Nano-fluid memristor based on two-dimensional material nanopores and preparation method of nano-fluid memristor

Abstract

The invention provides a nanofluid memristor based on a two-dimensional material nanopore and a preparation method thereof, and belongs to the technical field of brain-like memorizers, and the preparation method comprises the following steps: transferring a two-dimensional material prepared by a chemical vapor deposition method to a suspended silicon nitride film substrate with a single micron pore through a polymer auxiliary transfer method to form a two-dimensional material device; a nanopore device is controllably prepared and formed through an electrochemical etching method; wherein the etching of atoms is realized by applying voltage to the two sides of the graphene in the electrolyte solution. According to the invention, only the nanopores with the atomic-scale length are provided, the thickness is small, the ion transport efficiency is high, and ultra-low power consumption under the action of each pulse can be brought; compared with a traditional electronic material memristor and an existing fluid memristor, the electrical property can be switched by an ionic conductance value, and the memristive response and the resistance switching ratio can be regulated and controlled by an ionic valence; the preparation method is simple, is compatible with an MEMS process, and can realize large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of brain-like memories, and particularly to a nanofluidic memristor based on two-dimensional material nanopores and a preparation method thereof. Background Art

[0002] A memristor is a memory-computing integrated device with multiple advantages such as charge programmability, high integration, and low power consumption, and is expected to develop next-generation brain-like chips and integrated systems for intelligent information perception, storage, and processing. However, the existing memristors based on solid-state electronic materials have essential differences from the biological brain based on aqueous ions, and there are problems such as poor biocompatibility, which limit the application of brain-like integrated systems. To solve this problem, it is necessary to design a new type of fluid memristor based on aqueous solution ions to achieve the storage and processing of ionic information on a single device like the brain. The fluid memristor based on microelectromechanical systems (MEMS) has the advantages of low-voltage operation, adjustable physical and chemical properties, and compatibility with CMOS processes, and is expected to break through the brain-like integration technology. However, the lengths of existing fluid memristors are all in the micron size, and it is impossible to achieve a low-power bionic design of the nanoscale structure of biological synapses in terms of structure and function, and the preparation process is complex and cannot be scaled up.

[0003] In summary, the existing fluid memristors have long lengths, high energy consumption, and cannot achieve bionic design; poor performance, small resistance switching ratio; complex preparation process and cannot be scaled up. Summary of the Invention

[0004] The purpose of the present invention is to provide a nanofluidic memristor based on two-dimensional material nanopores and a preparation method thereof, and to prepare a nanofluidic memristor with atomic-level length, adjustable resistance switching ratio, and low power consumption of two-dimensional material nanopores, so as to solve at least one of the technical problems existing in the above background art.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] The present invention provides a preparation method of a nanofluidic memristor based on two-dimensional material nanopores, including:

[0007] Transferring the two-dimensional material prepared by chemical vapor deposition to a suspended silicon nitride thin film substrate with a single micron pore by a polymer-assisted transfer method to form a two-dimensional material device;

[0008] Controllably preparing a nanopore device by an electrochemical etching method; wherein, the etching of atoms is achieved by applying a voltage on both sides of graphene placed in an electrolyte solution; as the application time of the voltage extends, a nanopore with ionic conductance is prepared by monitoring the increase of the ionic current. The relationship between the ionic conductance G and the nanopore diameter d is as follows:

[0009]

[0010] σ is the solution conductivity (1.29 S / m), and l is the effective thickness of the graphene film (0.6 nm). The prepared nanopore diameter range with an ionic conductance range of 5 - 10 nS is about 2 - 3 nm.

[0011] Furthermore, electrochemical etching is achieved by applying a voltage across the graphene placed in a 0.1 M KCl electrolyte solution for atomic etching.

[0012] Furthermore, a continuous voltage with a time of 320 s and an amplitude of 1.5 V is applied across the graphene using an electrochemical workstation through Ag / AgCl electrodes.

[0013] Advantages of the present invention: It only has nanopores with atomic - level length, is thin in thickness, has high ion transport efficiency, and can bring ultra - low power consumption under each pulse action; compared with traditional electronic material memristors and existing fluid memristors, its electrical characteristics can be switched by the ionic conductance value, and the memristive response and resistance switching ratio can be regulated by the ionic valence; the preparation method is simple, compatible with MEMS processes, and can be mass - produced.

[0014] Additional aspects and advantages of the present invention will be given in part in the following description, which will become apparent from the following description, or can be understood through the practice of the present invention. Brief Description of the Drawings

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0016] Figure 1 It is a schematic diagram of simulating the atomic - level length ion transport path of a biological synaptic interface using the nanopore structure of two - dimensional materials according to the embodiments of the present invention.

[0017] Figure 2 It is a flowchart of the preparation method of a nanofluidic memristor based on two - dimensional material nanopores according to the embodiments of the present invention.

[0018] Figure 3 It is a controllable preparation process and characterization diagram of two - dimensional material nanopores according to the embodiments of the present invention.

[0019] Figure 4 It is a schematic diagram of the memristive response of a nanopore fluid memristor in ions with different valences according to the embodiments of the present invention. Among them, Figure 4 (a) is potassium chloride, Figure 4 (b) is lanthanum chloride.

[0020] Figure 5 This is a schematic diagram of the memory learning and decay curves of the two-dimensional material nanopore memristor under 60 consecutive pulses according to the embodiments of the present invention.

[0021] Figure 6 This is a schematic diagram of the current curve under two consecutive voltage pulses according to the embodiments of the present invention. Detailed implementation manners

[0022] The following details the implementation manners of the present invention. Examples of the implementation manners are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The implementation manners described through the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0023] Those skilled in the art of this technology can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used here have the same meaning as the general understanding of those of ordinary skill in the art to which the present invention belongs.

[0024] It should also be understood that terms such as those defined in a general dictionary should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted with an idealized or overly formal meaning unless defined as here.

[0025] Those skilled in the art of this technology can understand that, unless specifically stated, the singular forms "a", "an", "the" and "said" used here may also include the plural forms. It should be further understood that the term "comprising" used in the description of the present invention means the presence of the described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements and / or their groups.

[0026] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0027] In the description of this specification, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality of" means two or more, unless otherwise specifically defined.

[0028] In the description of this specification, the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present technology and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation on the present technology.

[0029] Unless otherwise clearly specified and defined, the terms "installed", "connected", "coupled", "set" shall be understood in a broad sense. For example, it may be fixedly connected and set, or detachably connected and set, or integrally connected and set. For those of ordinary skill in the art, the specific meanings of the above terms in the present technology can be understood according to specific circumstances.

[0030] For the convenience of understanding the present invention, the following further explains the present invention with specific embodiments in conjunction with the drawings, and the specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0031] Those skilled in the art should understand that the drawings are only schematic diagrams of the embodiments, and the components in the drawings are not necessarily essential for implementing the present invention.

[0032] In this embodiment, a nanofluidic memristor based on two-dimensional material nanopores and its preparation method are proposed, which is a design method of a two-dimensional material (such as graphene, molybdenum disulfide, etc.) nanopore fluid memristor applied to a biomimetic neural synapse chip. Through an electrochemical etching method, controllable nanoscale structure preparation is realized, and nanopores are introduced on the two-dimensional material film to simulate the biological synapse structure, realizing a low-power nanofluidic memristor that can recognize multiple ion information.

[0033] Such as Figure 1As shown in the figure, graphene, a representative of two-dimensional materials, is an atomically thin material composed of carbon atoms, with stable physical and chemical properties. Combining with the controllable atomic-scale pore etching technology of two-dimensional materials, it is possible to achieve precise bionic design of biological neuron nanochannels in terms of structural dimensions. Through the interaction between the surface charge of the nanopore and ions with different valences, ion recognition can be achieved, and it is compatible with the MEMS process. Thus, a two-dimensional material nanopore fluid memristor with nanoscale length, capable of responding to ion valence information, and simple and easy to scale up in the preparation process can be realized, which can be applied to bionic neural synapse chips.

[0034] As Figure 2 shown, in this embodiment, the preparation method of the nanofluid memristor based on two-dimensional material nanopores includes the following steps: First, the transfer of two-dimensional materials such as graphene is carried out to prepare MEMS devices. The two-dimensional materials prepared by chemical vapor deposition are transferred to a suspended silicon nitride thin film substrate with a single micron pore through polymer-assisted transfer method to form two-dimensional material devices. Then, a nanopore device can be controllably prepared by electrochemical etching method. Electrochemical etching is achieved by applying a voltage on both sides of the graphene placed in a 0.1M KCl electrolyte solution to etch atoms. In the experiment, a continuous voltage with a time of 320s and an amplitude of 1.5V is applied on both sides of the graphene through an Ag / AgCl electrode by using an electrochemical workstation (CH 650E). As the application time of the voltage is extended, a nanopore with ionic conductivity is prepared by monitoring the increase of the ionic current. The I–t curve of the graphene device during the electrochemical etching process is as Figure 3 (a) shown. After reaching the threshold, the voltage stimulation is timely shut down to complete the preparation of graphene nanopores. The comparison of the I–V curves before and after electrochemical etching ( Figure 3 (b)) shows the successful preparation of the device, and the ionic conductivity increases by about two orders of magnitude.

[0035] In this embodiment, the performance test of the prepared nanopore fluid memristor is continued. Based on the prepared two-dimensional material nanopores, electrochemical tests with a dynamic alternating electric field are carried out. An alternating voltage of 0.1V / s is applied on both sides of the device through an Ag / AgCl electrode by using an electrochemical workstation (CH 650E). The memristive response characteristics of different conductivities and valence ions under the oscillating electric field are studied. The nanopores prepared in the experiment can realize different memristive response identifications of monovalent and trivalent ions, Figure 4 which is a typical data graph for ion valence regulation of memristive characteristics. Figure 4 (a) is the data in potassium chloride solution, and the memristor shows bipolarity. Figure 4 (b) is the data in lanthanum chloride, and the memristor shows unipolarity, negative differential conductivity characteristics and a large hysteresis curve area. In addition, by Figure 4It can be seen that indicators such as the high resistance state (HRS) resistance and low resistance state (LRS) resistance of the nanopore fluid memristor can also be adjusted by ions with different valences. The resistance switching ratio in trivalent ions can reach 8, which is 4 times that of monovalent ions.

[0036] The fluid memristor applied to the bionic neural chip not only needs to show responses to a wide variety of ionic information but also needs to exhibit the functions of neuromorphic synapses under pulsed voltages. Therefore, measuring the synaptic response of the two-dimensional material nanopore memristor can effectively simulate its application prospects in neuromorphic chips. Figure 5 is the memory learning and decay curve of the two-dimensional material nanopore memristor under 60 consecutive pulses, which can reflect the bionics of the learning and forgetting functions of biological synapses. Figure 6 is the current curve under two consecutive voltage pulses. The current is suppressed by consecutive negative voltages, showing the characteristic of paired-pulse facilitation (PPF). By integrating the current-voltage curve of the second pulse, the energy consumption per pulse can be obtained to be about 0.546 pJ, demonstrating the characteristic of ultra-low power consumption.

[0037] In summary, the present invention proposes a design method for a two-dimensional material nanopore fluid memristor applied to an artificial neural synapse chip. The present invention has no special requirements for the types of two-dimensional materials, and graphene and molybdenum disulfide can be replaced with other two-dimensional materials, such as other transition metal sulfides, black phosphorus, boron nitride, etc.

[0038] The present invention can form a nanofluid memristor by precisely introducing nanopores on a two-dimensional material with atomic thickness, achieving a bionic design of the nanoscale structure of biological synapses from a structural perspective. Moreover, the sub-nanometer-thick pore structure greatly improves the efficiency of ion transport and reduces the power consumption of functions such as memory learning per pulse. At the same time, the interaction between the negative charges on the nanopore surface and ions with different valences can be used to achieve the recognition of different types of ions and the regulation of memristive properties, and the response to 7 aqueous ions can be realized.

[0039] Traditional electronic material memristors are limited by their intrinsic physical properties and cannot simulate the biological aqueous ion environment; while existing fluid memristors have long lengths, poor performance, and complex preparation processes, making them unable to be scaled up. The fluid memristor designed in the present invention prepares a two-dimensional material nanopore structure with atomic thickness, realizes the response to a variety of ionic information, and the process is compatible with MEMS processing technology, having the potential for mass production.

[0040] Although the specific implementation manners of the present invention have been described in conjunction with the accompanying drawings, it is not a limitation on the protection scope of the present invention. Those skilled in the art should understand that based on the technical solutions disclosed in the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a nanofluid memristor based on two-dimensional material nanopores, characterized in that: include: The two-dimensional material prepared by chemical vapor deposition is transferred to a suspended silicon nitride film substrate with a single micron hole by polymer-assisted transfer to form a two-dimensional material device; Nanopore devices can be prepared and formed by electrochemical etching methods; wherein, etching of atoms is achieved by applying voltage on both sides of graphene placed in an electrolyte solution; as the voltage application time increases, nanopores with ionic conductivity are prepared by monitoring the increase in ion current.

2. The method for preparing a nanofluid memristor based on two-dimensional material nanopores according to claim 1, characterized in that: Electrochemical etching is achieved by applying voltage across the graphene in a 0.1 M KCl electrolyte solution.

3. The method for preparing a nanofluid memristor based on two-dimensional material nanopores according to claim 2, characterized in that: A continuous voltage of 1.5 V with a duration of 320 s was applied to both sides of the graphene through Ag / AgCl electrodes using an electrochemical workstation.

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