-emitting device including the MoS2 heterojunction and the preparation method of the MoS2 heterojunction provided by the present application at least have the following beneficial effects:

[0035] By disposing a combined MoS2 structure including a first monolayer MoS2 and a multilayer MoS2 on the surface of the bottom layer material of the heterojunction facing away from the substrate, a van der Waals heterostructure is formed. The bottom layer material of the heterojunction and MoS2 are vertically arranged correspondingly, and the combined MoS2 structure of the first monolayer MoS2 and the multilayer MoS2 is horizontally arranged correspondingly. By using the hybrid interface of horizontal and vertical arrangements, beyond the limitations of traditional single horizontal and vertical heterostructures, the inherent low photoluminescence (PL) intensity of monolayer MoS2 can be improved. Description of the Drawings

[0036] To more clearly illustrate the technical solutions in the specific embodiments of the present application, the following will briefly introduce the drawings required to be used in the specific embodiments in conjunction with the drawings. Obviously, the drawings in the following description are some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings or solutions can also be obtained based on these drawings.

[0037] Figure 1 Schematic diagram of the structure of the MoS2 heterojunction in an embodiment of the present application;

[0038] Figure 2 Schematic diagram of the vertical configuration of the MoS2 heterojunction in an embodiment of the present application;

[0039] Figure 3 (a) is a light microscope comparison diagram;

[0040] Figure 3 (b) is Figure 3 PL intensity comparison diagram of three 1L-MoS2 in (a);

[0041] Figure 3 (c) is Figure 3 PL intensity curve comparison diagram of three 1L-MoS2 in (a);

[0042] Figure 4 (d) is a light microscope comparison diagram before and after bridging with an Au bridge;

[0043] Figure 4 (e) is a PL intensity comparison diagram before and after bridging with an Au bridge;

[0044] Figure 4 (f) is a PL intensity curve comparison diagram;

[0045] Figure 5 Flow chart of the preparation method of the MoS2 heterojunction in an embodiment of the present application. Detailed Embodiments

[0046] To make the above and other features and advantages of the present application more clear, the present application will be further described below with reference to the accompanying drawings. It should be understood that the specific embodiments given herein are for the purpose of explaining to those skilled in the art and are merely exemplary, rather than restrictive.

[0047] In the following description, many specific details are set forth to provide a thorough understanding of the present application. However, it is obvious to those skilled in the art that specific details are not required to practice the present application. In other cases, well-known steps or operations are not described in detail to avoid obscuring the present application.

[0048] As described in the background art, existing single-layer MoS2 has the problem of low PL intensity. Based on this, the present application provides a light-emitting device including a MoS2 heterojunction with horizontal and vertical configurations.

[0049] Referring to Figure 1 , the present application provides a light-emitting device including a MoS2 heterojunction, wherein the MoS2 heterojunction includes: a substrate 10, a heterojunction bottom material layer 20, and a combined single-layer and multi-layer MoS2 structure. Among them, the combined single-layer and multi-layer MoS2 structure is the ML-1L MoS2 structure, where ML represents multi-layer and 1L represents single-layer; as Figure 1 , the combined MoS2 structure includes a first single-layer MoS2 31 and a multi-layer MoS2 32 formed in a partial region of the first single-layer MoS2 31. The heterojunction bottom material layer 20 is disposed on one side surface of the substrate 10; the combined MoS2 structure is disposed on the side of the heterojunction bottom material layer 20 away from the substrate 10. Specifically, the multi-layer MoS2 32 formed in a partial region of the first single-layer MoS2 31 is stacked in a direction away from the substrate 10 along the thickness direction of the substrate 10.

[0050] In the combined single-layer and multi-layer MoS2 structure, the first single-layer MoS2 31 at the bottom is close to the heterojunction bottom material layer 20, and the multi-layer MoS2 32 is formed in a partial region of the first single-layer MoS2 31. For example Figure 1 as shown, the multi-layer MoS2 32 is formed at one side edge of the first single-layer MoS2 31. It can be understood that the multi-layer MoS2 32 can also be formed in other regions of the first single-layer MoS2 31 and is randomly generated by the surface deposition method for growing the combined MoS2 structure.

[0051] For example, a combined MoS2 structure of single-layer and multi-layer can be generated on a preset substrate by surface deposition method using sulfur powder and MoO3, and individual single-layer MoS2 without multi-layer MoS2 stacking can also be grown. Specifically, MoS2 is grown by CVD (Chemical Vapor Deposition) in a three-zone APCVD (Atmospheric Pressure Chemical Vapor Deposition) system. The operations include: loading 15 g of S (sulfur) powder with a purity of 99.995% into the main tube and carrier gas transporting it with 100 standard cubic centimeters per minute of argon gas (100 SCCM Ar); loading 50 mg of MoO3 powder with a purity of 99.95% into the microtube, heating it until the temperature of MoO3 reaches 550 °C and then carrier gas transporting it with 100 SCCM Ar; placing a clean SiO2 downstream as the preset substrate. Under the conditions that the temperatures of S powder, MoO3 and the preset substrate reach 200 °C, 580 °C and 750 °C respectively, the growth duration is maintained for 10 minutes, and then the furnace is naturally cooled to room temperature to grow the combined MoS2 structure, and individual single-layer MoS2 can also be grown.

[0052] The heterojunction bottom layer material layer 20 and the combined MoS2 structure form a van der Waals heterostructure. Taking the heterojunction bottom layer material layer 20 being CrOCl as an example, the charge transfer mechanism of the MoS2 heterojunction is as follows:

[0053] The band diagrams of CrOCl and MoS2 are calculated using DFT (First Principles). The valence band maximum (VBM) of CrOCl is higher than that of 1L-MoS2 (single-layer MoS2), while the conduction band minimum (CBM) of 1L-MoS2 is lower than that of CrOCl, where the van der Waals heterostructure forms a type-II heterointerface. The Fermi level of 1L-MoS2 is higher than that of CrOCl, prompting electrons to spontaneously enter the interface band of CrOCl from MoS2 until the Fermi levels are balanced. For the case of ML-1L MoS2 (a combined MoS2 structure of multi-layer MoS2 and single-layer MoS2), many reconstructed bonds at the edges of ML-MoS2 (multi-layer MoS2) result in the formation of metallic edge states within the bandgap of ML / 1L-MoS2. Due to the strong coupling interface and p-doping characteristics of CrOCl, the CrOCl substrate manipulates the carrier density in MoS2 and shifts the energy levels of the conduction band and valence band of 1L-MoS2 upward relative to its Fermi level, opening a new lateral electron transfer channel from ML to 1L-MoS2. This interlayer and intralayer cooperative doping effect, using a hybrid interface regulation technique with lateral and vertical configurations in the heterojunction, transcends the limitations of traditional single lateral and vertical heterostructures and realizes an enhancement of the PL intensity.

[0054] The above-mentioned light-emitting device including the MoS2 heterojunction forms a van der Waals heterostructure by setting a combined MoS2 structure including a first monolayer MoS2 31 and a multilayer MoS2 32 on the surface of the bottom material layer 20 of the heterojunction facing away from the substrate 10. The bottom material layer 20 of the heterojunction and MoS2 are vertically arranged correspondingly, and the combined MoS2 structure of the first monolayer MoS2 31 and the multilayer MoS2 32 is horizontally arranged correspondingly. Using the mixed interface of horizontal and vertical arrangements, beyond the limitations of traditional single horizontal and vertical heterostructures, the PL intensity of the monolayer MoS2 can be improved, thereby improving the light-emitting intensity of the light-emitting device.

[0055] Specifically, along the thickness direction of the substrate 10, the multilayer MoS2 32 is stacked on the first monolayer MoS2 31. For example Figure 1 In, 5 layers of MoS2 are stacked in sequence along the thickness direction of the substrate 10, and have a shape that is narrower at the top and wider at the bottom. It can be understood that the number of layers / thickness of the multilayer MoS2 32 can be other numbers of layers / thickness such as 4 layers, 6 layers, 7 layers, etc., and can also be other shapes, and the present application does not limit this.

[0056] In some embodiments, the substrate 10 is a P-type doped SiO2 / Si substrate. Refer to Figure 2 , Si is located at the bottom layer of the substrate 10, and SiO2 is located at the upper layer of the substrate 10, close to the bottom material layer 20 of the heterojunction. It can be understood that in other embodiments, the substrate 10 can also be made of other materials, such as an N-type doped substrate.

[0057] In some embodiments, the bottom material layer 20 of the heterojunction is a CrOCl thin film, so that CrOCl and MoS2 form a van der Waals heterostructure.

[0058] CrOCl is a low-symmetry vdW (two-dimensional van der Waals) antiferromagnetic insulator with a magnetoelectric effect. When it constructs a van der Waals heterostructure with MoS2, the carrier polarity of the insulating material can be effectively regulated through strong van der Waals interface coupling. At the same time, the field-effect transistor based on CrOCl has excellent electrical properties, such as the room-temperature hole mobility of the MoS2 / CrOCl transistor is as high as about 425 cm 2 V -1 s -1 , and the on-off ratio reaches 10 6, showing great potential in the applications of high-speed and high-performance electronic devices. Moreover, under conventional conditions such as normal temperature and pressure, CrOCl exhibits good chemical stability, providing a basis for its applications in various complex environments and enabling it to maintain its performance and structural integrity for a long time. Benefiting from the stable p-doping of monolayer MoS2 by CrOCl and the coupled synergistic regulation at the hybrid interface, more efficient regulation of charge transfer during the Fermi level equilibrium process is achieved, presenting an almost complete charge depletion phenomenon in monolayer MoS2.

[0059] It has been experimentally proven that for the MoS2 / CrOCl van der Waals heterostructure of the present application, the PL emission intensity has reached a 26.5-fold enhancement of the PL signal compared to the PL emission intensity of traditional monolayer MoS2. For example Figure 3 (a) shows that points q0, q1, and q2 respectively represent a position in 1L-MoS2 on SiO2, 1L-MoS2 on CrOCl, and 1L-MoS2 in the combined MoS2 structure on CrOCl. Laser irradiation is performed on the three 1L-MoS2, and the images under an optical microscope (OM) are as shown in Figure 3 (a), and the corresponding PL intensity mapping of the A-exciton (one of the intensity peaks in the PL image of MoS2) is as shown in Figure 3 (b), where brightness is used to reflect the intensity; the intensity curves at points q0, q1, and q2 are as shown in Figure 3 (c), and it can be clearly observed that the PL signal intensity of the monolayer MoS2 in the combined MoS2 structure on CrOCl is the strongest.

[0060] In some embodiments, the above MoS2 heterojunction further includes a second monolayer MoS2 and a conductive bridge. The second monolayer MoS2 is disposed on the side of the heterojunction bottom layer material layer 20 away from the substrate 10 and is connected to the combined MoS2 structure through the conductive bridge. That is, on one side surface of the same heterojunction bottom layer material layer 20, there is both a combined MoS2 structure and a second monolayer MoS2. The combined MoS2 structure and the second monolayer MoS2 are distributed at intervals and are connected through the conductive bridge. Among them, the second monolayer MoS2 is a single monolayer MoS2 without the stacking of multiple layers of MoS2. When using the surface deposition method to generate the combined MoS2 structure from sulfur powder and MoO3 on a preset substrate, a single monolayer MoS2 can also be grown.

[0061] Aiming at the problems of limited area and low quality of single-layer MoS2 films, this application designs a conductive bridge as a conductive channel to connect the combined MoS2 structure and the second single-layer MoS2. A significant PL transition from the "off state" to the "on state" is successfully generated in a single monolayer MoS2, realizing further expansion of in-plane charge transfer and a larger area of PL regulation effect, breaking through the in-plane covalent bonding in traditional lateral heterostructures, expanding the geometric stacking mode of the structure, increasing the PL intensity of single-layer MoS2, laying a foundation for the development of high-efficiency light-emitting devices based on single-layer MoS2, and contributing to the development of new and efficient MoS2 light-emitting devices.

[0062] In some embodiments, the material of the conductive bridge includes: Cr (chromium) and Au (gold). In micro- and nano-scale devices, obtaining an intuitive understanding of the charge transfer path is crucial for optimizing the device assembly structure and performance. Au is known for its low resistance and high reliability. Using Cr and Au as electrode materials, an Au bridge is made to bridge ML-1L MoS2 and single-layer MoS2, ensuring good electrical conductivity and reducing the Schottky barrier.

[0063] In some embodiments, the conductive bridge may include: a Cr-containing layer of 5 nm to 7 nm and an Au-containing layer of 50 nm to 70 nm. The Cr-containing layer is disposed on the lower layer of the conductive bridge, closer to the substrate side, and the Au-containing layer is disposed on the upper layer of the conductive bridge, farther from the substrate side.

[0064] For example, the conductive bridge may include: a Cr-containing layer of 5 nm and an Au-containing layer of 70 nm. Specifically, first, a layer of photoresist is spin-coated on the surfaces of the second single-layer MoS2 and the combined MoS2 structure, then a preset shape is obtained through electron beam lithography, a 5-nm Cr-containing layer and a 70-nm Au-containing layer are evaporated on the preset shape through electron beam evaporation, and after removing the photoresist, a conductive bridge that bridges the combined MoS2 structure and the second single-layer MoS2 is obtained.

[0065] For example, Figure 4 In (d), a light microscope image of the structure of single-layer MoS2 and the combined MoS2 structure on CrOCl before being bridged by an Au bridge and a light microscope image of the structure after being bridged by an Au bridge are shown. Laser irradiation is performed on the structure before bridging and the structure after bridging, and the respective PL intensity mappings are as Figure 4(e), where, before bridging, the individual monolayer MoS2 is in the "off state" and the combined MoS2 structure is in the "on state". After conduction through the Au bridge, both the individual monolayer MoS2 and the combined MoS2 structure are in the "on state". Bridging causes a significant PL transition from the "off state" to the "on state" in the monolayer MoS2. The PL intensities of the monolayer MoS2 before bridging on CrOCl, the monolayer MoS2 after bridging on CrOCl, and the monolayer MoS2 on SiO2 were compared, as Figure 4 (f) shows. It is clearly seen that the PL intensity of the monolayer MoS2 with the combined MoS2 bridged on CrOCl is greater than that of the unbridged monolayer MoS2, and the PL intensity of the unbridged monolayer MoS2 on CrOCl is greater than that of the monolayer MoS2 on SiO2.

[0066] This application also provides a method for preparing a MoS2 heterojunction for preparing the MoS2 heterojunction of the light-emitting devices in the above embodiments. Refer to Figure 5 , the method for preparing a MoS2 heterojunction includes the following steps:

[0067] MoS2 generation step S110: Using sulfur powder and MoO3, at least a combined structure of monolayer and multilayer MoS2 is generated on a preset substrate by surface deposition method.

[0068] Bottom layer setting step S130: Set the heterojunction bottom layer material layer on one surface of the substrate.

[0069] Transfer step S150: Separate the combined structure of monolayer and multilayer MoS2 from the preset substrate and transfer it to the surface of the heterojunction bottom layer material layer facing away from the substrate, and complete the heterostructure manufacturing through thermal release.

[0070] Specifically, the surface deposition method can adopt chemical vapor deposition method. It can be understood that in other embodiments, other surface deposition methods can also be adopted to grow the combined structure of monolayer and multilayer MoS2 on the preset substrate, such as physical vapor deposition method.

[0071] In some embodiments, the MoS2 generation step includes steps (a1) to (a4).

[0072] Step (a1): Place the preset substrate downstream of the deposition system and heat the temperature to the first preset temperature.

[0073] Among them, the value range of the first preset temperature is 700°C - 800°C, and specifically it can be 750°C. For example, the deposition system can be a three-zone APCVD (atmospheric pressure chemical vapor deposition) system, and MoS2 is grown by chemical vapor deposition method. Specifically, the preset substrate can be SiO2, or it can also be a substrate of other materials, such as a silicon substrate.

[0074] Step (a2): Carry the sulfur powder in the main pipe of the deposition system using argon gas at a second preset temperature.

[0075] Among them, the value range of the second preset temperature is 150°C - 250°C, and specifically it can be 200°C. For example, load the sulfur powder in the main pipe, and when the sulfur powder is heated to 200°C, carry it using argon gas.

[0076] Step (a3): When the microtube of the deposition system is heated to a third preset temperature, carry MoO3 in the microtube using argon gas, and continue to heat the microtube to a fourth preset temperature.

[0077] Among them, the value range of the third preset temperature is 500°C - 600°C, and specifically it can be 550°C. The value range of the fourth preset temperature is 530°C - 630°C, and specifically it can be 580°C.

[0078] Step (a4): Wait for a preset reaction duration to obtain at least a combined MoS2 structure.

[0079] Specifically, under the condition that the temperatures of the sulfur S powder, MoO3, and the preset substrate reach the second preset temperature, the fourth preset temperature, and the first preset temperature respectively, the growth continues for a preset duration, and then the furnace is naturally cooled to room temperature to grow a combined MoS2 structure with single-layer and multi-layer MoS2, and a single-layer MoS2 can also be grown alone.

[0080] In some embodiments, step (a2) includes: carrying the sulfur powder in the main pipe of the deposition system using argon gas at a rate of 100 standard cubic centimeters per minute at the second preset temperature. Further, when carrying MoO3 in the microtube using argon gas in step (a3), it can also be carried using argon gas at a rate of 100 standard cubic centimeters per minute.

[0081] In some embodiments, the preset duration is 10 minutes. After reaching the temperature conditions, the growth duration is maintained at 10 minutes to ensure that a combined MoS2 structure with multi-layer MoS2 superimposed on a partial area of the first single-layer MoS2 can be grown.

[0082] For example, in a three-zone APCVD (atmospheric pressure chemical vapor deposition) system, MoS2 is grown by CVD (chemical vapor deposition), and the operation includes: loading 15g of S (sulfur) powder with a purity of 99.995% in a main tube and carrying it by 100 standard cubic centimeters of argon gas (100SCCM Ar) per minute; loading 50mg of MoO3 powder with a purity of 99.95% in a microtube, heating it to 550°C when the temperature of MoO3 reaches 100SCCM Ar; placing a piece of clean SiO2 downstream as a preset substrate. Under the conditions that the temperatures of S powder, MoO3 and the preset substrate reach 200°C, 580°C and 750°C respectively, the growth duration is maintained for 10 minutes, and then the furnace is naturally cooled to room temperature to grow a single-layer and multi-layer combined MoS2 structure, and a single single-layer MoS2 can also be grown.

[0083] In some embodiments, the heterojunction bottom material layer may be a CrOCl film. The bottom layer setting step includes: obtaining the CrOCl film by mechanical peeling, and then transferring the CrOCl film to one side surface of the substrate.

[0084] Specifically, the substrate may be a 285nm p-doped SiO2 / Si substrate.

[0085] In some embodiments, the transfer step includes: connecting a transfer medium film to a glass slide, placing a drop of water on the surface of the glass slide and fixing the glass slide on a fixed-point transfer platform, and then gently bringing the transfer medium film close to the surface of the combined MoS2 structure, inserting the water on the transfer medium film between the combined MoS2 structure and the preset substrate, and leaving the combined MoS2 structure on the transfer medium film. Next, the transfer medium film with the combined MoS2 structure is transferred to the surface of the CrOCl film placed on the substrate, and the heterostructure is manufactured by thermal release.

[0086] Specifically, the transfer medium film may be 3 mm×5 mm PDMS (polydimethylsiloxane). It is understood that in other embodiments, other transfer media for material separation may also be used.

[0087] In some embodiments, the MoS2 generation step is also used to generate a second single-layer MoS2. The transfer step also includes: separating the second single-layer MoS2 from the preset substrate and transferring it to a surface of the heterojunction bottom material layer facing away from the substrate, and then completing the heterostructure manufacturing of the second single-layer MoS2 and the heterojunction bottom material layer by thermal release. Specifically, the operation of transferring the second single-layer MoS2 is the same as the specific operation of transferring the combined MoS2 structure, which will not be repeated here.

[0088] In some embodiments, the method for preparing the MoS2 heterojunction further includes: preparing a conductive bridge by using electron beam lithography and electron beam evaporation procedures, and connecting the second monolayer MoS2 to the combined MoS2 structure through the conductive bridge.

[0089] Specifically, first, a layer of photoresist is spin-coated on the surfaces of the second monolayer MoS2 and the combined MoS2 structure, and then a preset shape is obtained through electron beam lithography. A 5-nm Cr-containing layer and a 70-nm Au-containing layer are evaporated on the preset shape through electron beam evaporation. After removing the photoresist, a bridged conductive bridge is obtained.

[0090] The technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification as long as such a combination is not contradictory.

[0091] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A light-emitting device comprising a molybdenum disulfide (MoS2) heterojunction, characterized in that, The MoS2 heterojunction includes: A substrate; A heterojunction bottom layer material layer disposed on one side surface of the substrate; A combined MoS2 structure of monolayer and multilayer, the combined MoS2 structure is disposed on the side of the heterojunction bottom layer material layer away from the substrate, and the combined MoS2 structure includes a first monolayer MoS2 and a multilayer MoS2 formed in a partial area of the first monolayer MoS2.

2. The light-emitting device comprising a MoS2 heterojunction according to claim 1, wherein The heterojunction bottom layer material layer is a CrOCl thin film.

3. The light-emitting device comprising a MoS2 heterojunction according to claim 1, characterized in that, Along the thickness direction of the substrate, the multilayer MoS2 is stacked on the first monolayer MoS2.

4. The light-emitting device comprising a MoS2 heterojunction according to any one of claims 1-3, characterized in that, It further includes: a second monolayer MoS2 and a conductive bridge; The second monolayer MoS2 is disposed on the side of the heterojunction bottom layer material layer away from the substrate and is connected to the combined MoS2 structure through the conductive bridge.

5. The light-emitting device comprising the MoS2 heterojunction according to claim 4, wherein The material of the conductive bridge includes: Cr and Au.

6. The light-emitting device comprising the MoS2 heterojunction according to claim 5, wherein The conductive bridge includes: a Cr-containing layer of 5 nm to 7 nm and an Au-containing layer of 50 nm to 70 nm, wherein the Cr-containing layer is disposed on the lower layer of the conductive bridge, close to the substrate side, and the Au-containing layer is disposed on the upper layer of the conductive bridge, away from the substrate side.

7. A preparation method of a MoS2 heterojunction for preparing the MoS2 heterojunction of the light-emitting device according to any one of claims 1 to 6, characterized in that, The method includes the following steps: MoS2 generation step: At least generate the combined MoS2 structure of monolayer and multilayer on a preset substrate by surface deposition method using sulfur powder and MoO3; Bottom layer setting step: Set the heterojunction bottom layer material layer on one side surface of the substrate; Transfer step: Separate the combined MoS2 structure of monolayer and multilayer from the preset substrate and transfer it to the side surface of the heterojunction bottom layer material layer away from the substrate, and complete the heterostructure manufacturing through thermal release.

8. The method according to claim 7, wherein The MoS2 generation step is also used to generate a second monolayer MoS2; The transfer step further includes: Separating the second monolayer MoS2 from the preset substrate and transferring it to the side surface of the heterojunction bottom layer material layer away from the substrate.

9. The method according to claim 8, wherein The method further includes: Preparing the conductive bridge by electron beam lithography and electron beam evaporation process, and connecting the second monolayer MoS2 to the combined MoS2 structure through the conductive bridge.

10. The method according to claim 7, wherein The MoS2 generation step includes: Placing the preset substrate at the downstream of the deposition system and heating the temperature to a first preset temperature; Carrying the sulfur powder in the main pipe of the deposition system using argon at a second preset temperature; When heating the microtube of the deposition system to a third preset temperature, carrying the MoO3 in the microtube using argon, and continuing to heat the microtube to a fourth preset temperature; Waiting for a preset reaction duration to obtain at least the combined MoS2 structure.

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