A ScN channel layer, a preparation method thereof, and a photoelectric synaptic device and system comprising the channel layer

Abstract

The application discloses a ScN channel layer and a preparation method thereof, and an optoelectronic synapse device and system comprising the channel layer, and belongs to the technical field of semiconductors. In view of the problems of poor uniformity, inaccurate thickness control and insufficient compatibility with CMOS technology of the ScN film in wafer-level preparation in the prior art, the ScN film is prepared by using an atomic layer deposition technology, and the self-limiting surface reaction mechanism is utilized, so that the thickness and composition uniformity of the wafer-level ScN film are fundamentally solved. The application further provides an optoelectronic synapse device and an optoelectronic synapse vision system. Combined with the accurate control of the ALD process, the speed, durability and energy consumption and other comprehensive performance indexes of the optoelectronic synapse device can be synergistically optimized.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, specifically relating to an ScN channel layer, its fabrication method, and a photoelectric synaptic device and system containing the channel layer. Background Technology

[0002] Currently, in the field of neuromorphic computing, opto-synaptic devices, as key units for simulating biological synaptic functions, have received widespread attention. Mainstream opto-synaptic devices are primarily constructed based on systems such as metal oxides, two-dimensional materials, perovskites, and organic materials. Among them, scandium nitride, as an emerging group III nitride semiconductor, exhibits enormous application potential in the optoelectronic field due to its high electron mobility and excellent chemical and thermal stability.

[0003] Currently, ScN thin film fabrication mainly relies on physical vapor deposition (PVD) technology, especially magnetron sputtering and pulsed laser deposition. These traditional methods struggle to achieve precise control of nanometer-scale thickness and excellent uniformity at the wafer level (especially 8 inches and above). Furthermore, the inherent directional deposition and line-of-sight characteristics of PVD fundamentally limit its ability to achieve uniform, conformal coverage on high aspect ratio three-dimensional nanostructures. This is a key limitation for back-end circuitry (BEOL) integration in advanced CMOS nodes. Rayner et al. (GB Rayner, N. O'Toole, B. Liu, J. Shallenberger, J. Zhu, T. Palacios, P. Behera, S. Cheema, B. Johs, NAStrnad, J. Vac. Sci. Technol. A 2025, 43, 020401.) reported the successful deposition of ScN thin films via plasma-enhanced atomic layer deposition (PEALD), demonstrating a 75% step coverage from top to bottom for trench structures with an aspect ratio of 4:1. However, the high-energy materials involved in the plasma process can lead to interfacial damage and defect state formation in the near-surface region, thereby impairing device performance and reliability.

[0004] The crystallinity, defect density, and interface states of thin films are crucial to photoelectric synaptic performance, but existing methods have limited ability to control these properties. Therefore, providing a method for scalable fabrication of ScN thin films that is highly compatible with standard integrated circuit processes, in order to obtain high-quality, uniform, and interface-controllable ScN thin films on large-size wafers, is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] To address the problems of poor uniformity, imprecise thickness control, and insufficient compatibility with CMOS processes in existing ScN thin film fabrication technologies, this invention provides an ScN channel layer, its fabrication method, and optoelectronic synaptic devices and systems incorporating the channel layer. This achieves high-quality, uniform, and interface-controllable ScN thin film fabrication and constructs high-performance, scalable optoelectronic synaptic devices.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for fabricating an ScN channel layer includes the following steps:

[0008] In the reaction chamber, scandium-containing precursors and nitrogen-containing active reaction sources are alternately introduced, and ScN channel layers are deposited on the substrate through a specific ALD cycle.

[0009] In the above-described method, the scandium-containing precursor is tris(N,N'-diisopropylmethylamidinyl)scandium (Sc( i PrAMD)3), tris(cyclopentadienyl)scandium (ScCp3) or tris(N,N'-diisopropylethamidinyl)scandium and its derivatives, preferably tris(N,N'-diisopropylmethamidinyl)scandium; the nitrogen-containing active reaction source is ammonia, hydrazine or methylhydrazine, preferably ammonia; the wafer-level substrate is an 8-inch or 12-inch large-size wafer substrate.

[0010] The deposition temperature was controlled between 370°C and 450°C; the pressure was maintained in a constant range of 1-10 mbar.

[0011] The specific ALD cycle is an alternating pulse-purge ALD cycle, the process of which is as follows: First pulse: A gaseous scandium precursor is pulsed into the chamber for 0.5-2 seconds, causing it to chemically adsorb onto the substrate surface; First purge: An inert gas is purged for 2-30 seconds. Due to the large size of the scandium precursor molecules, this purge time needs to be long enough to ensure thorough removal and avoid cross-contamination; Second pulse: A nitrogen-containing reactive source is pulsed into the chamber for 1-5 seconds, causing it to react with the adsorbed scandium precursor to generate an atomic layer of ScN; Second purge: An inert gas is purged for 2-20 seconds, completing the cleaning of the reaction chamber. The above steps are repeated multiple times as needed to achieve a thickness of 10-100 nm.

[0012] The above method utilizes the self-limited growth characteristics of atomic layer deposition (ALD) technology and selects a specific metal-organic precursor Sc( iThe reaction of PrAMD3 with ammonia gas within a specific temperature window enables efficient chemical adsorption and reaction, ensuring a high deposition rate and excellent stoichiometry for ScN films. This allows for atomic-level precise control of ScN film thickness and ensures excellent uniformity on wafer-level substrates, solving the problem of uneven thickness on large-size wafers caused by traditional physical deposition methods. Furthermore, this process is highly compatible with CMOS processes, providing a foundation for large-scale integration.

[0013] The present invention also provides a photoelectric synapse device, including a substrate, a ScN channel layer prepared above on the substrate, and an electrode located on the surface of the ScN channel layer; based on the ALD-ScN channel layer, non-volatile continuous conductance adjustment can be achieved under the synergistic stimulation of applied light pulses and electrical pulses; by using the high-quality ScN thin film prepared by ALD as the channel layer, the high carrier mobility and good photoelectric response characteristics of ScN material are fully utilized, and the weight update process of biological synapses is accurately simulated through photoelectric synergistic effect, thus achieving high performance and stability of the device.

[0014] The present invention also provides an opto-synaptic vision system, including a photosensitive unit, the aforementioned opto-synaptic device, and peripheral circuitry.

[0015] Beneficial effects: This invention provides an ScN channel layer, a method for fabricating the same, and a photoelectric synapse device and system comprising the channel layer, which have the following advantages compared with the prior art:

[0016] This invention employs atomic layer deposition (ALD) technology to fabricate ScN thin films. Leveraging its self-limiting surface reaction mechanism, it fundamentally solves the problems of thickness and compositional uniformity in wafer-level ScN thin films. Film thickness non-uniformity can be controlled within ±6%, laying the foundation for the fabrication of large-scale uniform device arrays. ALD technology exhibits excellent conformal properties and 3D compatibility, enabling conformal coverage on high aspect ratio structures, providing possibilities for the future development of 3D integrated neuromorphic chips. Furthermore, the ALD process operates at lower temperatures, allowing for direct back-end integration on partially completed silicon substrates, and is highly compatible with standard CMOS process lines. The fabricated ScN possesses an tunable bandgap, high carrier mobility, and good stability. Combined with the precise control of the ALD process, it can synergistically optimize the overall performance indicators of opto-synaptic devices, including speed, durability, and energy consumption. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the process for preparing ScN thin films by atomic layer deposition in an embodiment of the present invention;

[0018] Figure 2 These are the XPS energy spectrum and wafer-level film thickness and refractive index mapping diagrams of the ScN thin films prepared in the embodiments of the present invention;

[0019] Figure 3 This is a schematic diagram of the structure of the photoelectric synapse device in an embodiment of the present invention;

[0020] Figure 4 This is a test curve of the photoelectric response performance of the photoelectric synaptic device in the embodiment of the present invention;

[0021] Figure 5 This refers to the energy consumption of each synaptic event in this embodiment of the invention. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments:

[0023] Example 1:

[0024] This embodiment provides a method for atomic layer deposition of wafer-level ScN channel layers for use in optoelectronic synaptic devices, such as... Figure 1 As shown, the method specifically includes the following steps:

[0025] S1: Provide a wafer-level substrate and place it in the reaction chamber.

[0026] In this embodiment, wafer-level substrate refers to a semiconductor substrate with a diameter of 8 inches or more, such as a silicon substrate, sapphire substrate, or silicon carbide substrate. Placing a large-size substrate in the reaction chamber aims to solve the problem of uneven film thickness in traditional physical vapor deposition (such as sputtering) on ​​large-area substrates. The reaction chamber needs to have precise temperature control and pressure regulation functions to ensure the stability of subsequent reactions.

[0027] S2: In the reaction chamber, scandium-containing precursors and nitrogen-containing active reaction sources are alternately introduced into the wafer-level substrate to form ScN thin films through a specific ALD cycle.

[0028] Specifically, the atomic layer deposition (ALD) process utilizes the self-limiting property of surface reactions, where precursor molecules undergo chemisorption on the substrate surface until saturation is reached, ceasing further deposition. This ensures that regardless of the gas flow distribution, the thin film can be grown layer by layer with a single-atom-layer or sub-single-atom-layer precision. This self-limiting growth mechanism is key to achieving highly uniform thickness of large-area wafer-level thin films. In this embodiment, the specific ALD cycle includes four stages: First pulse: A gaseous scandium precursor is pulsed into the chamber for 0.5-2 seconds, causing it to chemisorb onto the substrate surface; First purge: An inert gas is purged for 2-30 seconds. Due to the large size of the scandium precursor molecules, this purge time needs to be long enough to ensure thorough removal and avoid cross-contamination; Second pulse: A nitrogen-containing reactive source is pulsed into the chamber for 1-5 seconds, causing it to react with the adsorbed scandium precursor to generate an atomic layer of ScN; Second purge: An inert gas is purged for 2-20 seconds, completing the cleaning of the reaction chamber. Repeat the above steps as needed.

[0029] In this embodiment, the number of cycles is more than 500, and the film thickness ranges from 10 to 100 nm.

[0030] To obtain high-quality ScN films, specific ALD cycles need to be performed under specific temperature and pressure conditions. In this embodiment, the temperature of the reaction chamber is controlled between 370°C and 450°C, specifically 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, and 450°C. The selection of this temperature window is crucial: if the temperature is too low, the precursor may not be able to obtain enough energy to overcome the surface activation energy, resulting in low adsorption efficiency or condensation; if the temperature is too high, the precursor may undergo thermal decomposition before reaching the substrate surface, disrupting the self-limiting growth mechanism and affecting the stoichiometry and crystal quality of the film. The pressure of the reaction chamber is typically controlled within a constant range of 1-10 mbar, specifically 1 mbar, 3 mbar, 5 mbar, 7 mbar, 9 mbar, and 10 mbar, to ensure that the gas flow is in a molecular flow or transitional flow state, which is beneficial for the diffusion and coverage of the precursor on complex morphological surfaces.

[0031] Through the above scheme, this embodiment utilizes the self-limiting growth characteristics of ALD technology. By precisely designing and synergistically controlling key parameters such as pulse time, purge time, and deposition cycle number of the scandium-containing precursor and nitrogen-containing reaction source, nanometer-level precise control of film thickness is achieved, ensuring excellent uniformity and high repeatability on 8-inch wafers. Figure 2 (c) and Figure 2As shown in (d), the thickness non-uniformity of the ScN film deposited on the 8-inch wafer is 5.73%, and the refractive index non-uniformity is 1.62%. This not only overcomes the defect of poor uniformity of traditional sputtering process on large-size wafers, but also ensures high crystallinity quality and excellent optoelectronic properties of the film through precise process parameter control, laying a material foundation for the subsequent fabrication of high-performance optoelectronic synaptic devices.

[0032] Example 2:

[0033] This embodiment is a further refinement based on Embodiment 1. In this embodiment, the scandium-containing precursor is tris(N,N'-diisopropylmethylamidinyl)scandium (Sc( i PrAMD)3), the nitrogen-containing active reaction source is ammonia.

[0034] Specifically, choose Sc( i PrAMD)3 is used as a precursor based on its unique physicochemical properties, Sc( i PrAMD3 exhibits more suitable volatility, enabling stable gas-phase transport at lower temperatures and avoiding pipeline blockage or film contamination issues caused by precursor condensation. More importantly, the NCN framework in this precursor ligand structure can undergo efficient ligand exchange reactions with ammonia. The reaction byproducts are mostly volatile small organic molecules, easily and completely removed during the purging stage, thus ensuring the high purity and ideal stoichiometry of the ScN film. This "easy-to-remove" characteristic is crucial for reducing the carbon and oxygen impurity content in the film, directly determining the carrier mobility and interface state density of subsequent optoelectronic synaptic devices.

[0035] Example 3:

[0036] The scandium precursor is tris(N,N'-diisopropylmethylammonium)scandium (Sc( i PrAMD)3), ammonia was selected as the nitrogen-containing reactive source. A static (immersion) ALD process was used for thin film preparation, as detailed below:

[0037] First pulse and immersion: A gaseous scandium precursor is pulsed into the chamber for 0.5-2 seconds. Then, all inlet and outlet valves of the chamber are closed, allowing the precursor to "immerse" in the static chamber for 5-30 seconds. The diffusion effect allows the precursor to fully penetrate into the micropores or complex three-dimensional structures, achieving surface saturation chemisorption.

[0038] First purge / evacuation: Open the inert gas purge valve and vacuum pump to thoroughly clean the chamber for 2-20 seconds to remove residual scandium precursors in the gas phase.

[0039] Second pulse and immersion: Nitrogen-containing active reaction source is pulsed into the cavity for 1-5 seconds. All inlet and outlet valves are closed again to allow the reaction source to immerse under static conditions for 5-20 seconds, ensuring that it fully reacts with the scandium precursor adsorbed in the deep structure to generate a dense ScN atomic layer.

[0040] Second purging / evacuation: Open the inert gas purging valve and vacuum pump to thoroughly clean the chamber for 2-20 seconds, removing reaction byproducts and unreacted reaction sources.

[0041] Repeat the above steps multiple times, depending on the required film thickness.

[0042] By incorporating a static diffusion step after the pulse is introduced into the precursor, the contact time between the precursor and the substrate surface is significantly extended, thereby further improving the uniform coverage of the bottom of the high aspect ratio structure based on pulse convection. Simultaneously, the duration of this static diffusion (i.e., immersion) of the precursor also takes into account the thermal stability of the precursor at the process temperature.

[0043] Example 4:

[0044] This embodiment provides a photoelectric synapse device, which is constructed based on the ScN thin film prepared by the ALD method described in Examples 1-3. Figure 3 As shown, the opto-synaptic device specifically includes a substrate, an isolation layer on the surface of the substrate, an ScN channel layer on the surface of the insulating layer, and interdigitated electrodes on the surface of the ScN channel layer.

[0045] The substrate is typically a silicon substrate, which serves both a supporting function and conductivity. The isolation layer is silicon dioxide (SiO2), providing electrical isolation. The ScN channel layer is the core functional layer of the device, deposited using the ALD process described in the aforementioned embodiments. Its thickness can be precisely controlled at the nanometer level according to specific device design requirements. The interdigitated electrodes are located on the surface of the ScN channel layer and are typically formed using metals such as gold, platinum, or titanium through magnetron sputtering and lift-off processes. It should be understood that although... Figure 3 The diagram shows an interdigitated electrode structure, but in other embodiments, the electrodes can also be simple strip or dot structures, as long as they can achieve the input and output of electrical signals.

[0046] The photoelectric synaptic device in this embodiment can achieve non-volatile continuous conductance adjustment under the synergistic stimulation of applied optical pulses and electrical pulses. Its working principle is based on the unique photoelectric properties and defect-state physical mechanism of ScN thin films. Combined with... Figure 4As shown in (a)-(c), when a light pulse of a specific wavelength (such as 450nm, 532nm, or 635nm) irradiates the ScN channel layer, the ScN thin film absorbs photon energy, generating photogenerated carriers. Under the influence of the electric field applied between the interdigitated electrodes, the photogenerated carriers separate and move directionally. During this process, some photogenerated carriers are captured by defect states inside the ScN thin film or by interface states at the interface between ScN and the insulating layer / electrode. This carrier capture effect leads to a significant change in the channel conductivity of the device, specifically an increase in the drain current. When the light pulse stimulation is removed, the captured carriers do not immediately recombine and disappear, but are released from the trap at a slow rate. This allows the device conductivity to be maintained at a high level, thus achieving a "non-volatile" memory function similar to that of a biological synapse. This photoelectric synergistic effect can accurately simulate the continuous, non-volatile adjustment of weights (i.e., device conductivity) in a biological synapse, realizing various synaptic plasticities, including the pairwise pulse facilitation factor (PPF).

[0047] Example 5:

[0048] The performance of the ScN thin film and photoelectric synapse device prepared in the above embodiments was characterized and verified to demonstrate the effectiveness and superiority of the technical solution of the present invention.

[0049] First, the chemical composition of the prepared ScN thin film was analyzed using X-ray photoelectron spectroscopy (XPS), such as... Figure 2 (a) and Figure 2 As shown in (b), XPS test results demonstrate that ScN films can be successfully deposited via thermal ALD. Figure 2 As shown in (a) and (b), the characteristic peaks of Sc 2p and N 1s are clearly visible in the spectra. The peaks at approximately 402 eV and approximately 409 eV in the Sc 2p spectrum correspond to the Sc 2p peaks at approximately 402 eV and approximately 409 eV, respectively. 3 / 2 and Sc 2p 1 / 2 Furthermore, the peak positions closely match the standard binding energy of the Sc-N bond, confirming the successful formation of Sc-N chemical bonds in the thin film. Simultaneously, no significant impurity peaks were detected in the spectrum (such as extremely weak carbon oxide peaks), indicating that the ALD process and specific precursor combination effectively suppressed impurity introduction, resulting in a high-purity ScN thin film. This high purity is fundamental to ensuring the carrier mobility and photoelectric response stability of subsequent devices.

[0050] Secondly, to verify the uniformity advantage of the ALD process of this invention in wafer-level fabrication, mapping tests on film thickness and refractive index were performed on an 8-inch wafer, such as... Figure 2As shown in (c) and (d), the thickness distribution at each test point on the wafer surface is extremely uniform, with thickness non-uniformity controlled within ±6%. The refractive index distribution also exhibits high consistency, reflecting the uniformity of film density and optical properties at the wafer scale. In contrast, if ScN films are prepared using traditional magnetron sputtering processes, significant thickness attenuation often occurs at the edges of large-size wafers due to the non-uniformity of particle flow and shading effects, with non-uniformity typically exceeding ±10%, making it difficult to meet the stringent consistency requirements of large-scale integrated circuits. The method of this invention utilizes the self-limiting surface reaction mechanism of ALD, enabling precursor molecules to be uniformly adsorbed onto the substrate surface, thereby overcoming the inherent defect of poor uniformity in physical deposition methods on large-size substrates and achieving high-quality film formation at the wafer scale.

[0051] The photoelectric response performance of the constructed photoelectric synaptic device was tested. For example... Figure 4 As shown in (a)-(c), under visible light pulse stimulation at wavelengths of 450 nm, 532 nm, and 635 nm, the current values ​​of the device all exhibit a step-like upward trend, simulating the excitatory postsynaptic current (EPSC) behavior of biological synapses. When the light pulse is removed, the current does not immediately return to its initial state but decays slowly, demonstrating its non-volatile memory characteristics. The physical mechanism of this phenomenon lies in the fact that the ScN thin film prepared by ALD has a high-quality lattice structure and controllable defect state density. After photogenerated carriers are captured by defects or interface states, the release process is slow, thus maintaining the change in conductance. Figure 5 As shown, the minimum energy consumption required for a single event of the photoelectric synaptic device in this embodiment is 9.2 fJ. A comparison of the minimum energy consumption of each functional layer in neural synapse applications in Table 1 shows that the photoelectric synaptic device in this embodiment exhibits excellent energy efficiency.

[0052] Table 1. Comparison of minimum energy consumption for different materials used in neural synapse applications

[0053] <![CDATA[MoS2]]> 445 26.67 <![CDATA[Bi2Te3]]> 360-1064 37.2 InSe 400 0.51 <![CDATA[MoSe2 / Bi2Se3]]> 790 <![CDATA[1×10 5 ]]> MXene / violet phosphorus 360 <![CDATA[1.47×10 4 <!-- 5 -->]]> <![CDATA[In2Se3 / MoS2]]> 1060 28 <![CDATA[CsPbBr3]]> 405 / 515 <![CDATA[3.93×10 8 ]]> <![CDATA[CsPbBr3QDs]]> 375 <![CDATA[1.4×10 6 ]]> <![CDATA[P3HT / TCP]]> 630 6300 ZnO 375 1.2 <![CDATA[In2O3 / ZnO]]> 365 <![CDATA[2×10 5 ]]> <![CDATA[SiO2 / Ca2Nb3O 10 ]]> 365 / 310 / 254 37.9 IZO / RGB-M-QD / IZO 406-640 500 ZnO / GO 365 23 <![CDATA[MoO3 / WO3]]> 405 67.6 <![CDATA[MoTe2 / MoS2]]> 532 / 780 / GaN 375 53.5 <![CDATA[ReS2 / h-BN / Gra]]> 405 500 ScN 375 / 450 / 532 / 635 9.2

[0054] In addition, the device's paired pulse facilitation (PPF) index was tested to verify its ability to simulate short-term plasticity of biological synapses. Figure 4 As shown in (d), the PPF exponent decreases with increasing pulse interval time, a trend consistent with the time-dependent plasticity of biological synapses. This indicates that the photoelectric synaptic device prepared by this invention not only possesses basic photoelectric response functions but also accurately simulates the dynamic behavior of biological synapses, providing a reliable hardware foundation for constructing high-precision, low-power neuromorphic computing systems. Through the above characterization and testing, the significant advantages of the ScN thin film ALD preparation method provided by this invention in terms of material quality, uniformity control, and device performance are fully demonstrated.

[0055] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A photoelectric synapse device, characterized in that: It includes a substrate, an ScN channel layer on the substrate, and an electrode on the surface of the ScN channel layer.

2. The photoelectric synapse device according to claim 1, characterized in that: It also includes an isolation layer located between the substrate and the ScN channel layer.

3. The photoelectric synapse device according to claim 1, characterized in that: The thickness of the ScN channel layer ranges from 10 to 100 nm.

4. A method for preparing the ScN channel layer according to any one of claims 1-3, characterized in that, The process includes the following steps: alternately introducing a scandium-containing precursor and a nitrogen-containing active reaction source into a reaction chamber, and depositing a ScN channel layer on the substrate through a specific ALD cycle.

5. The method for preparing the ScN channel layer according to claim 4, characterized in that, The scandium-containing precursor is tris(N,N'-diisopropylmethylammonium)scandium, tris(cyclopentadienyl)scandium, or tris(N,N'-diisopropylethamidinium)scandium and their derivatives.

6. The method for preparing the ScN channel layer according to claim 4, characterized in that, The nitrogen-containing reactive source is ammonia, hydrazine, or methylhydrazine.

7. The method for preparing the ScN channel layer according to claim 4, characterized in that, The ALD deposition temperature was controlled between 370°C and 450°C; the pressure was maintained in a constant range of 1-10 mbar.

8. The method for preparing the ScN channel layer according to claim 4 or 7, characterized in that, The specific ALD cycle is an alternating pulse-purge ALD cycle.

9. The method for preparing the ScN channel layer according to claim 8, characterized in that, The specific process of the alternating pulse-purge ALD cycle is as follows: First pulse: A gaseous scandium precursor is pulsed into the chamber for 0.5-2 seconds, causing it to chemically adsorb onto the substrate surface; First purge: An inert gas is introduced for 2-30 seconds. Due to the large size of the scandium precursor molecules, this purge time needs to be long enough to ensure thorough removal and avoid cross-contamination; Second pulse: A nitrogen-containing reactive source is pulsed into the chamber for 1-5 seconds, causing it to react with the adsorbed scandium precursor to generate an atomic layer of ScN; Second purge: An inert gas is introduced for 2-20 seconds to complete the cleaning of the reaction chamber; The above steps are repeated multiple times as needed.

10. An ScN channel layer, characterized in that, Prepared using the method described in any one of claims 4-9.

11. A photoelectric synaptic vision system, characterized in that: It includes a photosensitive unit, a photoelectric synaptic device as described in any one of claims 1-3, and peripheral circuitry.

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