A light-controlled artificial synaptic device and preparation method thereof

Abstract

The present invention discloses a light-controlled artificial synaptic device and a preparation method thereof, wherein the light-controlled artificial synaptic device comprises: an inert electrode; a transparent electrode; a photoelectric memristor layer, wherein the photoelectric memristor layer is arranged between the transparent electrode and the inert electrode, and is used to simulate a synapse. The light-controlled artificial synaptic device of the present invention can apply a positive voltage to the inert electrode, the transparent electrode is grounded, the photoelectric memristor layer forms a conductive channel under the action of an electric field, the conductivity rises, and the reversible activation / inhibition of light gating is achieved under the regulation of ultraviolet light and visible light. The light-controlled artificial synaptic device of the present invention is a two-terminal structure with a simple structure. The device size can be reduced to the nanometer level, the power consumption is small, and the reversible regulation of the conductivity variation range can be achieved by means of visible / ultraviolet light signals, providing a device basis for realizing a photoelectric brain-like computing system. Since multi-dimensional regulation of light, electricity, temperature, and humidity can be achieved based on a composite of common materials, it has good application prospects in the field of new photoelectric materials in the future.

Description

Technical Field

[0001] The present invention belongs to the technical field of microelectronic materials and devices, and in particular relates to a light-controlled artificial synapse device and a preparation method thereof. Background Art

[0002] Brain-like research is at the forefront of artificial intelligence research, and building artificial synapses provides the hardware foundation for realizing neuromorphic computing. Synaptic systems - also known as artificial neural networks - are computing systems that allow electronic systems to work in a manner similar to biological brains. Synaptic systems can be composed of various electronic circuits modeled on biological neurons and synapses. Existing artificial synaptic devices are based on the simulation of electrical signal synaptic functions, with low adjustability and accuracy. Summary of the invention

[0003] (I) Purpose of the invention

[0004] The purpose of the present invention is to provide a light-controlled artificial synaptic device and a preparation method thereof to solve the technical problem of low adjustability and accuracy of artificial synaptic devices in the prior art.

[0005] (II) Technical solution

[0006] To solve the above problems, the first aspect of the present invention provides a light-controlled artificial synapse device, comprising: an inert electrode; a transparent electrode; a photoelectric memristor layer, wherein the photoelectric memristor layer is arranged between the transparent electrode and the inert electrode, and is used to simulate a synapse.

[0007] Furthermore, the photoelectric memristor layer is a porous titanium oxide doped silver nanoparticle composite film.

[0008] Furthermore, the thickness of the inert electrode is 100±20 nm; and the thickness of the photoelectric memristive layer is 900±50 nm.

[0009] Furthermore, the silver nanoparticles in the photoelectric memristor layer are spherical and have a diameter of 11±4 nm.

[0010] According to another aspect of the present invention, a method for preparing a light-controlled artificial synaptic device is provided, comprising: S1, preparing a transparent electrode with a porous titanium oxide film on a transparent electrode by using a pulling method; S2, immersing the transparent electrode with the porous titanium oxide film in a 0.1 mol / L silver nitrate solution under ultraviolet light to deposit silver nanoparticles to prepare a transparent electrode with a photoelectric memristor layer; S3, depositing an inert electrode on a side of the transparent electrode with the photoelectric memristor layer away from the transparent electrode to prepare a light-controlled artificial synaptic device.

[0011] Furthermore, the deposition of the inert electrode in step S3 is performed by a thermal evaporation or sputtering process.

[0012] Furthermore, after pulling in step S1, the step further includes: annealing, and the annealing temperature is 450-500°C.

[0013] Furthermore, the wavelength of the ultraviolet light in the ultraviolet light irradiation in step S2 is 365 nm, and the irradiation time is 15 minutes.

[0014] Furthermore, in step S3, the metal mask used for depositing the inert electrode has an aperture of 100-500 μm, and an electrode thickness of 100±20 nm.

[0015] (III) Beneficial effects

[0016] The above technical solution of the present invention has the following beneficial technical effects:

[0017] The light-controlled artificial synaptic device of the present invention can apply a positive voltage to the inert electrode, the transparent electrode is grounded, the photoelectric memristor layer forms a conductive channel under the action of the electric field, the conductivity increases, and the reversible activation / inhibition of light gating is achieved under the regulation of ultraviolet light and visible light. The light-controlled artificial synaptic device of the present invention is a two-terminal structure with a simple structure. The device size can be reduced to the nanometer level, the power consumption is small, and the reversible regulation of the conductivity change range can be achieved with the help of visible / ultraviolet light signals, providing a device foundation for realizing a photoelectric brain-like computing system. Since multi-dimensional regulation of light, electricity, temperature, and humidity can be achieved based on the composite of common materials, it has good application prospects in the field of new photoelectric materials in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of a light-controlled artificial synapse device according to one embodiment of the present invention.

[0019] Figure 2 It is a flow chart of a method for preparing a light-controlled artificial synaptic device according to one embodiment of the present invention.

[0020] Figure 3 4 is a current-voltage curve diagram of a light-controlled artificial synapse device after being irradiated with ultraviolet light according to one embodiment of the present invention.

[0021] Figure 4 4 is a current-voltage curve diagram of a light-controlled artificial synapse device after being irradiated with visible light according to one embodiment of the present invention.

[0022] Figure 5 This is a diagram of the conductance change of a light-controlled artificial synaptic device according to one embodiment of the present invention after being irradiated with ultraviolet light and visible light and stimulated by electrical pulses.

[0023] Figure 6 This is a pulse facilitation function diagram of a light-controlled artificial synaptic device according to one embodiment of the present invention after being irradiated with ultraviolet light and visible light.

[0024] Figure 7 It is a STDP function diagram of a light-controlled artificial synaptic device according to an embodiment of the present invention after being irradiated with ultraviolet light and visible light.

[0025] Reference numerals:

[0026] 1: Inert electrode; 2: Transparent electrode; 3: Photoelectric memristor layer; 31: Silver nanoparticles. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0028] The accompanying drawings show schematic diagrams of layer structures according to embodiments of the present invention. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clarity. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0029] Obviously, the described embodiments are only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] The present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, the same elements are represented by similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale.

[0032] Figure 1 Schematic diagram of the structure of a light-controlled artificial synapse device according to one embodiment of the present invention.

[0033] like Figure 1As shown, according to an implementation in an embodiment of the present invention, a light-controlled artificial synaptic device is provided, comprising: an inert electrode 1; a transparent electrode 2; a photoelectric memristor layer 3, wherein the photoelectric memristor layer 3 is arranged between the transparent electrode 2 and the inert electrode 1, and is used to simulate synapses. The light-controlled artificial synaptic device of the present invention can apply a positive voltage to the inert electrode, the transparent electrode is grounded, and the photoelectric memristor layer forms a conductive channel under the action of the electric field, the conductivity rises, and the reversible activation / inhibition of light gating is achieved under the regulation of ultraviolet light and visible light. The light-controlled artificial synaptic device of the present invention is a two-terminal structure with a simple structure. The device size can be reduced to the nanometer level, the power consumption is small, and the reversible regulation of the conductivity change range can be achieved by means of visible / ultraviolet light signals, which provides a device basis for realizing a photoelectric brain-like computing system. Since multi-dimensional regulation of light, electricity, temperature, and humidity can be achieved based on the composite of common materials, it has good application prospects in the field of new photoelectric materials in the future.

[0034] The photoelectric memristor layer 3 introduces optical signals on the basis of the original electrical signal regulation to adjust the state of conductance.

[0035] The electrical characteristic functions of the light-controlled artificial synaptic device of the present invention are: after visible light irradiation, the device memristive characteristics are activated, which can simulate synaptic functions; after ultraviolet light irradiation, the device memristive characteristics are eliminated, and the simulated synaptic functions disappear; the alternating operation of visible light and ultraviolet light can achieve reversible activation and inhibition of memristive synaptic functions. The working mechanism of the device is that visible light can induce plasma resonance of silver nanoparticles 31, promote the oxidation of silver atoms into silver ions, make them easier to migrate under the action of electric fields, thereby activating the memristor operation; ultraviolet light excites titanium oxide valence band electrons, promotes the reduction of silver ions into silver atoms, hinders the migration of silver ions, and thus inhibits the operation of the memristor. The optical signal reversible activation and inhibition memristive synaptic device of the present invention provides a device basis for realizing optoelectronic brain-like computing systems.

[0036] In the present invention, we introduce the titanium oxide / silver material system into the light-controlled artificial synaptic device. The silver nanoparticles 31 in the material undergo plasma resonance under the action of visible light and are oxidized into silver ions, which are easier to migrate under the action of an electric field; under the action of ultraviolet light, the titanium oxide valence band electrons are excited to reduce the silver ions to atoms, thereby achieving bidirectional regulation of conductivity induced by multi-band light signals. Silver / titanium oxide nanocomposites have good application prospects in the field of new optoelectronic materials in the future because they can achieve multi-dimensional regulation of light, electricity, temperature, and humidity based on the composite of common materials.

[0037] In an optional embodiment, the photoelectric memristor layer 3 is a porous titanium oxide doped silver nanoparticle composite film.

[0038] In an optional embodiment, the thickness of the inert electrode 1 is 100±20 nm; the thickness of the photoelectric memristor layer 3 is 900±50 nm.

[0039] In an optional embodiment, the silver nanoparticles 31 in the photoelectric memristor layer 3 are spherical and have a diameter of 11±4 nm.

[0040] In an optional embodiment, the number of silver nanoparticles in the porous titanium oxide doped silver nanoparticle composite film is distributed in a decreasing manner in a first direction; the first direction is a vertical direction from one end of the photoelectric memristor layer 3 close to the inert electrode 1 to one end close to the transparent electrode 2.

[0041] In an optional embodiment, the transparent electrode 2 may be FTO conductive glass.

[0042] The conductive glass is fluorine-doped SnO2 conductive glass (SnO2:F), referred to as FTO.

[0043] In an optional embodiment, the transparent electrode 2 may be ITO conductive glass.

[0044] ITO conductive glass is made by coating a layer of indium tin oxide (commonly known as ITO) on a soda-lime-based or silicon-boron-based substrate glass using the magnetron sputtering method.

[0045] In an optional embodiment, the inert electrode 1 may be an inert metal.

[0046] In an optional embodiment, the inert electrode 1 may be a metal gold electrode.

[0047] In an optional embodiment, the inert electrode 1 may be a metal platinum electrode.

[0048] The irradiation conditions of the light-controlled artificial synaptic device of the present invention are: the wavelength of visible light is 500-720nm, and the irradiation time is 5-15 minutes; the wavelength of ultraviolet light is 365nm, and the irradiation time is 5-15 minutes.

[0049] Figure 2 It is a flow chart of a method for preparing a light-controlled artificial synaptic device according to one embodiment of the present invention.

[0050] like Figure 2 As shown, according to an implementation in another embodiment of the present invention, a method for preparing a light-controlled artificial synapse device is provided, comprising:

[0051] S1. A transparent electrode 2 with a porous titanium oxide film is prepared on the transparent electrode 2 by using a pulling method.

[0052] In an optional embodiment, the pulling in step S1 may include: uniformly stirring the titanium dioxide sol and the block copolymer PEO20-PPO70-PPO20 on the transparent electrode 2, and forming a titanium oxide film on the surface of the transparent electrode 2 by the pulling method.

[0053] In an optional embodiment, after pulling in step S1, annealing may also be included, and the annealing temperature is 450-500° C. After annealing, the titanium oxide film on the surface of the transparent electrode 2 forms a porous structure, and a transparent electrode 2 with a porous titanium oxide film is obtained.

[0054] In an optional embodiment, annealing is performed at 450-500° C. for 30 minutes in an atmospheric environment. Under high temperature conditioning, the high molecular polymer is completely decomposed to form a titanium oxide film with a porous structure.

[0055] In an optional embodiment, step S1 may also include: cleaning, ultrasonically cleaning the transparent electrode 2 with trichloroethylene, acetone, ethanol, and secondary deionized water in an ultrasonic cleaning machine for 10 minutes to remove dust, grease and other impurities on the surface of the substrate, and then drying it.

[0056] In an optional embodiment, the pulling in step S1 may include: uniformly stirring the titanium dioxide sol and the block copolymer PEO20-PPO70-PPO20 on the cleaned transparent electrode 2 to form a titanium oxide film on the surface of the cleaned transparent electrode 2.

[0057] In an optional embodiment, the drying is performed by using air through an air compressor.

[0058] In an optional embodiment, nitrogen is used for the drying.

[0059] S2, immersing the transparent electrode 2 with the porous titanium oxide film in a 0.1 mol / L silver nitrate solution under ultraviolet light to deposit silver nanoparticles 31, so as to obtain a transparent electrode 2 with a photoelectric memristive layer 3.

[0060] In an optional embodiment, the wavelength of the ultraviolet light in the ultraviolet light irradiation in step S2 is 365 nm, and the irradiation time is 15 minutes.

[0061] In an optional embodiment, in step S2, the silver nanoparticles 31 are deposited by immersing in a 0.1 mol / L silver nitrate solution under ultraviolet light and then rinsed with deionized water and dried to obtain a transparent electrode 2 with a photoelectric memristor layer 3.

[0062] S3, depositing an inert electrode 1 on a side of the transparent electrode 2 with the photoelectric memristor layer 3 away from the transparent electrode 2 to obtain a light-controlled artificial synaptic device.

[0063] In an optional embodiment, the deposition of the inert electrode 1 in step S3 is performed by a thermal evaporation or sputtering process.

[0064] In an optional embodiment, the metal mask used for depositing the inert electrode 1 in step S3 has an aperture of 100-500 μm, and the electrode thickness is 100±20 nm.

[0065] In the preparation method of the light-controlled artificial synaptic device of the present invention, the silver particles deposited in the porous titanium oxide film by ultraviolet light have photoinduced redox properties. Under the action of visible light, the silver nanoparticles undergo plasma resonance, and the silver atoms are oxidized into silver ions; under the action of ultraviolet light, the electrons in the titanium oxide valence band are excited to reduce the silver ions into silver atoms. The thickness of the silver / titanium oxide film is 900±50nm, and the silver particles in the film are spherical and have a diameter of 11±4nm.

[0066] Figure 3 4 is a current-voltage curve diagram of a light-controlled artificial synapse device after being irradiated with ultraviolet light according to one embodiment of the present invention.

[0067] Figure 4 4 is a current-voltage curve diagram of a light-controlled artificial synapse device after being irradiated with visible light according to one embodiment of the present invention.

[0068] Electrical test: Figure 3 and Figure 4 The memristive properties (current-voltage) of the light-controlled artificial synaptic device after irradiation with ultraviolet light (365nm) and visible light (500-720nm) are shown.

[0069] like Figure 3 As shown, for the device irradiated with UV light for 15 minutes, positive and negative voltage scans will not change the conductivity of the device, and under continuous positive or negative voltage scans, the device conductivity has no regular change trend.

[0070] like Figure 4 As shown in the figure, for the light-controlled artificial synaptic device that was irradiated with visible light for 15 minutes, the resistance-changing behavior of continuous resistance change occurred under the same voltage scan. Under continuous positive voltage scan, the device conductance continued to rise; under continuous negative voltage scan, the device conductance continued to decrease.

[0071] Figure 5 This is a diagram of the conductance change of a light-controlled artificial synaptic device according to one embodiment of the present invention after being irradiated with ultraviolet light and visible light and stimulated by electrical pulses.

[0072] Figure 5The response of the light-controlled artificial synaptic device under specific electrical signal stimulation after being adjusted by visible light (500-720nm) and ultraviolet light (365nm) in turn is shown. The initial device (i.e., the light-controlled artificial synaptic device after ultraviolet light reduction) did not show a significant change in conductance under the stimulation of five consecutive electrical pulses (0.5V, 100μs). After being irradiated with visible light, the device's conductance showed a significant increase under the stimulation of the same electrical pulse, and there was a significant facilitation phenomenon between pulses. After the pulse ended, the relaxation process was longer and finally stabilized in a state with higher conductance. After the device was irradiated with ultraviolet light again, under the same pulse stimulation, the response amplitude became smaller and quickly returned to the initial state after the pulse stimulation ended.

[0073] Figure 6 This is a pulse facilitation function diagram of a light-controlled artificial synaptic device according to one embodiment of the present invention after being irradiated with ultraviolet light and visible light.

[0074] Figure 6 The pulse facilitation phenomenon of the light-controlled artificial synaptic device in the initial state and after 5 / 10 / 15 minutes of visible light irradiation is shown. Under the same conditions, the longer the visible light irradiation time, the more obvious the facilitation effect between adjacent pulses, that is, the greater the change in PPF.

[0075] Figure 7 It is a STDP function diagram of a light-controlled artificial synaptic device according to an embodiment of the present invention after being irradiated with ultraviolet light and visible light.

[0076] Figure 7 The results of simulating the pulse time-dependent synaptic plasticity (STDP) learning rule of the light-controlled artificial synaptic device are given. There is an exponential relationship between the synaptic weight change (ΔW) of the light-controlled artificial synaptic device and the pulse stimulation timing (Δt). The enhancement / inhibition effect increases with the decrease of the time difference. And under the same conditions, the longer the visible light irradiation time, the more obvious the change of synaptic weight.

[0077] STDP is the abbreviation of Spike Timing Dependnt Plasticity. Plasticity (of synaptic devices) based on timing discharge, or timing-dependent plasticity, is one of the synaptic learning rules discovered in experimental biology.

[0078] The present invention aims to protect a light-controlled artificial synaptic device and a preparation method thereof, wherein the light-controlled artificial synaptic device comprises: an inert electrode 1; a transparent electrode 2; a photoelectric memristor layer 3, wherein the photoelectric memristor layer 3 is arranged between the transparent electrode 2 and the inert electrode 1, and is used to simulate a synapse. The light-controlled artificial synaptic device of the present invention can apply a positive voltage to the inert electrode, the transparent electrode is grounded, and the photoelectric memristor layer forms a conductive channel under the action of the electric field, the conductivity rises, and the reversible activation / inhibition of light gating is achieved under the regulation of ultraviolet light and visible light. The light-controlled artificial synaptic device of the present invention is a two-terminal structure with a simple structure. The device size can be reduced to the nanometer level, the power consumption is small, and the reversible regulation of the conductivity variation range can be achieved by means of visible / ultraviolet light signals, which provides a device basis for realizing a photoelectric brain-like computing system. Since multi-dimensional regulation of light, electricity, temperature, and humidity can be achieved based on the composite of common materials, it has good application prospects in the field of new photoelectric materials in the future.

[0079] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A light-controlled artificial synaptic device, characterized in that: include: Inert electrode (1); Transparent electrode (2); A photoelectric memristor layer (3), the photoelectric memristor layer (3) being arranged between the transparent electrode (2) and the inert electrode (1) and being used for simulating a synapse; The photoelectric memristor layer (3) is a porous titanium oxide-doped silver nanoparticle composite film; The silver nanoparticles (31) in the photoelectric memristor layer (3) are spherical and have a diameter of 11±4 nm; The number of silver nanoparticles in the porous titanium oxide doped silver nanoparticle composite film is distributed in a decreasing manner in a first direction; the first direction is a vertical direction from one end of the photoelectric memristor layer (3) close to the inert electrode 1 to one end close to the transparent electrode (2).

2. The light-controlled artificial synaptic device according to claim 1, characterized in that: The thickness of the inert electrode (1) is 100±20 nm; The thickness of the photoelectric memristor layer (3) is 900±50 nm.

3. A method for preparing a light-controlled artificial synaptic device, characterized in that: include: S1, using a Czochralski method to prepare a transparent electrode (2) with a porous titanium oxide film on a transparent electrode (2); S2, immersing the transparent electrode (2) with the porous titanium oxide film in a 0.1 mol / L silver nitrate solution under ultraviolet light to deposit silver nanoparticles (31), thereby obtaining a transparent electrode (2) with a photoelectric memristor layer (3); the silver nanoparticles (31) in the photoelectric memristor layer (3) are spherical and have a diameter of 11±4 nm; S3. Depositing an inert electrode (1) on a side of the transparent electrode (2) with the photoelectric memristor layer (3) away from the transparent electrode (2) to obtain a light-controlled artificial synaptic device; the number of silver nanoparticles in the porous titanium oxide doped silver nanoparticle composite film is distributed in a decreasing manner in a first direction; the first direction is a vertical direction from one end of the photoelectric memristor layer (3) close to the inert electrode 1 to one end close to the transparent electrode (2).

4. The method for preparing a light-controlled artificial synaptic device according to claim 3, characterized in that: The deposition of the inert electrode (1) in step S3 is carried out by thermal evaporation or sputtering.

5. The method for preparing a light-controlled artificial synaptic device according to claim 3, characterized in that: After the pulling in step S1, the following steps are further included: Annealing, the annealing temperature is 450-500℃.

6. The method for preparing a light-controlled artificial synaptic device according to claim 3, characterized in that: The wavelength of the ultraviolet light used in the ultraviolet light irradiation in step S2 is 365 nm, and the irradiation time is 15 minutes.

7. The method for preparing a light-controlled artificial synaptic device according to claim 3, characterized in that: The metal mask used for depositing the inert electrode (1) in step S3 has an aperture of 100-500 μm and an electrode thickness of 100±20 nm.

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