Non-volatile optoelectronic synapse device with fluorescence monitoring and preparation method thereof

Abstract

The application discloses a non-volatile optoelectronic neurosynaptic device with fluorescence monitoring, comprising a gate electrode, a dielectric layer, a two-dimensional layered film, a source electrode, a drain electrode and semiconductor silicon quantum dots, wherein the dielectric layer is located on the gate electrode, the two-dimensional layered film is located on the dielectric layer, and the source electrode, the drain electrode and the semiconductor silicon quantum dot film are all located on the two-dimensional layered film, wherein the semiconductor silicon quantum dot film separates the source electrode and the drain electrode; when external light irradiates the semiconductor silicon quantum dot film, a fluorescence monitoring signal is emitted from the semiconductor silicon quantum dot film, and after the external light irradiation is removed, the non-volatility of the synaptic weight change of the optoelectronic neurosynaptic device is realized based on the change of the conductance of the two-dimensional layered film. The device can easily realize fluorescence effect and non-volatile photocurrent at the same time under the stimulation of light. The application further discloses a preparation method of the device. The preparation method is simple and efficient.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of neuro-mimicry computing, and particularly relates to a non-volatile optoelectronic synapse device with fluorescence monitoring and a preparation method thereof. BACKGROUND

[0002] With the increasing deepening of the informatization degree of modern society, the modern digital computer system relying on the von Neumann architecture will face a series of problems such as unstructured real-time information processing, improvement of computing speed and energy consumption of data processing due to the physical separation of memory modules and processors, which is called the "von Neumann bottleneck" (M.M. Waldrop, Nature 2016, 530, 145.). Neuromorphic computing (brain-like computing) is considered to be one of the most promising ways to solve the development bottleneck of current computing based on the von Neumann architecture due to its highly parallel computing, adaptive learning and low power consumption. Neuro-mimicry computing relies on a neural network constructed by connecting neurons by synapses. Therefore, an important prerequisite for realizing neuromorphic computing is to develop a synapse device that can simulate the behavior of biological synapses.

[0003] Inspired by biological optogenetics, in recent years, light has been introduced into synapse devices, and a series of optoelectronic synapse devices have been developed, bringing new opportunities for the development of synapse devices. Non-contact light input has the advantages of high bandwidth, low crosstalk, low power consumption and no resistance-capacitance delay that cannot be matched by electrical input. Documents Y. Wang, et. al. Adv. Intell. Syst. 2021, 3, 2000099.; Li Yaoyao et al., Science in China: Information Sciences, 2021, 64, 162401. disclose that more than 70% of the information received by humans comes from vision, and therefore optoelectronic synapse devices stimulated by light can lay the foundation for important human vision simulation.

[0004] A light synapse device simulating synaptic plasticity in a neural network is disclosed in Chinese Patent Publication No. CN114664961A, which comprises: a substrate; a first dielectric layer located above the substrate; a channel layer composed of a molybdenum sulfide film located above the first dielectric layer, and the molybdenum sulfide film is a single atomic layer in thickness; a source electrode layer and a drain electrode layer located on both sides of the channel layer and spaced apart; and a second dielectric layer located above the channel layer and formed in the space range between the source electrode layer and the drain electrode layer. The channel layer composed of a molybdenum sulfide film has a visible optical band gap of 1.2-1.9 eV. When a gate voltage is applied to the gate electrode layer and a visible light waveband light pulse is applied to the device, a readout voltage is applied based on the source and drain electrode layers to realize the simulation of the excitatory postsynaptic potential of the light synapse device after light stimulation.

[0005] At present, photoelectric neural synapse devices with optical input and electrical output have been developed rapidly. Since biological imaging is usually used for the visualization of neural network activity in neuroscience, the above-mentioned patent only realizes the simulation of synaptic potential under light stimulation, but does not realize the induced fluorescence of light involved in neural activity. Therefore, the mode of triggering electrical signals to complete synaptic performance and fluorescence to complete work monitoring at the same time under optical input is of great significance for system-level diagnosis and device-level positioning of hardware implementation system. SUMMARY

[0006] The present application provides a non-volatile optoelectronic neural synapse device with fluorescence monitoring, which can easily realize the fluorescence effect of light and non-volatility at the same time under the stimulation of light.

[0007] A non-volatile optoelectronic neural synapse device with fluorescence monitoring, comprising a gate electrode, a dielectric layer, a two-dimensional layered film, a source electrode, a drain electrode and a semiconductor silicon quantum dot, wherein:

[0008] The dielectric layer is located on the gate electrode, the two-dimensional layered film is located on the dielectric layer, and the source electrode, the drain electrode and the semiconductor silicon quantum dot film are all located on the two-dimensional layered film, wherein the semiconductor silicon quantum dot film separates the source electrode and the drain electrode;

[0009] When external light irradiates the semiconductor silicon quantum dot film, a fluorescence monitoring signal is emitted from the semiconductor silicon quantum dot film, and after the external light irradiation is removed, the non-volatility of the synaptic weight change of the optoelectronic neural synapse device is realized based on the change of the conductance of the two-dimensional layered film.

[0010] The gate electrode is a heavily doped p-type silicon substrate.

[0011] The gate electrode can accept electrical stimulation, and the capacitance effect of the dielectric layer reduces the conductance of the synaptic device, realizing the erasure of the synaptic weight. The device can bidirectionally adjust the synaptic weight, and is expected to be applied to the hardware implementation of future artificial neural networks.

[0012] The dielectric layer is silicon dioxide, aluminum oxide or hafnium oxide. The dielectric layer isolates the gate electrode from the source electrode, the drain electrode, the two-dimensional layered material and the semiconductor silicon quantum dot film, prevents device leakage, and thus makes the gate electrode have good regulation performance on the conductivity of the transistor channel material.

[0013] The material of the two-dimensional layered film is molybdenum disulfide.

[0014] The size of the two-dimensional layered film needs to be greater than 10 μm 2 to ensure that the subsequently patterned multiple pairs of source electrodes and drain electrodes have space to arrange thereon. The number of layers of the two-dimensional layered film is 1-10 to ensure a high carrier mobility.

[0015] The source electrode and the drain electrode are both metal thin film electrodes, wherein the material of the source electrode is gold, titanium gold alloy, nickel gold alloy or chromium gold alloy, and the material of the drain electrode is gold, titanium gold alloy, nickel gold alloy or chromium gold alloy.

[0016] The wavelength of the light in the external light irradiation is 300-650 nm.

[0017] Based on the patterned design of multiple pairs of source electrodes and drain electrodes, multiple groups of neural synapse devices are integrated.

[0018] By patterning multiple pairs of source electrodes and drain electrodes, a group of synaptic devices is constructed, and different current responses generated by different devices in the group to the same light stimulation are combined to simulate the group coding behavior of the neural synaptic group, and the robustness of the artificial neural synaptic device group is exhibited, thereby laying a foundation for constructing an artificial neural network at the hardware level.

[0019] The application further discloses a preparation method of the nonvolatile optoelectronic neural synaptic device with fluorescent monitoring, comprising the following steps:

[0020] (1) generating a dielectric layer on the surface of the gate electrode;

[0021] (2) transferring a two-dimensional layered film to the surface of the dielectric layer;

[0022] (3) designing an electrode pattern on the surface of the two-dimensional layered film, sequentially performing electron beam exposure, development and electron etching on the electrode pattern to obtain a soft mask plate, and then depositing the source electrode and the drain electrode on the basis of the soft mask plate through electron beam evaporation;

[0023] (4) dissolving and removing the soft mask plate by using acetone, so as to leave the patterned source and drain electrodes on the two-dimensional layered material, and obtain a patterned device;

[0024] (5) spin-coating a cyclohexane solution of silicon quantum dots on the patterned device obtained in step (4), and annealing at 90-150 DEG C for 15-30 min to obtain an optoelectronic neural synaptic device.

[0025] The preparation method for transferring the two-dimensional layered film to the surface of the dielectric layer comprises the following steps:

[0026] A polydimethylsiloxane film is obtained, a two-dimensional layered material is attached to one side of the polydimethylsiloxane film, and the two-dimensional material is attached to the dielectric layer, and after heating at 50-80 DEG C for 10-30 min, the polydimethylsiloxane film is removed, so that the two-dimensional material is transferred to the dielectric layer.

[0027] The preparation method of the cyclohexane solution of silicon quantum dots comprises the following steps:

[0028] The silicon quantum dots are prepared by a cold plasma method, the surface of the silicon quantum dots is subjected to silicane hydride by using 1-heptene, and then the silicon quantum dots subjected to silicane hydride are dispersed in cyclohexane to obtain a stable solution with a concentration of 10-15 mg / mL.

[0029] The spin coating process is as follows: the spin coating speed is 1000-2500 rpm, the spin coating time is 30-90 s, and the closed natural volatilization is performed for 1-4 hours.

[0030] Compared with the prior art, the application has the following beneficial effects:

[0031] (1) The optoelectronic neural synapse device constructed in the application generates fluorescence monitoring signals by radiation recombination of part of the photo-generated electrons and holes in the silicon quantum dots under external light stimulation, and the other part of the photo-generated electrons is transferred to the two-dimensional layered film under the action of the heterojunction built-in electric field, and the photo-generated holes of the two-dimensional layered film are transferred to the silicon quantum dots, thereby producing a grating control effect to control the conductance of the two-dimensional layered material channel, so that the plasticity of the biological synapse weight is simulated, and when the external light stimulation stops, the remaining photo-generated holes in the semiconductor silicon quantum dot film continuously affect the conductance of the two-dimensional layered film, thereby realizing the non-volatile synapse plasticity.

[0032] (2) The transistor-type optoelectronic neural synapse device based on the heterojunction of the semiconductor silicon quantum dots and the two-dimensional layered material in the application utilizes the excellent optical absorption and emission properties of the semiconductor silicon quantum dots, not only assists in enhancing the optical absorption of the ultra-thin two-dimensional layered material device, improving the photosensitivity, and expanding the ability of the device to receive weak light stimulation signals, but also can emit fluorescence synchronously for device working state monitoring, diagnosis and positioning.

[0033] (3) The transistor-type optoelectronic neural synapse device based on the heterojunction of the semiconductor silicon quantum dots and the two-dimensional layered material in the application can accept light pulse stimulation to realize a series of important synaptic functions, and can well simulate the biological synaptic behavior. More importantly, compared with the way of utilizing the defects of the channel material itself to control the carrier behavior, the regulation of the photo-generated carrier behavior based on the controllable heterojunction band barrier can improve the consistency of the device in simulating synaptic plasticity, and provide support for future hardware implementation of large-scale neural networks. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 A structure diagram of the non-volatile optoelectronic neural synapse device with fluorescence monitoring prepared for the embodiment of the application;

[0035] Figure 2 A characterization effect diagram of the non-volatile optoelectronic neural synapse device with fluorescence monitoring prepared for the embodiment 1 of the application;

[0036] Figure 3A characterization effect diagram of the nonvolatile optoelectronic neurosynaptic device with fluorescent monitoring prepared for Embodiment 2 of the present application.

[0037] The gate electrode 1, the dielectric layer 2, the two-dimensional layered film 3, the source electrode 4, the drain electrode 5, and the semiconductor silicon quantum dot film 6. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application.

[0039] The present application provides a nonvolatile optoelectronic neurosynaptic device with fluorescent monitoring, as shown in the figure, comprising: Figure 1

[0040] The gate electrode 1, the dielectric layer 2, the two-dimensional layered film 3, the source electrode 4, the drain electrode 5, and the semiconductor silicon quantum dot film 6.

[0041] The dielectric layer 2 is located on the gate electrode 1, the two-dimensional layered film 3 is located on the dielectric layer 2, and the source electrode 4, the drain electrode 5, and the semiconductor silicon quantum dot film 6 are all located on the two-dimensional layered film 3, wherein the semiconductor silicon quantum dot film 6 separates the source electrode 4 and the drain electrode 5;

[0042] When external light irradiates the semiconductor silicon quantum dot film 6, a fluorescent monitoring signal is emitted from the semiconductor silicon quantum dot film 6, and after the external light irradiation is removed, the non-volatility of the change of the synaptic weight of the optoelectronic neurosynaptic device is realized based on the change of the conductance of the two-dimensional layered film 3.

[0043] Embodiment 1

[0044] A preparation method of a nonvolatile optoelectronic neurosynaptic device with fluorescent monitoring, comprising:

[0045] (1) A silicon dioxide dielectric layer 2 is grown on the upper surface of p-type silicon by thermal oxidation, and the thickness of the silicon dioxide dielectric layer 2 is 280 nm, and the used p-type silicon serves as a gate electrode 1;

[0046] (2) A polydimethylsiloxane film is used to adhere molybdenum disulfide crystals. Under an optical microscope, molybdenum disulfide with a suitable size and number of layers is found, the molybdenum disulfide is attached to the dielectric layer by reversing the polydimethylsiloxane film, heated on a heating table at 65℃ for 20 min, and the polydimethylsiloxane film is removed to transfer the single-layer molybdenum disulfide to the dielectric layer 2 to form a two-dimensional layered film 3;

[0047] ​(3) On the two-dimensional layered film 3, a plurality of adjacent chromium-gold alloy films are grown as a pair of adjacent source electrode 4 and drain electrode 5 by electron beam deposition and thermal evaporation technology, the thickness of chromium is 5 nm, and the thickness of gold is 50 nm;

[0048] (4) After the device is patterned, 45 microliters of 10 mg / mL silicon quantum dot cyclohexane solution is spin-coated on the device, the spin-coating speed is 2000 rpm, and the spin-coating time is 40 s. After natural volatilization for 3 hours, 100°C annealing for 30 min, a semiconductor silicon quantum dot film 6 is formed, and a photoelectric synapse device based on a two-dimensional layered material and silicon quantum dot hybrid structure is obtained.

[0049] The photoelectric synapse device based on a two-dimensional layered material and silicon quantum dot hybrid structure prepared in the present example can not only generate a non-volatile excitatory post-synaptic current, but also synchronously emit a fluorescence monitoring signal after being stimulated by an external light signal (from ultraviolet to visible light). For example, Figure 2 The synchronous fluorescence monitoring signal and non-volatile photocurrent under the light stimulation of wavelength 375 nm, pulse width 1 s, and power density 8 mW / cm 2 are given. The fluorescence monitoring signal can realize system-level diagnosis and device-level positioning, and the non-volatile photocurrent is used to realize synaptic plasticity.

[0050] Embodiment 2

[0051] A preparation method of a non-volatile photoelectric synapse device with fluorescence monitoring, comprising:

[0052] (1) A silicon dioxide dielectric layer 2 is grown on the upper surface of p-type silicon by thermal oxidation, the thickness of the silicon dioxide dielectric layer 2 is 280 nm, and the used p-type silicon serves as a gate electrode 1;

[0053] (2) A molybdenum disulfide crystal is adhered using a polydimethylsiloxane film. Under an optical microscope, a molybdenum disulfide with a suitable size and layer number is found, the molybdenum disulfide is attached to the dielectric layer by reversing the polydimethylsiloxane film, and is heated on a heating table at 70°C for 10 min. The polydimethylsiloxane film makes the single-layer molybdenum disulfide transfer to the dielectric layer 2, forming a two-dimensional layered film 3;

[0054] (3) On the two-dimensional layered film 3, a plurality of adjacent chromium-gold alloy films are grown as a pair of adjacent source electrode 4 and drain electrode 5 by electron beam deposition and thermal evaporation technology, the thickness of chromium is 5 nm, and the thickness of gold is 50 nm;

[0055] (4) After patterning, 45 microliters of 10 mg / mL silicon quantum dot cyclohexane solution was spin-coated on the device at a speed of 1500 rpm for 80 s. After natural volatilization for 1.5 hours, a semiconductor silicon quantum dot film 6 was formed by annealing at 130°C for 20 min, thereby obtaining a photoelectric neural synapse device based on a two-dimensional layered material and silicon quantum dot hybrid structure.

[0056] The photoelectric neural synapse device based on a two-dimensional layered material and silicon quantum dot hybrid structure prepared in this example can not only generate a non-volatile excitatory post-synaptic current, but also synchronously emit a fluorescent monitoring signal after being stimulated by an external light signal (from ultraviolet to visible light). As shown in FIG. 6, the device can generate a non-volatile excitatory post-synaptic current and a fluorescent monitoring signal simultaneously. Figure 3 The synchronous fluorescent monitoring signal and non-volatile photocurrent under the stimulation of light with a wavelength of 532 nm, a pulse width of 1 s, and a power density of 6 mW / cm 2 are given. The fluorescent monitoring signal can realize system-level diagnosis and device-level positioning, and the non-volatile photocurrent is used to realize synaptic plasticity.

[0057] The above disclosure is only a specific embodiment of the present application, but the present application is not limited thereto, and those skilled in the art can make various modifications and changes to the present application without departing from the spirit and scope of the present application. Obviously, these modifications and changes should all belong to the protection scope of the present application. In addition, although some specific terms are used in the present specification, these terms are only for convenience of description and do not constitute any special limitation on the present application.

Claims

1. A non-volatile optoelectronic synapse device with fluorescence monitoring, characterized in that, include: Gate electrode, dielectric layer, two-dimensional layered thin film, source electrode, drain electrode, and semiconductor silicon quantum dot, wherein: The dielectric layer is located on the gate electrode, the two-dimensional layered thin film is located on the dielectric layer, and the source electrode, drain electrode and semiconductor silicon quantum dot thin film are all located on the two-dimensional layered thin film. The semiconductor silicon quantum dot thin film separates the source electrode and the drain electrode. When external light irradiates the semiconductor silicon quantum dot film, a fluorescence monitoring signal is emitted from the semiconductor silicon quantum dot film. After the external light irradiation is removed, the non-volatility of the synaptic weight change of the photoelectric nerve synapse device is realized based on the change in the conductivity of the two-dimensional layered film. The material of the two-dimensional layered film is molybdenum disulfide.

2. The non-volatile optoelectronic neurosynaptic device with fluorescence monitoring of claim 1, wherein, The gate electrode is a heavily p-doped silicon substrate.

3. The non-volatile optoelectronic neurosynaptic device with fluorescence monitoring of claim 1, wherein, The dielectric layer is silicon dioxide, aluminum oxide, or hafnium oxide.

4. The non-volatile optoelectronic neurosynaptic device with fluorescence monitoring of claim 1, wherein, The two-dimensional layered thin film has a size of greater than 10 µm 2 The two-dimensional layered thin film has a layer number of 1-10 layers to ensure a high carrier mobility.

5. The non-volatile optoelectronic neurosynaptic device with fluorescence monitoring of claim 1, wherein, Both the source electrode and the drain electrode are metal thin film electrodes. The source electrode is made of gold, titanium-gold alloy, nickel-gold alloy, or chromium-gold alloy, and the drain electrode is made of gold, titanium-gold alloy, nickel-gold alloy, or chromium-gold alloy.

6. The non-volatile optoelectronic neurosynaptic device with fluorescence monitoring of claim 1, wherein, Based on patterned design of multiple pairs of source and drain electrodes, multiple neural synaptic devices can be integrated into a group.

7. A method of fabricating a non-volatile optoelectronic synapse device with fluorescence monitoring according to any one of claims 1-6, characterized in that, include: (1) A dielectric layer is generated on the surface of the gate electrode; (2) Transferring a two-dimensional layered thin film to the surface of a dielectric layer; (3) Design an electrode pattern on the surface of a two-dimensional layered thin film, and perform electron beam exposure, development and electron etching on the electrode pattern in sequence to obtain a soft mask. Then, based on the soft mask, deposit the source electrode and the drain electrode by electron beam evaporation. (4) Dissolve and remove the soft mask with acetone to leave patterned source and drain electrodes on the two-dimensional layered material to obtain a patterned device; (5) A cyclohexane solution of silicon quantum dots is spin-coated onto the patterned device obtained in step (4), and annealed at 90-150℃ for 15-30 min to obtain a photoelectric nerve synapse device.

8. The method of claim 7, wherein the method further comprises the step of: The method for preparing a two-dimensional layered thin film by transferring it to the surface of a dielectric layer includes: ​ A polydimethylsiloxane film is obtained. A two-dimensional layered material is adhered to one side of the polydimethylsiloxane film. A dielectric layer is then attached to the side with the two-dimensional layered material. After heating at 50-80℃ for 10-30 min, the polydimethylsiloxane film is removed, allowing the two-dimensional layered material to transfer to the dielectric layer.

9. The method of claim 7, wherein the method further comprises: depositing a first electrode layer on the substrate; depositing a second electrode layer on the first electrode layer; and depositing a third electrode layer on the second electrode layer. The method for preparing the cyclohexane solution of the silicon quantum dots includes: Silicon quantum dots were prepared by cold plasma method. The surface of the silicon quantum dots was hydrogenated and silanized using 1-heptene. The hydrogenated and silanized silicon quantum dots were then dispersed in cyclohexane to obtain a stable solution with a concentration of 10-15 mg / mL.

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