Flexible self-rectifying memory and preparation method and application thereof

Abstract

This invention provides a flexible self-rectifying memory, its fabrication method, and its application. In this flexible self-rectifying memory, a polydiallyldimethylammonium chloride buffer switch layer serves as the active switching medium, and its quaternary ammonium salt functional groups provide oxygen ion adsorption sites, promoting oxygen ion aggregation and movement; Ti3C2T x The charge-trapping layer achieves efficient charge trapping through large interlayer spacing and a nanoporous structure. The flexible self-rectifying memory of this invention exhibits tunable self-rectification characteristics and significant crosstalk suppression. The fabrication process of this invention is simple and inexpensive. The advantages of combining the polymer and inorganic layers are not only reflected in the preservation of material flexibility but also in innovative high-performance features such as adjustable self-rectification. The flexible self-rectifying memory of this invention demonstrates great application potential in high-density and ultra-large-scale parallel memory arrays struggling with creeping currents and in learning through neural synaptic plasticity.

Description

Technical Field

[0001] This invention relates to the field of semiconductor memory technology, and in particular to a flexible self-rectifying memory, its fabrication method, and its application. Background Technology

[0002] Traditional mainstream non-volatile memory NAND Flash is based on floating gate transistor technology. Its speed and density have approached the physical limit. Planar processes are difficult to shrink to below 10nm. Although 3D vertical structure NAND improves storage density, there is an upper limit to the number of stacked layers, and the speed limitation has not been fundamentally solved.

[0003] Resistive random access memory (RRAM) is considered a core candidate for next-generation non-volatile memory due to its good scalability, low latency, and low power consumption. 3D cross-connected RRAM arrays can achieve ultra-high storage density, but crosstalk currents between adjacent cross cells can cause severe read / write interference. In existing solutions, the one-transistor-one-memory (1T1R) architecture can suppress crosstalk, but the large feature size of the transistors limits the miniaturization and integration density of the array. Self-rectified memory (SRM), with its inherent rectification characteristics, eliminates the need for additional series transistors or selectors, simplifying circuit structure and reducing costs. However, existing SRMs suffer from drawbacks such as unadjustable self-rectification characteristics, poor reliability, and insufficient flexibility and compatibility.

[0004] Two-dimensional materials, due to their ultrathin layered structure and excellent electrical properties, have great potential for application in the memory field. Ti3C2T x MXene, as a typical two-dimensional material, possesses large interlayer spacing and a nanoporous structure, exhibiting excellent charge trapping capabilities. However, single Ti3C2T... x During cycling, oxygen ions migrate and form an insulating layer, leading to device failure. Furthermore, it is difficult to control the self-rectification characteristics of the base memory.

[0005] Based on the above problems, there is an urgent need to develop a flexible memory that is simple to manufacture, low in cost, highly reliable, and has adjustable self-rectification characteristics, while also simulating synaptic functions, so as to promote the industrial application of RRAM in the fields of neuromorphic computing and flexible electronics. Summary of the Invention

[0006] To address the aforementioned technical deficiencies, this invention provides a flexible self-rectifying memory, its fabrication method, and its applications. The flexible self-rectifying memory of this invention features adjustable self-rectification characteristics, significant crosstalk suppression, high device reliability, excellent performance, and combines flexibility with synaptic functionality, making it suitable for a wide range of applications.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a flexible self-rectifying memory, comprising:

[0009] Flexible substrate;

[0010] The bottom electrode is located on the surface of the flexible substrate;

[0011] Ti3C2T x A charge trapping layer is located on the surface of the bottom electrode away from the flexible substrate;

[0012] The polydiallyl dimethylammonium chloride buffer switch layer is located in the Ti3C2T x The charge trapping layer is located away from the surface of the flexible substrate;

[0013] The top electrode is located on the surface of the polydiallyldimethylammonium chloride buffer switch layer away from the flexible substrate.

[0014] Preferably, the flexible substrate is made of any one of PET, PEN, PI, PDMS, and PVB.

[0015] The material of the bottom electrode is any one of ITO, AZO, and FTO;

[0016] The material of the top electrode is any one of Al, Au, Ag, Cu, Pt, and Ti.

[0017] Preferably, the thickness of the flexible substrate is 1~10μm;

[0018] The thickness of the bottom electrode is 200~300nm;

[0019] The Ti3C2T x The thickness of the charge trapping layer is 30~50nm;

[0020] The thickness of the polydiallyldimethylammonium chloride buffer switch layer is 450~550 nm;

[0021] The thickness of the top electrode is 50~70nm.

[0022] Secondly, the present invention also provides a method for fabricating the aforementioned flexible self-rectifying memory, comprising the following steps:

[0023] Configuring Ti3C2T x suspension;

[0024] A bottom electrode is fabricated on the surface of a flexible substrate, and Ti3C2T is coated on the surface of the bottom electrode. x Suspension, annealing, to prepare Ti3C2T x Charge trapping layer;

[0025] Prepare an aqueous solution of polydiallyldimethylammonium chloride;

[0026] Aqueous solution of polydiallyldimethylammonium chloride was coated onto Ti3C2T. x The surface of the charge trapping layer is annealed to prepare a polydiallyldimethylammonium chloride buffer switch layer;

[0027] A top electrode was fabricated on the surface of a polydiallyldimethylammonium chloride buffer switch layer.

[0028] Preferably, the Ti3C2T x The method for preparing a suspension includes the following steps:

[0029] Lithium fluoride was added to hydrochloric acid and stirred to obtain an etching solution;

[0030] Ti3AlC2 was added to the etching solution for etching, centrifuged, the supernatant was removed, and the resulting precipitate was washed to obtain the precipitate.

[0031] The precipitate was added to water, sonicated, centrifuged, and the supernatant was collected, which is Ti3C2T. x Suspension.

[0032] Preferably, polydiallyl dimethyl ammonium chloride is added to water to obtain an aqueous solution of polydiallyl dimethyl ammonium chloride, wherein the concentration of the aqueous solution of polydiallyl dimethyl ammonium chloride is 90~110 g / L.

[0033] Preferably, in the step of adding Ti3AlC2 to the etching solution for etching, the etching specifically includes etching at 40~45℃ and 200~250rpm for 48~50h;

[0034] Add the precipitate to water, sonicate at 10°C or below for 1-2 hours, centrifuge, and collect the supernatant, which is Ti3C2T. x suspension;

[0035] The mass-volume ratio of lithium fluoride, Ti3AlC2, and hydrochloric acid is (3.0~3.5)g:(3.0~3.5)g:(18~22)mL, and the concentration of hydrochloric acid is 9~10mol / L; the precipitate is added to water, wherein the volume ratio of water to hydrochloric acid is (40~45):(18~22).

[0036] Preferably, Ti3C2T is spin-coated onto the surface of the bottom electrode. x Suspension, annealing, to prepare Ti3C2T x Charge trapping layer;

[0037] The spin coating parameters are as follows: spin rotation speed of 3000~3200 rpm and acceleration of 1000~1100 rad / s.2 Spin coating time is 30~35s;

[0038] The annealing temperature is 100~110℃ and the time is 5~10min.

[0039] Preferably, an aqueous solution of polydiallyldimethylammonium chloride is spin-coated onto Ti3C2T. x The surface of the charge trapping layer is annealed to prepare a polydiallyldimethylammonium chloride buffer switch layer;

[0040] The spin coating parameters are as follows: spin rotation speed of 4000~4200 rpm and acceleration of 2000~2100 rad / s. 2 Spin coating time is 60~70s;

[0041] The annealing temperature is 150~160℃ and the time is 10~15min.

[0042] Thirdly, the present invention also provides an application of the flexible self-rectified memory described above or the flexible self-rectified memory prepared by the aforementioned preparation method in the fields of neuromorphic computing and flexible wearable electronics.

[0043] The flexible self-rectifying memory, its fabrication method, and its application of the present invention have the following advantages compared to the prior art:

[0044] 1. The flexible self-rectifying memory of the present invention includes a flexible substrate, a bottom electrode, and a Ti3C2T electrode stacked sequentially. x The system comprises a charge trapping layer, a polydiallyldimethylammonium chloride (PDDA) buffer switching layer, and a top electrode. The PDDA buffer switching layer serves as the active switching medium, with its quaternary ammonium salt functional groups providing oxygen ion adsorption sites, promoting oxygen ion aggregation and movement. (Ti3C2T) x The charge trapping layer achieves efficient charge trapping through large interlayer spacing and a nanoporous structure. The flexible self-rectifying memory of this invention features adjustable self-rectification characteristics and significant crosstalk suppression: by controlling the limiting current (less than 1mA), the self-rectification characteristics of the device can be flexibly adjusted without the need for additional series transistors or selectors, simplifying the circuit structure and increasing the integration density of the 3D cross array. The flexible self-rectifying memory of this invention exhibits high reliability and excellent performance: PDDA / Ti3C2T x The dual-layer structure design solves the problem of single Ti3C2T x The failure problem of base memory, the device on / off ratio is greater than 10. 4 Cyclic durability greater than 1000 cycles, high and low resistance state retention time greater than 5 × 10⁻⁶ cycles. 3The device exhibits excellent environmental stability, showing no significant performance degradation after 9 months of storage at 25℃ and 40% humidity. The resistive switching mechanism of this flexible self-rectifying memory is charge-trapping. Combining characterization and current mechanism analysis, and considering that the functional layer is prepared using solution processing, even when designed as a thin film, complete separation of the two components cannot be guaranteed. Furthermore, it involves -OH, -O, and other Ti3C2T... x Changes in surface functional groups and Ti vacancies, etc., in the composite PDDA / Ti3C2T x Thin films may contain a large number of defects, and electrons store charge through the action of these defects. The flexible self-rectified memory of the present invention combines flexibility and synaptic function, and has a wide range of applications: the device maintains stable resistive switching characteristics after bending angles of up to 60° and bending times of more than 200 times; it can simulate the PPF and LTP characteristics of biological synapses, providing core device support for neuromorphic computing and flexible wearable electronics.

[0045] 2. The fabrication method of the flexible self-rectifying memory of the present invention, Ti3C2T x The charge trapping layer and the polydiallyldimethylammonium chloride buffer switch layer respectively utilize Ti3C2T x The suspension and aqueous solution of polydiallyldimethylammonium chloride were prepared by spin coating, which eliminates the need for expensive vacuum deposition equipment, has a short process cycle, and is simple to operate, making it suitable for large-scale mass production. The preparation process of this invention is simple and low-cost. The composite advantages of the polymer layer and the inorganic layer are not only reflected in the retention of the material's flexibility, but also in the innovative high performance such as self-rectification and adjustable properties. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a schematic diagram of the flexible self-rectifying memory of the present invention;

[0048] Figure 2 Al / PDDA / Ti3C2T in Example 1 x Scanning electron microscope image of ITO / PET flexible self-rectifying memory;

[0049] Figure 3 For Comparative Example 1, Al / Ti3C2T x IV curves for ITO / glass memory;

[0050] Figure 4 Al / PDDA / Ti3C2T in Example 1 x IV curve of ITO / PET flexible self-rectifying memory;

[0051] Figure 5 For Comparative Example 1, Al / Ti3C2T x Tolerance test curves for ITO / glass memory;

[0052] Figure 6 Al / PDDA / Ti3C2T in Example 1 x Endurance test curves of ITO / PET flexible self-rectifying memory;

[0053] Figure 7 Al / PDDA / Ti3C2T in Example 1 x / ITO / PET flexible self-rectifying memory IV curves at different limiting currents;

[0054] Figure 8 Al / PDDA / Ti3C2T in Example 1 x Conductivity changes of ITO / PET flexible self-rectifying memory under 5 consecutive sets of LTP / LTD pulses;

[0055] Figure 9 Al / PDDA / Ti3C2T in Example 1 x A graph showing the relationship between the PPF index of the ITO / PET flexible self-rectifying memory and the two-pulse interval (Δt);

[0056] Figure 10 Al / PDDA / Ti3C2T in Example 1 x IV curves of / ITO / PET flexible self-rectifying memory after being folded at different angles;

[0057] Figure 11 Al / PDDA / Ti3C2T in Example 1 x Resistance distribution of / ITO / PET flexible self-rectifying memory after 200 switching cycles of folding at a 30° angle. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0059] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0060] This application provides a flexible self-rectifying memory, comprising:

[0061] Flexible substrate 1;

[0062] Bottom electrode 2 is located on the surface of flexible substrate 1;

[0063] Ti3C2T x The charge trapping layer 3 is located on the surface of the bottom electrode 2 away from the flexible substrate 1;

[0064] Polydiallyl dimethylammonium chloride buffer switch layer 4, located in Ti3C2T x The charge trapping layer 3 is located away from the surface of the flexible substrate 1;

[0065] The top electrode 5 is located on the surface of the polydiallyldimethylammonium chloride buffer switch layer 4 away from the flexible substrate 1.

[0066] like Figure 1 As shown, the flexible self-rectifying memory of the present invention includes a flexible substrate 1, a bottom electrode 2, and a Ti3C2T electrode stacked sequentially. x The structure consists of a charge trapping layer 3, a polydiallyldimethylammonium chloride (PDDA) buffer switching layer 4, and a top electrode 5. The PDDA buffer switching layer 4 serves as the active switching medium, with its quaternary ammonium salt functional groups providing oxygen ion adsorption sites to promote oxygen ion aggregation and movement. (Ti3C2T) x Charge trapping layer 3 achieves efficient charge trapping through its large interlayer spacing and nanoporous structure; the quaternary ammonium salt groups in the PDDA buffer layer repel Al through electrostatic dual regulation. 3+ To reduce the formation of insulating phase, adsorb oxygen ions to form ion-conducting channels, and then combine Ti3C2T x The interface and conductivity advantages of the charge trapping layer solve the problem of pure Ti3C2T x

[0067] The memristor overcomes the low-resistance volatile problem and also endows the device with self-rectification characteristics, improving the switching ratio by 1 to 2 orders of magnitude.

[0068] In some embodiments, the flexible substrate is made of any one of PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PI (polyimide), PDMS (polydimethylsiloxane), and PVB (polyvinyl butyral).

[0069] The bottom electrode material is any one of ITO (indium tin oxide), AZO (aluminum-doped zinc oxide), and FTO (fluorine-doped tin oxide);

[0070] The material of the top electrode is any one of Al, Au, Ag, Cu, Pt, and Ti.

[0071] Furthermore, preferably, the flexible substrate is made of PET, the bottom electrode is made of ITO, and the top electrode is made of Al, in which case the memory is Al / PDDA / Ti3C2T. x / ITO / PET stacked structure.

[0072] The flexible self-rectifying memory of the present invention has the following advantages:

[0073] Adjustable self-rectification characteristics and significant crosstalk suppression: By adjusting the limiting current (less than 1mA), the self-rectification characteristics of the device can be flexibly adjusted without the need for additional series transistors or selectors, simplifying the circuit structure and improving the integration density of the 3D cross array.

[0074] High device reliability and excellent performance: PDDA / Ti3C2T x The dual-layer structure design solves the problem of single Ti3C2T x The failure problem of base memory, the device on / off ratio is greater than 10. 4 Cyclic durability greater than 1000 cycles, high and low resistance state retention time greater than 5 × 10⁻⁶ cycles. 3 It exhibits excellent environmental stability, showing no significant performance degradation after being stored at 25℃ and 40% humidity for 9 months.

[0075] The resistive switching mechanism of the device is charge-trapping type: through IV curve fitting, top electrode control experiment, band structure analysis and characterization; at the same time, considering that the functional layer is prepared by solution processing, even if it is designed as a thin film, complete separation of the two cannot be guaranteed, and it also involves -OH, -O and other Ti3C2T x Changes in surface functional groups and Ti vacancies, etc., in the composite PDDA / Ti3C2T xThe thin film contains a large number of defects, through which electrons store charge. The resistive switching mechanism of the device is identified as a trap-controlled space charge confinement current mechanism rather than a non-conductive filament mechanism, providing theoretical support for its industrial application in neuromorphic computing, high-density storage and other fields.

[0076] Combining flexibility and synaptic functionality, it has a wide range of applications: the device maintains stable resistive switching characteristics even after bending at an angle of up to 60° and more than 200 bending cycles; it can simulate the PPF and LTP characteristics of biological synapses, providing core device support for neuromorphic computing and flexible wearable electronics.

[0077] In some embodiments, the thickness of the flexible substrate is 1~10μm;

[0078] The thickness of the bottom electrode is 200~300nm;

[0079] Ti3C2T x The thickness of the charge trapping layer is 30~50nm;

[0080] The thickness of the polydiallyldimethylammonium chloride buffer switch layer is 450~550 nm;

[0081] The thickness of the top electrode is 50~70nm.

[0082] Based on the same inventive concept, the present invention also provides a method for fabricating the above-mentioned flexible self-rectifying memory, comprising the following steps:

[0083] S1, Preparation of Ti3C2T x suspension;

[0084] S2. Fabricate a bottom electrode on the surface of a flexible substrate, and coat the surface of the bottom electrode with Ti3C2T. x Suspension, annealing, to prepare Ti3C2T x Charge trapping layer;

[0085] S3. Prepare an aqueous solution of polydiallyldimethylammonium chloride;

[0086] S4. Coating Ti3C2T with an aqueous solution of polydiallyldimethylammonium chloride. x The surface of the charge trapping layer is annealed to prepare a polydiallyldimethylammonium chloride buffer switch layer;

[0087] S5. A top electrode is prepared on the surface of a polydiallyldimethylammonium chloride buffer switch layer.

[0088] In some embodiments, Ti3C2T x The method for preparing a suspension includes the following steps:

[0089] Lithium fluoride was added to hydrochloric acid and stirred to obtain an etching solution;

[0090] Ti3AlC2 was added to the etching solution for etching, centrifuged, the supernatant was removed, and the resulting precipitate was washed to obtain the precipitate.

[0091] The precipitate was added to water, sonicated, centrifuged, and the supernatant was collected, which is Ti3C2T. x Suspension.

[0092] In some embodiments, polydiallyl dimethyl ammonium chloride (CAS No. 26062-79-3) is added to water to obtain an aqueous solution of polydiallyl dimethyl ammonium chloride, wherein the concentration of the aqueous solution of polydiallyl dimethyl ammonium chloride is 90~110 g / L.

[0093] In some embodiments, the etching step of adding Ti3AlC2 to the etching solution and etching specifically includes etching at 40~45°C and 200~250rpm for 48~50h.

[0094] Add the precipitate to water, sonicate at 10°C or below for 1-2 hours, centrifuge, and collect the supernatant, which is Ti3C2T. x suspension;

[0095] The mass-volume ratio of lithium fluoride, Ti3AlC2, and hydrochloric acid is (3.0~3.5)g:(3.0~3.5)g:(18~22)mL, and the concentration of hydrochloric acid is 9~10mol / L; the precipitate is added to water, wherein the volume ratio of water to hydrochloric acid is (40~45):(18~22).

[0096] In some embodiments, Ti3AlC2 is added to the etching solution for etching. After etching, the solution is centrifuged at 200-300 rpm for 1-2 min, the supernatant is removed, and the resulting precipitate is washed three times with 9-10 M HCl by centrifugation, and then washed 5-6 times with deionized water by centrifugation (each washing centrifugation rate is 4000 rpm and time is 5 min) until the pH reaches neutral, and the precipitate is obtained.

[0097] In some embodiments, the precipitate is added to water and sonicated at 10°C or less for 1-2 hours with an ultrasonic power of 300-500W, followed by centrifugation at 4000-4500 rpm for 0.5-1 hour. The supernatant is collected, which is Ti3C2T. x Suspension.

[0098] In some embodiments, Ti3C2T is spin-coated onto the surface of the bottom electrode. x Suspension, annealing, to prepare Ti3C2T x Charge trapping layer;

[0099] The spin coating parameters are as follows: spin rotation speed of 3000~3200 rpm and acceleration of 1000~1100 rad / s. 2 (Angular acceleration, in radians squared per second (rad / s²)), spin coating time is 30~35s;

[0100] The annealing temperature is 100~110℃ and the time is 5~10min.

[0101] In some embodiments, an aqueous solution of polydiallyldimethylammonium chloride is spin-coated onto Ti3C2T x The surface of the charge trapping layer is annealed to prepare a polydiallyldimethylammonium chloride buffer switch layer;

[0102] The spin coating parameters are as follows: spin rotation speed of 4000~4200 rpm and acceleration of 2000~2100 rad / s. 2 Spin coating time is 60~70s;

[0103] The annealing temperature is 150~160℃ and the time is 10~15min.

[0104] In some embodiments, a top electrode is prepared on the surface of a polydiallyldimethylammonium chloride buffer switch layer by vapor deposition, wherein the vapor deposition power is 180~200 W and the vapor deposition rate is 0.1~0.3 nm / s.

[0105] In some embodiments, the flexible substrate is made of PET and the bottom electrode is made of ITO. The bottom electrode ITO is prepared on the surface of the flexible PET substrate by using ITO ceramic target as sputtering source and magnetron sputtering. The process parameters are: Ar gas flow rate 20~30 sccm, working pressure 0.3~0.8 Pa, and RF power 100~200 W.

[0106] In some embodiments, before fabricating the bottom electrode on the surface of the flexible substrate, the flexible substrate is further cleaned, specifically by ultrasonically cleaning the flexible substrate with acetone, anhydrous ethanol and deionized water for 15-20 minutes each.

[0107] The method for fabricating the flexible self-rectifying memory of the present invention, Ti3C2T x The charge trapping layer and the polydiallyldimethylammonium chloride buffer switch layer respectively utilize Ti3C2T xThe suspension and aqueous solution of polydiallyldimethylammonium chloride were prepared by spin coating, eliminating the need for expensive vacuum deposition equipment. The process is short, simple, and suitable for large-scale production. The preparation process of this invention is simple and low-cost. The composite advantages of the polymer layer and inorganic layer are not only reflected in the preservation of the material's flexibility but also in innovative high-performance features such as self-rectification and adjustable current. A thorough study of the resistive switching mechanism of the device leads to the proposal that this device is a charge-trapping memory. In summary, Al / PDDA / Ti3C2T x / ITO memory shows great potential for applications in high-density and ultra-large-scale parallel memory arrays plagued by creeping currents and in learning about synaptic plasticity.

[0108] Based on the same inventive concept, the present invention also provides an application of the above-described flexible self-rectified memory or the flexible self-rectified memory prepared by the above-described preparation method in the fields of neuromorphic computing and flexible wearable electronics.

[0109] The following further illustrates the flexible self-rectifying memory, its fabrication method, and its application with specific embodiments. This section further describes the content of the present invention in conjunction with specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0110] In the following examples and comparative examples, the Ti3AlC2 powder was a commercially available product purchased from Maclean's reagents, specifically T698534 titanium aluminum carbide (Ti3AlC2) MAX phase ceramic material.

[0111] Example 1

[0112] This embodiment provides a flexible self-rectifying memory, including:

[0113] Flexible substrate;

[0114] The bottom electrode is located on the surface of the flexible substrate;

[0115] Ti3C2T x A charge trapping layer is located on the surface of the bottom electrode away from the flexible substrate;

[0116] Polydiallyl dimethylammonium chloride buffer switch layer, located in Ti3C2T x The charge trapping layer is located away from the surface of the flexible substrate;

[0117] The top electrode is located on the surface of the polydiallyldimethylammonium chloride buffer switch layer away from the flexible substrate;

[0118] The flexible substrate is made of PET, the bottom electrode is made of ITO, and the top electrode is made of Al. Therefore, the memory is an Al / PDDA / Ti3C2T system. x / ITO / PET stacked structure;

[0119] The thickness of the flexible substrate is 1.5 μm;

[0120] The thickness of the bottom electrode is 250 nm;

[0121] Ti3C2T x The charge trapping layer has a thickness of 40 nm;

[0122] The thickness of the polydiallyldimethylammonium chloride buffer switch layer is 500 nm;

[0123] The thickness of the top electrode is 60 nm.

[0124] The above-mentioned method for fabricating a flexible self-rectifying memory includes the following steps:

[0125] S1. The flexible PET substrate is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 15 min each. After ultrasonic cleaning, it is placed in a drying oven for drying and ready for use.

[0126] S2. Fabrication of the bottom electrode ITO on the surface of a flexible PET substrate, specifically including: using an ITO ceramic target as the sputtering source, ITO is fabricated by magnetron sputtering; the process parameters are: Ar gas flow rate 25 sccm, working pressure 0.5 Pa, and RF power 120 W;

[0127] S3, Configuring Ti3C2T x The suspension specifically includes the following steps:

[0128] S31. Add 3.2 g of lithium fluoride to 20 mL of 9 M (i.e. 9 mol / L) hydrochloric acid solution and stir at room temperature for 20 minutes to obtain an HF-rich etching solution. Then transfer the etching solution to a polytetrafluoroethylene bottle and place it in a water bath stirrer and stir continuously at 40 ℃ and 200 rpm.

[0129] S32. Add 3.2 g of precursor Ti3AlC2 powder to the etching solution being stirred, and stir and etch for 48 h. After etching is completed, centrifuge at 200 rpm for 1 min, remove the supernatant, and wash the obtained precipitate three times with 9 M HCl by centrifugation, and then wash it six times with deionized water by centrifugation (each washing centrifugation rate is 4000 rpm and time is 5 min) until the pH reaches neutral to obtain the precipitate.

[0130] S33. Add the precipitate from S32 to 40 mL of deionized water, sonicate at 5°C for 1 h at a sonic power of 350 W, then centrifuge at 4000 rpm for 0.5 h. Collect the supernatant after centrifugation, which is Ti3C2T. x suspension;

[0131] S4. Spin-coating Ti3C2T onto the bottom electrode surface x Suspension, annealing, to prepare Ti3C2T x Charge trapping layer;

[0132] The spin coating parameters are as follows: spin rotation speed of 3000 rpm and acceleration of 1000 rad / s². 2 (Angular acceleration, in radians squared per second (rad / s²)), spin coating time is 30s;

[0133] The annealing temperature was 100℃ and the time was 5 minutes.

[0134] S5. Polydiallyldimethylammonium chloride is added to water to obtain an aqueous solution of polydiallyldimethylammonium chloride, the concentration of which is 100 g / L.

[0135] S6. Spin-coating an aqueous solution of polydiallyl dimethylammonium chloride onto Ti3C2T x The surface of the charge trapping layer is annealed to prepare a polydiallyldimethylammonium chloride buffer switch layer;

[0136] The spin coating parameters are as follows: spin rotation speed of 4000 rpm and acceleration of 2000 rad / s². 2 Spin coating time is 60s;

[0137] The annealing temperature was 150℃ and the time was 10 minutes.

[0138] S7. A top electrode is prepared on the surface of a polydiallyldimethylammonium chloride buffer switch layer by vapor deposition, wherein the vapor deposition power is 200 W and the vapor deposition rate is 0.1 nm / s.

[0139] Figure 2 The Al / PDDA / Ti3C2T prepared in Example 1 of this invention x Scanning electron microscope image of ITO / PET flexible self-rectifying memory;

[0140] from Figure 2 As can be seen from the cross-sectional SEM, the interfaces of each layer are clear and the thickness is uniform, with no obvious peeling defects, proving that the solution process can achieve high-quality film formation on flexible substrates. From bottom to top, the thickness of the flexible substrate is shown to be 1.5 μm; the thickness of the bottom electrode is 250 nm; and the thickness of Ti3C2T is shown. xThe charge trapping layer has a thickness of 40 nm; the polydiallyldimethylammonium chloride buffer switch layer has a thickness of 500 nm; and the top electrode has a thickness of 60 nm.

[0141] Comparative Example 1

[0142] This comparative example provides an Al / Ti3C2T x The / ITO / glass memory, similar to Example 1, differs in that it does not contain a polydiallyldimethylammonium chloride (PDDA) buffer switch layer. Its preparation method is as follows:

[0143] S1. Clean the substrate glass (i.e., glass substrate) with acetone, anhydrous ethanol and deionized water for 15 min each. After ultrasonic cleaning, put it in a drying oven to dry and set aside.

[0144] S2. Fabrication of the bottom electrode ITO on the substrate glass surface, specifically including: using ITO ceramic target as sputtering source, ITO is fabricated by magnetron sputtering; the process parameters are: Ar gas flow rate 25 sccm, working pressure 0.5 Pa, RF power 120 W;

[0145] S3. Prepare Ti3C2T according to the method in Example 1. x suspension;

[0146] S4. Spin-coating Ti3C2T onto the bottom electrode surface x Suspension, annealing, to prepare Ti3C2T x Charge trapping layer;

[0147] The spin coating parameters are as follows: spin rotation speed of 3000 rpm and acceleration of 1000 rad / s². 2 (Angular acceleration, in radians squared per second (rad / s²)), spin coating time is 30s;

[0148] The annealing temperature was 100℃ and the time was 5 minutes.

[0149] S5, using vapor deposition method on Ti3C2T x A top electrode was fabricated on the surface of the charge trapping layer, wherein the evaporation power was 200 W and the evaporation rate was 0.1 nm / s.

[0150] Memory performance testing

[0151] Electrical performance testing

[0152] A semiconductor parameter analyzer was connected to the top and bottom electrodes of the memory in Example 1 and Comparative Example 1, respectively. A DC scan voltage was applied to the top electrode, and the cyclic IV curves were tested. The results are as follows: Figures 3-4 As shown. Figure 3Stop=-4~3.5V indicates the scanning voltage range of -4~3.5V, I CC =1mA indicates that the current limit is 1mA, Q1 represents the first test cycle curve; Q20 represents the 20th test cycle curve, Q40 represents the 40th test cycle curve; Q60 represents the 60th test cycle curve, and Q80 represents the 80th test cycle curve. Figure 4 Stop=-3~4.5V indicates the scanning voltage range of -3~4.5V, I CC =10mA indicates that the current limit is 10mA, and Q1~Q500 represent the 1st to 500th cycle curves of the test;

[0153] like Figure 3 As shown, it is Al / Ti3C2T in Comparative Example 1. x The IV curve of the ITO / glass memory shows a steep increase in current when a positive bias voltage is applied to the top electrode of the memory, increasing from 0V to 1.5V, at which point the device resistance changes abruptly. The high-resistivity state (HRS) then transitions to the low-resistivity state (LRS), a process corresponding to the electrical SET mechanism. Similarly, when the scan voltage increases towards the negative direction, the current drops sharply at approximately 2V; this process is known as the "RESET" process. Figure 3 The image shows typical IV curves of the memory at 80 DC scan voltages (0 V→3.5 V→0 V→-4 V→0 V, and all current values ​​in this study are considered absolute values). The switching characteristics of the resistor indicate that the memristor has bipolar RS behavior, but the IV curves exhibit poor consistency.

[0154] Figure 4 Al / PDDA / Ti3C2T in Example 1 x IV test curves of / ITO / PET flexible self-rectifying memory; from Figure 4 As can be seen, the voltage range of the SET / RESET process of the memory is stable between -3 and 4.5V during 500 cycles, and the overlap of the current curves is high, indicating that its resistive switching behavior is consistent.

[0155] Figure 5 For Comparative Example 1, Al / Ti3C2T x The tolerance test curve of the ITO / glass memory; specifically, take... Figure 3 The current value corresponding to -0.5V on the IV curve is converted into a withstand test curve through the volt-ampere characteristic, showing that the ratio of high to low resistance states is approximately 10. 2 Similarly, after about 80 switching cycles, the resistive window of the device suddenly disappears and continues to exhibit high-resistivity behavior.

[0156] Figure 6 Al / PDDA / Ti3C2T in Example 1 x The tolerance test curve of the ITO / PET flexible self-rectifying memory; specifically, take... Figure 4 The current value corresponding to 0.6V on the IV curve is converted into a withstand test curve through the volt-ampere characteristic. Within 500 cycles, the low resistance state (LRS) resistance value is stably maintained at 10. 2 The resistance is around Ω, and the high resistance state (HRS) resistance remains at 10. 5 The two are on the order of Ω, and the distinction between them remains at about 3 orders of magnitude, with no obvious resistance degradation.

[0157] Self-rectification characteristic test

[0158] Figure 7 Al / PDDA / Ti3C2T in Example 1 x / ITO / PET flexible self-rectifying memory under different limiting currents (I CC 10μA~10mA Figure 7 In the range of -5 to 4V (where Stop = -5~4V indicates the scanning voltage range), it exhibits self-rectification characteristics and adjustability; the test method is the same as... Figure 3 IV test, when I CC As the current limit is gradually increased from 10μA to 10mA, the self-rectification characteristics of the device gradually improve—the current under reverse bias is significantly suppressed, while the forward bias conduction current increases with I. CC The current increases and improves, and it can stably exhibit self-rectification characteristics under three different limiting currents.

[0159] Synaptic function simulation test

[0160] Figure 8 Al / PDDA / Ti3C2T in Example 1 xThe conductivity change of the ITO / PET flexible self-rectifying memory under five consecutive sets of LTP / LTD pulses; the memory conductivity changes linearly when continuous LTP / LTD pulses are applied, which can simulate the long-term enhancement / de-enhancement characteristics of synapses; the simulation test of the memory's long-term learning and forgetting behavior is carried out by applying the same continuous pulses to the memory and observing the current change of the memory; LTP refers to the process of the memory current gradually increasing when continuous pulses (amplitude of -0.5 V, pulse width tpw=0.08 ms, pulse interval tpi=0.04 ms) are applied, and LTD refers to the process of the device current gradually decreasing when continuous pulses (amplitude of 0.5 V, pulse width tpw=0.08 ms, pulse interval tpi=0.04 ms) are applied. It can be seen that the conductivity change of the device under continuous LTP / LTD pulses is basically linear.

[0161] Figure 9 Al / PDDA / Ti3C2T in Example 1 x The graph shows the relationship between the PPF index of the ITO / PET flexible self-rectifying memory and the interval (Δt) between two pulses. Specifically, when two identical pulses (amplitude 1.4 V, pulse width 50 μs) are applied sequentially to the memory, the excitatory postsynaptic current (EPSC) of the second pulse is higher than that of the first pulse, exhibiting a double-pulse promotion (PPF) characteristic. PPF measures the effect of the time interval between two identical pulses on the current response of the device. The PPF was measured for five sets of pulse intervals (tpi = 20 μs, 40 μs, 60 μs, 80 μs). As the pulse interval increases, the EPSC of the second pulse gradually decreases, indicating that the device's response to the stimulus at the current moment is influenced by previous stimuli, and this influence gradually decreases with increasing time interval.

[0162] Flexible stability test

[0163] Figure 10 Al / PDDA / Ti3C2T in Example 1 x / ITO / PET flexible self-rectifying memory is passed through different angles (15°~90°, Flat means no bending, i.e., 0°). Figure 10 Middle I CC (10mA, Stop=-4~4V indicates the scan voltage range of -4~4V) The folded IV curve is tested using the same method. Figure 3 ;from Figure 10 As can be seen, even when the memory is bent at angles ranging from 0° to 60°, its SET / RESET voltage range remains stable around -4 to 4V, and the current curves show a high degree of overlap.

[0164] Figure 11Al / PDDA / Ti3C2T in Example 1 x Resistance distribution of / ITO / PET flexible self-rectifying memory after 200 switching cycles folded at a 30° angle. From Figure 11 As can be seen, the high resistance state (HRS) of the device remains at 10 throughout 200 bending cycles. 6 Ω in magnitude, stable at 10 in the low resistance state (LRS). 2 The resistance values ​​of the two are around Ω, with very small fluctuations, and the resistance state differentiation remains at about 4 orders of magnitude throughout 50 switching cycles.

[0165] Environmental stability test

[0166] The Al / PDDA / Ti3C2T in Example 1 x The ITO / PET flexible self-rectifying memory was stored at 25℃ and 40% humidity for 9 months, and its IV curve and retention characteristics were tested periodically. The results showed no significant degradation on the thin film surface, and the retention time in both high and low resistivity states remained greater than 5 × 10⁻⁶. 3 s has good stability.

[0167] It is understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0168] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A flexible self-rectifying memory, characterized in that, include: Flexible substrate; The bottom electrode is located on the surface of the flexible substrate; Ti3C2T x a charge trapping layer located on a surface of the bottom electrode distal from the flexible substrate; A polydiallyldimethylammonium chloride buffer switch layer is located on the Ti3C2T x The charge-trapping layer is distanced from the surface of the flexible substrate. The top electrode is located on the surface of the polydiallyldimethylammonium chloride buffer switch layer away from the flexible substrate.

2. The flexible self-rectifying memory as described in claim 1, characterized in that, The flexible substrate is made of any one of PET, PEN, PI, PDMS, and PVB. The material of the bottom electrode is any one of ITO, AZO, and FTO; The material of the top electrode is any one of Al, Au, Ag, Cu, Pt, and Ti.

3. The flexible self-rectifying memory as described in claim 1, characterized in that, The thickness of the flexible substrate is 1~10μm; The thickness of the bottom electrode is 200~300nm; The Ti3C2T x The thickness of the charge trapping layer is 30-50 nm. The thickness of the polydiallyldimethylammonium chloride buffer switch layer is 450~550 nm; The thickness of the top electrode is 50~70nm.

4. A method for fabricating a flexible self-rectifying memory as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Formulating Ti3C2T x Suspension; Preparation of bottom electrode on flexible substrate surface, coating Ti3C2T x Suspension, annealing to produce Ti3C2T x Charge trapping layer; Prepare an aqueous solution of polydiallyldimethylammonium chloride; A poly(diallyldimethylammonium chloride) aqueous solution is coated on the Ti3C2T x The charge-trapping layer surface is annealed to produce a poly(diallyldimethylammonium chloride) buffer switch layer; A top electrode was fabricated on the surface of a polydiallyldimethylammonium chloride buffer switch layer.

5. The method for fabricating the flexible self-rectifying memory as described in claim 4, characterized in that, The Ti3C2T x A method of formulating a suspension, comprising the steps of: Lithium fluoride was added to hydrochloric acid and stirred to obtain an etching solution; Ti3AlC2 was added to the etching solution for etching, centrifuged, the supernatant was removed, and the resulting precipitate was washed to obtain the precipitate. The precipitate was added to water, sonicated, centrifuged, and the supernatant collected, which was Ti3C2T x suspension.

6. The method for fabricating the flexible self-rectifying memory as described in claim 4, characterized in that, Polydiallyl dimethyl ammonium chloride is added to water to obtain an aqueous solution of polydiallyl dimethyl ammonium chloride, wherein the concentration of the aqueous solution of polydiallyl dimethyl ammonium chloride is 90~110 g / L.

7. The method for fabricating the flexible self-rectifying memory as described in claim 4, characterized in that, The etching process involves adding Ti3AlC2 to the etching solution. The etching process specifically includes etching at 40~45℃ and 200~250rpm for 48~50h. The precipitate is added to water, sonicated for 1-2 h at less than or equal to 10 °C, centrifuged, and the supernatant collected, which is Ti3C2T x suspension; The mass-volume ratio of lithium fluoride, Ti3AlC2, and hydrochloric acid is (3.0~3.5)g:(3.0~3.5)g:(18~22)mL, and the concentration of hydrochloric acid is 9~10mol / L; the precipitate is added to water, wherein the volume ratio of water to hydrochloric acid is (40~45):(18~22).

8. The method for fabricating the flexible self-rectifying memory as described in claim 4, characterized in that, Spin coating Ti3C2T on the surface of the bottom electrode x Suspension, annealing to produce Ti3C2T x Charge trapping layer; The spin coating parameters are as follows: the spin coating speed is 3000-3200 rpm, the acceleration is 1000-1100 rad / s, and the spin coating time is 30-35 s. 2 , the spin coating time is 30-35 s. The annealing temperature is 100~110℃ and the time is 5~10min.

9. The method for fabricating the flexible self-rectifying memory as described in claim 4, characterized in that, Aqueous polydiallyldimethylammonium chloride solution was spin-coated onto Ti3C2T x The surface of the charge trapping layer is annealed to prepare a polydiallyldimethylammonium chloride buffer switch layer; The spin coating parameters are as follows: spin rotation speed of 4000~4200 rpm and acceleration of 2000~2100 rad / s. 2 Spin coating time is 60~70s; The annealing temperature is 150~160℃ and the time is 10~15min.

10. The application of a flexible self-rectified memory as described in any one of claims 1 to 3 or a flexible self-rectified memory prepared by any one of claims 4 to 9 in the fields of neuromorphic computing and flexible wearable electronics.

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