All-light-operated artificial synaptic device and preparation method thereof

Abstract

The invention discloses a full-light-operated artificial synaptic device and a preparation method thereof, and belongs to the technical field of microelectronic materials and devices. The light-operated artificial synapse device comprises an inert metal top electrode, an all-optical memristor layer and a transparent electrode, and the all-optical memristor layer is arranged between the transparent electrode and the inert metal top electrode and used for simulating synapses. The synaptic device is of a two-end structure and is simple in structure, the size of the device can be reduced to the nanometer magnitude, power consumption is small, reversible adjustment of the conductivity change range can be achieved by means of visible / ultraviolet light signals, and a device basis is provided for achieving a photoelectric brain computing system. The device can be built on the basis of various common materials, so that all-electric regulation is realized, and the device has a good application prospect in the field of novel 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 an all-light-controlled artificial synapse device and a preparation method thereof. Background Art

[0002] Artificial intelligence technology is leading us into the fourth industrial revolution, and the low integration and high power consumption of devices are the problems that need to be solved urgently. The construction of all-light-controlled brain-like intelligent devices is expected to achieve high integration, low power consumption, and integrated sensing, storage, and computing, and will be widely used in the fields of brain-like chips and new artificial recognition systems. Existing memristors mainly regulate conductivity based on optical signals. Their working principle is mainly based on the formation and breaking of conductive channels inside the device, involving changes in the microstructure inside the device, and there is a lot of randomness. Therefore, conventional memristors have certain instability. Summary of the invention

[0003] The present invention proposes an all-light-controlled artificial synapse device and a preparation method thereof to solve the problem that it is difficult to achieve all-light control of artificial synapses in the prior art. Through a new material system with wide and narrow band gaps and a simple preparation method, an all-light-controlled artificial synapse of the system is constructed to achieve synaptic regulation.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] An all-optically controlled artificial synaptic device comprises, from bottom to top, a transparent electrode, an all-optical memristor layer and an inert metal top electrode; the all-optical memristor layer is a composite film prepared from silicon carbide, copper phthalocyanine and block copolymer cellulose as raw materials.

[0006] Furthermore, the transparent electrode is indium-doped SnO2 conductive glass.

[0007] Furthermore, the thickness of the all-optical memristive layer is 1000±50 nm, and the thickness of the inert metal top electrode is 100±15 nm.

[0008] Furthermore, the preparation method of the all-optical memristive layer is: silicon carbide, copper phthalocyanine and block copolymer cellulose are stirred evenly, and spin-coated on the transparent electrode to form a composite film on the surface thereof. The mass ratio of silicon carbide, copper phthalocyanine and block copolymer cellulose is 10:4:8.

[0009] Furthermore, the inert metal of the inert metal top electrode is gold or platinum.

[0010] The present invention also provides a method for preparing the all-optical-controlled artificial synaptic device, comprising the following steps: spin coating an all-optical memristive layer on a transparent electrode, and then depositing an inert metal top electrode on the all-optical memristive layer to obtain the all-optical-controlled artificial synaptic device.

[0011] Furthermore, the deposition process adopts thermal evaporation or sputtering technology.

[0012] Furthermore, the aperture of the metal mask used in the deposition process is 100-500 μm.

[0013] Compared with the prior art, the present invention has the following advantages and technical effects:

[0014] The all-optical-controlled artificial synaptic device provided by the present invention includes: an inert metal top electrode, an all-optical memristive layer and a transparent electrode, wherein the all-optical memristive layer is arranged between the transparent electrode and the inert metal top electrode, and is used to simulate synapses. The all-optical memristive layer of the artificial synaptic device in the present invention can increase the conductivity under the stimulation of a red light signal and decrease the conductivity under the stimulation of an ultraviolet light signal, thereby realizing reversible promotion / inhibition regulation of all-optical control. The conductance is reversibly regulated by means of an all-optical signal to achieve ultra-low power consumption, providing a device foundation for realizing an optoelectronic brain-like computing system. The all-optical-controlled artificial synaptic device of the present invention is a two-terminal structure with a simple structure, especially its functional layer selects a material system with a wide and narrow band gap combination, and based on such a material system, there are a variety of common and inexpensive materials to choose from, thereby realizing all-optical-controlled regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0016] Figure 1 This is a schematic diagram of the structure of the all-light-controlled artificial synapse device prepared in Example 1 of the present invention;

[0017] Among them, 1: inert metal top electrode; 2: all-optical memristor layer; 3: transparent electrode;

[0018] Figure 2 This is a flow chart of the method for preparing the all-light-controlled artificial synaptic device of the present invention;

[0019] Figure 3 A current change-time curve diagram of the all-light-controlled artificial synaptic device prepared in Example 1 of the present invention after being irradiated with ultraviolet light;

[0020] Figure 4 This is a curve diagram of the simulated synaptic PPD behavior of the all-light-controlled artificial synaptic device prepared in Example 1 of the present invention after ultraviolet irradiation;

[0021] Figure 5 The current change-time curve diagram of the all-light-controlled artificial synapse device prepared in Example 1 of the present invention after being stimulated by ultraviolet light pulses of different times, so as to simulate the transition from synaptic STD to LTD;

[0022] Figure 6 This is a current change-time curve diagram of the all-light-controlled artificial synaptic device prepared in Example 1 of the present invention after being irradiated with red light;

[0023] Figure 7 This is a curve diagram of the simulated synaptic PPF behavior of the all-light-controlled artificial synaptic device prepared in Example 1 of the present invention after being irradiated with red light;

[0024] Figure 8 The current change-time curve diagram of the all-light-controlled artificial synaptic device prepared in Example 1 of the present invention after being stimulated by red light pulses of different times, so as to simulate the transition from synaptic STP to LTP;

[0025] Fig. 9 This is a photocurrent-time curve diagram of the all-light-controlled artificial synaptic device prepared in Example 2 of the present invention after being irradiated with ultraviolet light;

[0026] Fig.10 This is a photocurrent-time curve diagram of the all-light-controlled artificial synaptic device prepared in Example 2 of the present invention after being irradiated with green light;

[0027] Figure numerals: 1: inert metal top electrode; 2: all-optical memristor layer; 3: transparent electrode. DETAILED DESCRIPTION

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0029] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0030] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0031] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0032] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0033] The schematic diagram of the layer structure of the embodiment of the present invention is shown in the accompanying drawings. 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] The construction of a fully optically controlled memristor uses only optical signals to adjust the device conductance, without involving changes in the device microstructure, making the device more stable. In addition, there is no Joule heat generated, which can achieve ultra-low power consumption.

[0038] The present invention provides an all-optically controlled artificial synaptic device, which comprises, from bottom to top, a transparent electrode, an all-optical memristor layer and an inert metal top electrode; the all-optical memristor layer is a composite film composed of silicon carbide, copper phthalocyanine and block copolymer cellulose.

[0039] Figure 1 This is a schematic diagram of the structure of the all-light-controlled artificial synapse device prepared in Example 1 of the present invention. Figure 1As shown, according to the implementation provided by Example 1 of the present invention, a light-controlled artificial synaptic device is obtained, including: an inert metal top electrode 1; an all-optical memristive layer 2; a transparent electrode 3, wherein the all-optical memristive layer 2 is arranged between the transparent electrode 3 and the inert metal top electrode 1, and is used to simulate synapses. The all-optical 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 conductance change range can be achieved by means of visible / ultraviolet light signals, providing a device foundation for realizing an optoelectronic brain-like computing system.

[0040] The all-optical memristor layer is used as a functional layer, and a material system with a wide and narrow band gap is used to construct a heterostructure, which serves as the main light-responsive material. The system can show two opposite response trends under the stimulation of light signals in different bands. Therefore, the present invention can construct multiple artificial synapses constructed with this combination to achieve full light-controlled regulation. Since the selection and matching of the materials of this system are diverse, and various materials have their own unique properties, different material combinations can achieve full light-controlled regulation, and there will be other differences. Targeted research on specific materials is required, and it is expected that there will be research on other properties based on full light-controlled regulation. In addition, the materials of this system are relatively common, cheap, and easy to obtain, and the device preparation method is simple and has good light response.

[0041] In the following preferred embodiments of the present invention, the transparent electrode can be a conductive glass, which is made by coating a layer of indium tin oxide (commonly known as ITO) film on a soda-lime-based or silicon-boron-based substrate glass by magnetron sputtering. The conductive glass used in the present invention is purchased. It is an indium-doped SnO2 conductive glass purchased from Hefei Kejing Material Technology Co., Ltd., referred to as ITO.

[0042] In the following preferred embodiments of the present invention, the thickness of the all-optical memristive layer is 1000±50 nm, and the thickness of the inert metal top electrode is 100±15 nm.

[0043] In the following preferred embodiment of the present invention, the preparation method of the all-optical memristive layer is: silicon carbide, copper phthalocyanine and block copolymer cellulose are stirred evenly, and spin-coated on the transparent electrode to form a composite film on the surface thereof. The mass ratio of silicon carbide, copper phthalocyanine and block copolymer cellulose is 10:4:8.

[0044] In the following preferred embodiments of the present invention, the inert metal of the inert metal top electrode is gold or platinum.

[0045] The present invention also provides a method for preparing the all-optically controlled artificial synaptic device, the flow chart of which is shown in Figure 2 , including the following steps:

[0046] S1. The transparent electrode is ultrasonically treated with trichloroethylene, acetone, ethanol, and secondary deionized water in an ultrasonic cleaning machine for 10 minutes in sequence to remove dust, grease and other impurities on the surface of the substrate, and then blow-dried; then a composite film (i.e., an all-optical memristive layer) prepared by spin coating silicon carbide, copper phthalocyanine and block copolymer cellulose is spin-coated on the pretreated transparent electrode; the blow-drying can be air blow-drying or nitrogen blow-drying.

[0047] S2. Depositing an inert metal top electrode on the all-optical memristor layer to obtain an all-optically controlled artificial synaptic device.

[0048] In the following preferred embodiments of the present invention, the deposition process adopts thermal evaporation or sputtering technology.

[0049] In the following preferred embodiments of the present invention, the aperture of the metal mask used in the deposition process is 100-500 μm.

[0050] The all-optical memristive layer in the present invention exhibits two different carrier migration directions under light stimulation in different bands, based on which all-optical bidirectional regulation is achieved. The specific mechanism is explained as follows: silicon carbide and copper phthalocyanine form a type II heterojunction. Under visible light irradiation, copper phthalocyanine nanoparticles generate electron-hole pairs, resulting in an increase in photocurrent, while the band gap of silicon carbide nanoparticles is 3.1eV, and visible light cannot excite electrons in the conduction band of silicon carbide. After the visible light is removed, some photogenerated holes recombine with electrons, and the photocurrent spontaneously decays. Under ultraviolet irradiation, the photogenerated electrons in the conduction band of silicon carbide recombine with the holes generated in copper phthalocyanine, the number of carriers decreases, and the photocurrent decreases. The same is true for the other combinations.

[0051] The irradiation conditions of the all-light-controlled artificial synaptic device prepared by the present invention are: the wavelength of visible light is 620nm, and the irradiation time is 5-15 minutes; the wavelength of ultraviolet light is 350nm, and the irradiation time is 5-15 minutes.

[0052] The raw materials used in the present invention are all purchased from the market.

[0053] The technical solution of the present invention is further illustrated by the following embodiments.

[0054] Example 1

[0055] Preparation of the all-light-controlled artificial synaptic device:

[0056] S1. The transparent electrode (ITO conductive glass) is ultrasonically cleaned in an ultrasonic cleaning machine with trichloroethylene, acetone, ethanol, and secondary deionized water for 10 minutes to remove dust, grease and other impurities on the surface of the substrate, and then blown dry with air;

[0057] Silicon carbide, copper phthalocyanine and block copolymer cellulose were mixed in a mass ratio of 10:4:8 and stirred evenly to obtain a composite thin film precursor (all-optical memristor layer) with a thickness of 1000 nm;

[0058] The obtained composite thin film precursor is spin-coated on the pre-treated transparent electrode surface and dried to form a thin film, i.e., the all-optical memristive layer, on the transparent electrode surface;

[0059] S2, depositing an inert metal top electrode gold electrode with a thickness of 100 nm on the surface of the all-optical memristor layer (i.e., the side away from the transparent electrode) to obtain an all-optical controlled artificial synaptic device;

[0060] The top electrode Au is prepared by thermal evaporation method, specifically: the background vacuum of the chamber is greater than 10 -4 Pa; the purity of Au wire evaporation material is 99.99%; the heating current is 105A; and the thermal evaporation time is 10 minutes.

[0061] Example 2

[0062] Same as Example 1, except that the silicon carbide is replaced with zinc oxide. Fig. 9 Fig.10 shown.

[0063] Figure 3 The all-light-controlled artificial synaptic device prepared in Example 1 of the present invention is subjected to light with a wavelength of 350nm and a light intensity of 11.12mW / cm 2 From the current-time curve 10s after UV irradiation, it can be seen that under UV irradiation, the conductivity decreases and the resistance increases.

[0064] Figure 4 The all-optically controlled artificial synaptic device prepared in Example 1 of the present invention uses a wavelength of 350nm and a light intensity of 11.12mW / cm 2 After ultraviolet light acts as a pulse signal (pulse time 5s, pulse interval 5s), the current-time curve of two light pulses is applied. It can be seen that its response behavior can simulate the synaptic PPD (PPD is the abbreviation of Paired-pulsed depression, which is one of the synaptic learning rules discovered in experimental biology) behavior. The conductance value under the second pulse stimulation is significantly lower than that after the first pulse.

[0065] Figure 5 The all-optically controlled artificial synaptic device prepared in Example 1 of the present invention uses a wavelength of 350nm and a light intensity of 11.12mW / cm 2After ultraviolet light was used as a pulse signal (pulse time 5s, pulse interval 5s), the current change-time curve (STD: short-term inhibition, LTD: long-term inhibition) after applying 3 and 15 light pulses showed that under the stimulation of 3 ultraviolet light pulses, the relaxation time was short, simulating the short-term memory of biological inhibition; under the stimulation of 15 light pulses, the relaxation time was long, simulating the long-term memory of biological inhibition. By adjusting the number of stimulations, the transition from short-term to long-term inhibition behavior of simulated synaptic memory behavior was achieved.

[0066] Figure 6 The all-light-controlled artificial synaptic device prepared in Example 1 of the present invention is subjected to a light beam with a wavelength of 620 nm and a light intensity of 239.6 mW / cm 2 From the current-time curve 10s after red light irradiation, it can be seen that under red light irradiation, the conductivity increases and the resistance decreases.

[0067] Figure 7 The all-optically controlled artificial synaptic device prepared in Example 1 of the present invention uses a wavelength of 620nm and a light intensity of 239.6mW / cm 2 From the current-time curve after ultraviolet light acts as a pulse signal (pulse time 5s, pulse interval 5s), it can be seen that its response behavior can simulate the synaptic PPF (PPF is the abbreviation of Paired-pulse facilitation) behavior, and the conductance value under the second pulse stimulation is significantly higher than that after the first pulse.

[0068] Figure 8 The all-optically controlled artificial synaptic device prepared in Example 1 of the present invention uses a wavelength of 620nm and a light intensity of 239.6mW / cm 2 After red light acts as a pulse signal (pulse time 5s, pulse interval 5s), the current change-time curve after applying 3 and 15 light pulses (STP: short-term potentiation, LTP: long-term potentiation) shows that under the stimulation of 3 red light pulses, the relaxation time is short, simulating the short-term memory of biological excitability; under the stimulation of 15 light pulses, the relaxation time is long, simulating the long-term memory of biological excitability. By adjusting the number of stimulations, the transition from short-term to long-term inhibition behavior of simulated synaptic memory behavior can be achieved.

[0069] Fig. 9 The all-optically controlled artificial synaptic device of Example 2 of the present invention is subjected to light with a wavelength of 350nm and a light intensity of 11.12mW / cm 2 From the photocurrent-time curve 5s after UV irradiation, it can be seen that under UV irradiation, the conductivity decreases and the resistance increases.

[0070] Fig.10The all-light-controlled artificial synaptic device prepared in Example 2 of the present invention is subjected to light with a wavelength of 520nm and a light intensity of 239.6mW / cm 2 The photocurrent-time curve 30s after green light irradiation shows that the conductivity increases and the resistance decreases under green light irradiation.

[0071] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An all-optically controlled artificial synaptic device, characterized in that: From bottom to top, they are the transparent electrode, the all-optical memristor layer, and the inert metal top electrode; The all-optical memristor layer is a composite film prepared from silicon carbide, copper phthalocyanine and block copolymer cellulose as raw materials.

2. The all-optically controlled artificial synaptic device according to claim 1, characterized in that: The transparent electrode is indium-doped SnO2 conductive glass.

3. The all-optically controlled artificial synaptic device according to claim 1, characterized in that: The thickness of the all-optical memristive layer is 1000±50 nm, and the thickness of the inert metal top electrode is 100±15 nm.

4. The all-optically controlled artificial synapse device according to claim 3, characterized in that: The preparation method of the all-optical memristor layer is as follows: silicon carbide, copper phthalocyanine and block copolymer cellulose are uniformly stirred, and spin-coated on the transparent electrode to form a composite film on the surface thereof, namely the all-optical memristor layer.

5. The all-optically controlled artificial synaptic device according to claim 4, characterized in that: The mass ratio of silicon carbide, copper phthalocyanine and block copolymer cellulose is 10:4:

8.

6. The all-optically controlled artificial synaptic device according to claim 1, characterized in that: The inert metal of the inert metal top electrode is gold or platinum.

7. A method for preparing an all-light-controlled artificial synapse device according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: preparing an all-optical memristive layer on a transparent electrode by spin coating, and then depositing an inert metal top electrode on the all-optical memristive layer to obtain an all-optically controlled artificial synaptic device.

8. The method for preparing the all-light-controlled artificial synaptic device according to claim 7, characterized in that: The deposition process adopts thermal evaporation or sputtering technology.

9. The method for preparing the all-light-controlled artificial synaptic device according to claim 7, characterized in that: The aperture of the metal mask used in the deposition process is 100-500 μm.

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