Heterojunction artificial synaptic device with multi-wavelength response and bionic injury perception
By designing a heterojunction artificial synapse device that combines multi-wavelength response and biomimetic damage perception, the problem of insufficient wavelength sensitivity visual damage perception in existing biomimetic vision systems has been solved. This enables efficient response and damage warning to light stimuli of different wavelengths, improves the robustness and reliability of the system, and is applicable to fields such as neuromorphic sensing and biomimetic electronic skin.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUIZHOU UNIV
- Filing Date
- 2026-01-15
- Publication Date
- 2026-04-14
AI Technical Summary
Existing bionic vision systems lack the ability to perceive visual damage sensitive to wavelengths, making it difficult to effectively cope with atypical samples and adversarial disturbances in open and complex environments. Furthermore, they lack adaptive protection mechanisms and are at risk of light damage.
A heterojunction artificial synapse device combining multi-wavelength response and biomimetic damage perception is designed. By constructing a molybdenum disulfide and silicon-rich silicon nitride heterojunction structure, and combining the high-density charge trapping state introduced by Si–Si bonds and the two-dimensional semiconductor characteristics, it realizes the response to light stimulation of different wavelengths and the biomimetic synaptic function. It has the characteristics of excitatory postsynaptic current, pairing pulse facilitation, short-term memory and long-term memory, and simulates the threshold characteristics, relaxation behavior, hyperalgesia and abnormal pain characteristics of biological damage perception.
It achieves efficient response to light stimuli of different wavelengths, improves the robustness and reliability of the bionic vision system, has low power consumption and low latency visual information perception and damage warning capabilities, simplifies the device structure, reduces the difficulty of fabrication and integration cost, and is suitable for fields such as neuromorphic sensing and bionic electronic skin.
Smart Images
Figure CN121865704A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electronic information technology, specifically to a heterojunction artificial synapse device that combines multi-wavelength response and biomimetic damage perception. Background Technology
[0002] Vision, as the core means by which humans perceive the external world, undertakes over 80% of the task of receiving environmental information. Therefore, machine vision technology, which mimics the functions of biological vision, has become a key research direction, widely applied in industrial automation, quality control, robot navigation, and many other critical fields. Traditional machine vision systems often employ complex architectures where photodetectors, memory, and information processing units are separated. This architecture leads to inherent drawbacks such as high power consumption, high latency, and high complexity, making it difficult to meet the demands of next-generation intelligent devices for efficient information processing. Therefore, simpler structures and integrated sensing and processing have become important development trends for biomimetic vision systems. In recent years, artificial synaptic devices combining optical sensing and information processing functions have emerged, providing a new path for building biomimetic vision systems based on single devices, demonstrating enormous application potential in areas such as image recognition and learning. However, most current optical sensing systems are trained based on idealized, clean data input presets. In open and complex real-world scenarios, these systems struggle to effectively handle atypical samples or adversarial perturbations, easily producing highly misleading high-confidence misjudgments and lacking effective early warning mechanisms. This subtle "potential fault" poses significant reliability risks to most safety-critical applications. In biological sensory systems, nociceptive neurons play a crucial role. When they detect harmful stimuli or stimuli exceeding the safe range, they can transmit pain signals to the brain and trigger a protective response, thereby avoiding potential physiological damage. Therefore, biomimicking this nociceptive mechanism is of great significance for developing biomimetic visual systems with adaptive protective capabilities.
[0003] In ophthalmology, optical damage to the retina is a common type of light-induced eye injury, potentially leading to retinal inflammation. The degree of damage is closely related to the wavelength of the irradiated light; shorter wavelengths lower the critical intensity threshold for photochemical retinal damage, meaning shorter wavelengths pose a greater potential risk. Furthermore, after injury from short-wavelength light, previously harmless long-wavelength light may cause secondary damage. This phenomenon highlights the importance of developing visual impairment recognition capabilities sensitive to wavelength changes. This not only reduces the threat of light damage to bionic visual systems but also promotes the development of intelligent vision technologies with excellent robustness and reliability. Although some studies have attempted to simulate nociceptors—for example, Kim's team successfully simulated the four basic characteristics of nociceptors, namely threshold, relaxation, analgesia, and hyperalgesia, by utilizing the charge trapping and releasing properties of Pt / HfO2 / TiN memristors, and Yoon et al. achieved simulation of nociceptors by utilizing the similarity between the dynamic characteristics of diffused memristors and biological biochemical processes—there is still a lack of biomimetic research in this field on wavelength-sensitive visual nociceptive behavior. Developing an optical synaptic device that can respond to light stimuli of different wavelengths and has wavelength-sensitive characteristics has become an urgent technical problem to be solved and has important scientific and technological value. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a heterojunction artificial synapse device that combines multi-wavelength response and biomimetic damage sensing, thus solving the problems mentioned in the background section.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a heterojunction artificial synapse device combining multi-wavelength response and biomimetic damage sensing, comprising a substrate, a silicon dioxide layer, a silicon-rich silicon nitride layer, a molybdenum disulfide layer, and an electrode layer; the silicon dioxide layer covers the surface of the substrate, the silicon-rich silicon nitride layer is deposited on the side of the silicon dioxide layer away from the substrate, the molybdenum disulfide layer is transferred to the side of the silicon-rich silicon nitride layer away from the silicon dioxide layer, and the electrode layer is disposed on the side of the molybdenum disulfide layer away from the silicon-rich silicon nitride layer; the substrate is p ++ The silicon substrate is a silicon-rich silicon nitride layer prepared by plasma-enhanced chemical vapor deposition, and the molybdenum disulfide layer is a thin layer structure with atomic-level thickness.
[0006] Preferably, the silicon dioxide layer has a thickness of 285 nm, the silicon-rich silicon nitride layer has a thickness of 100 nm, the molybdenum disulfide layer has six layers, and the electrode layer consists of a chromium adhesion layer and a gold conductive layer, wherein the chromium adhesion layer has a thickness of 5 nm and the gold conductive layer has a thickness of 45 nm.
[0007] Preferably, the ratio of silicon atoms to nitrogen atoms in the silicon-rich silicon nitride layer exceeds the stoichiometric ratio of silicon atoms to nitrogen atoms in Si3N4 (3:4), and Si–Si bonds are formed in the silicon-rich silicon nitride layer, which introduce charge-trapping states in the band gap of the silicon-rich silicon nitride layer.
[0008] Preferably, the device is capable of responding to short-wavelength light with a wavelength of 365nm and long-wavelength light with a wavelength of 530nm, generating photocurrent under different wavelength light stimulation, and the photocurrent generated under short-wavelength light stimulation is greater than the photocurrent generated under long-wavelength light stimulation.
[0009] Preferably, the device has a biomimetic synaptic function, which can realize excitatory postsynaptic current, pairing pulse facilitation, short-term memory and long-term memory; the pairing pulse facilitation is induced by applying a pair of light pulses with a duration of 1 second and an interval of 0.1 seconds to 9 seconds; the short-term memory and long-term memory are realized by adjusting the frequency and number of light stimulation pulses.
[0010] Preferably, the device has a biomimetic injury sensing function, which can simulate the threshold characteristics, relaxation behavior, hyperalgesia characteristics and abnormal pain characteristics in biological injury sensing; the threshold characteristics are manifested in that when the postsynaptic current caused by light stimulation reaches a set threshold, the device generates pain sensing; the relaxation behavior is manifested in that the photocurrent gradually increases during illumination and slowly decays after the illumination is removed.
[0011] Preferably, the hyperalgesia characteristic is manifested as the device responding to light stimulation that did not originally reach the threshold after being damaged by low-intensity light stimulation; the abnormal pain characteristic is manifested as the device responding to long-wavelength light stimulation that was originally harmless after being damaged by high-intensity light stimulation.
[0012] Preferably, the parameters of the plasma-enhanced chemical vapor deposition process are: deposition temperature 330°C-370°C, radio frequency power 90W-110W, and the silicon content of the silicon-rich silicon nitride layer is adjusted by regulating the gas flow ratio of silane and nitrogen precursor.
[0013] Preferably, the molybdenum disulfide layer is obtained from the bulk molybdenum disulfide crystal by mechanical peeling and transferred to the surface of the silicon-rich silicon nitride layer using a dry transfer technique with the help of a polydimethylsiloxane film as a transfer medium.
[0014] Preferably, the electrode layer is prepared by electron beam lithography, magnetron sputtering, and a lift-off process. In electron beam lithography, electron beam photoresist is used, and a patterned window is formed by pre-baking, exposure, and development. In magnetron sputtering, a chromium adhesion layer and a gold conductive layer are deposited sequentially at room temperature. In the lift-off process, the sample is immersed in a photoresist remover solution to remove the photoresist in the unexposed area and the metal layer above it. After cleaning and drying, a complete electrode is formed.
[0015] This invention provides a heterojunction artificial synapse device that combines multi-wavelength response and biomimetic damage sensing. It offers the following advantages: 1. This invention constructs a heterojunction structure of molybdenum disulfide and silicon-rich silicon nitride and optimizes the material parameters and fabrication process of each layer to achieve a device with high efficiency in response to short-wavelength light of 350nm-380nm and long-wavelength light of 510nm-550nm. Moreover, the photocurrent generated under short-wavelength light stimulation is greater than that under long-wavelength light stimulation, which meets the needs of multi-wavelength visual information perception and provides hardware support for optical signal recognition and processing in complex environments.
[0016] 2. This invention utilizes the high-density charge-trapping states introduced by Si–Si bonds in the silicon-rich silicon nitride layer, combined with the excellent two-dimensional semiconductor properties of the molybdenum disulfide layer, to realize biomimetic synaptic functions such as excitatory postsynaptic current, pairing pulse facilitation, short-term memory, and long-term memory. At the same time, it simulates the threshold characteristics, relaxation behavior, hyperalgesia, and abnormal pain characteristics in biological damage perception, enabling the device to have both information processing and active protection capabilities, thereby improving the robustness and reliability of the biomimetic vision system.
[0017] 3. This invention adopts an integrated design of sensing and storage processing, abandoning the complex architecture of separating photodetectors, memory and processor in traditional machine vision. Through the all-optical-controlled triggering mechanism and the charge regulation effect of the heterojunction interface, it realizes low-power, low-latency visual information perception and damage warning, providing a new path for the miniaturization and high-efficiency development of brain-like computing systems, neuromorphic chips and intelligent vision devices.
[0018] 4. This invention, through a simplified device structure design, overcomes the limitations of traditional injury sensing devices that rely on complex components or additional programming to achieve their functions. While maintaining multi-wavelength response characteristics, it can directly simulate the core sensing function of biological injury receptors. This not only reduces the difficulty of device fabrication, integration cost, and operating power consumption, but also ensures the accuracy and timeliness of injury sensing through structural synergy. It provides an efficient solution for miniaturized and low-cost applications in fields such as neuromorphic sensing and bionic electronic skin. Attached Figure Description
[0019] Figure 1 This is a schematic diagram showing the structure and material properties of the synaptic device of the present invention; Figure 2 This is a schematic diagram illustrating the basic characteristics and operating mechanism of the device of the present invention; Figure 3 This is a schematic diagram of the PPF characteristics of the device of the present invention; Figure 4 This is a schematic diagram of the STM and LTM characteristics of the device of the present invention; Figure 5This is a biomimetic demonstration diagram of the threshold characteristics in the injury perception of the present invention; Figure 6 This is a schematic diagram illustrating the biomimetic demonstration of allergic reactions, abnormal pain, and relaxation behavior in injury perception according to the present invention. Detailed Implementation
[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0021] Please see the appendix Figure 1 -Appendix Figure 6 This invention provides a heterojunction artificial synapse device that combines multi-wavelength response and biomimetic damage perception.
[0022] Example 1 In the device structure, the substrate is selected as p ++ A silicon substrate was used, with a silicon dioxide layer of 285 nm thickness covering its surface. On the side of the silicon dioxide layer away from the substrate, a silicon-rich silicon nitride layer of 100 nm thickness was deposited using plasma-enhanced chemical vapor deposition (PECVD). During deposition, the gas flow ratio of silane to nitrogen was controlled at 1:8, the deposition temperature was set at 350°C, and the RF power was 100 W to ensure that the ratio of silicon atoms to nitrogen atoms in the silicon-rich silicon nitride layer exceeded 3:4, forming a large number of Si–Si bonds to introduce sufficient charge-trapping states. A molybdenum disulfide layer was obtained from a bulk molybdenum disulfide crystal with a purity >99.999% using mechanical exfoliation. The six layers were precisely transferred to the surface of the silicon-rich silicon nitride layer using a dry transfer technique with polydimethylsiloxane film as the transfer medium. The electrode layer consists of a chromium adhesion layer and a gold conductive layer. The chromium adhesion layer is 5 nm thick and the gold conductive layer is 45 nm thick. It is prepared by electron beam lithography, magnetron sputtering and lift-off process. In the electron beam lithography process, AZ5214E photoresist is used. The patterned window is formed by pre-baking, exposure and development. Magnetron sputtering is performed at room temperature. After lift-off, the electrode is cleaned and dried with anhydrous ethanol and deionized water to obtain a complete electrode.
[0023] During testing, the device used short-wavelength light (365nm) and long-wavelength light (530nm) as stimulation sources. The light power was calibrated using a power meter, and the power and pulse width of the light stimulation were controlled by a signal generator. Test results showed that the photocurrent generated by the device under 365nm light stimulation was significantly greater than that under 530nm light stimulation, and it could stably achieve excitatory postsynaptic current, paired pulse facilitation, short-term memory, and long-term memory functions. Paired pulse facilitation was induced by applying a pair of light pulses with a duration of 1 second and a 1-second interval. In biomimetic injury perception testing, when the postsynaptic current induced by light stimulation reached the set injury threshold of 15nA, the device generated injury perception, exhibiting clear threshold characteristics. The photocurrent gradually increased during illumination and slowly decayed after the light was removed, simulating the relaxation behavior of biological injury perception. After being damaged by 200uW low-intensity light stimulation, the device responds to light stimulation that did not originally reach the threshold, exhibiting hyperalgesia characteristics; after being damaged by 400uW high-intensity light stimulation, it responds to 530nm long-wavelength light stimulation that was originally harmless, achieving biomimetic simulation of abnormal pain characteristics.
[0024] Example 2 This embodiment provides another heterojunction artificial synapse device that combines multi-wavelength response and biomimetic damage sensing. The specific structure and fabrication process are as follows: The substrate uses p ++ A silicon substrate is formed, with a 275 nm thick silicon dioxide layer covering its surface. A 110 nm thick silicon nitride layer is deposited on the side of the silicon dioxide layer furthest from the substrate. This layer is fabricated using plasma-enhanced chemical vapor deposition (PECVD), with a silane to nitrogen gas flow rate ratio of 1:5, a deposition temperature of 340°C, and an RF power of 90 W. This process ensures sufficient Si–Si bonds within the silicon nitride layer, guaranteeing abundant charge-trapped states within the bandgap. A five-layer molybdenum disulfide layer is obtained from a bulk molybdenum disulfide crystal via mechanical exfoliation and is transferred to the surface of the silicon nitride layer using a polydimethylsiloxane film. Strict environmental cleanliness control is maintained during the transfer process to prevent interface contamination. The chromium adhesion layer of the electrode layer is 4 nm thick, and the gold conductive layer is 42 nm thick. The fabrication process includes electron beam lithography, magnetron sputtering, and lift-off. AZ5214E photoresist is used for electron beam lithography. The patterned window is formed by pre-baking, exposure, and development. The chromium adhesion layer and the gold conductive layer are deposited sequentially at room temperature by magnetron sputtering. After lift-off, the electrode is cleaned with anhydrous ethanol and deionized water and dried to obtain a complete electrode structure.
[0025] Performance tests were conducted on the device, using short-wavelength light (355nm) and long-wavelength light (520nm) as stimulation signals. The photostimulation parameters were controlled by a signal generator, and the light power was calibrated using a PM100A power meter. Test results showed that the device could generate stable photocurrents under different wavelengths of light stimulation, with the photocurrent under 355nm short-wavelength light stimulation being significantly greater than that under 520nm long-wavelength light stimulation. In biomimetic synaptic function tests, pairing pulse facilitation was successfully induced by applying a pair of light pulses with a duration of 1 second and an interval of 0.1 to 9 seconds. Furthermore, the short-term and long-term memory could be flexibly switched by adjusting the light stimulation frequency (0.1Hz-1Hz) and the number of pulses. In biomimetic injury perception tests, the device showed a significant response and clear threshold characteristics when the light stimulation intensity reached the power corresponding to 13nA. The photocurrent gradually increased during illumination and slowly decayed after the light was removed, simulating the relaxation behavior of biological injury perception. After being damaged by low-intensity light stimulation of 180uW and 1.0mW, the device responded to light stimulation that was not originally at the threshold, exhibiting hyperalgesia. After being damaged by high-intensity light stimulation of 1.5mW, it responded to the originally harmless 520nm long-wavelength light stimulation, successfully achieving biomimetic simulation of abnormal pain characteristics. Moreover, the device performance was stable and the repeatability was good throughout the test.
[0026] First, plasma-enhanced chemical vapor deposition (PECVD) was used to coat the surface of p with a 285 nm thick silicon dioxide layer. ++ A 100 nm thick sr-SiN layer was deposited on a silicon substrate. X Thin film. During deposition, the silicon content in the film was effectively controlled by precisely adjusting the gas flow ratio of silane (SiH4) and nitrogen (N2) precursors. This process was carried out at a deposition temperature of 350°C and a radio frequency power of 100W, ensuring the uniformity and compositional controllability of the film. Subsequently, atomically thin samples were obtained from bulk molybdenum disulfide crystals using mechanical exfoliation. Using polydimethylsiloxane (PDMS) film as a transfer medium, the obtained MoS2 thin film was precisely transferred to the aforementioned sr-SiN using a dry transfer technique. X On the surface of the / SiO2 / Si substrate, a material stack structure is formed that can be used for subsequent device fabrication.
[0027] Based on the above-prepared MoS2 / sr-SiN XThe SiO2 / Si material stacked structure was fabricated using electron beam lithography. First, electron beam photoresist was spin-coated onto the sample surface. After pre-baking, electron beam exposure was performed to define the electrode pattern, followed by development to form patterned windows. A 5 nm chromium (Cr) adhesion layer and a 45 nm gold (Au) conductive layer were sequentially deposited at room temperature using a magnetron sputtering system. Finally, a lift-off process was used: the sample was immersed in a resist remover to completely remove the photoresist and the overlying metal layer from the unexposed areas. After cleaning and drying with anhydrous ethanol and deionized water, a complete Cr / Au electrode structure was obtained, completing the device fabrication.
[0028] The electrical and photosynaptic properties of the fabricated device were measured at room temperature using a semiconductor parameter analyzer (FS-Pro). Two laser sources with wavelengths of 365 nm and 530 nm were used to program the optoelectronic device. The power and pulse width of the photostimulation were controlled by a signal generator. This study designed and fabricated a device based on MoS2 / sr-SiN. X Heterojunction synaptic transistor. Figure 1 (a) shows a schematic diagram of the device, with the corresponding optical micrograph in the upper right corner (scale bar: 20 μm). This device is a fully optically controlled biomimetic synapse device, and its biomimetic synapse principle is as follows: Figure 1 (a) As shown in the schematic diagram on the right, two light signals with wavelengths of 365 nm and 530 nm, respectively, are used as presynaptic stimulation inputs. After photoexcitation, an excitatory postsynaptic current is generated at the device output. This photoelectric response behavior successfully simulates the signal transmission characteristics of biological synapses, and its specific dynamic response mechanism will be described in detail later. To clarify the physical and chemical properties of the key materials, we performed systematic material characterization of the device. Figure 1 (b) shows the Raman spectrum of the MoS2 thin film in the device, visible at 382.2 cm⁻¹. -1 With 407.0cm -1 There are two significant and sharp characteristic peaks at this point, corresponding to the in-plane vibration modes of MoS2 ( ) and out-of-plane vibration modes ( The wavenumber difference between the two peaks is approximately 24.8 cm⁻¹. -1 ,according to and The dependence of peak spacing on the number of layers suggests that the prepared MoS2 nanosheets are approximately six layers thick, indicating their excellent two-dimensional semiconductor properties. Furthermore, the silicon nitride dielectric layer used in the device is sr-SiN grown via PECVD. X The chemical composition of the thin film was analyzed by X-ray photoelectron spectroscopy (XPS), and the results are as follows: Figure 1As shown in (c) and (d), the shaded areas correspond to the integrated areas of the Si2p and N1s core energy level peaks, respectively. Notably, the integrated area of Si2p is significantly larger than that of N1s, exceeding the theoretical Si:N ratio (3:4) in Si3N4. This result indicates the presence of excess silicon atoms in the film, which tend to form Si–Si bonds, thereby introducing abundant charge-trapped states into the band gap. (sr-SiN) X The widespread presence of these Si–Si bonds in the dielectric layer significantly enhances its charge trapping and storage capabilities, providing important material support for the development of photoreactive storage devices that rely on this medium and the realization of synaptic weighted photoelectric modulation.
[0029] Subsequently, the electrical performance of the device was tested. For example... Figure 2 As shown in (a), the transfer characteristic curves of the device exhibit typical n-type semiconductor behavior. At V ds Clockwise gate voltage scan at 0.1V (V gs =20-40V), it can be observed that as V increases... gs The increased and expanded hysteresis window is due to the hysteresis characteristic of sr-SiN. X The trapping and release of electrons by interface trap states reveals the charge trapping mechanism present in the device. Figure 2 (b) shows that the device exhibits excellent photoelectric response characteristics under light stimulation. The photocurrent measured under different wavelengths of light is significantly higher than the dark current, with the photocurrent being even greater under shorter wavelengths of light. This is due to the higher excitation energy generating more photogenerated carriers. Furthermore, the device further exhibits non-volatile photoconductive behavior. Figure 2 As shown in (c), in V gs =0V、V ds Under a voltage of 1V, a single laser pulse (wavelength 530nm, power density 0.1mWcm²) is applied. -2 At a frequency of 0.5 Hz and a pulse width of 1 s, the photocurrent exhibits typical synaptic response characteristics. This photoelectric conversion process can be analogous to the neurotransmitter release mechanism in biological synapses: when the presynaptic neuron is stimulated, the action potential triggers the release of neurotransmitters, thereby changing the membrane potential of the postsynaptic neuron and inducing an excitatory postsynaptic current. The photocurrent changes generated by the device under light pulse stimulation simulate the electrical signal response of such biological synapses. This behavior mainly originates from Sr-SiN. X High-density trap states introduced by Si-Si bonds in the dielectric layer. Figure 2 (d) illustrates the operating mechanism of the device. Under ideal conditions without trapped states, the photogeneration and recombination energies in MoS2 rapidly reach dynamic equilibrium under laser irradiation, thereby generating a constant photocurrent. In the Sr-SiN dielectric layer... XBy introducing trapped states to capture electrons, the electron-hole recombination rate is significantly slowed down. This leads to a gradual increase in photocurrent, which takes a long time to reach equilibrium. The photocurrent exhibits a gradual increase during illumination and a slow decay after illumination is removed, a phenomenon similar to the enhancement and relaxation of excitatory postsynaptic current in the dynamic response of biological excitatory synapses. This device successfully simulates the excitatory electrical signals and memory behavior of biological synapses by capturing photogenerated carriers through interface trapped states, demonstrating its potential in low-power and neuromorphic computing applications.
[0030] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A heterojunction artificial synapse device combining multi-wavelength response and biomimetic damage sensing, characterized in that, The system comprises a substrate, a silicon dioxide layer, a silicon-rich silicon nitride layer, a molybdenum disulfide layer, and an electrode layer. The silicon dioxide layer covers the surface of the substrate. The silicon-rich silicon nitride layer is deposited on the side of the silicon dioxide layer away from the substrate. The molybdenum disulfide layer is transferred to the side of the silicon-rich silicon nitride layer away from the silicon dioxide layer. The electrode layer is disposed on the side of the molybdenum disulfide layer away from the silicon-rich silicon nitride layer. The substrate is p-type. ++ The silicon substrate is a silicon-rich silicon nitride layer prepared by plasma-enhanced chemical vapor deposition, and the molybdenum disulfide layer is a thin layer structure with atomic-level thickness.
2. The heterojunction artificial synapse device according to claim 1, characterized in that, The thickness of the silicon dioxide layer is 270nm-300nm, the thickness of the silicon-rich silicon nitride layer is 90nm-110nm, the number of molybdenum disulfide layers is 4-8, and the electrode layer is composed of a chromium adhesion layer and a gold conductive layer, the thickness of the chromium adhesion layer is 3nm-7nm, and the thickness of the gold conductive layer is 40nm-50nm.
3. The heterojunction artificial synapse device according to claim 1, characterized in that, The ratio of silicon atoms to nitrogen atoms in the silicon-rich silicon nitride layer exceeds the stoichiometric ratio of silicon atoms to nitrogen atoms of 3:4 in Si3N4. Si–Si bonds are formed in the silicon-rich silicon nitride layer, and the Si–Si bonds introduce charge-trapping states in the band gap of the silicon-rich silicon nitride layer.
4. The heterojunction artificial synapse device according to claim 1, characterized in that, The device is capable of responding to short-wavelength light with wavelengths of 350nm-380nm and long-wavelength light with wavelengths of 510nm-550nm, generating photocurrent under different wavelength light stimulation, and the photocurrent generated under short-wavelength light stimulation is greater than that generated under long-wavelength light stimulation.
5. The heterojunction artificial synapse device according to claim 1, characterized in that, The device has a biomimetic synaptic function, which can realize excitatory postsynaptic current, pairing pulse facilitation, short-term memory and long-term memory; the pairing pulse facilitation is induced by applying a pair of light pulses with a duration of 1 second and an interval of 0.1 seconds to 9 seconds; the short-term memory and long-term memory are achieved by adjusting the frequency and number of light stimulation pulses.
6. The heterojunction artificial synapse device according to claim 1, characterized in that, The device has a biomimetic injury sensing function, which can simulate the threshold characteristics, relaxation behavior, hyperalgesia characteristics and abnormal pain characteristics in biological injury sensing. The threshold characteristics are manifested in that when the postsynaptic current caused by light stimulation reaches a set threshold of 15nA, the device generates pain sensing. The relaxation behavior is manifested in that the photocurrent gradually increases during illumination and slowly decays after the illumination is removed.
7. The heterojunction artificial synapse device according to claim 6, characterized in that, The hyperalgesia characteristic is that after the device is damaged by low-intensity light stimulation, it responds to light stimulation that did not originally reach the threshold; the abnormal pain characteristic is that after the device is damaged by high-intensity light stimulation, it responds to long-wavelength light stimulation that was originally harmless.
8. The heterojunction artificial synapse device according to claim 1, characterized in that, The parameters of the plasma-enhanced chemical vapor deposition process are: deposition temperature 330°C-370°C, radio frequency power 90W-110W, and the silicon content of the silicon-rich silicon nitride layer is adjusted by regulating the gas flow ratio of silane and nitrogen precursor.
9. The heterojunction artificial synapse device according to claim 1, characterized in that, The molybdenum disulfide layer was obtained from the bulk molybdenum disulfide crystal by mechanical exfoliation and transferred to the surface of the silicon-rich silicon nitride layer using a dry transfer technique with the help of a polydimethylsiloxane film as a transfer medium.
10. The heterojunction artificial synapse device according to claim 1, characterized in that, The electrode layer is prepared by electron beam lithography, magnetron sputtering and lift-off process; in electron beam lithography, electron beam photoresist is used, and a patterned window is formed by pre-baking, exposure and development; magnetron sputtering process deposits a chromium adhesion layer and a gold conductive layer sequentially at room temperature. The stripping process involves immersing the sample in a stripping solution to peel off the photoresist and the metal layer above it from the unexposed areas. After cleaning and drying, a complete electrode is formed.