All-light-controlled photoelectric synaptic device and preparation method and application thereof

Abstract

The invention discloses a full-light-controlled photoelectric synaptic device and a preparation method and application thereof. The device successfully simulates the nerve cell synaptic behavior in a spectrum range from ultraviolet light to visible light. In addition, the response of the device to ultraviolet light and visible light is positive response, and photo-generated current rises. However, when the ultraviolet light is firstly used for irradiation and then the visible light is used for irradiation, the visible light has an inhibition effect on the photo-generated current of the ultraviolet light, and the light current is rapidly reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of microelectronic devices, and particularly relates to an all-optical regulation optoelectronic synapse device and a preparation method and application thereof. BACKGROUND

[0002] In recent years, with the rapid development of artificial intelligence and edge computing, the traditional von Neumann architecture faces bottlenecks such as "memory wall" and high energy consumption in processing high-dimensional perception data (such as vision and hearing), prompting researchers to turn to neuromorphic computing paradigm inspired by biological nervous systems. In this context, artificial synapse devices, as the core unit to simulate the plasticity of biological synapses, become the key to building low-power, high-parallel brain-like hardware. Compared with electrically controlled synapses, optically controlled artificial synapses are considered as an important path to realize intelligent visual systems integrating sensing and computing, because they can directly modulate synaptic weights through optical signals, which not only saves complex optical-electric conversion and peripheral circuits, but also realizes in-situ image preprocessing, dynamic adaptation and spatiotemporal information coding at the device level, providing new possibilities for the next generation of neuromorphic visual chips.

[0003] In the current research of artificial synapse devices, although optically controlled synapses have attracted widespread attention due to their non-contact, low power consumption and high parallelism, existing technologies still have significant limitations. Most light-responsive synapse devices can only achieve monotonic increase of photocurrent under a single waveband (such as ultraviolet or visible light), and rely on light intensity or frequency to regulate synaptic weights, making it difficult to simulate the complex bidirectional plasticity of biological synapses (i.e. long-term potentiation LTP and long-term depression LTD). SUMMARY

[0004] In view of the problem that the existing synapse devices are difficult to realize optical regulation, the present application provides an all-optical regulation optoelectronic synapse device, which has a non-monotonic and nonlinear optical-electric coupling mechanism, successfully simulating the behavior of neural cell synapses in the ultraviolet to visible light waveband range. Whether it is ultraviolet light or visible light irradiation, the device shows positive light response, i.e. the photocurrent rises with light irradiation. However, when ultraviolet light irradiation is applied first and then visible light is introduced, the visible light shows a significant inhibitory effect on the photocurrent excited by the ultraviolet light, resulting in a rapid decrease in photocurrent, providing a new idea for constructing optically controlled artificial synapses with multi-modal perception and dynamic regulation capabilities.

[0005] One of the technical solutions of the present application is to provide a preparation method of an all-optical regulation optoelectronic synapse device, which has the following steps: (1) preparing indium gallium zinc oxide nanofibers on a substrate; (2) A heterojunction was obtained by uniformly depositing poly(3-hexylthiophene) (P3HT) onto the surface of indium gallium zinc oxide nanofibers covering the substrate using a spin coating process; (3) Electrodes are deposited on the heterojunction to prepare photoelectric synaptic devices.

[0006] Further, the method for preparing indium gallium zinc oxide nanofibers in step 1 is as follows: nanofibers are prepared on a substrate by electrospinning a spinning solution containing hydrated indium nitrate, hydrated zinc nitrate, hydrated gallium nitrate, and a polymer, followed by oxidation in a tube furnace to obtain indium gallium zinc oxide nanofibers (IGZO). The polymer is polyvinylpyrrolidone.

[0007] Further, the atomic ratio of indium, gallium, and zinc is (1-3):1:(1-3); the substrate is silicon dioxide with a thickness of 300 nm; the oxidation method is oxidation in a high-purity air environment at 450℃-500℃.

[0008] Furthermore, the diameter of the indium gallium zinc oxide nanofibers is 20nm-40nm.

[0009] Furthermore, the voltage for electrospinning is 13-17kV.

[0010] Furthermore, in step 2, the concentration of the poly(3-hexylthiophene) solution is 2.5-10 mg / ml, preferably 3-7 mg / ml.

[0011] Further, the electrode described in step 3 is one of a chromium-gold electrode, an indium electrode, a silver electrode, and an aluminum electrode; the thickness of the chromium in the chromium-gold electrode is 5 nm, and the thickness of the gold is 50 nm; the electrode spacing is 50-200 μm, preferably 80-120 μm, and most preferably 100 μm.

[0012] Generally, the thickness of the electrodes in photoelectric synaptic devices is 10-100 nm, and those skilled in the art can adjust the thickness based on experience.

[0013] A second technical solution of the present invention provides a photoelectric synapse device prepared by the above method, comprising a silicon dioxide substrate, an indium gallium zinc oxide nanofiber / poly(3-hexylthiophene) layer, and electrodes. The poly(3-hexylthiophene) and indium gallium zinc oxide nanofibers serve as the channel layer of the device.

[0014] The third technical solution of the present invention is to provide the application of the above-mentioned photoelectric synaptic device.

[0015] When irradiated with ultraviolet light, electrons in the valence band of IGZO absorb energy and transition to the conduction band, while some holes are trapped by defects within the IGZO. Subsequently, when irradiated with visible light, electrons generated by P3HT preferentially recombine with the trapped holes within the IGZO, causing a decrease in current.

[0016] Ultraviolet light modulates the visible light response. Without ultraviolet light irradiation, the device responds positively to visible light. After ultraviolet light irradiation, the device responds negatively to visible light.

[0017] The advantage of this invention lies in its innovative combination of IGZO and P3HT. When the device is irradiated with ultraviolet light, electrons in the valence band of IGZO absorb photon energy and transition to the conduction band, leaving holes in the valence band. Some of these holes are subsequently trapped by defect states within the IGZO. Upon subsequent application of visible light, electrons excited in the P3HT layer preferentially recombine with the trapped holes in the IGZO, thereby reducing the number of charge carriers participating in conduction and resulting in a significant decrease in current.

[0018] This mechanism demonstrates that ultraviolet light pre-modulates the device's response to subsequent visible light stimuli: without ultraviolet pre-irradiation, the device exhibits a typical positive photoelectric response to visible light; however, after ultraviolet irradiation, the device switches to a negative photoelectric response to the same visible light stimulus. This tunable photoresponse characteristic, programmed by ultraviolet light and readout by visible light, provides a physical basis for realizing wavelength-selective, memory-enabled light-controlled artificial synapses. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the photoelectric synapse device in Example 1; Figure 2 Here is the AFM image of the heterojunction in Example 1; Figure 3 The photoresponse of the photoelectric synaptic device to light sources of 365nm, 488nm, 555nm and 650nm under different pulse numbers; Figure 4 The PPF characteristic curves and PPF factor curves of the photoelectric synaptic device under a 365nm light source are shown. Figure 5 To enhance the all-optical modulation performance of the photoelectric synaptic device, the device is stimulated with 365nm light followed by 488nm, 555nm, and 650nm light sources. Detailed Implementation

[0020] The following examples are provided to further illustrate the present invention and are intended to explain the invention, not to limit its scope. Unless otherwise specified, all figures are expressed in parts by weight and weight percentages.

[0021] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0022] The embodiments of the present invention will be further described below with reference to several examples.

[0023] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0024] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0025] In this invention, the electrode can be any optoelectronic device electrode well known to those skilled in the art. In this embodiment, the electrode can be, in addition to Cr / Au electrode, In electrode, Ag electrode, or Al electrode, or other metal or doped semiconductor material electrode.

[0026] The amount of polymer added in the spinning solution of the present invention can be adjusted by those skilled in the art based on experience.

[0027] Example 1 S1. The silicon dioxide substrate is ultrasonicated for 15 minutes each in the order of acetone, isopropanol, and deionized water to remove surface impurities. Then, nitrogen gas is used to blow away the surface liquid.

[0028] S2, hydrated indium nitrate, hydrated zinc nitrate, hydrated gallium nitrate, and polyvinylpyrrolidone were mixed uniformly in water to form a spinning solution, which was then used to prepare a nanofiber network on a substrate via electrospinning. The electrospinning voltage was 13 kV. The dispersion contained 40 g / L of hydrated indium nitrate, with an atomic ratio of indium, gallium, and zinc of 3:1:3, and 100 g / L of polyvinylpyrrolidone.

[0029] S3. The material obtained in step 2 is transferred to a tube furnace and oxidized in a high-purity air environment at 450°C to obtain an indium gallium zinc oxide nanofiber network, wherein the molecular formula of indium gallium zinc oxide is IGZO and the diameter of the indium gallium zinc oxide nanofiber is 20 nm.

[0030] S4. A heterojunction was obtained by spin-coating poly(3-hexylthiophene) solution with indium gallium zinc oxide nanofibers. The concentration of the poly(3-hexylthiophene) solution was 5 mg / ml. During spin-coating, the solution was first spin-coated at 400 rpm for 10 seconds, followed by spin-coating at 2000 rpm for 20 seconds.

[0031] S5, a photoelectric synaptic device was fabricated by depositing chromium-gold electrodes on a heterojunction using thermal evaporation and metal masking processes. The thickness of the chromium electrode was 5 nm, the thickness of the gold electrode was 50 nm, and the electrode spacing was 100 μm.

[0032] Specifically, A high-precision nickel alloy metal mask is used, with a source-drain aperture spacing of 100 μm. The mask is fixed directly above the sample using vacuum adsorption or a precision clamp, ensuring precise alignment of the mask pattern with the heterojunction channel region. To minimize diffusion effects at the vapor deposition edges, the distance between the mask and the sample is controlled to ≤100 μm.

[0033] Thermal Cr / Au electrode deposition: Transfer the aligned sample to a high-vacuum thermal evaporation system and evacuate to a base pressure ≤ 2×10⁻⁶. -6 Torr. The following vapor deposition steps are performed sequentially: Chromium (Cr): A 5 nm thick Cr layer was deposited as an adhesion layer using a high-purity (99.99%) chromium source at a rate of 0.3 Å / s. Gold (Au): Following this, a 50 nm thick Au layer was deposited using a high-purity (99.999%) gold source at a rate of 1.0 Å / s, serving as the conductive electrode. The resulting photoelectric synapse device structure is as follows... Figure 1 As shown, its heterojunction portion is as follows Figure 2 As shown.

[0034] Based on a photoelectric testing platform built with Keithley 2650, the photoelectric response characteristics of IGZO nanofiber / P3HT heterojunction photoelectric synaptic devices at 365nm, 488nm, 555nm and 650nm were studied.

[0035] In the measurement of photoelectric synaptic devices, two electrodes simulate the presynaptic and postsynaptic membranes of a biological synapse, respectively, and the semiconductor channel between the electrodes is equivalent to the synaptic gap. An externally applied light signal serves as the stimulus input to the artificial synapse, and the resulting photocurrent corresponds to the postsynaptic current. Synaptic weight is characterized by the difference between the photocurrent and the dark current. In the experiment, light with wavelengths of 365 nm, 488 nm, 555 nm, and 650 nm was used as the input stimulus signal to study the synaptic plasticity behavior of the device in different spectral ranges.

[0036] First, use the same power level (7mW / cm) respectively.2 The device was illuminated with light pulses at wavelengths of 365 nm, 488 nm, 555 nm, and 650 nm. The pulse duration was one second, and the pulse interval was one second. The results were obtained from... Figure 3 As shown, under stimulation from all light sources, the photocurrent increases with the number of pulses, consistent with the plastic behavior of synaptic cells. The device successfully mimics the function of synaptic cells.

[0037] Two consecutive ultraviolet light irradiations using a 365 nm wavelength, with a pulse duration of one second and an interval of one second. Figure 4 As shown, the amplitude of the second postsynaptic potential (A2) is significantly greater than that of the first (A1). Double-pulse facilitation (PPF) was implemented in the device. Since its response amplitude depends on the pulse interval, multiple measurements were taken by varying the interval between the two pulses to 0.1 s, 0.2 s, 0.4 s, 0.5 s, 1 s, 1.5 s, and 2 s. The PPF factor was calculated using the formula PPF = A2 / A1 * 100%.

[0038] Furthermore, we first irradiated the device with 365 nm ultraviolet light, then with visible light sources at 488 nm, 555 nm, and 650 nm. Compared to the dark state, the device current showed a significant decrease under visible light irradiation, such as... Figure 5 As shown in the figure. This indicates that the visible light response of the device is changed by the modulation of ultraviolet light.

[0039] Example 2 S1 was subjected to ultrasonic treatment on a 300 nm thick silicon dioxide substrate, in the order of acetone, isopropanol, and deionized water, for 15 min each, to remove surface impurities. Then, nitrogen gas was used to blow away the surface liquid.

[0040] S2, hydrated indium nitrate, hydrated zinc nitrate, hydrated gallium nitrate, and polyvinylpyrrolidone were mixed uniformly in water to form a spinning solution, and a nanofiber network was prepared on a substrate by electrospinning at a voltage of 13 kV. The dispersion contained 30 g / L of hydrated indium nitrate, with an atomic ratio of indium, gallium, and zinc of 1:1:3, and 90 g / L of polyvinylpyrrolidone.

[0041] S3. The material obtained in step 2 is transferred to a tube furnace and oxidized in a high-purity air environment at 500°C to obtain an indium gallium zinc oxide nanofiber network, wherein the molecular formula of indium gallium zinc oxide is IGZO and the diameter of the indium gallium zinc oxide nanofiber is 40 nm.

[0042] S4. A heterojunction was obtained by spin-coating poly(3-hexylthiophene) solution with indium gallium zinc oxide nanofibers. The concentration of the poly(3-hexylthiophene) solution was 5 mg / ml. During spin-coating, the solution was first spin-coated at 400 rpm for 10 seconds, followed by spin-coating at 2000 rpm for 20 seconds.

[0043] S5, a photoelectric synaptic device was fabricated by depositing chromium-gold electrodes on a heterojunction using thermal evaporation and metal masking processes. The thickness of the chromium electrode was 5 nm, the thickness of the gold electrode was 50 nm, and the electrode spacing was 80 μm.

[0044] Specifically, A high-precision nickel alloy metal mask is used, with a source-drain aperture spacing of 80 μm. The mask is fixed directly above the sample using vacuum adsorption or a precision clamp to ensure precise alignment of the mask pattern with the heterojunction channel region. To reduce the diffusion effect at the vapor deposition edge, the distance between the mask and the sample is controlled to ≤100 μm.

[0045] Thermal Cr / Au electrode deposition: Transfer the aligned sample to a high-vacuum thermal evaporation system and evacuate to a base pressure ≤ 2×10⁻⁶. -6 Torr. The following vapor deposition steps are performed sequentially: Chromium (Cr): A 5 nm thick Cr layer was deposited as an adhesion layer using a high-purity (99.99%) chromium source at a rate of 0.3 Å / s. Gold (Au): A 50 nm thick Au layer was then deposited using a high-purity (99.999%) gold source at a rate of 1.0 Å / s as a conductive electrode.

[0046] Example 3 S1. The silicon dioxide substrate is ultrasonicated for 15 minutes each in the order of acetone, isopropanol, and deionized water to remove surface impurities. Then, nitrogen gas is used to blow away the surface liquid.

[0047] S2, hydrated indium nitrate, hydrated zinc nitrate, hydrated gallium nitrate, and polyvinylpyrrolidone were uniformly mixed in water to form a spinning solution, which was then used to prepare a nanofiber network on a substrate via electrospinning. The electrospinning voltage was 17 kV. The dispersion contained 30 g / L of hydrated indium nitrate, with an atomic ratio of indium, gallium, and zinc of 1:1:3, and 90 g / L of polyvinylpyrrolidone.

[0048] S3. The material obtained in step 2 is transferred to a tube furnace and oxidized in a high-purity air environment at 500°C to obtain an indium gallium zinc oxide nanofiber network, wherein the molecular formula of indium gallium zinc oxide is IGZO and the diameter of the indium gallium zinc oxide nanofiber is 40 nm.

[0049] S4. A heterojunction was obtained by spin-coating poly(3-hexylthiophene) solution with indium gallium zinc oxide nanofibers. The concentration of the poly(3-hexylthiophene) solution was 2.5 mg / ml. During spin-coating, the solution was first spin-coated at 400 rpm for 10 seconds, followed by spin-coating at 2000 rpm for 20 seconds.

[0050] S5 deposits an In electrode on a heterojunction using thermal evaporation and metal masking processes. The In electrode thickness is 50 nm and the electrode spacing is 200 μm.

[0051] Example 4 S1. The silicon dioxide substrate is ultrasonicated for 15 minutes each in the order of acetone, isopropanol, and deionized water to remove surface impurities. Then, nitrogen gas is used to blow away the surface liquid.

[0052] S2, hydrated indium nitrate, hydrated zinc nitrate, hydrated gallium nitrate, and polyvinylpyrrolidone were mixed uniformly in water to form a spinning solution, which was then used to prepare a nanofiber network on a substrate via electrospinning. The electrospinning voltage was 17 kV. The dispersion contained 30 g / L of hydrated indium nitrate, with an atomic ratio of indium, gallium, and zinc of 3:1:1, and 90 g / L of polyvinylpyrrolidone.

[0053] S3. The material obtained in step 2 is transferred to a tube furnace and oxidized in a high-purity air environment at 500°C to obtain an indium gallium zinc oxide nanofiber network, wherein the molecular formula of indium gallium zinc oxide is IGZO and the diameter of the indium gallium zinc oxide nanofiber is 20 nm.

[0054] S4. A heterojunction was obtained by spin-coating poly(3-hexylthiophene) solution with indium gallium zinc oxide nanofibers. The concentration of the poly(3-hexylthiophene) solution was 10 mg / ml. During spin-coating, the solution was first spin-coated at 400 rpm for 10 seconds, followed by spin-coating at 2000 rpm for 20 seconds.

[0055] S5 deposits silver electrodes on a heterojunction using thermal evaporation and metal masking processes. The silver thickness is 50 nm and the electrode spacing is 50 μm.

[0056] Example 5 S1. The silicon dioxide substrate is ultrasonicated for 15 minutes each in the order of acetone, isopropanol, and deionized water to remove surface impurities. Then, nitrogen gas is used to blow away the surface liquid.

[0057] S2, hydrated indium nitrate, hydrated zinc nitrate, hydrated gallium nitrate, and polyvinylpyrrolidone were mixed uniformly in water to form a spinning solution, which was then used to prepare a nanofiber network on a substrate via electrospinning. The electrospinning voltage was 15 kV. The dispersion contained 30 g / L of hydrated indium nitrate, with an atomic ratio of indium, gallium, and zinc of 1:1:1, and 90 g / L of polyvinylpyrrolidone.

[0058] S3. The material obtained in step 2 is transferred to a tube furnace and oxidized in a high-purity air environment at 500°C to obtain an indium gallium zinc oxide nanofiber network, wherein the molecular formula of indium gallium zinc oxide is IGZO and the diameter of the indium gallium zinc oxide nanofiber is 20 nm.

[0059] S4. A heterojunction was obtained by spin-coating poly(3-hexylthiophene) solution with indium gallium zinc oxide nanofibers. The concentration of the poly(3-hexylthiophene) solution was 5 mg / ml. During spin-coating, the solution was first spin-coated at 400 rpm for 10 seconds, followed by spin-coating at 2000 rpm for 20 seconds.

[0060] S5 deposits aluminum electrodes on a heterojunction using thermal evaporation and metal masking processes. The aluminum thickness is 60 nm and the electrode spacing is 120 μm.

[0061] Comparative Example 1 The difference from Example 1 is that the concentration of the poly(3-hexylthiophene) solution is 15 mg / ml.

[0062] The results showed that the photoresponse effect of the prepared photoelectric synaptic devices did not exhibit a clear trend.

[0063] The above embodiments describe in detail the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall still fall within the scope of protection of the present invention if they do not exceed the scope covered by the specification.

Claims

1. A method for fabricating a fully optically modulated photoelectric synaptic device, characterized in that, It includes the following steps: (1) Indium gallium zinc oxide nanofibers were prepared on a substrate; (2) A heterojunction was obtained by uniformly depositing poly(3-hexylthiophene) solution onto the surface of indium gallium zinc oxide nanofibers covering the substrate using a spin coating process; (3) Electrodes are deposited on the heterojunction to prepare photoelectric synaptic devices.

2. The method according to claim 1, characterized in that, The method for preparing indium gallium zinc oxide nanofibers in step 1 is as follows: nanofibers are prepared on a substrate by electrospinning a spinning solution containing hydrated indium nitrate, hydrated zinc nitrate, hydrated gallium nitrate and polymer, and then oxidized in a tube furnace to obtain indium gallium zinc oxide nanofibers.

3. The method according to claim 2, characterized in that, The atomic ratio of indium, gallium, and zinc is (1-3):1:(1-3); the substrate is silicon dioxide with a thickness of 300 nm; the oxidation method is oxidation in air at 450℃-500℃; the polymer is polyvinylpyrrolidone.

4. The method according to claim 2, characterized in that, The indium gallium zinc oxide nanofibers have a diameter of 20nm-40nm.

5. The method according to claim 2, characterized in that, The voltage for electrospinning is 13kV-17kV.

6. The method according to claim 1, characterized in that, In step (2), the concentration of the poly(3-hexylthiophene) solution is 2.5 mg / ml-10 mg / ml.

7. The method according to claim 1, characterized in that, The electrode mentioned in step (3) is one of the following: chromium-gold electrode, indium electrode, silver electrode, and aluminum electrode; the thickness of chromium in the chromium-gold electrode is 5 nm, and the thickness of gold is 50 nm; the electrode spacing is 50 μm-200 μm.

8. A photoelectric synaptic device prepared by the method of claim 1.

9. An application of the photoelectric synapse device as described in claim 8.

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