Double-structure memristor based on Ag nanoparticle modified MoS2 / HfO2 and preparation method thereof

Abstract

The invention relates to the field of semiconductor devices and neuromorphic calculation, in particular to a dual-structure memristor based on Ag nanoparticle modified MoS2 / HfO2 and a preparation method of the dual-structure memristor. The preparation process comprises the steps of sequentially depositing the Pt bottom electrode and the HfO2 resistive layer on the substrate, forming the Ag nanoparticle layer through thermal evaporation and annealing, then transferring the MoS2 thin film, and finally preparing the Au / Ag top electrode. The device can realize 19ns quick response and 283-order conductance state regulation and control in a vertical structure, and shows wide-spectrum light response capability in a planar structure by virtue of a local surface plasma resonance effect of Ag nanoparticles. The device has ultra-low power consumption, high switch ratio and multi-wavelength light sensing characteristics, can simulate various nerve synaptic behaviors and a light pulse learning function, is suitable for the fields of brain-like calculation, intelligent robots, multi-mode artificial intelligence systems and the like, and effectively realizes integrated fusion of sensing and calculation.

Description

Technical Field

[0001] This invention relates to the fields of semiconductor devices and neuromorphic computing, specifically to a dual-structure memristor based on Ag nanoparticles modified with MoS2 / HfO2 and its preparation method. Background Technology

[0002] With the rapid growth in computing power demands in the era of artificial intelligence, the traditional von Neumann architecture's separation of storage and computation faces severe bottlenecks in power consumption and efficiency. Neuromorphic devices, as a new type of hardware that combines storage and computation functions, have emerged to address this need.

[0003] More specifically, memristor-based neuromorphic devices exhibit superior performance, including ultra-low power consumption, high on / off ratio, and multi-order conductance modulation capabilities. However, traditional memristors suffer from limitations such as single structural function and insufficient photoelectric response, restricting their widespread application in multimodal intelligent systems. The resistive switching mechanism of memristors is achieved through the formation and breakage of conductive filaments, but the randomness of filament formation and the single electrical response mode are insufficient to meet the needs of complex environmental sensing. For traditional devices, this limitation is mainly reflected in the inability to simultaneously achieve multiple operating modes and multimodal signal processing.

[0004] Therefore, the randomness of the formation of the conductive filaments in traditional memristors and their insufficient optical response limit the application of these devices in complex intelligent systems. Summary of the Invention

[0005] In view of this, this invention proposes a dual-structure memristor based on Ag nanoparticle-modified MoS2 / HfO2 and its fabrication method, to achieve dual-structure functionality in a single device, and the Ag nanoparticles enhance photoelectric response and conductive filament formation. The technical solution of this invention is implemented as follows: In a first aspect, the present invention proposes a method for preparing a dual-structure memristor based on Ag nanoparticles modified with MoS2 / HfO2, comprising the following steps: S1. Provide a substrate; deposit a bottom electrode on the substrate; S2. Deposit an HfO2 resistive switching layer on the bottom electrode; S3. Deposit an Ag nanoparticle layer on the HfO2 resistive switching layer; S4. Transfer the MoS2 film onto the Ag nanoparticle layer; S5. Prepare a top electrode on the MoS2 thin film.

[0006] Based on the above scheme, preferably, the size of the Ag nanoparticles is 15~35nm.

[0007] Specifically, the size of the Ag nanoparticles is preferably 10~35nm. If the size is too small, the local electric field is stronger, which is conducive to the nucleation of conductive filaments. However, due to the small Ag reserves, the conductive filaments will be thinner. If the size is too large, the Ag supply is sufficient, but "coarse filaments" are easily generated, which are difficult to reset and have high energy consumption.

[0008] Based on the above scheme, preferably, the thickness of the HfO2 resistive switching layer is 3~8nm.

[0009] Specifically, the thickness of the HfO2 resistive switching layer is preferably 3~8nm. If it is too thin, the turn-on voltage can be reduced, but leakage current is easily generated and the resistance fluctuation is aggravated; if it is too thick, the filamentation / reset voltage will be significantly increased, and the probability of filament formation failure will increase.

[0010] Based on the above scheme, preferably, the method for depositing the Ag nanoparticle layer in step S3 includes: firstly, thermally evaporating an Ag nanofilm on an HfO2 resistive switching layer, and then annealing the Ag nanofilm under an inert atmosphere to obtain the Ag nanoparticle layer.

[0011] Based on the above scheme, preferably, the thickness of the Ag nanofilm is 5 nm.

[0012] Specifically, the main function of rapid annealing is to transform the ultrathin Ag continuous film obtained by thermal evaporation into Ag nanoparticles with controllable size and adjustable distribution after heating through nucleation, growth and transformation.

[0013] Based on the above scheme, preferably, the annealing temperature is 200~350℃; the annealing time is 15~40min. The annealing time needs to be greater than 15min because the Ag film needs sufficient time for surface diffusion and aggregation to form uniform nanoparticles; less than 40min is to avoid excessive agglomeration of Ag nanoparticles, which would destroy the uniformity of particle size.

[0014] Specifically, the annealing temperature and time affect the average particle size of Ag nanoparticles. Therefore, the preferred annealing temperature is 200~350℃, because the particles are not fully formed at low temperatures and the size distribution becomes too wide and the particles are too large at high temperatures.

[0015] Based on the above scheme, preferably, the thickness of the MoS2 thin film is 2~10nm.

[0016] Specifically, the thickness of the MoS2 film is preferably 2~10nm. When the film is too thin, the exciton volume is limited, which in turn limits the photocurrent amplitude; when the film is too thick, the spectral coupling is weakened and the response is slowed down.

[0017] Based on the above scheme, preferably, the top electrode includes an Au / Ag composite electrode; and the bottom electrode includes a Pt electrode.

[0018] Further preferably, a Pt bottom electrode with a thickness of 200 nm is deposited using DC magnetron sputtering technology; and an Au / Ag top electrode is prepared using thermal evaporation technology, first depositing a 50 nm Ag layer and then depositing a 30 nm Au layer.

[0019] In a second aspect, the present invention provides a dual-structure memristor based on Ag nanoparticle-modified MoS2 / HfO2 obtained by the preparation method described in the first aspect.

[0020] Thirdly, the present invention provides an application of a dual-structure memristor based on Ag nanoparticle-modified MoS2 / HfO2 as described in the second aspect in neuromorphic computing, intelligent robots, multimodal artificial intelligence systems, or visual information processing systems.

[0021] Compared with the prior art, the advantages of the present invention are as follows: (1) This invention integrates vertical and planar operating modes in the same device through an innovative Ag nanoparticle-modified MoS2 / HfO2 heterostructure design. The vertical structure focuses on electrical resistive switching control, enabling fine control of 283 conductance states and a fast response of 19 ns; the planar structure enhances the photoelectric response of MoS2 through the LSPR effect of Ag nanoparticles, giving the device a broad-spectrum photoresponse characteristic and solving the problem of the single function of traditional memristors.

[0022] (2) In this device, Ag nanoparticles play a dual role: in the vertical structure, they act as an ion source to promote the formation of stable conductive filaments, effectively suppress random filamentation, and improve resistance switching consistency; in the planar structure, they significantly enhance photocurrent response through local surface plasmon resonance effect, realizing the synergistic effect of a single material in different working modes.

[0023] (3) This device successfully achieves the unification of multimodal perception and learning functions. It can simulate synaptic behaviors such as long-term enhancement / suppression (LTP / LTD), pulse timing-dependent plasticity (STDP) and paired pulse facilitation (PPF), and realize intelligent perception functions such as visual injury perception and light pulse learning-forgetting. It has completed the integration of "perception" and "computation" at the single device level, providing a hardware foundation for building an efficient multimodal artificial intelligence system.

[0024] (4) This device has excellent performance in key performance indicators: it has ultra-low power consumption and high switching ratio in the vertical structure, and good response to multiple wavelengths of light such as 450nm, 520nm and 620nm in the planar structure. At the same time, it achieves the best balance between turn-on voltage and resistive stability through HfO2 thickness optimization, which meets the needs of practical applications. Attached Figure Description

[0025] 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.

[0026] Figure 1 This is a structural view of the dual-structure memristor of the present invention; Figure 2 This is a partial process flow diagram of the dual-structure memristor of the present invention; Figure 3 This is a current-voltage curve diagram of the memristor vertical structure under different current limiting conditions in Example 1; Figure 4 The normalized conductivity modulation diagram of the memristor vertical structure in Example 1 is shown under 450 positive and negative pulses with an amplitude of 1V and a pulse width of 100ns. Figure 5 This is a diagram illustrating the simulated biological synaptic behavior of a memristor under 1000 pulse modulation cycles, as shown in Example 1. Figure 6 Example 1 was tested at three different wavelengths (620nm, 520nm, 450nm) and a constant light intensity (16mW / cm²). 2 The graph shows the change of current response over time under the given state. Figure 7 Example 1 serves as an artificial visual nociceptor for different light intensities (5mW / cm²). 2 8mW / cm 2 10mW / cm 2 16mW / cm 2 20mW / cm 2 The perception "threshold" diagram of a light pulse with a wavelength of 450nm, a frequency of 1Hz, and an illumination time of 10s; Figure 8 The current-voltage curves of a 1nm monolayer MoS2 under different current-limiting conditions are shown in Comparative Example 7. Detailed Implementation

[0027] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0028] Memristor-based resistive switching mechanisms typically rely on the formation and breakage of conductive filaments. However, the randomness of filament formation and the device's single electrical response mode limit its application in complex environment sensing. Traditional devices struggle to achieve multiple operating modes and multimodal signal processing within a single structure.

[0029] Existing research has attempted to introduce Ag nanoparticles (AgNPs) to improve memristor properties, for example, by using AgNPs to enhance conductivity in an "organic / metal particle / organic" sandwich structure, or by using Ag at the Ta2O5 / HfO2 interface. + While diffusion mimics biological synapses, these designs remain limited to single-function structures. Furthermore, although existing deep ultraviolet LED patents (CN202510924017.4) utilize the localized surface plasmon resonance (LSPR) effect of metal nanoparticles to improve light extraction efficiency, they lack neuromorphic computing capabilities and fail to achieve optoelectronic intelligence integration.

[0030] To address the aforementioned limitations, this invention proposes a neuromorphic device based on AgNPs-modified MoS2 / HfO2 heterostructures. The core innovation of this device lies in its ability to operate simultaneously in two modes: in a vertical structure, resistive switching is achieved through top / bottom electrodes; in a planar structure, photoelectric sensing is achieved through planar electrodes. Furthermore, the HfO2 layer, as a high-k dielectric, serves as both a resistive switching layer and an ion-modulating interface, effectively suppressing leakage current and influencing the formation of conductive filaments. Specifically, HfO2 interacts with AgNPs, and Ag... + It migrates along HfO2 defect / oxygen vacancy channels and participates in the formation of conductive filaments; its interface defects become Ag. + The capture and release points regulate the morphology of the conductive filaments.

[0031] Based on the above mechanism, AgNPs play a dual role in the structure: (1) acting as Ag in the vertical direction. + (1) The source promotes the formation of conductive filaments, realizes 283rd order conductivity control and 19ns fast response, and effectively suppresses random filamentation, improving the consistency of resistive switching; (2) In the planar direction, the light absorption of MoS2 is enhanced by the LSPR effect, the light response spectrum is broadened, and photoelectric signal synergistic processing is realized. Compared with the device without AgNPs, the photocurrent response is significantly enhanced. This device has broadband light response characteristics and photoelectric synergistic control function.

[0032] Correspondingly, this invention, through an innovative dual-structure design, enables a single device to operate in both vertical and planar modes: the vertical structure focuses on precise conductance control and synaptic behavior simulation, while the planar structure is responsible for optoelectronic collaborative sensing and visual information processing, achieving functional integration of computation and perception. AgNPs play a dual role in the device: in the vertical direction, they promote the formation of conductive filaments, improving the on / off ratio and multi-level control capability; in the planar direction, they enhance the photoresponse through plasmon resonance, achieving sensitive detection of multiple wavelengths such as 450nm, 520nm, and 620nm. This device integrates multimodal sensing and learning functions, simulating synaptic characteristics such as long-term enhancement / inhibition (LTP / LTD), pulse timing-dependent plasticity (STDP), and paired pulse facilitation (PPF), and can perform intelligent tasks such as visual damage perception, optical pulse learning, and image recognition. This design based on the dual-structure and Ag nanoparticle synergistic mechanism breaks through the functional limitations of traditional memristors, providing a new hardware foundation for neuromorphic computing, robotics, and multimodal artificial intelligence systems.

[0033] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0034] In this document, the terms “containing,” “comprising,” or “including” are open-ended expressions, meaning they include the contents specified in this invention but do not exclude other aspects.

[0035] In this document, the terms “optional,” “optionally,” or “optional” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0037] This invention provides an AgNPs-modified MoS2 / HfO2 heterostructure neuromorphic device and its fabrication method. The device structure involved in this invention is as follows: Figure 1 As shown ( Figure 1This is a structural view of the memristor, from top to bottom: Au / Ag electrode, MoS2 thin film, AgNPs layer, HfO2 layer, Pt bottom electrode, and Si substrate; the fabrication method specifically includes the following steps: (1) Substrate pretreatment: The Si substrate was ultrasonically cleaned with acetone, ethanol and deionized water respectively. The cleaning time for each solution was 15 min and the ultrasonic power was 70 W. (2) Depositing the bottom electrode: Using a DC magnetron sputtering device, a Pt bottom electrode with a thickness of 200 nm is deposited on the substrate described in step (1); (3) After step (2) is completed, an HfO2 resistive switching layer with a thickness of 3~8 nm is deposited using atomic layer deposition (ALD) technology; (4) An AgNPs layer is deposited on the film obtained in step (3) using thermal evaporation technology. Ag particles with a purity of 99.9% are placed on an evaporation boat, and a vacuum of 5 × 10⁻⁶ is applied. -4 After Pa, the film thickness gauge parameters were set to a maximum density of 10.5 and a z-coefficient of 0.53 (parameters for Ag). Then, 3–7 nm Ag nanofilms were obtained by evaporation at 0.5 nm / min for 10 min, 0.3 nm / min for 10 min, or 0.5 nm / min for 14 min. These films were then annealed in an OTF-1200X-4-RTP rapid annealing furnace to form AgNPs. The annealing environment was N2; the preferred annealing temperature was 200–350 °C, and the annealing time was 15–40 min. Statistical measurements showed that the AgNPs size was concentrated between 15 and 35 nm. (5) The multilayer MoS2 film deposited by chemical vapor deposition (CVD) is transferred to the surface of AgNPs using a non-destructive wet transfer technique. The preferred MoS2 film is 2~10nm. The specific steps are as follows: Prepare 10ml of HF (40% volume concentration) solution, dilute it with 40ml of deionized water, spin coat a PMMA (polymethyl methacrylate) protective layer on MoS2, rotate at 3000r / min for 1min, heat at 150℃ for 5min, peel off the MoS2 film with HF solution, wash with deionized water and transfer it to ethylene glycol solution, and finally transfer it to the device substrate. (6) Perform photolithography on the thin film after step (5), with the photolithographic pattern and size being 60×60μm. 2 Square electrodes; (7) The Au / Ag top electrode was prepared by thermal evaporation technology. First, a 50 nm Ag layer was deposited by evaporation, and then a 30 nm Au layer was deposited by evaporation. (8) The device was baked in an 80°C oven for 20 min, then heated on a 150°C hot plate for 5 min, and finally soaked in acetone solution for 30 min to remove PMMA residue; the device Au / Ag / MoS2 / AgNPs / HfO2 / Pt was obtained.

[0038] Preferably, the process conditions for DC magnetron sputtering in step (2) include: room temperature (20~30℃), argon flow rate (30 sccm), and cavity vacuum degree (5×10⁻⁶). -4 Pa.

[0039] Preferably, the ALD process conditions described in step (3) include: using an HfO2-H2O formulation, setting the source temperature to 75°C, the chamber temperature to 200°C, and depositing 3~8nm HfO2 films at a rate of 0.1nm / cycle; the detailed steps are as follows (taking one cycle as an example): a.Dose: Open the Hf source bottle for 0.15 seconds; b. Purge: Clean the pipelines and chambers with N2 for 15 seconds; c. Dose: Open the water source bottle for 0.015 seconds; d. Purge: Clean the piping and chambers with N2 for 15 seconds; e.Goto: Return to step a.

[0040] Figure 1 This is a structural view of the memristor, showing Ag nanoparticles arranged in an array on HfO2. Its vertical structure can be tested using Pt and Au / Ag electrodes; its horizontal structure can be tested using the topmost Au / Ag electrode. Figure 2 This is a partial process flow diagram of the device, which mainly illustrates the wet transfer process of MoS2 and Au / Ag electrodes. The entire process is as follows: after magnetron sputtering Pt electrodes on the cleaned silicon wafer, HfO2 is deposited using atomic layer deposition, and finally, MoS2 and the photolithographically etched Au / Ag electrodes are transferred sequentially according to the wet transfer process shown in the diagram.

[0041] The following examples and comparative examples further illustrate the specific implementation methods and beneficial effects of the present invention in detail.

[0042] Example 1 This embodiment provides a method for preparing a dual-structure memristor based on Ag nanoparticle-modified MoS2 / HfO2, including the following steps: (1) Substrate pretreatment: The Si substrate was ultrasonically cleaned with acetone, ethanol and deionized water respectively. The cleaning time for each solution was 15 min and the ultrasonic power was 70 W. (2) Depositing the bottom electrode: Using a DC magnetron sputtering device, a Pt bottom electrode with a thickness of 200 nm is deposited on the substrate described in step (1); (3) After step (2) is completed, an HfO2 resistive switching layer with a thickness of 5 nm is deposited using atomic layer deposition (ALD) technology; (4) An AgNPs layer is deposited on the film obtained in step (3) using thermal evaporation technology. Ag particles with a purity of 99.9% are placed on an evaporation boat, and a vacuum of 5 × 10⁻⁶ is applied. -4 After Pa, a 5 nm Ag nanofilm was obtained by evaporation at a rate of 0.5 nm / min for 10 min. Then, it was placed in an OTF-1200X-4-RTP rapid annealing furnace to form AgNPs. The annealing environment was N2; the annealing temperature was 300℃ and the annealing time was 30 min. According to the statistical measurement with the assistance of scanning electron microscopy image software, the size of AgNPs is concentrated between 15~35 nm. (5) The multilayer MoS2 film deposited by chemical vapor deposition (CVD) was transferred to the surface of AgNPs using a non-destructive wet transfer technique. The MoS2 film was 5 nm thick. The specific steps were as follows: 10 ml of HF (40%) solution was prepared and diluted with 40 ml of deionized water. A PMMA (polymethyl methacrylate) protective layer was spin-coated on the MoS2 film. The film was rotated at 3000 r / min for 1 min and heated at 150 °C for 5 min. The MoS2 film was then peeled off using HF solution. After being cleaned with deionized water, the film was transferred to an ethylene glycol solution and finally transferred to the device substrate. (6) Perform photolithography on the thin film after step (5), with the photolithographic pattern and size being 60×60μm. 2 Square electrodes; (7) The Au / Ag top electrode was prepared by thermal evaporation technology. First, a 50 nm Ag layer was deposited by evaporation, and then a 30 nm Au layer was deposited by evaporation. (8) The device was baked in an 80°C oven for 20 min, then heated on a 150°C hot plate for 5 min, and finally soaked in acetone solution for 30 min to remove PMMA residue; the device Au / Ag / MoS2 / AgNPs / HfO2 / Pt was obtained.

[0043] In a specific embodiment, the process conditions for DC magnetron sputtering in step (2) are: room temperature, argon flow rate of 30 sccm, and cavity vacuum of 5 × 10⁻⁶. -4 Pa.

[0044] In a specific embodiment, the ALD process conditions described in step (3) are as follows: using an HfO2-H2O formulation, the source temperature is set to 75°C, the chamber temperature is set to 200°C, and a 5nm HfO2 thin film is deposited at a rate of 0.1nm / cycle; the detailed steps are as follows (taking one cycle as an example): a.Dose: Open the Hf source bottle for 0.15 seconds; b. Purge: Clean the pipelines and chambers with N2 for 15 seconds; c. Dose: Open the water source bottle for 0.015 seconds; d. Purge: Clean the piping and chambers with N2 for 15 seconds; e.Goto: Return to step a, repeating 50 times.

[0045] Figure 3 The current-voltage curves of the memristor vertical structure in Example 1 under different current-limiting conditions are shown. These curves were obtained using a B1500 semiconductor analyzer for DC IV testing, demonstrating multi-level resistive characteristics. During the test, the Pt electrode was grounded, and an operating voltage was applied to the Au electrode. The device cyclically maintained an operating voltage of 1V for the positive scan and -1V for the negative scan. The results show that hysteresis still exists at pA-level currents, indicating that the device can finely modulate conductive filaments and possesses ultra-low power consumption characteristics.

[0046] Figure 4 This is the normalized conductance modulation plot of the memristor vertical structure in Example 1 under 450 positive and negative pulses with an amplitude of 1V and a pulse width of 100ns using a semiconductor analyzer B1500. During the test, the device was first modulated to a low-resistance state with a 1mA current limit, and then a -0.1V reset voltage was applied. Afterwards, a DC read voltage of 0.02V was applied to read the resistance value in this state; the slope obtained represents the resistance value at this time. Subsequently, after reading the resistance state, a -0.1V reset voltage was applied again, and the resistance was read again, and this cycle was repeated. Figure 4 As shown in the figure. In the study, the device exhibited up to 283 different resistance states, confirming its excellent multi-order conductance modulation capability.

[0047] Figure 5The results of pulse testing of the memristor in Example 1 using a B1500 semiconductor analyzer demonstrate the experimental results (long-term enhancement / inhibition) of simulating biological synaptic behavior under 1000 pulse modulations. Specifically, the Pt electrode was grounded, and a continuous periodic pulse voltage was applied to the Au top electrode. Each cycle contained 50 positive voltage pulses (enhancement pulses) and 50 negative voltage pulses (inhibition pulses). The results show that under the stimulation of the enhancement pulses in each cycle, the conductivity of the device gradually increases. After applying 50 enhancement pulses, the conductivity of the device gradually decreases with each application of an inhibition pulse. During the continuous application of enhancement and inhibition pulses, the conductivity of the device does not recover when the voltage is removed, and the synaptic weight can be maintained and continuously changed for a long time under the influence of the stimulation signal; demonstrating the application potential and stability of the device of the present invention in neuromorphic computing.

[0048] Figure 6 Example 1 was tested at three different wavelengths (620nm, 520nm, 450nm) and a constant light intensity (16mW / cm²). 2 The current response under these conditions changes over time. Tests were conducted using a B1500 semiconductor analyzer and laser pointers of different wavelengths. The results confirmed that shorter wavelength photons have higher energy and can effectively induce MoS2 excitons and drive Ag... + Ion migration facilitates the formation of stable conductive filaments; long-wavelength photons, due to insufficient energy, mainly rely on thermal assistance to generate charge carriers, resulting in a limited dynamic range.

[0049] Figure 7 Example 1 serves as an artificial visual nociceptor for different light intensities (5mW / cm²). 2 8mW / cm 2 10mW / cm 2 16mW / cm 2 20mW / cm 2 This experiment simulates the perception "threshold" of a light pulse at a wavelength of 450nm, a frequency of 1Hz, and an illumination time of 10s. The data in the figure were obtained using a semiconductor analyzer B1500 for pulse testing and tests with laser pointers of different power. The experiment simulates the process of visual impairment in the human eye using the magnitude of excitatory postsynaptic current (EPSC). A threshold of 50nA was set; when the current exceeds this threshold, it indicates that the human eye begins to feel discomfort. The current value gradually increases with increasing light intensity. When the light intensity reaches 16mW / cm², the current value exceeds the threshold current of 50nA, indicating that the eye begins to feel discomfort. With further increases in light intensity, the discomfort becomes more intense, demonstrating a direct correlation between light intensity and visual discomfort, reflecting the practical application of the device in photoelectric response.

[0050] Example 2 This embodiment provides a method for preparing a dual-structure memristor based on Ag nanoparticles modified with MoS2 / HfO2. The difference from Example 1 is that the thickness of the HfO2 resistive switching layer is 3 nm, the thickness of the Ag nanofilm is 3 nm (evaporated at a rate of 0.3 nm / min for 10 min), the annealing temperature is 200 °C, and the annealing time is 40 min. At this time, the AgNPs size is approximately 15~25 nm, and the MoS2 film is 2 nm. The rest is the same as in Example 1.

[0051] Example 3 This embodiment provides a method for preparing a dual-structure memristor based on Ag nanoparticles modified with MoS2 / HfO2. The difference from Example 1 is that the thickness of the HfO2 resistive switching layer is 8 nm, the thickness of the Ag nanofilm is 7 nm (evaporated at a rate of 0.5 nm / min for 14 min), the annealing temperature is 350 °C, and the annealing time is 15 min. At this time, the AgNPs size is approximately 20~32 nm, and the MoS2 film is 10 nm. The rest is the same as in Example 1.

[0052] Comparative Example 1 This comparative example provides a method for preparing a conventional MoS2 / HfO2 dual-structure memristor. The difference from Example 1 is that the Ag nanoparticle layer is not deposited, i.e., step (4) is omitted. The rest is the same as Example 1.

[0053] Comparative Example 1 suffers from a significantly reduced photocurrent response and a slower response speed due to the absence of surface plasmon resonance effect; the lack of photogenerated carrier enhancement mechanism means it relies solely on the intrinsic light absorption of MoS2, limiting its multi-wavelength response capability: it only responds at wavelengths close to the bandgap energy; therefore, devices lacking AgNPs are not suitable for multimodal sensing systems.

[0054] Comparative Example 2 This comparative example provides a method for preparing a dual-structure memristor based on Ag nanoparticles modified with MoS2 / HfO2. The difference from Example 1 is the different AgNPs size distribution, that is, the annealing temperature in step (4) is 150℃ and the annealing time is 30min, while the rest is the same as in Example 1. At this time, the size of AgNPs is approximately 7~18nm.

[0055] The low temperature in Comparative Example 2 is not conducive to the full growth and aggregation of AgNPs. At this time, the Ag reserves are small, which is not conducive to the formation of stable and robust conductive channels, thus affecting the resistivity consistency and retention of the device. The small size will also lead to the shift of the resonance peak position or the weakening of the intensity, which weakens the enhancement effect of LSPR on photocurrent.

[0056] Comparative Example 3 This comparative example provides a method for preparing a dual-structure memristor based on Ag nanoparticles modified with MoS2 / HfO2. The difference between this example and Example 1 is that the AgNPs scale distribution is different, that is, the annealing temperature in step (4) is 400℃ and the annealing time is 30min. The rest is the same as in Example 1.

[0057] The AgNPs in Comparative Example 3 have a larger scale distribution of approximately 25–45 nm, which leads to a decrease in the level spacing and resolvability of multi-level IV curves, an increase in intercycle oscillations, and a detuning and weakening of LSPR.

[0058] Comparative Example 4 This comparative example provides a method for preparing a dual-structure memristor based on Ag nanoparticles modified with MoS2 / HfO2. The difference from Example 1 is that the Ag nanofilm thickness is different, that is, in step (4), a 2nm Ag nanofilm is obtained by evaporation at a rate of 0.5nm / min for 4min. The rest is the same as Example 1.

[0059] At this point, due to the excessively thin Ag nanofilm layer, the number of Ag nanoparticles formed is small, and the size of each individual particle may be smaller than the optimal range (15~35nm). This results in a weak ability to form conductive filaments, increased randomness, and decreased controllability; correspondingly, the surface localized plasmon resonance effect is weakened, the photocurrent response is weakened, and the spectral enhancement range is reduced.

[0060] Comparative Example 5 This comparative example provides a method for preparing a dual-structure memristor based on Ag nanoparticles modified with MoS2 / HfO2. The difference from Example 1 is that the Ag nanofilm thickness is different, that is, in step (4), an 8nm Ag nanofilm is obtained by evaporation at a rate of 0.5nm / min for 16min. The rest is the same as in Example 1.

[0061] At this point, due to the excessive thickness of the Ag nanofilm layer and the excessive size and density of the AgNPs formed after annealing, the Ag reserves are too abundant, which easily leads to the formation of excessively thick conductive filaments. However, at this point, resetting is difficult, and energy consumption increases. The excessive size of the AgNPs causes the LSPR resonance wavelength to deviate from the target range, and the carrier dynamics response of large particles will slow down.

[0062] Comparative Example 6 This comparative example provides a method for preparing a dual-structure memristor based on Ag nanoparticle-modified MoS2 / HfO2. The difference from Example 1 is that the thickness of the HfO2 resistive switching layer is 10 nm, while the rest is the same as Example 1.

[0063] Comparative Example 6 changed the HfO2 thickness to 10 nm, while remaining the same as Example 1. DC-IV curve testing was performed using a B1500A semiconductor analyzer, revealing a significant increase in the device's threshold voltage. With increased HfO2 thickness, Ag... + The longer migration path requires a higher voltage to overcome the energy barrier along the path. Increasing the threshold voltage leads to increased device power consumption, requiring an even higher voltage to achieve the equivalent electric field.

[0064] Comparative Example 7 This comparative example provides a method for preparing a dual-structure memristor based on Ag nanoparticles modified with MoS2 / HfO2. The difference from Example 1 is that the number of MoS2 layers is a single layer with a thickness of about 0.7 nm, while the rest is the same as Example 1.

[0065] Comparative Example 7: By changing the number and thickness of MoS2 layers, the resolvable conductivity level of a single 0.7nm MoS2 layer was significantly reduced and the cycling fluctuations were increased. Figure 8 To compare the current-voltage curves under different current-limiting conditions in Example 7, DC IV tests were performed using a semiconductor analyzer B1500. The operating voltage for the device cycle was maintained at 2V for the positive scan and -1.3V for the negative scan. It can be seen that under the same current-limiting and scan voltage conditions, the IV curve of the monolayer MoS2 device exhibits fewer resolvable conductance levels and greater fluctuations. This indicates that the multilayer structure has a stronger and more stable ability to modulate the conductive filaments.

[0066] The embodiments described above are some, but not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a dual-structure memristor based on Ag nanoparticle-modified MoS2 / HfO2, characterized in that, Includes the following steps: S1. Provide a substrate; deposit a bottom electrode on the substrate; S2. Deposit an HfO2 resistive switching layer on the bottom electrode; S3. Deposit an Ag nanoparticle layer on the HfO2 resistive switching layer; S4. Transfer the MoS2 film onto the Ag nanoparticle layer; S5. Prepare a top electrode on the MoS2 thin film.

2. The preparation method according to claim 1, characterized in that, The Ag nanoparticles have a size of 15~35nm.

3. The preparation method according to claim 1, characterized in that, The thickness of the HfO2 resistive switching layer is 3~8nm.

4. The preparation method according to claim 1, characterized in that, The method for depositing the Ag nanoparticle layer in step S3 includes: firstly, thermally evaporating an Ag nanofilm on an HfO2 resistive switching layer, and then annealing the Ag nanofilm under an inert atmosphere to obtain the Ag nanoparticle layer.

5. The preparation method according to claim 4, characterized in that, The thickness of the Ag nanofilm is 3~7 nm.

6. The preparation method according to claim 4, characterized in that, The annealing temperature is 200~350℃; the annealing time is 15~40min.

7. The preparation method according to claim 1, characterized in that, The thickness of the MoS2 thin film is 2~10 nm.

8. The preparation method according to claim 1, characterized in that, The top electrode includes an Au / Ag composite electrode; the bottom electrode includes a Pt electrode.

9. A dual-structure memristor based on Ag nanoparticle-modified MoS2 / HfO2 obtained by the preparation method according to any one of claims 1 to 8.

10. An application of the dual-structure memristor based on Ag nanoparticle-modified MoS2 / HfO2 as described in claim 9 in neuromorphic computing, intelligent robots, multimodal artificial intelligence systems, or visual information processing systems.

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