A memristor and a preparation method and application thereof

Abstract

The application discloses a memristor and a preparation method and application thereof, which sequentially comprises a bottom electrode layer, a HOFs nanometer film functional layer and a metal top electrode from bottom to top; the thickness of the HOFs nanometer film functional layer is 80-120 nm; the film has a flat surface, good crystallinity and high orientation. As an active layer of the memristor, the film has good resistance state conversion performance, a low SET voltage of 0.86 V, excellent retention time of 1.64*10 4 s, good cycle performance of 60 times, and high thermal stability. The device benefits from the main hydrogen bond interaction and π-π conjugation in the structure, the film device preparation method is simple and perfect, the active functional layer PFC-73 can be recycled, the damaged device can be regenerated through a simple and direct dissolution recrystallization method, and the resistance state conversion performance is restored.

Description

Technical Field

[0001] This application belongs to the field of materials technology, specifically relating to a memristor, its preparation method, and its application. Background Technology

[0002] Since the concept of the "memristor" was proposed by Chinese-American scientist Shao-Tang Tsai in 1971, a device whose resistance changes with the amount of current flowing through it, remains unchanged after the current stops, and only recovers its resistance when a reverse current flows through it, has come into the researchers' view. However, the development of the memristor field has been slow until 2008 when Hewlett-Packard published a paper on a TiO2-based resistive switching memory device in Nature, and the emergence of the first nano-memristor sparked a research boom. Compared with traditional memory on the market, memristors can achieve non-volatile storage of information data and have advantages such as high storage density, fast erase and write speed, and low power consumption, laying a foundation for the manufacture of instant PCs, more energy-efficient computers, and analog computers that process and communicate information in a way similar to the human brain. At the same time, based on the storage mechanism of memristors, combined with their simple two-stage structure, ultra-high density integration, unique nonlinear electrical properties, and high similarity to biological synapses, memristors have attracted widespread attention in the field of artificial synaptic devices.

[0003] Traditional electroresistive memristors have a sandwich-like structure, consisting of a top electrode, a functional dielectric layer, and a bottom electrode. The resistance of a memristor changes non-volatilely with the applied voltage of an external electric field, exhibiting two or more high and low states; this phenomenon is called the resistive switching effect. Taking the two-state electroresistive switching effect as an example, if the high-resistive state (HRS) is defined as "0" and the low-resistive state (LRS) as "1", then by applying an electric field, the device can be triggered to switch between "0" and "1", achieving non-volatile storage of information data. Even when the electric field is removed, the data can be retained for a long time without loss. Currently, the electroresistive switching effect has been observed in many material systems, such as ZnO, HfO2, BiFeO3, graphene oxide, and carbon nanotubes.

[0004] The electrical characteristics of memristors often depend on their resistance switching mechanisms, which are generally classified into two main categories: ionic and electronic. The basic principle of the ionic migration type is that under external voltage or current stimulation, ions are driven to move within the material, ultimately causing a change in the device's conductivity. The resistance switching location occurring within the dielectric layer and producing only a local effect is generally referred to as the conductive filament model. This refers to the migration of cations and anions in the dielectric layer under the influence of an electric field, gradually forming a relatively stable local conductive channel, causing the device to transition to a high-conductivity state. Other models based on global migration conductivity are usually based on the modulation of the Schottky barrier or the interface barrier within the dielectric layer, including the Schottky emission model with the resistance switching location at the interface effect and partial models of bulk effects. The switching mechanism of a purely electronic memristor originates from the capture and decapture behavior of electrons at defects, also exhibiting global conductivity characteristics.

[0005] Memristors involve a wide range of materials, including perovskite, chalcogenides, organic materials, and metal oxides. Traditional RRAM research primarily focuses on forming devices using metal oxide materials. These inorganic materials possess certain memristor properties, good chemical stability, and are more compatible with existing semiconductor processes. The rapidly developing organic framework materials offer more possibilities for constructing novel memristors. Firstly, framework materials allow for ion or electron migration, enabling resistive switching as the active layer of the device. Furthermore, researchers can manipulate the pore structure of framework materials or combine them with quantum dots, two-dimensional materials, etc., thereby improving the memristor performance of the devices.

[0006] Traditional metal-insulator-metal (MRAM) structures are considered promising modern electronic devices for information storage, in-memory computing, and brain-inspired neuromorphic computing. The evolution of advanced MRAM electronic components largely depends on the development of innovative resistive switching materials with ideal performance. Over the past few decades, increasing research has focused on using ordered, tunable porous framework materials such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and carbon nanotubes as the active layer of resistive switching memristor devices. The periodic structure and tunable pore environment of these materials give them excellent resistance switching performance. However, most porous materials (such as MOFs and COFs) are often insoluble in common organic solvents and cannot be synthesized into thin films via solvent methods, resulting in insufficient film-forming ability and gradually increasing synthesis costs. Therefore, the current trend is to continue developing solution-preparable thin films based on emerging applications of innovative electronic devices.

[0007] Hydrogen-bonded organic frameworks (HOFs) are crystalline nanoporous materials formed through self-assembly of non-covalent interactions involving hydrogen bonding, π-π conjugation, and electrostatic interactions. As a novel class of crystalline nanomaterials, HOFs are rapidly developing. Compared to MOFs or COFs, HOFs offer more attractive advantages, such as low cost, ease of purification, and the ability to be recovered through simple recrystallization, making them important for applications in gas separation, catalysis, energy storage, and conversion. Currently, the high porosity, tunable electronic structure, ease of processing, and low density of HOFs make them excellent candidates for novel memristors. However, their application in the electronics field is limited by the lack of high-quality thin films. The synthesis of powder or thick-film devices is often hampered by large particle size and loose particle connections that hinder charge transport. For electronic device applications, achieving controllable synthesis of HOF nanofilms with adjustable thickness, surface roughness, interlayer orientation, and particle size at the nanoscale is a pressing problem to be solved. Summary of the Invention

[0008] This application provides a resistive switching memory (referred to as Ag / PFC-73 / ITO) based on hydrogen-bonded organic framework (HOF) nanofilm materials prepared by solution synthesis and its preparation method. The aforementioned memristor achieves a large on / off ratio, low SET voltage, good reproducibility, and high thermal stability, effectively solving the problems of poor reproducibility and high SET voltage in traditional RRAMs prepared on oxide substrates. It also marks an unprecedented use of HOF materials to prepare nanofilms.

[0009] According to one aspect of this application, a memristor is provided, comprising, from bottom to top, a bottom electrode layer, a HOF nanofilm functional layer, and a metal top electrode;

[0010] The HOFs nanofilm functional layer has a thickness in the nanometer range, ranging from 80 to 120 nm; and it can generate voltage changes in response to certain electrical signals to achieve non-volatile storage.

[0011] The functional layer of the HOF nanofilm is assembled from organic ligands containing a metal center. The metal center is Ni, and the organic ligand is [5,10,15,20-tetra(4-carboxyphenyl)porphyrin]. Each organic ligand interacts with four adjacent organic ligands through eight hydrogen bonds to form a two-dimensional square layer. Adjacent two-dimensional square layers are stacked axially to form one-dimensional channels, while interlayer orbital overlap, π-π interactions, and metal-carbon interactions are generated.

[0012] The bottom electrode layer is conductive glass; for example, with an area of ​​1 cm². 2 Conductive glass (ITO) with a thickness of approximately 1 mm.

[0013] The metal top electrode is made of silver.

[0014] In this application, the identifiable signal is an electrical signal.

[0015] HOF nanofilms are embodied as electrical sensing films; the device is sandwich-like, and the electrical signals received by the bottom and top electrodes can change the conductivity of the device.

[0016] According to another aspect of this application, a method for fabricating the above-mentioned memristor is provided, comprising the following steps:

[0017] A spin coating solution containing PFC-73, N,N-dimethylformamide, and chlorobenzene is spin-coated onto the bottom electrode layer. Using a mask designed according to requirements, a metal top electrode is formed by thermal evaporation with elemental silver as the metal source, thus obtaining the memristor.

[0018] Specifically,

[0019] Includes the following steps:

[0020] Step 1: Weigh 40 mg of PFC-73 and dissolve it evenly in 1500 μL of a mixed solution of N,N-dimethylformamide and chlorobenzene (V DMF :V 氯苯 In a mixture of 3:2, the solution is ultrasonically homogenized and then filtered to prepare a spin-coating solution;

[0021] Step 2: Using a KW-A4 desktop spin coater, apply the dried ITO to the center of the turntable with the conductive side facing up.

[0022] Step 3: Set the spin coating parameters to 1500 rpm and 40 s, take the HOFs spin coating solution and drop it onto ITO;

[0023] Step 4: Transfer the spin-coated ITO to a heating stage at 100°C and anneal for 10 minutes.

[0024] The actual concentration of the spin-coating solution was 26 mg / mL.

[0025] Spin coating controls the thickness of HOF nanofilms by adjusting the concentration of hydrogen-bonded organic framework materials, coating rate, and coating time.

[0026] The formation of the top electrode on the functional layer PFC-73 nanofilm includes the following steps:

[0027] Step 1: Fix the ITO conductive side of the grown HOFs nanofilm onto the PET substrate with the grown HOFs nanofilm facing up, and fix the mask plate designed to fit the actual application requirements onto the HOFs nanofilm.

[0028] Step 2: Form a metal top electrode of a certain thickness using thermal evaporation deposition technology;

[0029] The specific vapor deposition parameters are 10.-6 Torr, at room temperature, with elemental silver as the metal source.

[0030] According to some examples of this application, a silver electrode layer with a thickness of 50 nm is formed on a HOF thin film, and the deposition rate is approximately [missing information] when the thickness is in the range of 1-3 nm. In the thickness range of 3-50nm, the evaporation rate is approximately

[0031] The bottom electrode layer is modified with hydroxyl groups to hydroxylate the surface in order to facilitate the subsequent growth of HOF thin films.

[0032] The hydroxyl modification includes the following steps:

[0033] The cleaned bottom electrode layer was immersed in an alkaline piranha solution;

[0034] The alkaline piranha solution is obtained by mixing 0.2 mol / L sodium hydroxide solution and 30 wt% hydrogen peroxide in a volume ratio of 3:1.

[0035] Specifically,

[0036] Includes the following steps:

[0037] Step 1: Clean the ITO with organic solvents acetone, ethanol and isopropanol, and then dry it with nitrogen gas;

[0038] Step 2: Take 0.2 mol / L sodium hydroxide solution and 30 wt% hydrogen peroxide and mix them evenly at a volume ratio of 3:1 to prepare an alkaline piranha solution;

[0039] Step 3: Immerse the clean ITO in the above solution at 80°C for 30 minutes and then remove it.

[0040] The temperature of the thermal evaporation is 25–30°C;

[0041] The pressure of the thermal evaporation is 10. -6 ~10 -7 Torr.

[0042] According to another aspect of this application, an application of the above-described memristor is provided, the memristor having a SET voltage of 0.86V and a 1.64×10⁻⁶ mV / m³. 4 The retention time of s was stable after 60 cycles.

[0043] The advantages of this application are:

[0044] Compared with existing technologies, this application presents for the first time a cost-effective, solution spin-coated, controllable HOF thin film (PFC-73) exhibiting a smooth surface, good crystallinity, and high orientation. The surface roughness of the functional layer can reach 2.46 nm.

[0045] As the active layer of a memristor device, this thin film exhibits excellent resistive state transition performance, with a low SET voltage of 0.86V and a resistive state ratio of 1.64×10⁻⁶. 4 It boasts excellent retention time, good cycle performance of 60 cycles, and high thermal stability.

[0046] This memristor device benefits from the main hydrogen bonding interactions and π-π conjugation in its structure. The thin film device fabrication method is simple and complete. It can also realize the recovery of the active functional layer PFC-73. Damaged devices can be regenerated by simple and direct dissolution and recrystallization, and the performance of resistive state transition can be restored. Attached Figure Description

[0047] Figure 1 This is a spin-coating schematic diagram of the Ag / PFC-73 / ITO memristor prepared in Example 1.

[0048] Figure 2 XRD pattern of PFC-73 nanofilm prepared in Example 1.

[0049] Figure 3 The image shown is a scanning electron microscope (SEM) planar image of the PFC-73 nanofilm in Example 1, with a scale of 10 μm.

[0050] Figure 4 The image shows a scanning electron microscope cross-section of the PFC-73 nanofilm in Example 1, with a scale of 200 nm.

[0051] Figure 5 This is an atomic force microscope image of the PFC-73 nanofilm in Example 1, with a scale of 1 μm.

[0052] Figure 6 The characteristic current-voltage (IV) diagram of the Ag / PFC-73 / ITO memristor prepared in Example 1 is shown.

[0053] Figure 7 The distribution of high-resistivity and low-resistivity states of the Ag / PFC-73 / ITO memristor prepared in Example 1 during long-term testing.

[0054] Figure 8 Switching durability test of the Ag / PFC-73 / ITO memristor prepared in Example 1.

[0055] Figure 9The XRD patterns of the powder recovered from the preparation of the PFC-73 nanofilm in Example 1 and the film prepared by spin coating under the same conditions are shown. Detailed Implementation

[0056] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0057] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0058] Example 1

[0059] First, hydroxyl groups are modified on the bottom electrode:

[0060] Step 1: Clean the ITO with organic solvents acetone, ethanol and isopropanol, and then dry it with nitrogen gas;

[0061] Step 2: Take 0.2 mol / L sodium hydroxide solution and 30 wt% hydrogen peroxide and mix them evenly at a volume ratio of 3:1 to prepare an alkaline piranha solution;

[0062] Step 3: Immerse the clean ITO in the above solution at 80°C for 30 minutes and then remove it.

[0063] Then, a thin film is grown on the bottom electrode layer using PFC-73:

[0064] Step 1: Weigh 40 mg of PFC-73 and dissolve it uniformly in 1500 μL of a mixed solution of N,N-dimethylformamide and chlorobenzene. After ultrasonic homogenization, filter to prepare a spin-coating solution; the actual concentration of the spin-coating solution is 26 mg / mL.

[0065] Step 2: Using a KW-A4 desktop spin coater, apply the dried ITO to the center of the turntable with the conductive side facing up.

[0066] Step 3: Set the spin coating parameters to 1500 rpm and 40 s, and take 70 μL of HOFs spin coating solution and drop it onto ITO.

[0067] Step 4: Transfer the spin-coated ITO to a heating stage at 100°C and anneal for 10 minutes.

[0068] Finally, the top electrode was formed on the functional layer PFC-73 nanofilm:

[0069] Step 1: Fix the ITO conductive side of the grown HOFs nanofilm onto the PET substrate with the grown HOFs nanofilm facing up, and fix the mask plate designed to fit the actual application requirements onto the HOFs nanofilm.

[0070] Step 2: Form a metal top electrode of a certain thickness using thermal evaporation deposition technology;

[0071] The specific vapor deposition parameters are 10. -6 Torr, at room temperature, with elemental silver as the metal source.

[0072] The top electrode measures 0.5*0.5mm. 2 With a top electrode thickness of 50 nm, the deposition rate is approximately [missing information] when the deposition thickness is in the range of 1-3 nm. In the thickness range of 3-50nm, the evaporation rate is approximately

[0073] The Ag / PFC-73 / ITO memristor is obtained through the above steps;

[0074] Figure 1 This is a spin-coating schematic diagram of the Ag / PFC-73 / ITO memristor prepared in Example 1.

[0075] Figure 2 The XRD pattern of the PFC-73 nanofilm prepared in Example 1 demonstrates the successful preparation of the PFC-73 nanofilm.

[0076] Figure 3 The image shown is a scanning electron microscope (SEM) planar image of the PFC-73 nanofilm in Example 1, with a scale of 10 μm.

[0077] Figure 4 The image shows a scanning electron microscope (SEM) cross-sectional image of the PFC-73 nanofilm in Example 1, at a scale of 200 nm. It can be seen that the thickness of the prepared PFC-73 nanofilm is 114 nm.

[0078] Figure 5 The image shown is an atomic force microscope (AFM) image of the PFC-73 nanofilm from Example 1, at a scale of 1 μm. It can be seen that the average roughness of the prepared PFC-73 nanofilm is 2.46 nm.

[0079] The performance of the obtained Ag / PFC-73 / ITO memristor was tested;

[0080] Figure 6 The characteristic current-voltage (IV) diagram of the Ag / PFC-73 / ITO memristor prepared in Example 1 is shown.

[0081] Figure 6The current-voltage characteristics (i.e., IV characteristics) of the Ag / PFC-73 / ITO prepared in this application were tested using a semiconductor parameter analysis and testing instrument. The current-voltage characteristics of the Ag / PFC-73 / ITO were tested in the voltage continuous scan mode. When a scan bias voltage is applied to the Ag / PFC-73 / ITO memristor, the Ag / PFC-73 / ITO exhibits high resistance when the voltage initially scans from 0V. When the voltage exceeds +0.86V, the Ag / PFC-73 / ITO suddenly transitions to a low resistance state. At this point, a current limit value (0.002A in this embodiment) needs to be set to prevent excessive current from damaging the Ag / PFC-73 / ITO. When the voltage scans back from +2.0V to 0V, the Ag / PFC-73 / ITO remains in the low resistance state. When the voltage scans from 0V to -4.0V (the reset voltage), the Ag / PFC-73 / ITO transitions to a high resistance state. When the voltage scans back from -4.0V to 0V, the Ag / PFC-73 / ITO's memory cells remain in the high resistance state, and its switching ratio can reach 10. 3 .

[0082] Figure 7 The distribution of high-resistivity and low-resistivity states of the Ag / PFC-73 / ITO memristor prepared in Example 1 during long-term testing.

[0083] Figure 7 The Ag / PFC-73 / ITO prepared in this application was tested using a semiconductor parameter analysis and testing instrument. After multiple tests in continuous voltage scan mode until a stable state was reached, a reading voltage of 0.1V was set to test the holding time of Ag / PFC-73 / ITO in both high-resistance and low-resistance states. The sampling interval was set to 4s, with 4100 sampling points, for a total sampling time exceeding 1.64 × 10⁻⁶. 4 s. Compile and organize the above data.

[0084] Figure 8 Switching durability test of the Ag / PFC-73 / ITO memristor prepared in Example 1.

[0085] Figure 8The Ag / PFC-73 / ITO fabricated in this application was tested using a semiconductor parameter analysis and testing instrument. More than 60 current-voltage characteristic tests were performed on the Ag / PFC-73 / ITO in continuous voltage scan mode. First, the high-resistance data of the Ag / PFC-73 / ITO was tested. A scanning bias voltage was applied to the Ag / PFC-73 / ITO memristor, and the voltage was scanned from 0V to the maximum set voltage value (exceeding 0.86V) and back to 0V. The Ag / PFC-73 / ITO exhibited a transition from a high-resistance state to a low-resistance state, and the low-resistance state data was tested at this point. Then, the voltage was scanned from 0V to -4.0V (reset voltage) and back to 0V. The memory cell of the Ag / PFC-73 / ITO transitioned from a low-resistance state to a high-resistance state, and the high-resistance state value was tested at this point. The data from more than 60 cycles were statistically analyzed.

[0086] Figure 9 The XRD patterns of the powder recovered from N,N-dimethylformamide used in the preparation of PFC-73 nanofilms in Example 1, and the film prepared by spin-coating under the same conditions, are shown. The figures demonstrate that the recovery of the PFC-73 nanofilms was successful.

[0087] In summary, this application presents the first high-performance, cost-effective, and controllable solution spin-coated HOF thin film (PFC-73) exhibiting a smooth surface, good crystallinity, and high orientation.

[0088] As the active layer of a memristor device, this thin film exhibits excellent resistive state transition performance, with a low SET voltage of 0.86V and a resistive state ratio of 1.64×10⁻⁶. 4 It boasts excellent retention time, good cycle performance of 60 cycles, and high thermal stability.

[0089] This memristor device benefits from the main hydrogen bonding interactions and π-π conjugation in its structure. The thin film device fabrication method is simple and complete. It can also realize the recovery of the active functional layer PFC-73. Damaged devices can be regenerated by simple and direct dissolution and recrystallization, and the performance of resistive state transition can be restored.

[0090] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A memristor, characterized in that, From bottom to top, it consists of a bottom electrode layer, a HOF nanofilm functional layer, and a metal top electrode. The thickness of the HOFs nanofilm functional layer is 80–120 nm. The HOFs nanofilm functional layer is a two-dimensional porous film material, which is assembled from organic ligands containing metal centers. The metal center is Ni, and the organic ligand is [5,10,15,20-tetra(4-carboxyphenyl)porphyrin].

2. The memristor according to claim 1, characterized in that, In the two-dimensional porous film material, each porphyrin ligand interacts with four adjacent porphyrin ligands through eight OH···O hydrogen bonds to form a two-dimensional square layer. The adjacent layers are stacked axially to form a one-dimensional channel, while interlayer orbital overlap, π-π interaction and metal-carbon interaction are generated.

3. The memristor according to claim 1, characterized in that, The bottom electrode layer is conductive glass; The metal top electrode is made of silver.

4. A method for fabricating a memristor according to any one of claims 1 to 3, characterized in that, Includes the following steps: A spin coating solution containing PFC-73, N,N-dimethylformamide, and chlorobenzene is spin-coated onto the bottom electrode layer. Using a mask designed according to requirements, a metal top electrode is formed by thermal evaporation with elemental silver as the metal source, thus obtaining the memristor.

5. The preparation method according to claim 4, characterized in that, The bottom electrode layer is modified with hydroxyl groups; The hydroxyl modification includes the following steps: The cleaned bottom electrode layer was immersed in an alkaline piranha solution.

6. The preparation method according to claim 5, characterized in that, The alkaline piranha solution was obtained by mixing 0.2 mol / L sodium hydroxide solution and 30 wt% hydrogen peroxide in a volume ratio of 3:

1.

7. The preparation method according to claim 4, characterized in that, The temperature of the thermal evaporation is 25–30°C; The pressure of the thermal evaporation is 10. -6 ~10 -7 Torr.

8. An application of the memristor according to any one of claims 1 to 3, characterized in that, The memristor has a set voltage of 0.86V and a capacitance of 1.64 × 10⁻⁶. 4 The retention time of s was stable after 60 cycles.

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