High-entropy oxide / tungsten oxide heterojunction memristor and method and application

Abstract

The invention discloses a high-entropy oxide / tungsten oxide heterojunction memristor and a method and application thereof, and belongs to the technical field of nonvolatile resistive random access memories. The reverse self-current-limiting analog memristor with the heterojunction structure structurally comprises a bottom conductive electrode, a functional layer and an upper conductive electrode from bottom to top, the functional layer is composed of a high-entropy oxide film and a tungsten oxide film. And continuously depositing a second conductive film on the functional layer by adopting a physical vapor deposition mode to serve as an upper conductive electrode to obtain the reverse self-current-limiting memristor with the high-entropy oxide / tungsten oxide heterojunction structure. The structure and the preparation process are simple, and the material cost is low; the self-current-limiting characteristic can reduce the energy consumption of the device and the overheating risk of the device by inhibiting the current overshoot, and improves the reliability and integration density of the device, thereby supporting a storage and calculation integrated neural state architecture, reducing the data migration between a calculation unit and a storage unit, and improving the reliability of the device. And a hardware basis is provided for efficient real-time sensing and multi-modal information fusion.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-volatile memories, and particularly relates to a high-entropy oxide / tungsten oxide heterojunction memristor, a method and an application thereof. Background Art

[0002] As a core representative of the new generation of non-volatile memory devices, the unique property of a memristor that its resistance value can be dynamically adjusted with an electrical excitation provides a physical basis for breaking through the "memory wall" bottleneck of traditional computing architectures. The current mainstream metal-oxide memristors are based on the oxygen vacancy or metal ion migration mechanism. Such devices face an essential contradiction in practical applications: the randomness of the material microstructure makes it difficult to meet the requirement of precise regulation of synaptic weights in neuromorphic computing for the consistency of resistance state switching; while the interface accumulation effect during the ion migration process significantly restricts the cycle life of the device. More importantly, current runaway phenomenon is likely to occur during the high-low resistance state switching of traditional devices, which not only brings additional energy consumption but also accelerates the irreversible damage of the electrode material. As a core device for neuromorphic computing, an analog memristor simulates the weight plasticity of biological synapses through a continuous gradient resistive switching mechanism, showing technical characteristics different from those of the von Neumann architecture. Compared with the binary resistive switching characteristics shown by traditional digital devices, an analog memristor can achieve high-precision mapping of synaptic weights in a memory-computation integrated architecture by virtue of its dynamic conductance tuning ability. However, currently, the resistive switching devices based on a two-terminal structure generally face the bottleneck of abrupt resistance state changes - due to the random formation / breaking mechanism of oxygen vacancy conducting filaments, resulting in discrete jumps rather than ideal linear gradients in their conductance characteristics. To break through this bottleneck, it is necessary to cut in from two paths: material engineering and interface regulation. On the one hand, the stability of the ion migration path is optimized by designing the gradient distribution of oxygen vacancies; on the other hand, a heterojunction structure is adopted. Such technological breakthroughs will promote the extension of memristors from traditional storage to frontier fields such as pulse neural network hardware accelerators, providing a physical basis for low-power real-time computing of brain-like chips.

[0003] In recent years, the combination of high-entropy oxide alloys and functional oxide materials has become a research hotspot. The multi-element synergistic effect of high-entropy oxide materials can greatly inhibit the disordered ion migration, while tungsten oxide shows unique advantages in the stability of the conductive channel due to its special oxygen defect regulation ability. However, there are still two key limitations in the existing technology: firstly, simple material stacking will cause interface lattice mismatch problems, which will instead exacerbate the performance degradation; secondly, the traditional self-limiting current design relies on passive series current-limiting components, and essentially fails to solve the threshold shift problem caused by uneven electric field distribution.

[0004] These inherent defects make it difficult for existing memristors to balance high-density integration and reliability requirements, severely restricting their evolution to advanced process nodes. There is an urgent need to innovate through materials engineering optimization and interface regulation to achieve a memristor with high-precision resistive state continuous tuning, long cycle life, and low power consumption characteristics, providing a reliable hardware foundation for in-memory computing in neuromorphic computing. Summary of the Invention

[0005] To overcome the above-mentioned drawbacks of the prior art, the purpose of the present invention is to provide a high-entropy oxide / tungsten oxide heterojunction memristor, method, and application, so as to solve the technical problems of inaccurate resistive state regulation, short cycle life, and high energy consumption caused by the microscopic randomness of materials, interface cumulative effect, and current runaway in traditional memristors, and achieve stable and continuous gradient resistive switching characteristics through a high-flatness substrate, high-entropy oxide / tungsten oxide heterojunction structure design, and reverse self-limiting current mechanism.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions: The present invention discloses a preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor, including the following steps: 1) Deposit a first conductive film on a high-flatness insulating substrate by physical vapor deposition as the bottom conductive electrode; 2) Use a tungsten-containing target and a high-entropy oxide target, and grow a tungsten oxide film and a high-entropy oxide film in sequence on the bottom conductive electrode prepared in step 1) by physical vapor deposition to obtain a high-entropy oxide / tungsten oxide heterojunction as the functional layer; 3) Use a mask template to deposit a second conductive film on the functional layer prepared in step 2) by physical vapor deposition as the top conductive electrode to obtain a high-entropy oxide / tungsten oxide heterojunction memristor.

[0007] Preferably, in step 1), the high-flatness insulating substrate is a polished single-crystalline silicon grown with silicon dioxide or a highly transparent insulating glass.

[0008] Preferably, in step 1), the physical vapor deposition method is any one of magnetron sputtering, electron beam evaporation, and thermal evaporation; The first conductive film is any one of Au, W, Pt, and ITO; The thickness of the bottom conductive electrode is 20 - 200 nm.

[0009] Preferably, in step 2), the physical vapor deposition method is any one of radio frequency magnetron sputtering, direct current magnetron sputtering, pulsed laser deposition, and molecular beam epitaxy; The tungsten-containing target is a metallic tungsten target or a tungsten oxide target; The high-entropy oxide target is a high-entropy oxide alloy containing five elements of Cr, Mn, Fe, Co, and Ni.

[0010] Preferably, in step 2), the growth power of the tungsten oxide thin film is 10-100 w; the growth time is 5-10 min; the substrate heating temperature during the growth process is 50-500 °C; a mixed gas of argon and oxygen is introduced during the growth process; the growth gas pressure is 0.5-2.5 Pa, the argon gas flow rate is 10-30 sccm, and the oxygen gas flow rate is 2-10 sccm.

[0011] Preferably, in step 2), the growth power of the high-entropy oxide thin film is 10-70 w; the growth time is 1-10 min; the substrate heating temperature during the growth process is 50-500 °C; a mixed gas of argon and oxygen is introduced during the growth process; the growth gas pressure is 0.5-2 Pa, the argon gas flow rate is 5-10 sccm, and the oxygen gas flow rate is 10-30 sccm.

[0012] Preferably, in step 2), the thickness of the tungsten oxide thin film is 10-50 nm, and the thickness of the high-entropy oxide thin film is 10-20 nm.

[0013] Preferably, in step 3), the mask template is a circular mask template, and the diameter of the circular mask template is 20-300 μm; The physical vapor deposition method is any one of thermal evaporation, electron beam evaporation, and magnetron sputtering; The second conductive thin film is any one of Au, W, Pt, and ITO; The thickness of the upper conductive electrode is 20-200 nm.

[0014] The present invention also discloses a high-entropy oxide / tungsten oxide heterojunction memristor, which is prepared by using the above-mentioned preparation method of the high-entropy oxide / tungsten oxide heterojunction memristor, and includes a bottom conductive electrode, a functional layer, and an upper conductive electrode from bottom to top, and the functional layer is a high-entropy oxide / tungsten oxide heterojunction.

[0015] The present invention also discloses the application of the high-entropy oxide / tungsten oxide heterojunction memristor prepared by the above-mentioned preparation method of the high-entropy oxide / tungsten oxide heterojunction memristor in a non-volatile resistive random access memory.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor. A substrate with high flatness is selected to construct the memristor, and the substrate with high flatness is the basis for ensuring the stability and reliability of the electrical properties of the memristor; a first conductive film with high stability and a certain thickness is deposited on the substrate by physical vapor deposition as the bottom conductive electrode of the memristor; the physical vapor deposition method for coating the film has the characteristics of high stability and good repeatability, and the prepared conductive film with high stability has high adhesion to the substrate and the resistive switching functional layer; the conductive film with high stability as the bottom conductive electrode of the memristor is an important part of obtaining an excellent memristor. By physical vapor deposition, tungsten oxide film and high-entropy oxide film are prepared in sequence to obtain a high-entropy oxide / tungsten oxide heterojunction structure as the functional layer of the memristor; the physical vapor deposition method is used to prepare tungsten oxide film and high-entropy oxide film, which has good repeatability, and the prepared device has the advantage of high stability; according to the growth order of tungsten oxide and high-entropy oxide from bottom to top, the morphology of the conductive filament is regulated, which is the key to achieving a high switching window; the reverse self-limiting current reduces the possibility of excessive breakage or local overheating of the conductive filament during the Reset process, improving the durability of the device and the stability of the Reset process. Its self-limiting current characteristic reduces the device power consumption and the risk of device overheating by suppressing current overshoot, improves the reliability and integration density of the device, thus supporting the memory-computation-integrated neuromorphic architecture, and can reduce the data migration between the computing unit and the storage unit, providing a hardware foundation for efficient real-time perception and multimodal information fusion.

[0017] Further, a polished single-crystalline silicon with a layer of silicon dioxide grown on it or a highly transparent insulating glass with high flatness is used as the substrate to construct the memristor. If the flatness of the substrate is low, it will cause the subsequent conductive electrode and functional layer to be uneven, reducing the stability and performance of the device; the polished single-crystalline silicon with silicon dioxide grown on it or the insulating glass can ensure that the current of the constructed memristor does not pass through the substrate, thus improving the reliability of the memristor performance.

[0018] Further, physical vapor deposition such as thermal evaporation, electron beam evaporation and magnetron sputtering is used to prepare the bottom conductive electrode and the top conductive electrode. The conductive film prepared by the above physical vapor deposition method has high adhesion, high stability and repeatability. Any one of Pt, Au, W and ITO is used as the conductive electrode of the device. Compared with metal electrodes with relatively large atomic activity such as Ag and Cu, the above electrodes have certain inertness in electrochemical properties, so the electrode atoms of the constructed memristor will not participate in the resistive switching behavior, ensuring that the device has higher stability. The designed thicknesses of both the bottom conductive electrode and the top conductive electrode are 20-200 nm. An electrode that is too thin cannot ensure the stability of the memristor, and an electrode that is too thick will result in poor adhesion between the electrode and the contacted functional layer, and at the same time bring too high cost.

[0019] Further, a physical vapor deposition method such as radio frequency magnetron sputtering, direct current magnetron sputtering, pulsed laser deposition or molecular beam epitaxy is used to prepare the functional layer; the chemical vapor deposition film has poor continuity and high cost at the same time. High-purity tungsten target materials and high-entropy oxide target materials are used to prepare the functional layer, and the above high-purity materials are used for sputtering, which can reduce the introduction of impurities in the resistive switching functional layer.

[0020] Further, the growth power of the tungsten oxide film is 10-100 w, and the growth power of the high-entropy oxide film is 10-70 w. The films prepared below this range have low efficiency and increased cost; above this range, the flatness of the prepared films is not high, which in turn affects the device performance.

[0021] Further, during the deposition process of the tungsten oxide film and the high-entropy oxide film, argon and oxygen are both introduced. When preparing the tungsten oxide film, the argon flow rate is 10-30 sccm, and the oxygen flow rate is 2-10 sccm; when preparing the high-entropy oxide film, the argon flow rate is 5-10 sccm, and the oxygen flow rate is 10-30 sccm. The film thickness prepared at too low a flow rate is uncontrollable, and the device stability prepared at too high a flow rate is poor.

[0022] Further, during the deposition process of the tungsten oxide film, the substrate temperature is 50-500 °C, and the growth time is 5-10 min; during the high-entropy oxide substrate process, the substrate temperature is 50-500 °C, and the growth time is 1-10 min. If the growth temperature of the substrate is too low, it will lead to too many defects in the prepared resistive switching film, affecting the performance of the device; if the temperature of the substrate is too high, it will lead to uneven doping of the film and poor stability of the resistive switching characteristics. If the sputtering time is too short, the prepared resistive switching layer will be thin and the device is prone to breakdown; if the sputtering time is too long, the resistive switching layer will be thick and the resistive switching performance will deteriorate. Description of the Drawings

[0023] Figure 1 Schematic structural diagram of a high-entropy oxide / tungsten oxide heterojunction memristor prepared in Example 1 of the present invention; Figure 2 Logarithmic current-voltage curve diagram of a high-entropy oxide / tungsten oxide heterojunction memristor prepared in Example 1 of the present invention; Figure 3 Cyclic characteristic curve of a high-entropy oxide / tungsten oxide heterojunction memristor prepared in Example 1 of the present invention; Figure 4 Retention characteristic diagram of a high-entropy oxide / tungsten oxide heterojunction memristor prepared in Example 1 of the present invention; Figure 5 Long-term potentiation (LTP) and long-term depression (LTD) diagrams of a high-entropy oxide / tungsten oxide heterojunction memristor prepared in Example 1 of the present invention. Detailed Embodiments

[0024] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention.

[0025] In the present invention, if there is no special explanation, all the embodiments and preferred implementation methods mentioned in this article can be combined with each other to form a new technical solution.

[0026] In the present invention, if there is no special explanation, all the technical features and preferred features mentioned in this article can be combined with each other to form a new technical solution.

[0027] In the present invention, if there is no special explanation, the percentage (%) or part refers to the weight percentage or weight part relative to the composition.

[0028] In the present invention, if there is no special explanation, the various components or their preferred components involved can be combined with each other to form a new technical solution.

[0029] In the present invention, unless otherwise stated, the numerical range "a~b" represents an abbreviated representation of any real number combination between a and b, where both a and b are real numbers. For example, the numerical range "6~22" means that all real numbers between "6~22" have been fully listed in this article, and "6~22" is only an abbreviated representation of these numerical combinations.

[0030] The "range" disclosed in the present invention can be in the form of one or more lower limits and one or more upper limits, respectively.

[0031] In the present invention, the term "and / or" used in this article refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0032] In the present invention, unless otherwise stated, each reaction or operation step can be carried out sequentially or in sequence. Preferably, the reaction methods in this article are carried out sequentially.

[0033] Unless otherwise stated, the professional and scientific terms used in this article have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present invention.

[0034] The present invention discloses a preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor, which includes the following steps: 1) On a substrate with high flatness, a first conductive thin film is deposited on the insulating substrate by physical vapor deposition as the bottom conductive electrode of the memristor.

[0035] 2) A target containing tungsten element and a high-entropy oxide target are used. On the bottom conductive electrode prepared in step 1), tungsten oxide thin film and high-entropy oxide thin film are successively prepared by physical vapor deposition method and by controlling growth parameters such as substrate temperature, working pressure, ratio of argon to oxygen, deposition time, and power during the deposition process, to obtain a high-entropy oxide / tungsten oxide heterojunction structure as the functional layer of the memristor.

[0036] 3) Using a circular mask template with a certain diameter, a second conductive thin film is continuously deposited on the functional layer prepared in step 2) by physical vapor deposition method as the upper conductive electrode of the memristor, to obtain a high-entropy oxide / tungsten oxide heterojunction memristor. In step 1), the high-flatness substrate is a polished single crystal silicon grown with silicon dioxide or a highly transparent insulating glass.

[0037] In step 1) and step 3), the physical vapor deposition method is any one of thermal evaporation, electron beam evaporation, and magnetron sputtering; the first conductive thin film is any one of Au, W, Pt, and ITO; the thickness of the bottom conductive electrode is 20 - 200 nm.

[0038] In step 2), the physical vapor deposition method is any one of radio frequency magnetron sputtering, direct current magnetron sputtering, pulsed laser deposition, and molecular beam epitaxy; the target containing tungsten element is a metallic tungsten target or a tungsten oxide target; the high-entropy oxide target is a high-entropy oxide alloy containing five elements of Cr, Mn, Fe, Co, and Ni.

[0039] In step 2), when depositing the tungsten oxide thin film, the growth power is 10 - 100 w; the growth time is 5 - 10 min; the substrate heating temperature during the growth process is 50 - 500 °C; a mixed gas of argon and oxygen is introduced during the growth process; the growth gas pressure is 0.5 - 2.5 Pa, the argon flow rate is 10 - 30 sccm, and the oxygen flow rate is 2 - 10 sccm.

[0040] In step 2), when depositing the high-entropy oxide thin film, the growth power is 10 - 70 w; the growth time is 1 - 10 min; the substrate heating temperature during the growth process is 50 - 500 °C; a mixed gas of argon and oxygen is introduced during the growth process; the growth gas pressure is 0.5 - 2 Pa, the argon flow rate is 5 - 10 sccm, and the oxygen flow rate is 10 - 30 sccm.

[0041] In step 2), the thickness of the tungsten oxide thin film is 10 - 50 nm, and the thickness of the high-entropy oxide thin film is 10 - 20 nm.

[0042] In step 3), the mask is a circular mask with a diameter of 20 - 300 μm. The physical vapor deposition method is any one of thermal evaporation, electron beam evaporation, and magnetron sputtering; the second conductive film is any one of Au, W, Pt, and ITO. The thickness of the upper conductive electrode is 20 - 200 nm.

[0043] The present invention discloses a preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor, comprising the following steps: 1) On a device substrate with high flatness, deposit a certain thickness of a highly stable first conductive film by physical vapor deposition as the bottom conductive electrode of the memristor.

[0044] Preferably, the device substrate with high flatness is a polished single-crystalline silicon with a layer of silicon dioxide grown thereon or a highly transparent insulating glass; the magnetron sputtering method is selected to deposit the bottom conductive electrode; the bottom conductive electrode is Pt; the thickness of the conductive electrode is 100 nm.

[0045] 2) By physical vapor deposition, using a target containing tungsten element and a high-entropy oxide target, deposit a tungsten oxide film and a high-entropy oxide film in sequence on the bottom conductive electrode prepared in step 1) to obtain a high-entropy oxide / tungsten oxide heterojunction structure as the functional layer of the memristor.

[0046] Preferably, the tungsten oxide and high-entropy oxide films are prepared by radio frequency magnetron sputtering physical vapor deposition method; the targets containing tungsten element and high-entropy oxide are used as metal targets; in the generation parameters of the tungsten oxide film, the sputtering power is 100 W; the sputtering time is 10 min; the substrate heating temperature during the growth process is 250 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 2.5 Pa, the argon gas flow rate is 30 sccm, and the oxygen gas flow rate is 10 sccm.

[0047] Preferably, when depositing the high-entropy oxide film, the sputtering power is 70 w; the sputtering time is 1 min; the substrate heating temperature during the growth process is 250 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 2 Pa, the argon gas flow rate is 5 sccm, and the oxygen gas flow rate is 10 sccm. Preferably, the thickness of the tungsten oxide film is 25 nm, and the thickness of the high-entropy oxide film is 15 nm.

[0048] 3) Using a mask with a certain diameter, continue to deposit a certain thickness of a highly stable conductive film on the grown high-entropy oxide / tungsten oxide functional layer as the upper conductive electrode of the memristor to obtain a high-entropy oxide / tungsten oxide heterojunction memristor.

[0049] Preferably, the diameter of the circular mask is 100 μm. The magnetron sputtering method is selected to deposit the upper conductive electrode; the upper conductive electrode is W; the thickness of the upper conductive electrode is 100 nm.

[0050] A preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor. The structure of the reverse self-limiting current analog memristor with a heterojunction structure includes a bottom conductive electrode, a functional layer, and an upper conductive electrode from bottom to top; the functional layer is composed of a high-entropy oxide thin film and a tungsten oxide thin film. By means of physical vapor deposition, a second conductive thin film is continuously deposited on the functional layer as the upper conductive electrode, and a reverse self-limiting current memristor based on a high-entropy oxide / tungsten oxide heterojunction structure is obtained. It has the advantages of simple structure and preparation process, and low material cost; its self-limiting current characteristic can reduce the device energy consumption and the risk of device overheating by suppressing current overshoot, while improving the reliability and integration density of the device, thereby supporting the memory-computation integrated neural architecture and being able to reduce the data migration between the computing unit and the storage unit, providing a hardware basis for efficient real-time perception and multimodal information fusion.

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0052] Example 1 The present invention discloses a preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor, including the following steps: 1) On a polished single-crystalline silicon substrate with a high flatness and a layer of silicon dioxide grown thereon, a 100-nm-thick highly stable Pt conductive thin film is deposited by magnetron sputtering as the bottom conductive electrode of the memristor.

[0053] 2) The radio frequency magnetron sputtering method is adopted. Using a metal target containing tungsten element and high-entropy oxide, a 25-nm tungsten oxide thin film and a 15-nm high-entropy oxide thin film are sequentially deposited on the bottom conductive electrode. Among the preparation parameters of the tungsten oxide thin film, the sputtering power is 100 W; the sputtering time is 10 min; the substrate heating temperature during the growth process is 250 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 2.5 Pa, the argon gas flow rate is 30 sccm, and the oxygen gas flow rate is 10 sccm. When depositing the high-entropy oxide thin film, the sputtering power is 70 W; the sputtering time is 1 min; the substrate heating temperature during the growth process is 250 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 2 Pa, the argon gas flow rate is 5 sccm, and the oxygen gas flow rate is 10 sccm. A high-entropy oxide / tungsten oxide heterojunction structure is obtained as the functional layer of the memristor.

[0054] 3) Using a circular mask with a diameter of 100 μm, a 100-nm thick highly stable W conductive thin film is continuously deposited on the functional layer of the grown high-entropy oxide / tungsten oxide heterojunction structure by magnetron physical vapor deposition as the upper conductive electrode of the memristor, and a high-entropy oxide / tungsten oxide heterojunction memristor is obtained.

[0055] Please refer to Figure 1 Figure; is a schematic structural diagram of a high-entropy oxide / tungsten oxide heterojunction memristor prepared in Example 1 of the present invention; it can be seen from the figure that the prepared high-entropy oxide / tungsten oxide heterojunction memristor from bottom to top is sequentially a bottom conductive electrode, a functional layer, and an upper conductive electrode, and the functional layer is a high-entropy oxide / tungsten oxide heterojunction structure.

[0056] Please refer to Figure 2 Figure; is a logarithmic current-voltage curve graph of a high-entropy oxide / tungsten oxide heterojunction memristor prepared in Example 1 of the present invention; it can be seen from the figure that during multiple DC cycle tests, the high-entropy oxide / tungsten oxide heterojunction memristor has stable analog characteristics and high stability.

[0057] Please refer to Figure 3 Figure; is a cyclic characteristic curve of a high-entropy oxide / tungsten oxide heterojunction memristor prepared in Example 1 of the present invention; it can be seen from the figure that the constructed high-entropy oxide / tungsten oxide heterojunction memristor shows no sign of decline during one hundred cycles and maintains a switching window greater than one order of magnitude.

[0058] Please refer to Figure 4 Figure; is a retention characteristic graph of a high-entropy oxide / tungsten oxide heterojunction memristor prepared in Example 1 of the present invention; it can be observed from the figure that after 10,000 seconds, the overall device remains in good condition. Please refer to Figure 5This is the long-term potentiation (LTP) and long-term depression (LTD) diagram of a high-entropy oxide / tungsten oxide heterojunction memristor prepared in Example 1 of the present invention; as can be seen from the figure, the conductance response results have relatively high symmetry and linearity.

[0059] Example 2 The present invention discloses a preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor, comprising the following steps: 1) Deposit a 20-nm-thick highly stable ITO conductive film by magnetron sputtering on a highly flat and highly transparent insulating glass substrate as the bottom conductive electrode of the memristor.

[0060] 2) By using a direct current magnetron sputtering method and a metal target containing tungsten element and high-entropy oxide, deposit a 10-nm tungsten oxide film and a 10-nm high-entropy oxide film on the bottom conductive electrode in sequence. Among the preparation parameters of the tungsten oxide film, the sputtering power is 100 W; the sputtering time is 10 min; the substrate heating temperature during the growth process is 250 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 2.5 Pa, the argon gas flow rate is 30 sccm, and the oxygen gas flow rate is 10 sccm. When depositing the high-entropy oxide film, the sputtering power is 70 w; the sputtering time is 1 min; the substrate heating temperature during the growth process is 250 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 2 Pa, the argon gas flow rate is 5 sccm, and the oxygen gas flow rate is 10 sccm. Obtain a high-entropy oxide / tungsten oxide heterojunction structure as the functional layer of the memristor.

[0061] 3) Use a circular mask with a diameter of 20 μm to continue depositing a 20-nm-thick highly stable ITO conductive film on the grown high-entropy oxide / tungsten oxide heterojunction structure functional layer by magnetron sputtering as the top conductive electrode of the memristor, and obtain a high-entropy oxide / tungsten oxide heterojunction memristor.

[0062] In Example 2, a highly transparent insulating glass is selected as the highly flat insulating substrate, and a 20-nm-thick highly stable ITO conductive film is prepared by magnetron sputtering as the bottom conductive electrode; a circular mask with a diameter of 20 μm is used, and a 20-nm-thick highly stable ITO conductive film is prepared by magnetron sputtering as the top conductive electrode of the digital memristor, and at the same time, a direct current magnetron sputtering method is used to grow the functional layer. Compared with Example 1, the thickness of the upper and lower electrodes is smaller, the size of the mask is smaller, and the stability of the finally constructed memristor is lower.

[0063] Example 3 The present invention discloses a preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor, comprising the following steps: 1) On a polished single-crystalline silicon substrate with a high flatness and a layer of silicon dioxide grown thereon, a 200-nm-thick highly stable Pt conductive film is deposited by electron beam evaporation as the bottom conductive electrode of the memristor.

[0064] 2) By using radio frequency magnetron sputtering method and a metal target containing tungsten element and high-entropy oxide, a 50-nm-thick tungsten oxide film and a 20-nm-thick high-entropy oxide film are sequentially deposited on the bottom conductive electrode. Among the preparation parameters of the tungsten oxide film, the sputtering power is 100 W; the sputtering time is 10 min; the substrate heating temperature during the growth process is 250 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 2.5 Pa, the argon flow rate is 30 sccm, and the oxygen flow rate is 10 sccm. When depositing the high-entropy oxide film, the sputtering power is 70 W; the sputtering time is 1 min; the substrate heating temperature during the growth process is 250 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 2 Pa, the argon flow rate is 5 sccm, and the oxygen flow rate is 10 sccm. A high-entropy oxide / tungsten oxide heterojunction structure is obtained as the functional layer of the memristor.

[0065] 3) By using a circular mask with a diameter of 300 μm, on the grown high-entropy oxide / tungsten oxide heterojunction structure functional layer, a 200-nm-thick highly stable W conductive film is continuously deposited by electron beam evaporation as the top conductive electrode of the memristor, and a high-entropy oxide / tungsten oxide heterojunction memristor is obtained.

[0066] In Example 3, a 200-nm-thick highly stable Pt conductive film is prepared by electron beam evaporation as the bottom conductive electrode; by using a circular mask with a diameter of 300 μm, a 200-nm-thick highly stable W conductive film is deposited by electron beam evaporation as the top conductive electrode. Compared with Example 1, the thickness of the electrode is larger, the diameter of the mask is larger, and the operating voltage of the finally constructed memristor becomes larger, resulting in an increase in device power consumption.

[0067] Example 4 The present invention discloses a preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor, including the following steps: 1) On a highly flat and highly transparent insulating glass substrate, a 100-nm-thick highly stable Au conductive film is deposited by magnetron sputtering as the bottom conductive electrode of the memristor; 2) By using the DC magnetron sputtering method, a metal target containing tungsten elements and high-entropy oxides is used to deposit a 10-nm tungsten oxide film and a 20-nm high-entropy oxide film on the bottom conductive electrode in sequence. Among the preparation parameters of the tungsten oxide film, the growth power is 100 W; the growth time is 10 min; the substrate heating temperature during the growth process is 250 °C; a mixed gas of argon and oxygen is introduced during the growth process; the growth gas pressure is 2.5 Pa, the argon gas flow rate is 30 sccm, and the oxygen gas flow rate is 10 sccm. When depositing the high-entropy oxide film, the growth power is 70 W; the growth time is 1 min; the substrate heating temperature during the growth process is 250 °C; a mixed gas of argon and oxygen is introduced during the growth process; the growth gas pressure is 2 Pa, the argon gas flow rate is 5 sccm, and the oxygen gas flow rate is 10 sccm. A high-entropy oxide / tungsten oxide heterojunction structure is obtained as the functional layer of the memristor.

[0068] 3) Using a circular mask with a diameter of 100 μm, a 100-nm-thick highly stable W conductive film is continuously deposited on the functional layer of the grown high-entropy oxide / tungsten oxide heterojunction structure by magnetron sputtering as the upper conductive electrode of the memristor, and a high-entropy oxide / tungsten oxide heterojunction memristor is obtained.

[0069] In Example 4, the functional layer is deposited by magnetron sputtering, and the growth parameters of the tungsten oxide and high-entropy oxide films are relatively low, resulting in a smaller thickness of the prepared functional layer. Compared with the examples, the smaller functional layer reduces the stability of the fabricated analog memristor.

[0070] Example 5 The present invention discloses a preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor, which includes the following steps: 1) On a device substrate with high flatness, a 100-nm-thick highly stable Pt conductive film is deposited by magnetron sputtering as the bottom conductive electrode of the memristor.

[0071] 2) Using the radio frequency magnetron sputtering method, a metal target containing tungsten elements and high-entropy oxides is used to deposit a 50-nm tungsten oxide thin film and a 10-nm high-entropy oxide thin film on the bottom conductive electrode in sequence. Among the preparation parameters of the tungsten oxide thin film, the sputtering power is 100 W; the sputtering time is 10 min; the substrate heating temperature during the growth process is 500 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 2.5 Pa, the argon gas flow rate is 30 sccm, and the oxygen gas flow rate is 10 sccm. When depositing the high-entropy oxide thin film, the sputtering power is 70 W; the sputtering time is 5 min; the substrate heating temperature during the growth process is 500 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 2 Pa, the argon gas flow rate is 5 sccm, and the oxygen gas flow rate is 30 sccm. A high-entropy oxide / tungsten oxide heterojunction structure is obtained as the functional layer of the memristor.

[0072] 3) Using a circular mask with a diameter of 100 μm, a 100-nm thick highly stable W conductive thin film is continuously deposited on the functional layer of the grown high-entropy oxide / tungsten oxide heterojunction structure by magnetron physical vapor deposition as the upper conductive electrode of the memristor, and a high-entropy oxide / tungsten oxide heterojunction memristor is obtained.

[0073] In Example 5, the growth parameters of the tungsten oxide thin film and the high-entropy oxide thin film are at relatively large values, and the prepared functional layer has a relatively thick thickness. Compared with Example 1, due to the relatively thick functional layer, the switching voltage of the device is larger and the device power consumption increases.

[0074] Example 6 The present invention discloses a preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor, which includes the following steps: 1) On a highly flat and highly transparent insulating glass substrate, a 50-nm thick highly stable W conductive thin film is deposited by magnetron sputtering as the bottom conductive electrode of the memristor.

[0075] 2) The pulsed laser deposition method is adopted. Using a metal target containing tungsten element and high-entropy oxide, a 10-nm tungsten oxide thin film and a 10-nm high-entropy oxide thin film are sequentially deposited on the bottom conductive electrode. Among the preparation parameters of the tungsten oxide thin film, the sputtering power is 10 W; the sputtering time is 5 min; the substrate heating temperature during the growth process is 50 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 0.5 Pa, the argon gas flow rate is 10 sccm, and the oxygen gas flow rate is 2 sccm. When depositing the high-entropy oxide thin film, the sputtering power is 10 W; the sputtering time is 2 min; the substrate heating temperature during the growth process is 50 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 0.5 Pa, the argon gas flow rate is 6 sccm, and the oxygen gas flow rate is 15 sccm. A high-entropy oxide / tungsten oxide heterojunction structure is obtained as the functional layer of the memristor.

[0076] 3) Using a circular mask with a diameter of 150 μm, on the functional layer of the grown high-entropy oxide / tungsten oxide heterojunction structure, a 50-nm-thick highly stable ITO conductive thin film is continuously deposited by thermal evaporation as the upper conductive electrode of the memristor, and a high-entropy oxide / tungsten oxide heterojunction memristor is obtained.

[0077] In Example 6, the thicknesses of the bottom conductive electrode of the W conductive thin film and the upper conductive electrode ITO conductive thin film of the memristor are at relatively small values, and the thicknesses of the tungsten oxide thin film and the high-entropy oxide thin film are also at relatively small values. Compared with Example 1, due to the smaller electrode thickness, the stability of the device is poor, affecting the actual service life of the device.

[0078] Example 7 The present invention discloses a preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor, including the following steps: 1) On a highly flat and highly transparent insulating glass substrate, a 150-nm-thick highly stable Pt conductive thin film is deposited by magnetron sputtering as the bottom conductive electrode of the memristor.

[0079] 2) Using the molecular beam epitaxy method, a metal target containing tungsten element and high-entropy oxide is used to deposit a 20-nm tungsten oxide thin film and a 15-nm high-entropy oxide thin film on the bottom conductive electrode in sequence. Among the preparation parameters of the tungsten oxide thin film, the sputtering power is 50 W; the sputtering time is 6 min; the substrate heating temperature during the growth process is 200 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 1 Pa, the argon gas flow rate is 20 sccm, and the oxygen gas flow rate is 4 sccm. When depositing the high-entropy oxide thin film, the sputtering power is 40 W; the sputtering time is 4 min; the substrate heating temperature during the growth process is 200 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 1 Pa, the argon gas flow rate is 8 sccm, and the oxygen gas flow rate is 20 sccm. A high-entropy oxide / tungsten oxide heterojunction structure is obtained as the functional layer of the memristor.

[0080] 3) Using a circular mask with a diameter of 200 μm, a 150-nm-thick highly stable Au conductive thin film is continuously deposited on the functional layer of the grown high-entropy oxide / tungsten oxide heterojunction structure by electron beam evaporation as the upper conductive electrode of the memristor, and a high-entropy oxide / tungsten oxide heterojunction memristor is obtained.

[0081] In Example 7, the thicknesses of the bottom conductive electrode of the W conductive thin film and the upper conductive electrode ITO conductive thin film of the memristor are at relatively large values. Compared with Example 1, due to the larger electrode thickness, the internal stress between the electrode and the resistive switching layer becomes larger, and the anti-external force interference performance of the device becomes worse.

[0082] Example 8 The present invention discloses a preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor, which includes the following steps: 1) A 200-nm-thick highly stable ITO conductive thin film is deposited on a highly flat and highly transparent insulating glass substrate by magnetron sputtering as the bottom conductive electrode of the memristor.

[0083] 2) The DC magnetron sputtering method is adopted. Using a metal target containing tungsten elements and high-entropy oxides, a 50-nm tungsten oxide thin film and a 20-nm high-entropy oxide thin film are sequentially deposited on the bottom conductive electrode. Among the preparation parameters of the tungsten oxide thin film, the sputtering power is 80 W; the sputtering time is 8 min; the substrate heating temperature during the growth process is 300 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 2 Pa, the argon gas flow rate is 25 sccm, and the oxygen gas flow rate is 8 sccm. When depositing the high-entropy oxide thin film, the sputtering power is 60 W; the sputtering time is 10 min; the substrate heating temperature during the growth process is 400 °C; a mixed gas of argon and oxygen is introduced during the sputtering process; the growth gas pressure is 1.5 Pa, the argon gas flow rate is 10 sccm, and the oxygen gas flow rate is 25 sccm. A high-entropy oxide / tungsten oxide heterojunction structure is obtained as the functional layer of the memristor.

[0084] 3) Using a circular mask with a diameter of 250 μm, on the functional layer of the grown high-entropy oxide / tungsten oxide heterojunction structure, a 200-nm-thick high-stability Pt conductive thin film is continuously deposited by magnetron sputtering as the upper conductive electrode of the memristor, and a high-entropy oxide / tungsten oxide heterojunction memristor is obtained.

[0085] In Example 8, the growth parameters of the tungsten oxide thin film and the high-entropy oxide thin film are at relatively small values, and the thickness of the prepared functional layer is relatively thin. Compared with Example 1, due to the thinner functional layer, although the switching voltage of the device is reduced to a certain extent, the power consumption of the device is also reduced, but at the same time, the stability of the device becomes worse.

[0086] In summary, the present invention discloses a preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor, which has the following characteristics: 1) For the high-entropy oxide / tungsten oxide heterojunction memristor proposed by the present invention, the preparation method has simple process, low preparation cost, strong controllability, and relatively high device stability.

[0087] 2) For a single tungsten oxide resistive switching memristor, the reverse self-limiting current analog memristor with the high-entropy oxide / tungsten oxide heterojunction structure exhibits stable analog resistive switching characteristics, which has important application prospects in the fields of neural network computing, image recognition, etc.

[0088] The reverse self-limiting current analog memristor with the high-entropy oxide / tungsten oxide heterojunction structure has good reverse self-limiting current ability, reduces the device energy consumption and the risk of device overheating by suppressing current overshoot, improves the reliability and integration density of the device, thus supporting the memory-computation-integrated neural architecture, reducing the data migration between the computing unit and the storage unit, and providing a hardware foundation for efficient real-time perception and multi-modal information fusion.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a high-entropy oxide / tungsten oxide heterojunction memristor, characterized in that It includes the following steps: 1) Deposit a first conductive thin film on a highly flat insulating substrate by physical vapor deposition as the bottom conductive electrode; 2) Use a target containing tungsten element and a high-entropy oxide target, and grow a tungsten oxide thin film and a high-entropy oxide thin film in sequence on the bottom conductive electrode prepared in step 1) by physical vapor deposition to obtain a high-entropy oxide / tungsten oxide heterojunction as the functional layer; 3) Use a mask template, and deposit a second conductive thin film on the functional layer prepared in step 2) by physical vapor deposition as the top conductive electrode to obtain a high-entropy oxide / tungsten oxide heterojunction memristor.

2. The preparation method of the high-entropy oxide / tungsten oxide heterojunction memristor according to claim 1, wherein In step 1), the highly flat insulating substrate is a polished single crystal silicon grown with silicon dioxide or a highly transparent insulating glass.

3. The preparation method of the high-entropy oxide / tungsten oxide heterojunction memristor according to claim 1, characterized in that, In step 1), the physical vapor deposition method is any one of magnetron sputtering, electron beam evaporation, and thermal evaporation; The first conductive thin film is any one of Au, W, Pt, and ITO; The thickness of the bottom conductive electrode is 20 - 200 nm.

4. The preparation method of the high-entropy oxide / tungsten oxide heterojunction memristor according to claim 1, characterized in that, In step 2), the physical vapor deposition method is any one of radio frequency magnetron sputtering, direct current magnetron sputtering, pulsed laser deposition, and molecular beam epitaxy; The target containing tungsten element is a metallic tungsten target or a tungsten oxide target; The high-entropy oxide target is a high-entropy oxide alloy containing five elements of Cr, Mn, Fe, Co, and Ni.

5. The preparation method of the high-entropy oxide / tungsten oxide heterojunction memristor according to claim 1, wherein, In step 2), the growth power of the tungsten oxide thin film is 10 - 100 w; the growth time is 5 - 10 min; the substrate heating temperature during the growth process is 50 - 500 °C; a mixed gas of argon and oxygen is introduced during the growth process; the growth gas pressure is 0.5 - 2.5 Pa, the argon gas flow rate is 10 - 30 sccm, and the oxygen gas flow rate is 2 - 10 sccm.

6. The preparation method of the high-entropy oxide / tungsten oxide heterojunction memristor according to claim 1, characterized in that, In step 2), the growth power of the high-entropy oxide thin film is 10 - 70 w; the growth time is 1 - 10 min; the substrate heating temperature during the growth process is 50 - 500 °C; a mixed gas of argon and oxygen is introduced during the growth process; the growth gas pressure is 0.5 - 2 Pa, the argon gas flow rate is 5 - 10 sccm, and the oxygen gas flow rate is 10 - 30 sccm.

7. The preparation method of the high-entropy oxide / tungsten oxide heterojunction memristor according to claim 1, wherein, In step 2), the thickness of the tungsten oxide thin film is 10 - 50 nm, and the thickness of the high-entropy oxide thin film is 10 - 20 nm.

8. The preparation method of the high-entropy oxide / tungsten oxide heterojunction memristor according to claim 1, characterized in that In step 3), the mask template is a circular mask template, and the diameter of the circular mask template is 20 - 300 μm; The physical vapor deposition method is any one of thermal evaporation, electron beam evaporation, and magnetron sputtering; The second conductive thin film is any one of Au, W, Pt, and ITO; The thickness of the top conductive electrode is 20 - 200 nm.

9. A high-entropy oxide / tungsten oxide heterojunction memristor, characterized in that, Prepared by the method for preparing a high-entropy oxide / tungsten oxide heterojunction memristor according to any one of claims 1 - 8, from bottom to top are a bottom conductive electrode, a functional layer, and a top conductive electrode, and the functional layer is a high-entropy oxide / tungsten oxide heterojunction.

10. Application of the high-entropy oxide / tungsten oxide heterojunction memristor prepared by the method for preparing a high-entropy oxide / tungsten oxide heterojunction memristor according to any one of claims 1 - 8 in a non-volatile resistive random access memory.

Images