Artificial vision-oriented neural retina synaptic device and preparation method thereof

Abstract

The invention discloses a neural retina synaptic device for artificial vision and a preparation method thereof. The neural retina synaptic device includes: a substrate; the electrode consists of a gate electrode, a source electrode and a drain electrode and is formed on the substrate; the channel layer is formed by a zero-dimensional quantum dot / two-dimensional material heterojunction thin film, has enhanced response to optical signals, is formed on the substrate, is used for connecting the source electrode and the drain electrode to form an electrical path, and is far away from the gate electrode; and the gate dielectric layer is made of an electrolyte gate dielectric material and is connected with the channel and the gate electrode to form a double-electrode layer. The gate electrode receives an electric signal to simulate a synaptic front end, the channel layer receives an optical signal to simulate a retinal cell light sensor, the source electrode, the drain electrode and the channel layer complete information collection, processing and storage by reading voltage, and the electric synaptic front end is adjusted to obtain positive and negative light current response. The method is used for constructing a sensing, storage and calculation integrated visual neuromorphic sensing system.

Description

Technical Field

[0001] The present disclosure relates to the fields of semiconductor technology and semiconductor optoelectronic technology, and particularly relates to a neuroretinal synapse device for artificial vision and a preparation method thereof. Background Art

[0002] Traditional vision imaging systems are composed of a sensing unit, a computing unit, and a storage unit. Information needs to be collected by the vision sensing unit for optical effective data, and then converted into a form that can be processed by the computing and storage units through modules such as an analog-to-digital converter, and the information is transmitted to the storage and computing units through a data bus. However, traditional systems often suffer from problems such as relatively low field of view angle, high power consumption, large volume, and high complexity in practical applications.

[0003] The retina and the visual cortex of the brain, etc., constitute the human visual system, which realizes the efficient processing of visual information, and has advantages such as low redundancy, low power consumption, high dynamics, and strong robustness. It can efficiently and adaptively process dynamic and static information, and has the ability of ubiquitous perception with extremely small samples. Among them, the retina can sense light stimuli, preprocess image information, and then transmit the information to the visual cortex of the brain for further processing. Inspired by the biological visual system, a neuroretinal synapse device integrating the functions of light signal perception, storage, and processing is expected to solve the problems existing in traditional systems.

[0004] To fabricate a neuroretinal synapse device with high light responsiveness and the functions of biological synapses simultaneously, some new low-dimensional materials need to be selected, such as perovskite quantum dots, carbon quantum dots, graphene, carbon nanotubes, etc. These emerging materials not only have unique optoelectronic properties, but also have advantages such as thin thickness, bendability, and low power consumption, and are very advantageous in fabricating flexible and bendable devices. In addition, materials such as graphene also have unique energy band regulation characteristics, which are very suitable for application in neuroretinal synapse devices. Summary of the Invention

[0005] The present invention discloses a neuroretinal synapse device for artificial vision and a manufacturing method thereof, which can realize bipolar positive and negative light responses to simulate the functions of retinal cells and biological synapses in view of the problems existing in traditional vision sensing systems. The specific technical solutions are as follows:

[0006] The present invention discloses a neuroretinal synapse device for artificial vision, comprising:

[0007] A substrate, as a supporting material for the device, can be a rigid substrate or a flexible substrate;

[0008] An electrode, composed of a gate electrode, a source electrode, and a drain electrode, is formed on the substrate;

[0009] The channel layer, which is composed of a zero-dimensional quantum dot / two-dimensional material heterojunction thin film, has an enhanced response to optical signals, is formed on the substrate, is used to physically connect the source electrode and the drain electrode to form an electrical path, and is electrically insulated from the gate electrode.

[0010] The gate dielectric layer, which is composed of an electrolyte-based gate dielectric material, covers the channel, the substrate, and the gate electrode. A double electric layer is formed on the gate dielectric and the channel, and on the gate dielectric and the gate electrode by applying a voltage to the gate electrode.

[0011] In the artificial vision-oriented neural retina synaptic device of the present invention, the gate electrode receives an electrical signal to simulate the front end of a neural synapse on the gate dielectric, the channel layer receives an optical signal to simulate a neural retina photoreceptor, and a read voltage is applied to the source electrode, the drain electrode, and the channel layer to complete the collection, processing, and storage of signals. Adjusting the voltage of the gate electrode can simulate bipolar cells to obtain positive and negative photocurrent responses, simulating the image processing function of an artificial vision system, and is used to construct a vision neuromorphic perception system integrating sensing, storage, and computing.

[0012] In the artificial vision-oriented neural retina synaptic device of the present invention, the zero-dimensional quantum dot / two-dimensional material heterojunction thin film includes a zero-dimensional quantum dot material and a two-dimensional material. The zero-dimensional quantum dot material is stacked on the two-dimensional material, and a vertical heterojunction is formed in the overlapping area between the two.

[0013] Furthermore, in the artificial vision-oriented neural retina synaptic device of the present invention, the zero-dimensional quantum dot material is preferably a perovskite quantum dot material, a carbon quantum dot material, etc.

[0014] Furthermore, in the artificial vision-oriented neural retina synaptic device of the present invention, the two-dimensional material is preferably graphene, silicene, WSe 2 、WS 2 、MoS 2 etc.

[0015] In the artificial vision-oriented neural retina synaptic device of the present invention, the gate dielectric layer material is preferably an ionic gel, chitosan, egg white, etc.

[0016] Furthermore, in the artificial vision-oriented neural retina synaptic device of the present invention, the gate dielectric layer can completely cover the channel layer or partially cover the channel layer.

[0017] Furthermore, in the artificial vision-oriented neural retina synaptic device of the present invention, the gate dielectric layer partially covers the gate electrode.

[0018] The present invention also provides a method for fabricating a neuroretinal synaptic device for artificial vision, the fabrication method comprising:

[0019] Forming a gate electrode, a source electrode, and a drain electrode on the substrate; forming a zero-dimensional quantum dot / two-dimensional material channel layer on the source electrode, the drain electrode, and the substrate, ensuring that the zero-dimensional quantum dot material is stacked on the two-dimensional material, and a vertical heterojunction is formed in the overlapping region between the two, ensuring that the channel layer can connect the source electrode and the drain electrode to form an electrical channel and is away from the gate electrode; forming a gate dielectric layer on the channel layer, the substrate, and the gate electrode.

[0020] In the method for fabricating a neuroretinal synaptic device for artificial vision according to the present invention, preferably, magnetron sputtering, or electron beam evaporation technology, or physical vapor deposition and photolithography patterning technology are used to form the electrodes on the substrate.

[0021] In the method for fabricating a neuroretinal synaptic device for artificial vision according to the present invention, preferably, spin coating and drying are used to form the zero-dimensional quantum dots.

[0022] In the method for fabricating a neuroretinal synaptic device for artificial vision according to the present invention, preferably, wet transfer is used to form the two-dimensional material.

[0023] In the method for fabricating a neuroretinal synaptic device for artificial vision according to the present invention, preferably, drop coating and drying are used to form the gate dielectric layer.

[0024] In the method for fabricating a neuroretinal synaptic device for artificial vision according to the present invention, preferably, high-speed spray printing is used to form the electrodes, the zero-dimensional quantum dots, the two-dimensional materials, and the gate dielectric layer.

[0025] Advantages of the present invention:

[0026] 1. The present invention uses a low-dimensional material heterojunction thin film to form a channel layer. It not only utilizes the unique quantum confinement effect and efficient photon capture ability of zero-dimensional quantum dots to efficiently absorb photons and generate photo-generated carriers, but also utilizes the high carrier mobility of two-dimensional materials to quickly separate photo-generated electrons and photo-generated holes to obtain optoelectronic signals. It also utilizes the movement of ions in the electrolyte-like gate dielectric under the action of an electric field to regulate the carriers and heterojunction energy bands of two-dimensional materials, realizing positive and negative photocurrent responses under different gate voltages. By regulating the gate voltage, source-drain voltage, and light, it can receive light stimuli, electrical stimuli, and light and electrical co-stimulation to achieve a series of important optoelectronic synaptic functions in optogenetics, simulating the biological functions in artificial vision.

[0027] 2. The electrolyte-based gate dielectric and the heterojunction thin film of low-dimensional materials adopted by the present invention inherently possess flexible characteristics, which have advantages in the application of flexible electronics, providing a development idea of flexibility, low power consumption, low cost, and high performance for neuroretinal synaptic devices.

[0028] Of course, it is not necessary for any product or method implementing the present disclosure to achieve all the above-mentioned advantages simultaneously. The present invention is also not limited to the provided embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] To more clearly illustrate the embodiments of the present invention, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other embodiments can also be obtained based on these drawings.

[0030] Figure 1 It is a process flow diagram of a manufacturing method of a neuroretinal synaptic device for some embodiments of the present disclosure;

[0031] Figure 2 It is another process flow diagram of a manufacturing method of a neuroretinal synaptic device for some embodiments of the present disclosure;

[0032] Figure 3 It is a schematic structural diagram of a neuroretinal synaptic device for some embodiments of the present disclosure;

[0033] Figure 4 It is a test curve graph of positive and negative photocurrents obtained by controlling the gate electrode voltage of a neuroretinal synaptic device for some embodiments of the present disclosure; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] In order to make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. The described embodiments are only some embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be noted that the orientation or positional relationships indicated by the terms "upper", "lower", "vertical", "horizontal", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation of the present invention.

[0036] In addition, many specific details of the present invention are described below, such as the structure, materials, dimensions, processing techniques and technologies of the device, in order to understand the present invention more clearly. However, as those skilled in the art can understand, the present invention can be implemented without these specific details. Unless specifically indicated below, each part of the device can be made of materials well known to those skilled in the art, or materials with similar functions developed in the future can be used.

[0037] Example 1

[0038] The present invention uses technologies such as photolithography, electron beam evaporation, sputtering, plasma etching, wet etching, dry etching, dispensing and spin coating to prepare a neural retina synaptic device for artificial vision, as Figure 1 shown, and its preparation method includes the following steps:

[0039] In step S1, a substrate 100 is prepared for fabricating the neural retina synaptic device. First, a small amount of acetone and deionized water are used to clean the substrate to remove surface oil stains, dirt, etc.

[0040] In step S2, first, electrode patterns are fabricated on the substrate material by photolithography and development techniques. Then, an electrode layer is prepared on the substrate layer 100 by using magnetron sputtering, electron beam evaporation, or physical vapor deposition techniques. The electrode material selected can be Pd, Ti, Ta, Au, Ru, etc., or in the form of an alloy. Then, the photoresist is stripped with acetone, leaving the required gate, source, and drain electrodes 101.

[0041] In step S3, first, channel patterns are fabricated on the substrate 100 and the electrodes 101 by photolithography and development techniques. Then, the PMMA-assisted two-dimensional material is transferred to the surfaces of the substrate 100 and the electrodes 101 by wet transfer technology or the two-dimensional material is transferred by mechanical exfoliation. Then, the PMMA material on the surface of the two-dimensional material is removed with acetone or alcohol to obtain the two-dimensional material. The two-dimensional material selected can be graphene, or it can be two-dimensional materials such as MoS 2 , WS 2 and so on.

[0042] In step S4, a quantum dot solution with a concentration of 5 - 15 mg / mL is spin-coated onto the surface of the two-dimensional material by a spin coater, and then a quantum dot thin film is obtained by thermal evaporation. The quantum dot solution selected can be an all-inorganic perovskite quantum dot solution dispersed in n-hexane, or a carbon quantum dot solution dispersed in water, or a quantum dot solution with a core-shell structure, etc.

[0043] In step S5, acetone is used to strip the photoresist, obtaining the two-dimensional material channel pattern layer 102 and the quantum dot channel pattern layer 103, and finally forming a vertical heterojunction channel. The heterojunction channel enables electrical conduction between the source and drain electrodes, but forms electrical insulation with the gate electrode.

[0044] In step S6, an electrolyte solution is prepared, and the electrolyte solution is covered on the channel and the gate electrode by drop coating or spraying, and then a low-temperature heating is performed to form the electrolyte gate dielectric film 104. The electrolyte solution can be an ionic gel solution, a chitosan solution, egg white, etc.

[0045] Example 2

[0046] The present invention uses a high-speed spraying and printing technology to prepare a neural retina synaptic device for artificial vision, such as Figure 2 shown, and its preparation method includes the following steps:

[0047] In step S1′, a substrate 100 is prepared for fabricating the neural retina synaptic device. First, a small amount of acetone and deionized water are used to clean the substrate to remove surface oil stains, dirt, etc.

[0048] In step S2′, first, a high-speed spraying printer is used to print the gate, source, and drain electrode pattern layers 101 on the substrate layer 100. The selected electrode material can be Pd, Ti, Ta, Au, Ru, etc., or in the form of an alloy.

[0049] In step S3′, a two-dimensional material suspension solution is prepared, and then a high-speed spraying printer is used to print the two-dimensional material channel pattern 102 on the substrate layer 100 and between the source and drain electrodes. The selected two-dimensional material can be graphene, or it can be two-dimensional materials such as MoS 2 , WS 2 and other two-dimensional materials.

[0050] In step S4′, a quantum dot solution with a concentration of 5 - 15 mg / mL is printed onto the two-dimensional material surface by a high-speed spraying printer, and then thermal evaporation is performed to finally obtain the quantum dot thin film channel pattern 103, and finally a vertical heterojunction channel is formed. The selected quantum dot solution can be an all-inorganic perovskite quantum dot solution dispersed in n-hexane, or a carbon quantum dot solution dispersed in water, or a quantum dot solution with a shell structure, etc.

[0051] In step S5′, an electrolyte solution is prepared, and the electrolyte solution is printed onto the channel and the gate electrode by a high-speed spraying printer, and then a low-temperature heating is performed to form the electrolyte gate dielectric film layer 104. The electrolyte solution can be an ionic gel solution, a chitosan solution, egg white, etc.

[0052] The above are only the preferred embodiments of the present disclosure and are not intended to limit the protection scope of the present disclosure. Any modifications, equivalent replacements, improvements (such as forming a vertical top-gate structure by fabricating a gate electrode on top of an electrolyte gate dielectric), etc., made within the spirit and principles of the present disclosure are all included within the protection scope of the present disclosure.

Claims

1. A neuroretinal synaptic device for artificial vision, characterized in that, it includes: a substrate, serving as a supporting material for the device; electrodes, composed of a gate electrode, a source electrode, and a drain electrode, formed on the substrate; a channel layer, composed of a zero-dimensional quantum dot / two-dimensional material heterojunction thin film, having an enhanced response to optical signals, formed on the substrate, for physically connecting the source electrode and the drain electrode to form an electrical path, and being electrically insulated from the gate electrode; a gate dielectric layer, composed of an electrolyte-based gate dielectric material, covering the channel, the substrate, and the gate electrode, and forming an electric double layer on the gate dielectric and the channel as well as on the gate dielectric and the gate electrode by applying a voltage on the gate electrode.

2. The neuroretinal synaptic device according to claim 1, characterized in that, The described zero-dimensional quantum dot / two-dimensional material heterojunction thin film includes a zero-dimensional quantum dot material and a two-dimensional material. The zero-dimensional quantum dot material is stacked on the two-dimensional material, and the overlapping region between the two forms a vertical heterojunction. The zero-dimensional quantum dot material is preferably a perovskite quantum dot material, a carbon quantum dot material, etc. The two-dimensional material is preferably graphene, silicene, WSe 2 , WS 2 , MoS 2 etc.

3. The neuroretinal synaptic device according to claim 1, characterized in that, the gate dielectric layer material is preferably ion gel, chitosan, egg white, etc.; the gate dielectric layer can completely cover the channel layer or partially cover the channel layer; the gate dielectric layer partially covers the gate electrode.

4. The neuroretinal synaptic device according to claim 1, characterized in that, the gate electrode receives an electrical signal to simulate the front end of a neural synapse on the gate dielectric, the channel layer receives an optical signal to simulate a neuroretinal photoreceptor, a read voltage is applied on the source electrode, the drain electrode, and the channel layer to complete the collection, processing, and storage of signals, and adjusting the gate electrode voltage can simulate bipolar cells to obtain positive and negative photocurrent responses, simulating the image processing function of an artificial vision system, and being used to construct a vision neuromorphic perception system integrating sensing, storage, and computing.

5. A manufacturing method of a neuroretinal synaptic device for artificial vision, characterized in that, it includes: forming a gate electrode, a source electrode, and a drain electrode on the substrate; forming a zero-dimensional quantum dot / two-dimensional material channel layer on the source electrode, the drain electrode, and the substrate, ensuring that the zero-dimensional quantum dot material is stacked on the two-dimensional material, and a vertical heterojunction is formed in the overlapping area between the two, ensuring that the channel layer can connect the source electrode and the drain electrode to form an electrical channel and be away from the gate electrode; a gate dielectric layer is formed on the channel layer, the substrate, and the gate electrode to achieve the electric double layer effect.

6. In the manufacturing method of the neuroretinal synaptic device according to claim 5, characterized in that, the electrodes are formed on the substrate by magnetron sputtering, or electron beam evaporation technology, or physical vapor deposition and photolithography patterning technology, or high-speed spray printing.

7. In the manufacturing method of the neuroretinal synaptic device according to claim 5, characterized in that, the two-dimensional material is formed on the substrate by wet transfer or high-speed spray printing, connecting the source electrode and the drain electrode and being away from the gate electrode.

8. In the manufacturing method of the neuroretinal synaptic device according to claim 5, characterized in that, the zero-dimensional quantum dots are formed on the two-dimensional material and the substrate by spin coating, drying, or high-speed spray printing.

9. In the method for fabricating the neuroretinal synapse device according to claim 5, wherein, the gate dielectric layer is formed on the channel layer, the substrate and the gate electrode by dot coating, drying or high-speed spray printing.

Images