Neuromorphic photoelectric memristor based on two-dimensional epsilon-Ga2O3 and preparation method thereof

Abstract

The invention discloses a neuromorphic photoelectric memristor based on two-dimensional epsilon-Ga2O3 and a preparation method thereof. The memristor comprises a substrate, a bottom electrode, an epsilon-Ga2O3 photoelectric active layer and a top electrode which are sequentially stacked from bottom to top, the thickness of the epsilon-Ga2O3 photoelectric active layer is 5-10 nm, and the epsilon-Ga2O3 photoelectric active layer is prepared through a liquid metal self-limiting oxidation method; the high-quality two-dimensional epsilon-Ga2O3 thin film is prepared by combining a liquid metal self-limiting oxidation method with a transfer printing process, the two-dimensional epsilon-Ga2O3 thin film is adopted as a photoelectric activation layer, the memristor of an MIM vertical structure is constructed, the device can realize a synaptic bionic mechanism of a photoelectric coordinated regulation and control electric conduction state, and the device can be applied to the field of photoelectric devices. Namely, the memristor has the bimodal response capability to voltage and ultraviolet illumination, effectively simulates various biological synaptic plasticity behaviors, and solves the technical problems that a traditional memristor depends on single driving of an electric field and is single in response.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor electronic devices and neuromorphic computing, specifically a two-dimensional ε-Ga2O3-based neuromorphic optoelectronic memristor and its preparation method, which belongs to the cross-research field of novel neuromorphic optoelectronic devices and memristive storage devices, and is suitable for various high-end application scenarios such as brain-like computing, information storage, logic computing and adaptive sensing. BACKGROUND

[0002] In recent years, with the rapid development of deep learning and artificial intelligence technology, the traditional von Neumann architecture is facing the problems of data transmission rate limitation and energy consumption bottleneck. In order to break through the barrier between storage and calculation, neuromorphic computing architecture emerges as the times require, which simulates the synaptic connection mode between human brain neurons to improve the parallelism and efficiency of information processing. Under this background, as a non-volatile resistance state modulator, the memristor has become a key component in simulating biological synaptic behavior in neuromorphic computing due to its unique advantages such as high density, low power consumption, variable resistance state and synaptic plasticity.

[0003] At the same time, two-dimensional materials have attracted widespread attention in the construction of memristor devices due to their atomic thickness, excellent interface adaptability and control ability. Compared with traditional bulk materials, two-dimensional materials can significantly reduce device size, improve response speed and energy consumption ratio. For example, Liu et al. (Liu et al., Advanced Functional Materials, 2023) constructed a light-stimulated memristive synaptic device based on MoS2, realizing stable brain-like plasticity regulation; Wang et al. (Wang et al., Nano Letters, 2022) used WS2 thin film to realize the change of synaptic weight under light regulation. However, the light response of such transition metal sulfide devices is mainly concentrated in the visible and near-infrared regions, making it difficult to achieve effective regulation of the ultraviolet band, and the long-term stability is still limited. On the other hand, oxide memristive systems such as HfO2 and TiO2 have been widely used in electrically stimulated memristors and neuromorphic device research (Zhang et al., Applied Physics Letters, 2021; Chen et al., Nature Electronics, 2022), but their intrinsic photosensitivity is insufficient, making it difficult to achieve electric-optical co-control, limiting their application expansion in the field of optoelectronic fusion neuromorphic computing. SUMMARY

[0004] In order to overcome the above-mentioned defects in the prior art, the purpose of the present application is to provide a two-dimensional epsilon-Ga2O3-based neuromorphic optoelectronic memristor and a preparation method thereof, a high-quality two-dimensional epsilon-Ga2O3 film is prepared by a liquid metal self-limiting oxidation method combined with a transfer process, and a vertical metal-insulator-metal (MIM) structure device is constructed, so that a synaptic biomimetic mechanism of photoelectric synergistic regulation of conductive state is realized, that is, the memristor device has a dual-mode response capability to voltage and ultraviolet light, effectively simulates various biological synaptic plasticity behaviors, and improves the stability, integration and process compatibility of the device.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0006] A two-dimensional epsilon-Ga2O3-based neuromorphic optoelectronic memristor comprises, from bottom to top, a substrate, a bottom electrode, an epsilon-Ga2O3 photoelectric active layer and a top electrode, wherein the thickness of the epsilon-Ga2O3 photoelectric active layer is 5-10 nm and the epsilon-Ga2O3 photoelectric active layer is prepared by a liquid metal self-limiting oxidation method.

[0007] The substrate is Si / SiO2, the materials of the bottom electrode and the top electrode are both inert metals or conductive oxides with a thickness of 20-50 nm, the inert metal is Pt or Au or Cr, and the conductive oxide is ITO or AZO.

[0008] A preparation method of a two-dimensional epsilon-Ga2O3-based neuromorphic optoelectronic memristor comprises the following steps: growing an epsilon-Ga2O3 film with a thickness of 5-10 nm on the surface of a cleaned substrate by a liquid metal self-limiting oxidation method, and transferring the epsilon-Ga2O3 film to the cleaned substrate; then, respectively patterning electrodes on the upper and lower surfaces of the transferred epsilon-Ga2O3 film, and obtaining the neuromorphic optoelectronic memristor after heat annealing.

[0009] The substrate is Si / SiO2, the substrate is ultrasonically cleaned with deionized water, acetone and ethanol in sequence, and then dried with nitrogen.

[0010] The liquid metal self-limiting oxidation method specifically comprises the following steps: heating metallic gallium or Ga-In alloy until it is liquefied, then dropping it onto the surface of the cleaned substrate, and then naturally oxidizing it in humid air and at a low temperature for 30-60 minutes to generate an epsilon-Ga2O3 film with a thickness of 5-10 nm.

[0011] The relative humidity of the humid air is 60-80%, and the low temperature is 25-60 DEG C.

[0012] The PDMS-assisted transfer technology or the PVA aqueous film-assisted transfer technology is used to transfer the epsilon-Ga2O3 film to the cleaned Si / SiO2 substrate.

[0013] A bottom electrode with a thickness of 20-50 nm is deposited on the lower surface of the transferred ε-Ga2O3 film using a mask thermal evaporation process; a top electrode with a thickness of 20-50 nm is deposited on the upper surface of the transferred ε-Ga2O3 film using an electron beam evaporation process or a magnetron sputtering process.

[0014] The electrode material is an inert metal or a conductive oxide; the inert metal is Pt, Au, or Cr, and the conductive oxide is ITO or AZO.

[0015] The heat annealing process is as follows: annealing for 8 to 12 minutes in a nitrogen atmosphere at 300 to 500°C.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. This invention innovatively employs two-dimensional ε-phase gallium oxide (ε-Ga2O3) as the core photoelectric active layer of the memristor. Compared to common materials such as MoS2, β-Ga2O3, or TiO2, ε-Ga2O3 possesses a larger band gap (approximately 4.9 eV), higher breakdown field strength, and excellent short-wavelength ultraviolet light response capability. Furthermore, it exhibits hexagonal crystal symmetry and potential polarity, which facilitates stronger photoelectric coupling effects under low-dimensional conditions. The memristor constructed based on ε-Ga2O3 exhibits significant memristor behavior under the synergistic effect of voltage pulses and ultraviolet light illumination, including reversible switching of conductance states, cumulative modulation of pulse response, and synaptic biomimetic functions such as the conversion from short-time memory (STM) to long-time memory (LTM), breaking through the technical bottleneck of the single response of traditional memristors.

[0018] 2. This invention is the first to introduce liquid metal self-confined oxidation into the two-dimensional preparation process of ε-Ga2O3, allowing the thickness of the prepared film to be controlled within the range of 5-10 nm. Combined with a transfer process, an ε-Ga2O3 film with atomically smooth surface (surface roughness of approximately 0.41 nm) is obtained, exhibiting a dense and uniform structure that significantly suppresses interface traps and carrier scattering problems. Compared with traditional two-dimensional material growth methods such as CVD and MBE, this method can be directly grown at room temperature and atmospheric pressure, without the need for high temperature or vacuum environments, greatly simplifying the preparation process, reducing energy consumption and equipment dependence, and possessing excellent process controllability and large-area transferability.

[0019] In summary, compared to traditional memristors that rely on a single electric field for driving, this invention uses ε-Ga2O3 as the photoelectric activation layer to construct a memristor with a vertical MIM structure. This device can achieve coordinated control under dual channels of electric field and ultraviolet light, effectively simulating the sensing characteristics of biological synapses to various stimuli and realizing electro-optic dual-mode modulation function. Attached Figure Description

[0020] Figure 1This is a cross-sectional schematic diagram of the neuromorphic photomemristor provided by the present invention.

[0021] Figure 2 The X-ray diffraction pattern of the two-dimensional ε-Ga2O3 thin film prepared in Example 3.

[0022] Figure 3 An atomic force microscope image of the two-dimensional ε-Ga2O3 thin film prepared in Example 3.

[0023] Figure 4 The surface potential distribution of the two-dimensional ε-Ga2O3 thin film prepared in Example 3 is shown. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the embodiments and accompanying drawings.

[0025] like Figure 1 As shown, a neuromorphic photomemristor based on two-dimensional ε-Ga₂O₃ is disclosed. The device has a typical metal-insulator-metal (MIM) vertical structure, comprising, from bottom to top, a substrate, a bottom electrode, an ε-Ga₂O₃ photoactive layer, and a top electrode. The ε-Ga₂O₃ photoactive layer is a two-dimensional ε-Ga₂O₃ thin film with a thickness of 5-10 nm, fabricated by liquid metal self-confined oxidation, exhibiting photoelectric synergistic control capability. The substrate is Si / SiO₂. The bottom and top electrodes are both made of inert metals or conductive oxides with a thickness of 20-50 nm. The inert metals are preferably platinum (Pt), gold (Au), or chromium (Cr), and the conductive oxides are preferably ITO (indium tin oxide) or AZO (aluminum-doped zinc oxide), etc., to ensure device stability and CMOS compatibility. The bottom electrode is deposited using a mask evaporation process, and the top electrode is deposited using either electron beam evaporation or magnetron sputtering, exhibiting good interfacial contact performance.

[0026] This device exhibits typical memristor characteristics, improving its response to charge carriers and charge traps under voltage pulses of different amplitudes and frequencies and ultraviolet light stimulation. It possesses neuromorphic functions similar to synapses and is suitable for building brain-like computing hardware, opto-synaptic arrays, edge computing nodes, and artificial visual perception systems. It has comprehensive advantages such as low power consumption, high response, and high integration, making it easy to integrate into flexible or three-dimensional neural network structures.

[0027] A method for fabricating a neuromorphic photomemristor based on two-dimensional ε-Ga2O3 includes the following steps:

[0028] Step 1: Clean the highly stable Si / SiO2 substrate sequentially with deionized water, acetone, and ethanol using ultrasonic cleaning for 10-15 minutes each, and then dry it with nitrogen for later use.

[0029] Step 2: A two-dimensional ε-Ga2O3 thin film is grown on the surface of a Si / SiO2 substrate using a liquid metal self-confined oxidation method;

[0030] The liquid metal self-limited oxidation method (LM-SLO) specifically involves heating gallium or Ga-In alloy to 40-60°C to liquefy it, dropping it onto the cleaned Si / SiO2 substrate surface, and then allowing it to stand in air with a relative humidity of 60-80% and at 25-60°C for 30-60 minutes to allow the liquid metal surface to naturally oxidize and form an ε-Ga2O3 film with a thickness of 5-10 nm.

[0031] Step 3: Use polydimethylsiloxane (PDMS) assisted transfer technology or polyvinyl alcohol (PVA) water-soluble film assisted transfer technology to transfer the ε-Ga2O3 film from Step 2 onto the Si / SiO2 substrate cleaned in Step 1 to obtain an ε-Ga2O3 film with better surface uniformity and smoother surface.

[0032] The PDMS-assisted transfer technology specifically involves: attaching a PDMS film to the surface of an ε-Ga2O3 thin film, ensuring full contact, and then slowly peeling it off to remove the ε-Ga2O3 film. The film is then dried in a vacuum environment for 10 minutes to enhance adhesion. Subsequently, the PDMS / ε-Ga2O3 structure is aligned with a cleaned Si / SiO2 substrate and hot-pressed at 70-80°C for 5-10 minutes to achieve a smooth film transfer. The hot-pressing process assists in PDMS peeling and alignment during the transfer process, achieving crack-free film bonding and improving film-substrate adhesion strength. This method is suitable for large-area two-dimensional thin film transfer operations.

[0033] The PVA water-soluble film-assisted transfer technology specifically involves: spin-coating a water-soluble PVA solution onto the surface of an ε-Ga2O3 film to form a PVA / ε-Ga2O3 structure; after peeling, aligning the PVA / ε-Ga2O3 structure with a cleaned Si / SiO2 substrate; and then dissolving the PVA carrier film in warm water (approximately 30~50℃) to achieve a highly clean and smooth transfer.

[0034] Step 4: Pattern and grow metal electrodes on the upper and lower surfaces of the transferred ε-Ga2O3 thin film to form a typical MIM vertical device structure.

[0035] A bottom electrode with a thickness of 20-50 nm was deposited on the lower surface of an ε-Ga₂O₃ thin film using a mask thermal evaporation process. The evaporation current was set to 20-28 mA, and the system vacuum degree was 4 × 10⁻⁶. -6 ~8×10 -6 Torr, with a deposition rate controlled at 0.09~0.15 nm / s and a deposition time of approximately 6~8 minutes.

[0036] A top electrode with a thickness of 20-50 nm was deposited on the surface of an ε-Ga2O3 thin film using either electron beam evaporation or magnetron sputtering. The electron beam evaporation process parameters were: power set to 2.8-3.6 kW, target distance to 20-28 cm, and deposition rate to 0.2-0.5 nm / s. The magnetron sputtering process parameters were: working pressure controlled at 0.4 Pa, argon flow rate set to 25 sccm, target power to 90-100 W, and deposition time to 5-8 minutes.

[0037] The metal electrode material can be an inert metal, preferably Pt, Au, or Cr, or a conductive oxide, preferably ITO or AZO, to ensure the stability of the electrode interface and good conductivity.

[0038] Step 5: After the device structure is constructed, it undergoes post-processing using Rapid Thermal Annealing (RTA) to optimize thin film crystallinity and electrode contact performance. The device is placed in a nitrogen environment at 300–500°C for annealing time controlled between 8 and 12 minutes. This process effectively improves the device interface quality, reduces defect state density, and avoids film damage or substrate deformation caused by high temperatures, thereby improving the device's operational stability, durability, and photoelectric response consistency.

[0039] Example 1

[0040] A 4-inch Si / SiO2 substrate was selected as the substrate, and a neuromorphic photomemristor structure was sequentially deposited. The specific steps are as follows:

[0041] 1. Place the Si / SiO2 substrate in deionized water, acetone and ethanol in sequence for ultrasonic cleaning, each for 10 minutes, and then dry it with high-purity nitrogen.

[0042] 2. Using the liquid metal self-confined oxidation method, metallic gallium is heated to 40°C to form a liquid state, which is then dropped and evenly spread on the surface of an oxide Si / SiO2 substrate. The substrate is then placed in a closed air environment with a relative humidity of 60% and a temperature of about 40°C for 30 minutes to allow the liquid gallium surface to undergo a self-confined oxidation reaction, ultimately forming an ε-Ga2O3 thin film with a thickness of about 5nm.

[0043] 3. The PDMS film was coated and the ε-Ga2O3 film was peeled off using PDMS-assisted transfer technology. After drying in a vacuum environment for 10 minutes, it was transferred to the cleaned Si / SiO2 substrate surface and hot-pressed at 70°C for 5 minutes to complete the bonding.

[0044] 4. Cr was deposited on the lower surface of an ε-Ga₂O₃ thin film using a mask thermal evaporation process to obtain a bottom electrode with a thickness of 20 nm; the generating current was set to 20 mA, and the system vacuum degree was 4 × 10⁻⁶. -6Torr, deposition rate controlled at 0.09 nm / s, deposition time approximately 6 minutes;

[0045] Cr was deposited on the surface of an ε-Ga2O3 thin film using electron beam evaporation to obtain a bottom electrode with a thickness of 20 nm; the power was set to 2.8 kW, the target distance was 20 cm, and the deposition rate was 0.2 nm / s.

[0046] 5. The formed device was rapidly thermally annealed in a nitrogen atmosphere at 300°C for 8 minutes to obtain the neuromorphic photomemristor structure.

[0047] Example 2

[0048] A 4-inch Si / SiO2 substrate was selected as the substrate, and a neuromorphic photomemristor structure was sequentially deposited. The specific steps are as follows:

[0049] 1. Place the Si / SiO2 substrate in deionized water, acetone and ethanol in sequence for ultrasonic cleaning, each for 12 minutes, and then dry it with high-purity nitrogen.

[0050] 2. The Ga-In alloy was heated to 50°C to form a liquid state using the liquid metal self-confined oxidation method. The liquid was then dropped and evenly spread on the surface of a Si / SiO2 substrate. The substrate was then placed in a closed air environment with a relative humidity of 70% and a temperature of about 50°C for 45 minutes to allow the liquid gallium surface to undergo a self-confined oxidation reaction, ultimately forming an ε-Ga2O3 thin film with a thickness of about 7nm.

[0051] 3. PVA solution was spin-coated onto the surface of ε-Ga2O3 film using PVA water-soluble film-assisted transfer technology. After solidification and peeling, the film was transferred to the surface of Si / SiO2 substrate. The PVA carrier film was then removed using 40℃ warm water to complete the cleaning transfer.

[0052] 4. ITO was deposited on the lower surface of the ε-Ga2O3 thin film using a mask thermal evaporation process to obtain a bottom electrode with a thickness of 35 nm; the generating current was set to 24 mA, and the system vacuum degree was 6 × 10⁻⁶. -6 Torr, deposition rate controlled at 0.12 nm / s, deposition time approximately 7 minutes;

[0053] ITO was deposited on the surface of an ε-Ga2O3 thin film using magnetron sputtering to obtain a bottom electrode with a thickness of 35 nm. The working pressure was controlled at 0.4 Pa, the argon flow rate was set at 25 sccm, the target power was 95 W, and the deposition time was 7 minutes.

[0054] 5. The formed device was rapidly thermally annealed in a nitrogen atmosphere at 400°C for 10 minutes to finally obtain the neuromorphic photomemristor structure.

[0055] Example 3

[0056] A 4-inch Si / SiO2 substrate was selected as the substrate, and a neuromorphic photomemristor structure was sequentially deposited. The specific steps are as follows:

[0057] 1. The Si / SiO2 substrate was ultrasonically cleaned in deionized water, acetone and ethanol in sequence for 15 minutes each, and then dried with high-purity nitrogen.

[0058] 2. Using the liquid metal self-confined oxidation method, metallic gallium was heated to 60°C to form a liquid state, which was then dropped and evenly spread on the surface of a cleaned Si / SiO2 substrate. Subsequently, the substrate was placed in a closed air environment with a relative humidity of 80% and a temperature of about 60°C for 60 minutes to allow the liquid gallium surface to undergo a self-confined oxidation reaction, ultimately forming an ε-Ga2O3 thin film with a thickness of about 10 nm.

[0059] 3. The PDMS film was coated and the ε-Ga2O3 film was peeled off using PDMS-assisted transfer technology. After drying in a vacuum environment for 10 minutes, it was transferred to the cleaned Si / SiO2 substrate surface and hot-pressed at 80°C for 10 minutes to complete the bonding.

[0060] 4. Pt was deposited on the lower surface of an ε-Ga₂O₃ thin film using a mask thermal evaporation process to obtain a bottom electrode with a thickness of 50 nm; the generating current was set to 28 mA, and the system vacuum degree was 8 × 10⁻⁶. -6 Torr, with a deposition rate controlled at 0.15 nm / s and a deposition time of approximately 8 minutes.

[0061] Pt was deposited on the surface of an ε-Ga2O3 thin film using electron beam evaporation to obtain a bottom electrode with a thickness of 50 nm; the power was set to 3.6 kW, the target distance was 28 cm, and the deposition rate was 0.5 nm / s.

[0062] 5. The formed device was rapidly thermally annealed in a nitrogen atmosphere at 500°C for 12 minutes to finally obtain the neuromorphic photomemristor structure.

[0063] To verify the application potential of the fabricated two-dimensional ε-Ga2O3 thin film device in the field of neuromorphic computing, this invention conducted a systematic evaluation combining material structure characterization and device performance testing. X-ray diffraction analysis confirmed that the film possesses an amorphous or nanocrystalline structure, which is beneficial for providing abundant carrier traps and defect state distribution. Atomic force microscopy (AFM) results showed that the film surface is highly smooth with excellent interface continuity, effectively enhancing the stability of synaptic conductance modulation. Further surface potential imaging (KPFM) tests observed significant changes in potential distribution, indicating that the material has good responsiveness to dual stimulation by ultraviolet light and electric fields, verifying its practical feasibility in constructing biomimetic neural synapse functions. The results of the above three tests are shown below. Figures 2 to 4The results comprehensively demonstrate that this two-dimensional ε-Ga2O3 thin film device has significant advantages in realizing brain-like information processing and neural network hardware implementation.

[0064] Figure 2 This is an X-ray diffraction pattern of a two-dimensional ε-Ga₂O₃ thin film, used to analyze the material's crystallinity and structural order. From... Figure 2 As can be seen, no obvious diffraction peaks were observed in the range of 2θ = 10° to 60°, only the background signal of the substrate was observed, indicating that the prepared ε-Ga2O3 film is amorphous or has extremely low crystallinity. This structural characteristic is of great significance for constructing neuromorphic photomemristors. Amorphous ε-Ga2O3 can provide a relatively uniform distribution of carrier trap states, which is helpful in simulating the continuously tunable characteristics of synaptic weights. Overall, the XRD results verify the amorphous characteristics of the two-dimensional ε-Ga2O3 film structure, providing a structural basis for realizing bio-plasticity and multi-state memristor modulation mechanisms. It is conducive to the formation of rich surface states and defect states, providing excellent tunable memristor characteristics and photoresponse modulation capabilities for the device.

[0065] Figure 3 This is an atomic force microscopy (AFM) image of a two-dimensional ε-Ga2O3 thin film with a scanning area of ​​2×2μm and an average surface roughness (RMS) of 0.41nm. The film exhibits high overall flatness and good interfacial continuity with the substrate. This ultra-flat surface helps improve the quality of electrical contacts and electrical stability at the device interface, making it suitable for high-density, low-defect neuromorphic device structures.

[0066] Figure 4 The surface potential distribution (KPFM) of the two-dimensional ε-Ga2O3 thin film is shown in the image. The imaging area is 10 × 10 μm, and the potential color scale range is 382~402 mV. It shows a certain degree of spatial distribution difference, which improves the material's response to carriers and charge traps under ultraviolet light or electric field bias. This local potential modulation characteristic verifies the practical feasibility of the two-dimensional ε-Ga2O3 thin film in the optoelectronic synergistic memristor modulation mechanism.

Claims

1. A neuromorphic photomemristor based on two-dimensional ε-Ga₂O₃, characterized in that, include: The substrate, bottom electrode, ε-Ga2O3 photoactive layer, and top electrode are stacked sequentially from bottom to top; the thickness of the ε-Ga2O3 photoactive layer is 5~10nm, and it is prepared by liquid metal self-limiting oxidation.

2. The neuromorphic photomemristor according to claim 1, characterized in that: The substrate is Si / SiO2; the bottom electrode and the top electrode are both made of inert metal or conductive oxide with a thickness of 20~50nm; the inert metal is Pt or Au or Cr, and the conductive oxide is ITO or AZO.

3. A method for fabricating a neuromorphic photomemristor based on two-dimensional ε-Ga₂O₃, characterized in that, include: An ε-Ga2O3 thin film with a thickness of 5-10 nm was grown on the surface of a cleaned substrate using a liquid metal self-limiting oxidation method and then transferred onto the cleaned substrate. Electrodes were then patterned and grown on the upper and lower surfaces of the transferred ε-Ga2O3 thin film, and a neuromorphic photomemristor was obtained after thermal annealing.

4. The method for fabricating a neuromorphic photomemristor according to claim 3, characterized in that: The substrate is Si / SiO2. The substrate is ultrasonically cleaned sequentially with deionized water, acetone, and ethanol, and then dried with nitrogen.

5. The method for fabricating a neuromorphic photomemristor according to claim 3, characterized in that: The liquid metal self-limited oxidation method specifically involves heating gallium or Ga-In alloy until it liquefies, then dropping it onto the cleaned substrate surface, and subsequently oxidizing it naturally in a humid and low-temperature enclosed air environment for 30 to 60 minutes to generate an ε-Ga2O3 thin film with a thickness of 5 to 10 nm.

6. The method for fabricating a neuromorphic photomemristor according to claim 5, characterized in that: The relative humidity of the humidified air is 60-80%, and the low temperature is 25-60℃.

7. The method for fabricating a neuromorphic photomemristor according to claim 3, characterized in that: The ε-Ga2O3 film was transferred onto the cleaned Si / SiO2 substrate using PDMS-assisted transfer technology or PVA water-soluble film-assisted transfer technology.

8. The method for fabricating a neuromorphic photomemristor according to claim 3, characterized in that: A bottom electrode with a thickness of 20-50 nm is deposited on the lower surface of the transferred ε-Ga2O3 film using a mask thermal evaporation process; a top electrode with a thickness of 20-50 nm is deposited on the upper surface of the transferred ε-Ga2O3 film using an electron beam evaporation process or a magnetron sputtering process.

9. The method for fabricating a neuromorphic photomemristor according to claim 3 or 8, characterized in that: The electrode material is an inert metal or a conductive oxide; the inert metal is Pt, Au, or Cr, and the conductive oxide is ITO or AZO.

10. The method for fabricating a neuromorphic photomemristor according to claim 3, characterized in that: The heat annealing process is as follows: annealing for 8 to 12 minutes in a nitrogen atmosphere at 300 to 500°C.

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