Flexible self-supporting resistive random access memory with enhanced stability and preparation method thereof

Abstract

The invention discloses a stability-enhanced flexible self-supporting resistive random access memory and a preparation method thereof. The preparation method comprises the following steps: synthesizing MXene solid powder by taking MAX-phase Ti3AlC2 powder as a raw material; carrying out suction filtration by using MXene solid powder to obtain a bottom electrode composed of an MXene self-supporting film; preparing an oxide thin film on the MXene self-supporting thin film to form an oxide semiconductor layer; and preparing a top electrode on the upper surface of the oxide semiconductor layer. The flexible MXene self-supporting thin film is used as the bottom electrode to be applied to the resistive random access memory, so that the flexibility, the conductivity and the long-term stability of the resistive random access memory can be remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor resistive random access memory, and particularly relates to a flexible self-supporting resistive random access memory with enhanced stability and a preparation method thereof. Background Art

[0002] In recent years, with the rapid progress of flexible electronics technology, flexible electronic devices have been widely used in the fields of wearable devices, intelligent healthcare, electronic skin, flexible displays, etc. due to their unique advantages such as light weight, bendability, and large-scale integration. The practical applications of these devices in multiple scenarios require them to have excellent mechanical properties and reliable working stability, especially in complex and dynamic operating environments. The self-supporting performance of flexible electronic devices has become a key factor to ensure that they can maintain structural integrity and functional stability under deformation and external forces during long-term use.

[0003] Self-supporting films generally have a significant improvement in flexibility compared to ordinary metal foils, which is mainly reflected in multiple aspects. First of all, self-supporting films are usually made of two-dimensional materials (such as MXene, graphene, transition metal sulfides, etc.) or their composite materials, which themselves have excellent flexibility. Common metal foils (such as aluminum, copper, etc.) have good mechanical strength, but are prone to plastic deformation or fracture under large strains, showing relatively low flexibility. The self-supporting film adopts a thin and uniform two-dimensional layered structure, enabling it to better adapt to external deformations, not easily break or permanently deform, thus demonstrating higher flexibility. In addition, self-supporting films generally do not rely on external supports and can work independently in a flexible strain environment. Due to being thin and having inherent elasticity, self-supporting films can more easily disperse external mechanical stresses (such as bending, stretching, compression, etc.) without causing damage to the material. Therefore, how to improve the self-supporting ability of devices to ensure that their performance does not degrade under physical deformations such as continuous bending has become the core issue in the current research of flexible electronic devices.

[0004] In addition, flexible electronic devices often face electromagnetic interference (EMI) problems during actual operation. Electromagnetic interference not only has an adverse impact on the signal transmission and computing performance of the devices, but may also lead to data loss, misoperation, or functional failure, thus significantly affecting the overall stability and reliability of the system. To address this challenge, it is particularly important to combine flexible self-supporting materials with electromagnetic shielding capabilities with flexible electronic devices. By effectively shielding external electromagnetic radiation, electromagnetic shielding materials can ensure the stable operation of the devices in high-noise environments, guarantee the accuracy of signal transmission, and enhance the long-term reliability of the system. Therefore, how to achieve an organic combination among the self-supporting performance of the self-supporting film, the electromagnetic shielding ability, and the functionality and reliability of flexible electronic devices has become a technical problem that urgently needs to be solved in the field of flexible electronic devices.

[0005] As a new type of non-volatile memory technology, resistive random access memory (ReRAM) has become a research hotspot for next-generation memories due to its advantages such as high density, low power consumption, and high-speed writing. However, to achieve its long-term stable performance, the formation stability of conductive filaments and the mechanical stability of the devices are still the key issues restricting its application. First of all, the formation stability of conductive filaments is crucial for the reliability of resistive random access memory. During repeated voltage loading, oxygen deficiency or metal ion migration in oxide materials will lead to the formation and fracture of conductive filaments. The excessive growth or non-uniformity of conductive filaments will directly affect the writing stability and durability of the devices. For this reason, nano / microstructure induction has become an effective strategy to regulate the formation of conductive filaments by introducing specific nanostructures, thereby improving its stability and suppressing the generation of bad conduction paths. Secondly, especially for flexible resistive random access memory, mechanical stability is an important issue that urgently needs to be solved. Due to the use of flexible substrates and possible external stresses (such as bending, stretching, etc.), the devices may deform during operation, which will significantly affect their conductive characteristics and long-term performance. Insufficient mechanical stability may lead to the fracture of conductive filaments or the decline of device performance. Therefore, how to improve the mechanical stability of the devices while ensuring the formation stability of conductive filaments has become the key to improving the reliability and extending the service life of flexible resistive random access memory. Summary of the Invention

[0006] To solve the above problems existing in the prior art, the present invention provides a flexible self-supporting resistive random access memory with enhanced stability and a preparation method thereof. The technical problems to be solved by the present invention are realized through the following technical solutions:

[0007] One aspect of the present invention provides a preparation method of a flexible self-supporting resistive random access memory with enhanced stability, including:

[0008] Synthesize MXene solid powder using MAX phase Ti3AlC2 powder as raw material;

[0009] Use the MXene solid powder for suction filtration to obtain a bottom electrode composed of MXene self-supporting film;

[0010] Prepare an oxide film on the MXene self-supporting film to form an oxide semiconductor layer;

[0011] Prepare a top electrode on the upper surface of the oxide semiconductor layer.

[0012] In an embodiment of the present invention, synthesizing MXene solid powder using MAX phase Ti3AlC2 powder as raw material includes:

[0013] Use a predetermined amount of MAX phase Ti3AlC2 powder as raw material, add an etching solution composed of HCl and LiF for etching to obtain a Ti3C2T x dispersion liquid, and freeze-dry the Ti3C2T x dispersion liquid to obtain MXene solid powder.

[0014] In an embodiment of the present invention, the ratio of the MAX phase Ti3AlC2 powder to the etchant is 1 g:(10 mL - 20 mL); the ratio of HCl to LiF in the etching solution is 5 ml:(0.4 - 0.5 g).

[0015] In an embodiment of the present invention, using the MXene solid powder for suction filtration to obtain a bottom electrode composed of MXene self-supporting film includes:

[0016] Add the MXene solid powder into deionized water, and fully disperse the MXene solid powder through ultrasonic treatment to obtain a MXene dispersion liquid with a concentration of 1 - 10 mg / ml;

[0017] Add a predetermined amount of the MXene dispersion liquid into a negative pressure suction filter for suction filtration to form a MXene self-supporting film.

[0018] In an embodiment of the present invention, adding a predetermined amount of the MXene dispersion liquid into a negative pressure suction filter for suction filtration to form a MXene self-supporting film includes:

[0019] Add a predetermined amount of MXene dispersion liquid into the negative pressure suction filter, and perform suction filtration using a filter membrane with an appropriate pore size to ensure that impurities in the MXene dispersion liquid are filtered out and MXene nanosheets in the MXene dispersion liquid can be uniformly deposited on the filter membrane to form a MXene self-supporting film;

[0020] Take out the MXene self-supporting film formed by suction filtration and place it in an oven for drying. The drying temperature is 60-80 °C, and the drying time is 4-8 hours until the surface of the MXene self-supporting film is completely dry, forming a bottom electrode composed of the MXene self-supporting film.

[0021] In one embodiment of the present invention, the pore size of the filter membrane is 0.2-0.3 μm.

[0022] In one embodiment of the present invention, every 100 μm 2 The surface of the MXene self-supporting film has 3-5 wrinkles.

[0023] In one embodiment of the present invention, an oxide film is prepared on the MXene self-supporting film to form an oxide semiconductor layer, including:

[0024] Put the dried MXene self-supporting film into a magnetron sputtering chamber, put an oxide target, close the chamber door, and evacuate;

[0025] Introduce an inert gas, and start the power switch for pre-sputtering for a predetermined time after reaching the predetermined pressure to remove the surface impurities of the oxide target;

[0026] After the pre-sputtering is completed, use the oxide target to sputter an oxide film with a predetermined thickness on the surface of the MXene self-supporting film to form an oxide semiconductor layer. The material of the oxide film is gallium oxide, hafnium oxide, zinc oxide, indium oxide, zirconium oxide or aluminum oxide, and the thickness is 50 nm-200 nm.

[0027] In one embodiment of the present invention, a top electrode is prepared on the upper surface of the oxide semiconductor layer, including:

[0028] Fix the sample with the oxide semiconductor layer on a mask plate, put it into an evaporation chamber, and put the plating material on an evaporation boat, then close the chamber door;

[0029] Use a mechanical pump and a molecular pump to evacuate the vacuum to below 10 -4 Pa in sequence, gradually increase the current until the plating material starts to melt, and perform pre-evaporation for a predetermined time to remove the surface impurities of the plating material;

[0030] After the pre-evaporation is completed, use the mask plate to evaporate the top electrode with the required thickness and shape, thereby forming the required flexible self-supporting resistive random access memory.

[0031] Another aspect of the present invention provides a flexible self-supporting resistive random access memory with enhanced stability, which is prepared by using the preparation method described in any one of the above embodiments. The self-supporting resistive random access memory includes a bottom electrode, an oxide semiconductor layer, and a top electrode sequentially arranged from bottom to top.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. The present invention applies the flexible MXene self-supporting film as the bottom electrode in the resistive random access memory (RRAM), which can significantly improve the flexibility, conductivity and long-term stability of the device. Compared with the traditional metal bottom electrode, the MXene self-supporting film exhibits excellent flexibility and structural stability during mechanical deformation processes such as bending and stretching, avoiding the plastic deformation or fracture that may occur in metal electrodes under stress, thus ensuring the performance stability of the resistive random access memory under dynamic operation.

[0034] 2. The present invention uses a negative pressure filtration preparation process to prepare the MXene self-supporting film, which has the advantages of simple process and low cost. It can achieve large-area uniform coating and is applicable to a variety of flexible substrates, with good process adaptability. Therefore, as the bottom electrode, the MXene self-supporting film can not only significantly improve the electrical and mechanical properties of the resistive random access memory, but also enhance its long-term stability and reliability, expanding the broad application prospects in flexible electronic devices, especially wearable storage devices, intelligent sensors and other fields.

[0035] 3. The micron-scale wrinkled structure formed on the surface of the MXene self-supporting film in the present invention has multiple beneficial effects on the performance improvement of the resistive random access memory. First of all, these wrinkled structures not only enhance the flexibility and mechanical stability of the film by increasing the surface area of the film, but also enable it to better adapt to deformation under external stresses such as bending and stretching, avoiding material damage or performance degradation caused by stress concentration. Especially in flexible applications, the wrinkled structure can significantly improve the durability of the film, ensuring the stability of the device during long-term use. More importantly, the micron-scale wrinkles can significantly improve the stability of conductive filaments. In terms of electromagnetic shielding, the micron-scale wrinkles enhance the interaction between the film and external electromagnetic waves by increasing the surface complexity of the film, and can improve the electromagnetic wave absorption, reflection and scattering capabilities of the film, thus improving the signal stability and anti-interference ability of the resistive random access memory in a complex electromagnetic environment.

[0036] The following will further elaborate on the present invention in conjunction with the drawings and embodiments. Description of the Drawings

[0037] Figure 1 is a flowchart of a preparation method for a flexible self-supporting resistive random access memory with enhanced stability provided by an embodiment of the present invention;

[0038] Figure 2 is a SEM image of a MXene solid powder provided by an embodiment of the present invention;

[0039] Figure 3It is a schematic diagram of a self - supported MXene film obtained by suction filtration provided by an embodiment of the present invention;

[0040] Figure 4 It is a microscopic schematic diagram of the surface wrinkles of a self - supported MXene film provided by an embodiment of the present invention;

[0041] Figure 5 It is a schematic diagram of the electromagnetic shielding performance of a self - supported MXene film provided by an embodiment of the present invention;

[0042] Figure 6 It is the I - V characteristic curve of a flexible self - supported resistive random access memory with an Ag / Ga2O3 / MXene structure provided by an embodiment of the present invention. Detailed implementation manners

[0043] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following combines the accompanying drawings and specific implementation manners to detail the stability - enhanced flexible self - supported resistive random access memory and its preparation method proposed according to the present invention.

[0044] The foregoing and other technical contents, features and effects of the present invention can be clearly presented in the following detailed description in conjunction with the accompanying drawings. Through the description of the specific implementation manners, a more in - depth and specific understanding of the technical means and effects adopted by the present invention to achieve the predetermined purpose can be obtained. However, the accompanying drawings are only for reference and illustration, and are not used to limit the technical solution of the present invention.

[0045] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant is intended to cover non - exclusive inclusion, so that an article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed. Without more limitations, an element defined by the statement "including one..." does not exclude the existence of another identical element in the article or device including the said element.

[0046] Embodiment 1

[0047] Please refer to Figure 1 , Figure 1 It is a flowchart of a preparation method of a stability - enhanced flexible self - supported resistive random access memory provided by an embodiment of the present invention. The preparation method of this flexible self - supported resistive random access memory includes the following steps:

[0048] S1: Synthesize MXene solid powder using a predetermined amount of MAX phase Ti3AlC2 powder as the raw material.

[0049] Using a predetermined amount of MAX phase Ti3AlC2 powder as the raw material, add an etching solution composed of a predetermined amount of HCl (hydrochloric acid) and LiF (lithium fluoride) for etching to obtain a single-layer nanostructured Ti3C2T x dispersion liquid. Freeze-dry the single-layer nanostructured Ti3C2T x dispersion liquid to obtain MXene solid powder.

[0050] Preferably, the mesh number of Ti3AlC2 is 200 - 350; the ratio of MAX phase Ti3AlC2 powder to the etchant is 1 g : (10 mL - 20 mL); the ratio of HCl to LiF in the etching solution is 5 ml : (0.4 - 0.5 g); the etching time is 12 h - 36 h.

[0051] S2: Use the MXene solid powder for suction filtration to obtain a bottom electrode composed of MXene self-supporting films.

[0052] Add the MXene solid powder prepared in step S1 to deionized water, and ultrasonically treat it to fully disperse the MXene solid powder to obtain a MXene dispersion liquid with a concentration of 1 - 10 mg / ml for standby; add a predetermined amount of the MXene dispersion liquid to a negative pressure suction filter for suction filtration to form a MXene self-supporting film.

[0053] Specifically, slowly add a predetermined amount of the MXene dispersion liquid to the negative pressure suction filter, and use a filter membrane with an appropriate pore size (the pore size is 0.2 - 0.3 μm, preferably 0.22 μm) for suction filtration to ensure that impurities in the MXene dispersion liquid are filtered out and the MXene nanosheets in the MXene dispersion liquid can be evenly deposited on the filter membrane; take out the MXene self-supporting film formed by suction filtration and place it in an oven for drying. The drying temperature is 60 - 80 °C, and the drying time is 4 - 8 hours until the surface of the MXene self-supporting film is completely dry to form a bottom electrode composed of MXene self-supporting films.

[0054] In this embodiment, control the suction filtration time to be 45 min, so that the number of surface wrinkles of the MXene self-supporting film is 3 - 5 per 100 μm 2 That is, the surface of the MXene self-supporting film per 100 μm 2 has 3 - 5 wrinkles to achieve co-coupling with the subsequently prepared gallium oxide film (i.e., the oxide semiconductor layer) by the vacuum method to form conductive filaments and stable resistive switching performance. In addition, the suction filtration process needs to ensure the uniformity of the negative pressure in the negative pressure suction filter so that the MXene nanosheets can be deposited flatly on the filter membrane.

[0055] In the present invention, the micron-scale wrinkled structure formed on the surface of the MXene self-supporting film has multiple beneficial effects on improving the performance of the resistive random access memory. First of all, these wrinkled structures not only enhance the flexibility and mechanical stability of the film by increasing the surface area of the film, but also enable it to better adapt to deformation under external stresses such as bending and stretching, avoiding material damage or performance degradation caused by stress concentration. Especially in flexible applications, the wrinkled structure can significantly improve the durability of the film and ensure the stability of the device during long-term use. More importantly, the micron-scale wrinkles can significantly improve the stability of the conductive filaments. The working principle of the resistive random access memory relies on the formation and breaking process of conductive filaments driven by an electric field, and the wrinkled structure optimizes the uniformity of the conductive channels by providing more microstructures and enhancing the peak electric field of the microstructures to preferentially form conductive channels. These microstructures help to avoid randomness or instability during the formation of conductive filaments, ensuring their stable development during repeated writing processes, thereby reducing the inconsistency of the conductive performance. In terms of electromagnetic shielding, the micron-scale wrinkles enhance the interaction between the film and external electromagnetic waves by increasing the surface complexity of the film, can improve the electromagnetic wave absorption, reflection and scattering capabilities of the film, and improve the signal stability and anti-interference ability of the resistive random access memory in a complex electromagnetic environment.

[0056] S3: Prepare an oxide film on the MXene self-supporting film to form an oxide semiconductor layer.

[0057] This step can adopt any one of the following two processes:

[0058] (1) Magnetron sputtering:

[0059] Put the dried MXene self-supporting film into the substrate tray and place it on the substrate tray in the magnetron sputtering chamber. Place the oxide target, close the chamber door, and start pumping vacuum. Turn on the mechanical pump and pump the chamber vacuum to below 10 Pa, and then turn on the molecular pump. When the chamber vacuum is pumped to below 8×10 -4 Pa, the vacuum pumping is completed; during the vacuum pumping process, set parameters such as power, temperature, and air pressure according to specific requirements. After the vacuum pumping is completed, start introducing the inert gas Ar2. After reaching the set pressure, start the power switch for glow pre-sputtering. After successful glow, pre-sputter for 5 min to remove impurities on the target surface and clean the pipeline. After the pre-sputtering is completed, prepare the oxide film and sputter the oxide film with the required thickness under parameters such as the predetermined pressure, power, temperature, and argon-oxygen ratio to form an oxide semiconductor layer.

[0060] (2) Spin coating:

[0061] Use a dropper to suck up the oxide precursor solution and drop it on the center and four corners of the MXene self-supporting film, so that the oxide precursor solution can evenly cover the entire surface of the MXene self-supporting film, and spin-coat at a speed of 3000 r / min for 30 s to make the oxide precursor solution more evenly cover the MXene self-supporting film and volatilize part of the solvent in the oxide precursor solution to form a wet film on the surface of the MXene self-supporting film. Place the sample with the evenly covered wet film on a preheated hot stage, heat it at 150 °C for 10 min to evaporate the water on the surface and dry the wet film. Finally, put the sample into a tube annealing furnace and perform post-annealing treatment at 600 °C under an Ar₂ atmosphere to form an oxide film. The thickness of the oxide film can be controlled by controlling the number of spin-coating times.

[0062] Preferably, the thickness of the oxide film is 50 nm to 200 nm; the material of the oxide film is gallium oxide, hafnium oxide, zinc oxide, indium oxide, zirconium oxide or aluminum oxide. In this embodiment, the oxide precursor solution is an aqueous solution of gallium nitrate, and the material of the prepared oxide film is gallium oxide.

[0063] S4: Prepare a top electrode on the upper surface of the oxide semiconductor layer.

[0064] This step can adopt any one of the following two processes:

[0065] (1) Evaporation coating:

[0066] Paste the sample with the oxide semiconductor layer on the mask plate using high-temperature tape, put it into the evaporation coating chamber, and put the coating material on the evaporation boat (molybdenum boat), then close the chamber door. Then use a mechanical pump and a molecular pump to pump the vacuum to below 10 -4 Pa. At this time, gradually increase the current until the coating material starts to melt. When seeing the coating material melt, continue to increase the current to stabilize the evaporation rate at At this time, make the sample start to rotate, and set the rotation speed to 10 r / min. At the same time, pre-evaporate for 1 min to remove impurities on the surface of the coating material. After the pre-evaporation is completed, start to evaporate the top electrode with the required thickness. Using the mask plate, the top electrode with the required shape and size can be obtained, thus forming the required flexible self-supporting resistive random access memory. In this embodiment, the electrode is circular with a diameter of 100 μm, and the coating materials required for evaporation coating are silver, gold, and nickel.

[0067] (2) Printing process:

[0068] Disperse the conductive nanomaterials in a solvent and add an appropriate amount of dispersant or surfactant to ensure uniform dispersion, forming a conductive ink; load the conductive ink into a printing device (including spraying devices, inkjet printing devices, etc.), and spray the conductive ink onto the oxide film prepared in the previous step by controlling the pressure, spraying speed, and spraying time of the nozzle of the printing device; remove the residual solvent through heat treatment or light drying and perform annealing to obtain the top electrode, thereby forming the desired flexible self-supporting resistive random access memory.

[0069] Preferably, the conductive nanomaterials are silver nanowires, MXene, carbon nanotubes, graphene, etc.; the spraying time is 5 - 20 s; the annealing temperature is 100 - 150 °C.

[0070] Another embodiment of the present invention also provides a flexible self-supporting resistive random access memory with enhanced stability, including a bottom electrode, an oxide semiconductor layer, and a top electrode sequentially arranged from bottom to top, which has good electromagnetic interference resistance.

[0071] The present invention applies a flexible MXene self-supporting film as the bottom electrode to a resistive random access memory, which can significantly improve the flexibility, conductivity, and long-term stability of the device. Compared with traditional metal bottom electrodes, the MXene self-supporting film exhibits excellent flexibility and structural stability during mechanical deformation processes such as bending and stretching, avoiding the possible plastic deformation or fracture of metal electrodes under stress, thereby ensuring the performance stability of the resistive random access memory during dynamic operation. The MXene self-supporting film has extremely high conductivity, which can effectively reduce resistance loss, reduce energy dissipation, and ensure stable conductivity of the device during operation. In addition, the MXene self-supporting film has excellent electromagnetic shielding performance, and its shielding effect can exceed 50 dB, which can effectively shield external electromagnetic interference, ensuring the signal stability and anti-interference ability of the resistive random access memory, which is particularly important for improving the reliability of the device in a complex electromagnetic environment.

[0072] The present invention uses a negative pressure filtration preparation process to prepare the MXene self-supporting film, which has the advantages of simple process and low cost, can achieve large-area uniform coating, and is applicable to a variety of flexible substrates, with good process adaptability. Therefore, as the bottom electrode, the MXene self-supporting film can not only significantly improve the electrical and mechanical properties of the resistive random access memory, but also enhance its long-term stability and reliability, expanding its broad application prospects in flexible electronic devices, especially wearable storage devices, intelligent sensors, and other fields.

[0073] Example Two

[0074] Based on Example One, this example provides a preparation method for a flexible self-supporting resistive random access memory with enhanced stability, and the preparation method includes:

[0075] Step 1: Synthesize MXene solid powder.

[0076] Disperse 2 g of LiF in 5 mL of 10 mol / L hydrochloric acid solution, stir at 30 °C for 15 min to form an etching solution, slowly add 1 g of MAX phase Ti3AlC2, and stir at a constant temperature of 35 °C for 24 h to fully etch the Al layer in MAX phase Ti3AlC2 to form Ti3C2T x dispersion; then, centrifuge the Ti3C2T x dispersion at a speed of 3500 rpm for 5 min each time, take the lower precipitate until the pH value of the upper dispersion is 6; collect the precipitate, redisperse it in water, shake it evenly and then centrifuge it at a rotation speed of 3500 rpm for 15 min, take the precipitate and dry it to obtain the MXene solid powder, please refer to Figure 2 , Figure 2 is the SEM image of a kind of MXene solid powder provided by the embodiment of the present invention. It can be seen that the microscopic morphology of the MXene solid powder is nanosheets.

[0077] Step 2: Use the MXene solid powder for suction filtration to obtain a MXene self-supporting film.

[0078] Add the prepared MXene solid powder (the microstructure is MXene nanosheets) into deionized water, and disperse it fully by ultrasonic treatment to obtain a MXene dispersion with the required concentration for standby; slowly add a predetermined amount of MXene dispersion into a negative pressure suction filter. Use a filter membrane with an appropriate pore size (preferably 0.22 μm) for suction filtration to ensure that large particle impurities in the MXene dispersion are filtered out and the MXene sheets can be evenly deposited on the filter membrane. Control the suction filtration time to 45 min so that the number of wrinkles on the surface of the MXene self-supporting film is 3 - 5 per 100 μm 2 Have. Take out the MXene self-supporting film formed by suction filtration (as Figure 3 shown), and place it in an oven for drying. Control the drying temperature at 60 - 80 °C and the drying time at 4 - 8 hours until the surface of the MXene self-supporting film is completely dry. At the same time, ensure good air flow in the oven to promote the rapid evaporation of water and prevent warping or cracking of the MXene self-supporting film during the drying process. Take out the dried film. Please refer to Figure 4 and Figure 5 , Figure 4 is the microscopic schematic diagram of the surface wrinkles of a kind of MXene self-supporting film provided by the embodiment of the present invention; Figure 5 is the electromagnetic shielding effectiveness schematic diagram of a kind of MXene self-supporting film provided by the embodiment of the present invention. From Figure 4It can be seen that wrinkles are generated on the surface of the MXene self-supporting film, and the appearance of the wrinkles can be used to enhance the device stability. Figure 5 This reflects the electromagnetic shielding performance of the MXene self-supporting film, and the electromagnetic shielding performance is an embodiment of the multifunctionality of the device.

[0079] Step 3: Prepare an oxide film on the MXene self-supporting film to form an oxide semiconductor layer.

[0080] Put the dried MXene self-supporting film into the substrate tray, place it on the substrate tray in the magnetron sputtering chamber, put in the gallium oxide target, close the chamber door, and start pumping vacuum. Turn on the mechanical pump and pump the chamber vacuum to below 10 Pa, then turn on the molecular pump. When the chamber vacuum is pumped to below 8×10 -4 Pa, the vacuum pumping is completed; during the vacuum pumping process, set parameters such as power, temperature, and air pressure. Start introducing the inert gas Ar2. After reaching the set pressure, start the power switch for glow pre-sputtering. After successful glow, pre-sputter for 5 minutes to remove impurities on the target surface and clean the pipeline. After the pre-sputtering is completed, prepare the gallium oxide film and sputter the gallium oxide film with the required thickness under parameters such as the predetermined pressure, power, temperature, and argon-oxygen ratio.

[0081] Step 4: Prepare a top electrode on the upper surface of the oxide semiconductor layer.

[0082] Paste the sample with the prepared gallium oxide film on the mask plate using high-temperature tape, put it into the evaporation chamber, and put the evaporation material (silver) on the evaporation boat (molybdenum boat), then close the chamber door. Then use the mechanical pump and the molecular pump in turn to pump the vacuum to below 10 - 4 Pa. At this time, gradually increase the current until the evaporation material starts to melt. When seeing the evaporation material melting, continue to increase the current and stabilize the evaporation rate at At this time, make the sample start to rotate, set the rotation speed to 10 r / min, and pre-evaporate for 1 minute to remove impurities on the surface of the evaporation material. After the pre-evaporation is completed, start evaporating the electrode with the required thickness. Using the mask plate, the electrode with the required shape and size can be obtained, and finally the prepared flexible self-supporting resistive random access memory is obtained.

[0083] After the prepared flexible self-supporting resistive random access memory has undergone 50 bending tests, use a semiconductor tester 4200 to measure its current-voltage (I-V) characteristics. According to Figure 6From the shown test results, it can be clearly observed that the flexible self-supporting resistive random access memory exhibits obvious resistance changes during the voltage application process. This indicates that the flexible self-supporting resistive random access memory has good resistive switching characteristics and can achieve reversible changes in the resistance state, thus successfully completing the functions of data storage and reading. The results show that after bending deformation, the flexible self-supporting resistive random access memory still maintains stable electrical properties, demonstrating its potential and reliability in flexible applications.

[0084] Example Three

[0085] Based on Example One, this example provides a preparation method for a flexible self-supporting resistive random access memory with enhanced stability. The preparation method includes:

[0086] Step 1: Synthesize MXene solid powder.

[0087] Disperse 2 g of LiF in 5 mL of 10 mol / L hydrochloric acid solution, stir at 30 °C for 15 min to form an etching solution, slowly add 1 g of MAX phase Ti3AlC2, and stir at a constant temperature of 35 °C for 24 h to fully etch the Al layer in the MAX phase Ti3AlC2 to form a dispersion of single-layer Ti3C2T x dispersion; then, centrifuge the Ti3C2T x dispersion at a speed of 3500 rpm for 5 min each time, take the lower precipitate until the pH value of the upper dispersion is 6; collect the precipitate, redisperse it in water, shake it evenly and then centrifuge at a speed of 3500 rpm for 15 min, and take the precipitate to dry to obtain the MXene solid powder.

[0088] Step 2: Use the MXene solid powder for vacuum filtration to obtain a MXene self-supporting film.

[0089] Add the prepared MXene solid powder (with a microstructure of MXene nanosheets) into deionized water, and disperse it fully by ultrasonic treatment to obtain a MXene dispersion with the required concentration for standby; slowly add a predetermined amount of the MXene dispersion into a vacuum filtration device. Use a filter membrane with a pore size of 0.22 μm for vacuum filtration to ensure that large particle impurities in the MXene dispersion are filtered out and the MXene sheets can be evenly deposited on the filter membrane. Control the vacuum filtration time to 45 min, so that the number of surface wrinkles of the MXene self-supporting film per 100 μm 2It has 3 to 5 folds. Take out the MXene self-supporting film formed by suction filtration and place it in an oven for drying. Control the drying temperature at 60 to 80 °C and the drying time at 4 to 8 hours until the surface of the MXene self-supporting film is completely dry. At the same time, ensure good air flow in the oven to promote the rapid evaporation of moisture and prevent warping or cracking of the MXene self-supporting film during drying. Take out the dried film.

[0090] Step 3: Prepare an oxide film on the MXene self-supporting film to form an oxide semiconductor layer.

[0091] Use a dropper to suck up the gallium oxide precursor solution (i.e., an aqueous solution of gallium nitrate) and drop it on the center and four corners of the MXene self-supporting film, so that the gallium oxide precursor solution can evenly cover the entire surface of the MXene self-supporting film, and spin-coat at a speed of 3000 r / min for 30 s to make the gallium oxide precursor solution more evenly cover the MXene self-supporting film and volatilize part of the solvent (i.e., water) in the oxide precursor solution to form a wet film on the surface of the MXene self-supporting film. Place the sample with the evenly covered wet film on the heated hot stage and heat it at 150 °C for 10 min to evaporate the water on the surface and dry the wet film. Finally, put the prepared sample into a tube annealing furnace and perform post-annealing treatment at 600 °C in an Ar2 atmosphere to form a gallium oxide film. The thickness of the gallium oxide film can be controlled by controlling the number of spin-coating times.

[0092] Step 4: Prepare a top electrode on the upper surface of the oxide semiconductor layer.

[0093] Paste the sample with the prepared oxide film on the mask plate using high-temperature tape, put it into the evaporation chamber, and place the plating material (gold) on the evaporation boat (molybdenum boat), then close the chamber door. Then use a mechanical pump and a molecular pump to pump the vacuum to below 10 -4 Pa. At this time, gradually increase the current until the plating material starts to melt. When seeing the plating material melt, continue to increase the current to stabilize the evaporation rate at At this time, start to rotate the sample, set the rotation speed at 10 r / min, and pre-evaporate for 1 min to remove impurities on the surface of the plating material. After the pre-evaporation is completed, start to evaporate the electrode with the required thickness. Using the mask plate, the electrode with the required shape and size can be obtained, and finally the prepared flexible self-supporting resistive random access memory is obtained.

[0094] Example 4

[0095] On the basis of Example 1, this example provides a preparation method for a flexible self-supporting resistive random access memory with enhanced stability. The preparation method includes:

[0096] Step 1: Synthesize MXene solid powder.

[0097] Disperse 2 g of LiF in 5 mL of 10 mol / L hydrochloric acid solution, stir at 30 °C for 15 min to form an etching solution, slowly add 1 g of MAX phase Ti3AlC2, and stir at a constant temperature of 35 °C for 24 h to fully etch the Al layer in the MAX phase Ti3AlC2 to form single-piece Ti3C2T x dispersion; then, centrifuge the Ti3C2T x dispersion at a speed of 3500 rpm for 5 min each time, take the lower-layer precipitate until the pH value of the dispersion is 6; collect the precipitate, redisperse it in water, shake it evenly and then centrifuge it, with a rotation speed of 3500 rpm and a time of 15 min, take the precipitate and dry it to obtain the MXene solid powder.

[0098] Step 2: Use the MXene solid powder for vacuum filtration to obtain the MXene free-standing film.

[0099] Add the prepared MXene solid powder into deionized water, and make it fully dispersed by ultrasonic treatment to obtain the MXene dispersion with the required concentration for standby; slowly add a predetermined amount of the MXene dispersion into a vacuum filtration device. Use a filter membrane with a pore size of 0.22 μm for vacuum filtration to ensure that large-particle impurities in the MXene dispersion are filtered out and the MXene sheets can be evenly deposited on the filter membrane. Control the vacuum filtration time to be 45 min so that the number of wrinkles on the surface of the MXene free-standing film is 3 - 5 per 100 μm 2 There are 3 - 5 wrinkles. The vacuum filtration process needs to ensure the uniformity of the negative pressure so that the MXene nanosheets can be deposited flatly on the filter membrane. Take out the MXene free-standing film formed by vacuum filtration and place it in an oven for drying. The drying temperature is controlled at 60 - 80 °C, and the drying time is 4 - 8 hours until the surface of the MXene free-standing film is completely dry. At the same time, ensure good air flow in the oven to promote the rapid evaporation of water and prevent warping or cracking of the MXene free-standing film during the drying process. Take out the dried film.

[0100] Step 3: Prepare an oxide film on the MXene free-standing film to form an oxide semiconductor layer.

[0101] Put the dried MXene free-standing film into a substrate tray, place it on the substrate tray in the magnetron sputtering chamber, put a gallium oxide target, close the chamber door, and start pumping vacuum. Turn on the mechanical pump to pump the chamber vacuum to below 10 Pa, and then turn on the molecular pump. Wait until the chamber vacuum is pumped to 8×10 -4When the pressure is below Pa, the vacuum pumping is completed; during the vacuum pumping process, parameters such as power, temperature, and air pressure are set. Then, an inert gas Ar2 is introduced. After reaching the set pressure, the power switch is turned on for glow pre-sputtering. After successful glow, pre-sputtering is carried out for 5 minutes to remove impurities on the surface of the target and clean the pipeline. After the pre-sputtering is completed, the gallium oxide thin film is prepared. Under parameters such as the predetermined pressure, power, temperature, and argon-oxygen ratio, the gallium oxide thin film with the required thickness is sputtered.

[0102] Step 4: Prepare a top electrode on the upper surface of the oxide semiconductor layer.

[0103] Disperse the conductive nanomaterials in a solvent, and add an appropriate amount of dispersant or surfactant to ensure uniform dispersion to form a conductive ink; load the conductive ink into a printing device (including a spraying device, an inkjet printing device, etc.), and by controlling the pressure, spraying speed, and spraying time of the nozzle of the printing device, spray the conductive ink on the oxide thin film prepared in the previous step; remove the residual solvent through heat treatment or light drying and perform annealing to obtain the top electrode.

[0104] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should all be regarded as belonging to the protection scope of the present invention.

Claims

1. A preparation method of a flexible self-supporting resistive random access memory with enhanced stability, characterized in that, Including: Synthesizing MXene solid powder from MAX phase Ti3AlC2 powder as raw material; Performing suction filtration using the MXene solid powder to obtain a bottom electrode composed of MXene self-supporting film; Preparing an oxide film on the MXene self-supporting film to form an oxide semiconductor layer; Preparing a top electrode on the upper surface of the oxide semiconductor layer.

2. The preparation method of the flexible self-supporting resistive random access memory with enhanced stability according to claim 1, wherein, Synthesizing MXene solid powder from MAX phase Ti3AlC2 powder as raw material, including: Using a predetermined amount of MAX phase Ti3AlC2 powder as raw material, an etching solution composed of HCl and LiF is added for etching to obtain a Ti3C2T x dispersion liquid. The Ti3C2T x dispersion liquid is freeze-dried to obtain MXene solid powder.

3. The preparation method of the flexible self-supporting resistive random access memory with enhanced stability according to claim 2, characterized in that The ratio of the MAX phase Ti3AlC2 powder to the etchant is 1g:(10mL - 20mL); the ratio of HCl to LiF in the etching solution is 5ml:(0.4 - 0.5g).

4. The preparation method of the flexible self-supporting resistive random access memory with enhanced stability according to claim 1, characterized in that, Performing suction filtration using the MXene solid powder to obtain a bottom electrode composed of MXene self-supporting film, including: Adding the MXene solid powder into deionized water, and fully dispersing the MXene solid powder by ultrasonic treatment to obtain a MXene dispersion with a concentration of 1 - 10mg / ml; Adding a predetermined amount of the MXene dispersion into a negative pressure suction filter for suction filtration to form a MXene self-supporting film.

5. The preparation method of the flexible self-supporting resistive random access memory with enhanced stability according to claim 4, wherein, Adding a predetermined amount of the MXene dispersion into a negative pressure suction filter for suction filtration to form a MXene self-supporting film, including: Adding a predetermined amount of MXene dispersion into the negative pressure suction filter, and performing suction filtration using a filter membrane with an appropriate pore size to ensure that impurities in the MXene dispersion are filtered out and MXene nanosheets in the MXene dispersion can be evenly deposited on the filter membrane to form a MXene self-supporting film; Taking out the MXene self-supporting film formed by suction filtration, placing it in an oven for drying, with a drying temperature of 60 - 80°C and a drying time of 4 - 8 hours, until the surface of the MXene self-supporting film is completely dry, to form a bottom electrode composed of MXene self-supporting film.

6. The preparation method of the flexible self-supporting resistive random access memory with enhanced stability according to claim 5, wherein, The pore size of the filter membrane is 0.2 - 0.3μm.

7. The preparation method of the flexible self-supporting resistive random access memory with enhanced stability according to claim 5, wherein, Per 100 μm 2 The surface of the MXene self-supporting film has 3 to 5 wrinkles.

8. The preparation method of the flexible self-supporting resistive random access memory with enhanced stability according to claim 1, characterized in that, Preparing an oxide film on the MXene self-supporting film to form an oxide semiconductor layer, including: Putting the dried MXene self-supporting film into a magnetron sputtering chamber, putting an oxide target, closing the chamber door, and performing vacuum pumping; Introducing an inert gas, and starting the power switch for pre-sputtering for a predetermined time after reaching a predetermined pressure to remove surface impurities of the oxide target; After pre-sputtering is completed, sputtering a predetermined thickness of oxide film on the surface of the MXene self-supporting film using the oxide target to form an oxide semiconductor layer, the material of the oxide film is gallium oxide, hafnium oxide, zinc oxide, indium oxide, zirconium oxide or aluminum oxide, and the thickness is 50nm - 200nm.

9. The preparation method of the flexible self-supporting resistive random access memory with enhanced stability according to claim 4, characterized in that, Preparing a top electrode on the upper surface of the oxide semiconductor layer, including: Fixing the sample with an oxide semiconductor layer on a mask plate, putting it into an evaporation chamber, and putting the plating material on an evaporation boat, then closing the chamber door; Use a mechanical pump and a molecular pump successively to pump the vacuum down to 10 -4 Pa or less, gradually increase the current until the plating material starts to melt, and perform pre-evaporation plating for a predetermined time to remove impurities on the surface of the plating material; After pre-evaporation is completed, evaporating the top electrode with the required thickness and shape using the mask plate, thereby forming the required flexible self-supporting resistive random access memory.

10. A flexible self-supporting resistive random access memory with enhanced stability, characterized in that, Prepared by the preparation method according to any one of claims 1 to 9, the self-supporting resistive random access memory includes a bottom electrode, an oxide semiconductor layer, and a top electrode sequentially arranged from bottom to top.

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