A flexible substrate molybdenum disulfide memristor and a preparation method and application thereof

Abstract

The application provides a flexible substrate molybdenum disulfide memristor and a preparation method and application thereof, and belongs to the technical field of memristors. The application is based on pyrolysis to prepare a MoS2 film on one side of an insulating substrate to obtain an insulating substrate / MoS2 film device; a bottom electrode is prepared on one side of a flexible substrate to obtain a bottom electrode / flexible substrate device; the MoS2 film in the insulating substrate / MoS2 film device is transferred to the surface of the bottom electrode in the bottom electrode / flexible substrate device based on a water-assisted PDMS film transfer method to obtain a MoS2 film / bottom electrode / flexible substrate device; a top electrode is prepared on the surface of the MoS2 film in the MoS2 film / bottom electrode / flexible substrate device to obtain the flexible substrate molybdenum disulfide memristor. The flexible substrate molybdenum disulfide memristor prepared by the method has a low turn-on voltage, a good memory window and good retention characteristics, and can still maintain the original performance of the device after bending and stretching.

Description

Technical Field

[0001] This invention relates to the field of memristor technology, and in particular to a flexible substrate molybdenum disulfide memristor, its preparation method, and its application. Background Technology

[0002] With the continuous development of the electronic device field, flexible electronics technology has attracted much attention. Traditional silicon-based electronic devices are limited in shape and application range due to their rigidity. Flexible electronic devices, especially flexible memory, can adapt to various mechanical deformations, such as folding, bending, and stretching, and therefore have great application potential in wearable electronic devices, smart tags, medical sensors, and flexible displays.

[0003] In the development of flexible memory, memristors (or resistance-switched RAM) have shown broad application prospects. Memristors possess fast response times, low power consumption, excellent scalability, and long-term data retention capabilities, making them ideal non-volatile memory solutions. However, in flexible RRAM devices, poor adhesion between the dielectric material and the electrode substrate often leads to cracking or interface separation after bending or stretching, significantly impacting the device's lifespan. Summary of the Invention

[0004] The purpose of this invention is to provide a flexible substrate molybdenum disulfide memristor, its preparation method and application. The flexible substrate molybdenum disulfide memristor prepared by the method of this invention has a low turn-on voltage, a good memory window and good retention characteristics, and can still maintain the original performance of the device after bending and stretching.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for fabricating a flexible substrate molybdenum disulfide memristor, comprising the following steps: MoS2 films are prepared on one side of an insulating substrate using a pyrolysis method to obtain an insulating substrate / MoS2 film device. A bottom electrode is fabricated on one side of a flexible substrate to obtain a bottom electrode / flexible substrate device; The MoS2 film in the insulating substrate / MoS2 film device is transferred to the surface of the bottom electrode in the bottom electrode / flexible substrate device using the water-assisted PDMS film transfer method, thereby obtaining the MoS2 film / bottom electrode / flexible substrate device. A top electrode is fabricated on the surface of the MoS2 film in the MoS2 film / bottom electrode / flexible substrate device to obtain the flexible substrate molybdenum disulfide memristor.

[0006] Preferably, the pyrolysis method includes the following steps: A (NH4)2MoS4 solution is coated on one side of the insulating substrate and cured to form a (NH4)2MoS4 film, thus obtaining an insulating substrate / (NH4)2MoS4 film device. The insulating substrate / (NH4)2MoS4 film device is subjected to a first annealing treatment in an atmosphere of Ar and H2, and a second annealing treatment in an atmosphere of Ar and sulfur vapor, so that (NH4)2MoS4 reacts to generate MoS2, thereby obtaining the insulating substrate / MoS2 film device.

[0007] Preferably, the concentration of (NH4)2MoS4 in the (NH4)2MoS4 solution is 1~6wt%; the solvent in the (NH4)2MoS4 solution includes dimethylformamide, n-butylamine and ethanolamine, and the volume ratio of dimethylformamide, n-butylamine and ethanolamine is 4.5~5.5:1.5~2.5:1.

[0008] Preferably, the temperature of the first annealing treatment is 400~500℃ and the holding time is 10~30min; the temperature of the second annealing treatment is 500~900℃ and the holding time is 10~30min.

[0009] Preferably, the water-assisted PDMS membrane transfer method includes the following steps: A PDMS film and the insulating substrate / MoS2 film device are sequentially stacked on one side of a supporting substrate, and the MoS2 film in the insulating substrate / MoS2 film device is made to contact the PDMS film to obtain a supporting substrate / PDMS film / MoS2 film / insulating substrate device. The supporting substrate / PDMS film / MoS2 film / insulating substrate device is placed on the surface of water, and the insulating substrate in the supporting substrate / PDMS film / MoS2 film / insulating substrate device is brought into contact with the water surface. The insulating substrate is removed by a first peeling process to obtain the supporting substrate / PDMS film / MoS2 film device. The supporting substrate / PDMS film / MoS2 film device is subjected to a second peeling process to remove the supporting substrate, thereby obtaining the PDMS film / MoS2 film device. The PDMS film / MoS2 film device is stacked on the surface of the bottom electrode / flexible substrate device, and the MoS2 film in the PDMS film / MoS2 film device is in contact with the bottom electrode in the bottom electrode / flexible substrate device to obtain the PDMS film / MoS2 film / bottom electrode / flexible substrate device. The PDMS film / MoS2 film / bottom electrode / flexible substrate device is subjected to a third peeling process to remove the PDMS film, thereby obtaining the MoS2 film / bottom electrode / flexible substrate device.

[0010] Preferably, the supporting substrate is a quartz sheet or a silicon wafer, and the thickness of the supporting substrate is 1~5mm; the thickness of the PDMS film is 0.1~0.5mm.

[0011] Preferably, the first peeling process is performed at room temperature for 1-5 minutes; the second peeling process involves removing the support substrate using tweezers; and the third peeling process is performed at 70-90°C for 5-15 minutes.

[0012] Preferably, the insulating substrate comprises a sapphire substrate or a Si / SiO2 substrate, and the thickness of the insulating substrate is 200~600μm; the flexible substrate comprises a PEN substrate or a PI substrate, and the thickness of the flexible substrate is 150~200μm; the bottom electrode and the top electrode are metal electrodes, and the thickness of the bottom electrode and the top electrode is independently 40~45nm; the thickness of the MoS2 film is 1~5nm.

[0013] The present invention provides a flexible substrate molybdenum disulfide memristor prepared by the preparation method described above, comprising a flexible substrate, a bottom electrode, a MoS2 film and a top electrode stacked sequentially.

[0014] This invention provides the application of the flexible substrate molybdenum disulfide memristor described above in flexible electronic devices.

[0015] Beneficial Effects: This invention provides a method for fabricating a flexible substrate molybdenum disulfide memristor, specifically using a pyrolysis method to prepare a MoS2 film. Compared with other fabrication methods (such as CVD), this method is simpler to operate, allows for large-area growth in a tube furnace, and the growth thickness is easily controlled (e.g., the MoS2 film thickness can be adjusted based on the concentration of the (NH4)2MoS4 solution). The MoS2 film has low surface roughness (90~200 pm), good continuity, and is more compatible with CMOS processes. Furthermore, this invention utilizes a water-assisted PDMS film transfer method to transfer the MoS2 film. Compared to other thin film transfer methods (such as PMMA-assisted transfer), this method reduces contamination during the MoS2 film transfer process, ensuring the quality of the MoS2 film and facilitating stable device operation. The flexible substrate molybdenum disulfide memristor prepared using this method exhibits a low turn-on voltage (<1.5V) and a good memory window (on / off ratio of approximately 10). 3 ) and good retention properties (>10) 4 (s) can maintain the original performance of the device after bending and stretching, providing a more powerful storage solution for applications of flexible electronic devices such as smart wearable devices, sensors and smart tags. Attached Figure Description

[0016] Figure 1This is a schematic diagram of the structure of the flexible substrate molybdenum disulfide memristor prepared in Example 1; Figure 2 Optical images of the flexible substrate molybdenum disulfide memristor prepared in Example 1; Figure 3 Diagram of a memristor stretching device; Figure 4 Bipolar resistive switching IV curves of the flexible substrate molybdenum disulfide memristor prepared in Example 1 before bending and stretching. Figure 5 Bipolar resistive switching IV curves of the flexible substrate molybdenum disulfide memristor prepared in Example 1 after bending and stretching; Figure 6 Image showing the retention characteristics of the flexible substrate molybdenum disulfide memristor prepared in Example 1; Figure 7 Bipolar resistive switching IV curves of the flexible substrate molybdenum disulfide memristor prepared in Example 1 after different bending times under a bending radius of 0.75 cm; Figure 8 The bipolar resistivity I-V curves of the flexible substrate molybdenum disulfide memristor prepared in Example 1 after 400 bends with bending radii of 0.75 cm and 1 cm. Detailed Implementation

[0017] This invention provides a method for fabricating a flexible substrate molybdenum disulfide memristor, comprising the following steps: MoS2 films are prepared on one side of an insulating substrate using a pyrolysis method to obtain an insulating substrate / MoS2 film device. A bottom electrode is fabricated on one side of a flexible substrate to obtain a bottom electrode / flexible substrate device; The MoS2 film in the insulating substrate / MoS2 film device is transferred to the surface of the bottom electrode in the bottom electrode / flexible substrate device using the water-assisted PDMS film transfer method, thereby obtaining the MoS2 film / bottom electrode / flexible substrate device. A top electrode is fabricated on the surface of the MoS2 film in the MoS2 film / bottom electrode / flexible substrate device to obtain the flexible substrate molybdenum disulfide memristor.

[0018] In this invention, unless otherwise specified, all raw materials used are commercially available products well known to those skilled in the art; all equipment used are equipment well known to those skilled in the art.

[0019] This invention relates to a method for preparing a MoS2 film on one side of an insulating substrate using pyrolysis, resulting in an insulating substrate / MoS2 film device. In this invention, the insulating substrate preferably comprises a sapphire substrate or a Si / SiO2 substrate, and the thickness of the insulating substrate is preferably 200-600 μm, more preferably 250-300 μm. The Si / SiO2 substrate comprises a Si wafer and a SiO2 insulating layer disposed on the surface of the Si wafer. Specifically, a MoS2 film is prepared on the surface of the SiO2 insulating layer, and the thickness of the SiO2 insulating layer is preferably 200-600 nm, more preferably 250-300 nm. Before use, the insulating substrate of this invention is preferably subjected to washing, drying, and ultraviolet ozone treatment in sequence. This invention does not have specific limitations on the washing process; simply cleaning the insulating substrate is sufficient. The drying temperature is preferably 75-80°C, and the drying time is preferably 8-10 min. The ultraviolet ozone treatment time is preferably 0.5-1 min.

[0020] In this invention, the pyrolysis method preferably includes the following steps: A (NH4)2MoS4 solution is coated on one side of the insulating substrate and cured to form a (NH4)2MoS4 film, thus obtaining an insulating substrate / (NH4)2MoS4 film device. The insulating substrate / (NH4)2MoS4 film device is subjected to a first annealing treatment in an atmosphere of Ar and H2, and a second annealing treatment in an atmosphere of Ar and sulfur vapor, so that (NH4)2MoS4 reacts to generate MoS2, thereby obtaining the insulating substrate / MoS2 film device.

[0021] This invention involves coating one side of an insulating substrate with a (NH4)2MoS4 solution, followed by curing to form an (NH4)2MoS4 film, resulting in an insulating substrate / (NH4)2MoS4 film device. In this invention, the concentration of (NH4)2MoS4 in the (NH4)2MoS4 solution is preferably 1-6 wt%, more preferably 1.2-4.5 wt%, and even more preferably 1.25-3 wt%. The solvent in the (NH4)2MoS4 solution preferably includes dimethylformamide (DMF), n-butylamine, and 2-aminoethanol, and the volume ratio of DMF, n-butylamine, and ethanolamine is preferably 4.5-5.5:1.5-2.5:1, more preferably 5:2:1. Preferably, the DMF, n-butylamine, and ethanolamine are ultrasonically mixed, and then (NH4)2MoS4 is added to the resulting mixed solvent and ultrasonically mixed again to obtain the (NH4)2MoS4 solution. In this invention, the coating is preferably spin-coating, and the spin-coating speed is preferably 2000~3000 r / min, more preferably 2500 r / min; the time is preferably 10~60 s, more preferably 20~30 s. In this invention, the curing temperature is preferably 120~150℃, more preferably 125~130℃; the curing time is preferably 1~5 min, more preferably 2~3 min. In this invention, the thickness of the (NH4)2MoS4 film is preferably 30~50 nm, more preferably 35~40 nm.

[0022] After obtaining the insulating substrate / (NH4)2MoS4 film device, the present invention sequentially performs a first annealing treatment in an atmosphere of Ar and H2, and a second annealing treatment in an atmosphere of Ar and sulfur vapor, so that (NH4)2MoS4 reacts to generate MoS2, thereby obtaining the insulating substrate / MoS2 film device. In the present invention, the temperature of the first annealing treatment is preferably 400~500℃, more preferably 450~500℃; the holding time is preferably 10~30min, more preferably 15~20min; the volume ratio of Ar to H2 during the first annealing treatment is preferably 1:0.1~0.3, more preferably 1:0.25. In this invention, the temperature of the second annealing treatment is preferably 500~900℃, more preferably 600~700℃; the holding time is preferably 10~30min, more preferably 10~15min; the volume ratio of Ar to sulfur vapor during the second annealing treatment is preferably 1:0.05~0.2, more preferably 1:0.1. In this invention, the first annealing treatment is performed in an atmosphere of Ar and H2, and (NH4)2MoS4 initially decomposes to form a MoS2 film, at which point the quality of the MoS2 film is poor; subsequently, the second annealing treatment is performed in a sulfur vapor atmosphere, which can improve the quality of the MoS2 film. In this invention, the thickness of the MoS2 film in the insulating substrate / MoS2 film device is preferably 1~5nm, more preferably 2.5~3.5nm, and even more preferably 2.8nm; the surface roughness is preferably 90~200pm, more preferably 100~120pm, and even more preferably 111.4pm. In this invention, the reaction formula for the formation of MoS2 from (NH4)2MoS4 is as follows: (NH4)2MoS4+H2→2NH3+2H2S+MoS2.

[0023] In an embodiment of the present invention, the first annealing treatment and the second annealing treatment are preferably performed in a three-stage annealing furnace. The three-stage annealing furnace consists of a warm zone, a reaction zone, and a cold zone from left to right. Sulfur powder is placed in the warm zone, and the insulating substrate / (NH4)2MoS4 film device is placed in the cold zone. The three-stage annealing furnace is turned on. When the temperature of the reaction zone reaches the temperature of the first annealing treatment, the insulating substrate / (NH4)2MoS4 film device is pushed from the cold zone into the reaction zone using a push-pull rod. The first annealing treatment is performed in an atmosphere of Ar and H2. After the first annealing treatment is completed, the [process is then carried out using...] The push-pull rod pulls the insulating substrate / (NH4)2MoS4 film device back to the cold zone; when the sulfur powder in the warm zone is heated to generate sulfur vapor, and the temperature of the reaction zone reaches the temperature of the second annealing treatment, the push-pull rod pushes the insulating substrate / (NH4)2MoS4 film device from the cold zone into the reaction zone, and the second annealing treatment is carried out in the atmosphere of Ar and sulfur vapor. During the second annealing treatment, (NH4)2MoS4 is converted into MoS2, and the insulating substrate / MoS2 film device is obtained. After the second annealing treatment is completed, the push-pull rod pulls the insulating substrate / MoS2 film device back to the cold zone.

[0024] This invention fabricates a bottom electrode on one side of a flexible substrate, resulting in a bottom electrode / flexible substrate device. In this invention, the flexible substrate preferably comprises a polyethylene naphthalate (PEN) substrate or a polyimide (PI) substrate, and the thickness of the flexible substrate is preferably 150-200 μm, more preferably 170-180 μm; the bottom electrode is preferably a metal electrode, more preferably a gold electrode; and the thickness of the bottom electrode is preferably 40-45 nm. In this invention, an adhesion layer is preferably disposed between the flexible substrate and the bottom electrode, the adhesion layer being preferably a Ti layer, and the thickness of the adhesion layer being preferably 1.5-2 nm. In this invention, the bottom electrode is preferably a patterned bottom electrode. This invention preferably utilizes ultraviolet lithography, electron beam evaporation, and lift-off processes to fabricate the patterned bottom electrode on the flexible substrate. This invention does not specifically limit the operation method of the ultraviolet lithography process; any operation method well known to those skilled in the art can be used. In the embodiments of this invention, the preferred operation method of the ultraviolet lithography process includes: dropping AZ5214 photoresist onto the surface of a flexible substrate, spin-coating at a speed of 550~600 r / min for 1~1.5 min, baking on a heating plate at 85~90℃ for 1.5~2 min, and then using an ultraviolet lithography machine (UVLithography, Karl Suss). Exposure is performed using MA6 (photomask evaporation), employing a soft-contact exposure mode. Specific parameters include: exposure power of 7.0~7.5mW, exposure time of 4~5s, and a distance of 10~15μm between the photoresist and the sample surface. After exposure, the sample is baked on a heating plate at 100~110℃ for 45~50s, followed by full exposure with the same parameters: exposure power of 7.0~7.5mW, exposure time of 40~45s, and a distance of 10~15μm between the photoresist and the sample surface. Finally, development is performed with a developer for 90~95s, completing the ultraviolet lithography process. This invention does not specifically limit the specific operation method of the electron beam evaporation process; any operation method well-known to those skilled in the art can be used. In the embodiments of this invention, after sequentially depositing an adhesion layer and a bottom electrode on the flexible photolithography substrate using electron beam evaporation, the resulting device is immersed in acetone for 10~12h to allow the acetone to react with the photoresist, thereby achieving lift-off. The present invention does not impose any special limitation on the specific operation method of the lift-off process; any operation method known to those skilled in the art can be used.

[0025] After obtaining the insulating substrate / MoS2 film device and the bottom electrode / flexible substrate device, this invention uses a water-assisted PDMS film transfer method to transfer the MoS2 film from the insulating substrate / MoS2 film device to the surface of the bottom electrode in the bottom electrode / flexible substrate device, thus obtaining the MoS2 film / bottom electrode / flexible substrate device. In this invention, the water-assisted PDMS film transfer method preferably includes the following steps: A PDMS film and the insulating substrate / MoS2 film device are sequentially stacked on one side of a supporting substrate, and the MoS2 film in the insulating substrate / MoS2 film device is made to contact the PDMS film to obtain a supporting substrate / PDMS film / MoS2 film / insulating substrate device. The supporting substrate / PDMS film / MoS2 film / insulating substrate device is placed on the surface of water, and the insulating substrate in the supporting substrate / PDMS film / MoS2 film / insulating substrate device is brought into contact with the water surface. The insulating substrate is removed by a first peeling process to obtain the supporting substrate / PDMS film / MoS2 film device. The supporting substrate / PDMS film / MoS2 film device is subjected to a second peeling process to remove the supporting substrate, thereby obtaining the PDMS film / MoS2 film device. The PDMS film / MoS2 film device is stacked on the surface of the bottom electrode / flexible substrate device, and the MoS2 film in the PDMS film / MoS2 film device is in contact with the bottom electrode in the bottom electrode / flexible substrate device to obtain the PDMS film / MoS2 film / bottom electrode / flexible substrate device. The PDMS film / MoS2 film / bottom electrode / flexible substrate device is subjected to a third peeling process to remove the PDMS film, thereby obtaining the MoS2 film / bottom electrode / flexible substrate device.

[0026] In this invention, the supporting substrate is preferably a quartz sheet or a silicon wafer, and the thickness of the supporting substrate is preferably 1~5mm, more preferably 2~3mm; the thickness of the PDMS film is preferably 0.1~0.5mm, more preferably 0.15~0.25mm, and even more preferably 0.18mm.

[0027] In this invention, the water is preferably deionized water. In this invention, the temperature of the first stripping treatment is preferably room temperature, and the time is preferably 1-5 minutes, more preferably 2-3 minutes. After the first stripping treatment, this invention preferably rinses the obtained support substrate / PDMS film / MoS2 film device three times with water and then places it on the water surface for 25-30 minutes, ensuring that the MoS2 film is in contact with the water surface, to further reduce doping.

[0028] In this invention, the second peeling process is preferably performed by using tweezers to remove the supporting substrate. Preferably, the PDMS / MoS2 film device obtained after the second peeling process is dried and then stacked on the surface of the bottom electrode / flexible substrate device for subsequent processing.

[0029] In this invention, the temperature of the third exfoliation process is preferably 70-90°C, more preferably 75-80°C; the time is preferably 8-12 min, more preferably 10 min. Preferably, the PDMS film / MoS2 film / bottom electrode / flexible substrate device is placed on a heating plate for the third exfoliation process.

[0030] After obtaining the MoS2 film / bottom electrode / flexible substrate device, the present invention fabricates a top electrode on the surface of the MoS2 film in the MoS2 film / bottom electrode / flexible substrate device to obtain the flexible substrate molybdenum disulfide memristor. In the present invention, the top electrode is preferably a metal electrode, more preferably a gold electrode; the thickness of the top electrode is preferably 40~45 nm. In the present invention, an adhesion layer is preferably provided between the MoS2 film and the top electrode, the adhesion layer is preferably a Ti layer, and the thickness of the adhesion layer is preferably 1.5~2 nm. In the present invention, the top electrode is preferably a patterned top electrode. The present invention preferably utilizes ultraviolet lithography, electron beam evaporation, and lift-off processes to fabricate the patterned top electrode on the MoS2 film. The specific fabrication method is consistent with the patterned bottom electrode fabrication method and will not be repeated here.

[0031] This invention provides a flexible molybdenum disulfide memristor prepared by the preparation method described in the above technical solution, comprising a flexible substrate, a bottom electrode, a MoS2 film, and a top electrode stacked sequentially. In this invention, the specific materials and thicknesses of the flexible substrate, bottom electrode, and top electrode are the same as in the above technical solution and will not be repeated here; the thickness of the MoS2 film is also the same as in the above technical solution and will not be repeated here.

[0032] This invention provides the application of the flexible substrate molybdenum disulfide memristor described above in flexible electronic devices. In this invention, the flexible electronic device preferably includes a smart wearable device, a sensor, or a smart tag.

[0033] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] Example 1 (1) Dimethylformamide (DMF), n-butylamine, and 2-aminoethanol were mixed in a volume ratio of 5:2:1 and sonicated for 20 min, with the temperature not exceeding 40°C during the sonication process, to obtain a mixed solvent; ammonium thiomolybdate ((NH4)2MoS4, purity 99.99wt%) was added to the mixed solvent and sonicated for 30 min, with the temperature not exceeding 40°C during the sonication process, to obtain a (NH4)2MoS4 concentration of 1.25wt%. (NH4)2MoS4 solution; clean the sapphire substrate, bake it on an 80°C heating plate for 10 min, and then treat it with ultraviolet ozone for 1 min; spin-coat the (NH4)2MoS4 solution onto the treated sapphire substrate surface at a rotation speed of 2500 r / min for 30 s; after spin-coating, place it on a 125°C heating plate for 3 min to solidify the film, and obtain a (NH4)2MoS4 film with a thickness of 40 nm on the surface of the sapphire substrate, denoted as sapphire substrate / (NH4)2MoS4 film device; (2) The sapphire substrate / (NH4)2MoS4 film device is placed in a three-stage annealing furnace, which consists of a warm zone, a reaction zone, and a cold zone from left to right. Sulfur powder is placed in the warm zone, and the sapphire substrate / (NH4)2MoS4 film device is placed in the cold zone. The three-stage annealing furnace is turned on. When the temperature of the reaction zone reaches 500°C, the sapphire substrate / (NH4)2MoS4 film device is pushed from the cold zone into the reaction zone using a push-pull rod. The first annealing treatment is carried out for 20 minutes in an atmosphere of Ar and H2 (the volume ratio of Ar to H2 is 1:0.25). After the first annealing treatment is completed, the push-pull rod is used again. The sapphire substrate / (NH4)2MoS4 film device is pulled back to the cold zone. When the sulfur powder in the warm zone is heated to generate sulfur vapor and the temperature of the reaction zone reaches 700°C, the sapphire substrate / (NH4)2MoS4 film device is pushed from the cold zone into the reaction zone using a push-pull rod. A second annealing treatment is performed for 10 minutes in an atmosphere of Ar and sulfur vapor (the volume ratio of Ar to sulfur vapor is 1:0.1) to obtain the sapphire substrate / MoS2 film device. After the second annealing treatment is completed, the sapphire substrate / MoS2 film device is pulled back to the cold zone using a push-pull rod. The thickness of the MoS2 film is 2.8 nm and the surface roughness is 111.4 pm. (3) AZ5214 photoresist was dropped onto the surface of a flexible substrate (specifically a PEN film with a thickness of 180 μm) with a size of 1.5 cm × 1.5 cm, spin-coated at a speed of 600 r / min for 1 min, baked on a 90°C heating plate for 2 min, and then exposed to ultraviolet light (UV Lithography, Karl Suss). The photolithography process was performed using MA6, employing a soft-contact exposure mode with the following parameters: exposure power of 7.5mW, exposure time of 5s, and a distance of 15μm between the photolithography plate and the sample surface. After exposure, the sample was baked on a 110℃ heating plate for 50s, followed by full exposure with the following parameters: exposure power of 7.5mW, exposure time of 45s, and a distance of 15μm between the photolithography plate and the sample surface. Finally, the sample was developed with a developer for 95s, completing the UV lithography process and obtaining a flexible photolithographic substrate. An electron beam evaporation process was used to sequentially deposit a 2nm thick Ti layer as an adhesion layer and a 45nm thick Au layer on the surface of the flexible photolithographic substrate. The substrate was then immersed in acetone for 12 hours to allow the acetone to react with the photoresist. Finally, a lift-off process was used to fabricate a patterned metal bottom electrode on the flexible substrate, resulting in a bottom electrode / flexible substrate device. (4) A PDMS film (180 μm thick) and the sapphire substrate / MoS2 film device are sequentially stacked on one side of a quartz sheet (3 mm thick), with the MoS2 film in the sapphire substrate / MoS2 film device in contact with the PDMS film, and each layer is flat and bonded together to obtain a quartz sheet / PDMS film / MoS2 film / sapphire substrate device; the quartz sheet / PDMS film / MoS2 film / sapphire substrate device is placed on the surface of deionized water, with the sapphire substrate in contact with the deionized water surface, and placed at room temperature for 2 minutes to allow the sapphire substrate to detach through water immersion, thus obtaining a quartz sheet / PDMS film / MoS2 film device; the quartz sheet / PDMS film / MoS2 film device is rinsed 3 times with deionized water and then placed on the surface of deionized water. The sapphire film was placed on the surface for 30 minutes, with the MoS2 film in contact with the deionized water surface to further reduce doping. Then, the quartz sheet was removed from the quartz sheet / PDMS film / MoS2 film device using tweezers to obtain the PDMS film / MoS2 film device. After drying, it was stacked on the surface of the bottom electrode / flexible substrate device, with the MoS2 film in contact with the bottom electrode. Then, it was placed at room temperature to allow the MoS2 film to fully adhere to the bottom electrode, resulting in the PDMS film / MoS2 film / bottom electrode / flexible substrate device. The PDMS film / MoS2 film / bottom electrode / flexible substrate device was then placed on an 80°C heating plate and baked for 10 minutes to peel off the PDMS film, resulting in the MoS2 film / bottom electrode / flexible substrate device. This process transfers the MoS2 film from the sapphire substrate to the bottom electrode / flexible substrate device. (5) Following the ultraviolet lithography process, electron beam evaporation process and lift-off process in step (3), a top electrode is prepared on the surface of the MoS2 film in the MoS2 film / bottom electrode / flexible substrate device to obtain the top electrode / MoS2 film / bottom electrode / flexible substrate device, which is a flexible substrate molybdenum disulfide memristor.

[0035] Figure 1 This is a schematic diagram of the flexible substrate molybdenum disulfide memristor prepared in Example 1, which includes a gold top electrode, a MoS2 film, a gold bottom electrode, and a flexible substrate stacked together.

[0036] Figure 2 The image shows an optical image of the flexible molybdenum disulfide memristor prepared in Example 1, illustrating the successful preparation of the flexible molybdenum disulfide memristor.

[0037] The flexible molybdenum disulfide memristor prepared in Example 1 was sequentially bent and stretched, and the performance of the flexible molybdenum disulfide memristor before and after bending and stretching was tested. Specifically, the bending was performed using a stretching device (such as...). Figure 3 (As shown) A flexible molybdenum disulfide memristor on a flexible substrate is bent from a flat state to a curved state. Specifically, the stretching involves using a stretching device to stretch the flexible molybdenum disulfide memristor from a curved state to a flat state. The specific results are as follows: Figure 4 The bipolar resistive switching (IRS) curves of the flexible molybdenum disulfide memristor prepared in Example 1 before bending and stretching (i.e., in its original flat state, without any mechanical stress or deformation) are shown, where SET corresponds to the positive scan interval and RESET corresponds to the negative scan interval. The results show that the flexible molybdenum disulfide memristor works normally, with a low turn-on voltage (<1.5V) and an on / off ratio of approximately 10. 3 It possesses memristor properties.

[0038] Figure 5 The bipolar resistive switching (IRS) curves of the flexible molybdenum disulfide memristor prepared in Example 1 after bending and stretching were shown, with a bending radius of 0.75 cm and 200 bending cycles. The results show that the flexible molybdenum disulfide memristor has a low turn-on voltage (<1.5V) and an on / off ratio of approximately 10. 3 And compared to unbent flexible substrate molybdenum disulfide memristors ( Figure 4 The performance of the flexible substrate molybdenum disulfide memristor did not show significant degradation after bending and stretching, proving that the flexible substrate molybdenum disulfide memristor also has stable memristor performance after bending.

[0039] Figure 6Electrical images showing the retention characteristics of the flexible molybdenum disulfide memristor on the substrate prepared in Example 1 after bending and stretching are provided, where LRS represents the low resistance state and HRS represents the high resistance state. The results show that the flexible molybdenum disulfide memristor on the substrate has good retention characteristics after bending (>10). 4 s).

[0040] Figure 7 The bipolar resistivity-variable (IVR) curves of the flexible molybdenum disulfide memristor prepared in Example 1 after different bending cycles with a bending radius of 0.75 cm were obtained. The results showed that the performance of the flexible molybdenum disulfide memristor did not significantly decrease after 400, 600 and 800 bending cycles, indicating that it has good mechanical resistance.

[0041] Figure 8 The bipolar resistivity-variable (IVR) curves of the flexible molybdenum disulfide memristor prepared in Example 1 after 400 bends with bending radii of 0.75 cm and 1 cm show that the performance of the flexible molybdenum disulfide memristor does not significantly decrease, indicating that it has good mechanical resistance.

[0042] As can be seen from the above embodiments, the flexible substrate molybdenum disulfide memristor provided by the present invention has a low turn-on voltage (<1.5V) and a good memory window (on / off ratio of approximately 10). 3 ) and good retention properties (>10) 4 The flexible molybdenum disulfide memristor provided by this invention retains its basic characteristics even after repeated bending and stretching; moreover, it exhibits good stability at room temperature and has a simple manufacturing process. Compared with other non-flexible memristors, the flexible molybdenum disulfide memristor provided by this invention, with its bendable and stretchable characteristics, has high application value in various flexible devices, providing a foundation for future applications of flexible devices.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for fabricating a flexible substrate molybdenum disulfide memristor, comprising the following steps: MoS2 films are prepared on one side of an insulating substrate using a pyrolysis method to obtain an insulating substrate / MoS2 film device. A bottom electrode is fabricated on one side of a flexible substrate to obtain a bottom electrode / flexible substrate device; The MoS2 film in the insulating substrate / MoS2 film device is transferred to the surface of the bottom electrode in the bottom electrode / flexible substrate device using the water-assisted PDMS film transfer method, thereby obtaining the MoS2 film / bottom electrode / flexible substrate device. A top electrode is fabricated on the surface of the MoS2 film in the MoS2 film / bottom electrode / flexible substrate device to obtain the flexible substrate molybdenum disulfide memristor.

2. The preparation method according to claim 1, characterized in that, The pyrolysis method includes the following steps: A (NH4)2MoS4 solution is coated on one side of the insulating substrate and cured to form a (NH4)2MoS4 film, thus obtaining an insulating substrate / (NH4)2MoS4 film device. The insulating substrate / (NH4)2MoS4 film device is subjected to a first annealing treatment in an atmosphere of Ar and H2, and a second annealing treatment in an atmosphere of Ar and sulfur vapor, so that (NH4)2MoS4 reacts to generate MoS2, thereby obtaining the insulating substrate / MoS2 film device.

3. The preparation method according to claim 2, characterized in that, The concentration of (NH4)2MoS4 in the (NH4)2MoS4 solution is 1~6wt%; the solvent in the (NH4)2MoS4 solution includes dimethylformamide, n-butylamine and ethanolamine, and the volume ratio of dimethylformamide, n-butylamine and ethanolamine is 4.5~5.5:1.5~2.5:

1.

4. The preparation method according to claim 3, characterized in that, The temperature of the first annealing treatment is 400~500℃, and the holding time is 10~30min; the temperature of the second annealing treatment is 500~900℃, and the holding time is 10~30min.

5. The preparation method according to claim 1, characterized in that, The water-assisted PDMS membrane transfer method includes the following steps: A PDMS film and the insulating substrate / MoS2 film device are sequentially stacked on one side of a supporting substrate, and the MoS2 film in the insulating substrate / MoS2 film device is made to contact the PDMS film to obtain a supporting substrate / PDMS film / MoS2 film / insulating substrate device. The supporting substrate / PDMS film / MoS2 film / insulating substrate device is placed on the surface of water, and the insulating substrate in the supporting substrate / PDMS film / MoS2 film / insulating substrate device is brought into contact with the water surface. The insulating substrate is removed by a first peeling process to obtain the supporting substrate / PDMS film / MoS2 film device. The supporting substrate / PDMS film / MoS2 film device is subjected to a second peeling process to remove the supporting substrate, thereby obtaining the PDMS film / MoS2 film device. The PDMS film / MoS2 film device is stacked on the surface of the bottom electrode / flexible substrate device, and the MoS2 film in the PDMS film / MoS2 film device is in contact with the bottom electrode in the bottom electrode / flexible substrate device to obtain the PDMS film / MoS2 film / bottom electrode / flexible substrate device. The PDMS film / MoS2 film / bottom electrode / flexible substrate device is subjected to a third peeling process to remove the PDMS film, thereby obtaining the MoS2 film / bottom electrode / flexible substrate device.

6. The preparation method according to claim 5, characterized in that, The supporting substrate is a quartz sheet or a silicon wafer, and the thickness of the supporting substrate is 1~5mm; the thickness of the PDMS film is 0.1~0.5mm.

7. The preparation method according to claim 6, characterized in that, The first peeling process is performed at room temperature for 1-5 minutes; the second peeling process involves removing the support substrate using tweezers; and the third peeling process is performed at 70-90°C for 5-15 minutes.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The insulating substrate includes a sapphire substrate or a Si / SiO2 substrate, and the thickness of the insulating substrate is 200~600μm; the flexible substrate includes a PEN substrate or a PI substrate, and the thickness of the flexible substrate is 150~200μm; the bottom electrode and the top electrode are metal electrodes, and the thickness of the bottom electrode and the top electrode is 40~45nm independently; the thickness of the MoS2 film is 1~5nm.

9. The flexible substrate molybdenum disulfide memristor prepared by the preparation method according to any one of claims 1 to 8 comprises a flexible substrate, a bottom electrode, a MoS2 film and a top electrode stacked sequentially.

10. The application of the flexible substrate molybdenum disulfide memristor of claim 9 in flexible electronic devices.

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