Multifunctional photosensitive synapse device based on two-dimensional material and preparation method thereof

Abstract

The application discloses a multifunctional photosensitive synapse device based on a two-dimensional material and a preparation method thereof. The device comprises a substrate, a gate electrode, a source electrode, a drain electrode and a stacked structure arranged above the substrate. The stacked structure comprises a first two-dimensional material layer, a second two-dimensional material layer and a third two-dimensional material layer. The gate electrode is arranged above the substrate. The first two-dimensional material layer, the second two-dimensional material layer and the third two-dimensional material layer are sequentially arranged above the gate electrode. The source electrode and the drain electrode are respectively arranged above the third two-dimensional material layer, and a channel is formed between the source electrode and the drain electrode. Hexagonal boron nitride with a defect state is included in the second two-dimensional material layer. The first two-dimensional material layer serves as a light absorption layer, the second two-dimensional material layer serves as an isolation layer, and the third two-dimensional material layer serves as a readout layer. The device has a simple structure, a simple and easy-to-understand working principle, a simple preparation process and is easy to use. The device is based on a pure two-dimensional thin film material and is vertically stacked, has a small size and is conducive to the needs of high density and high integration.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a multifunctional photosensitive synaptic device based on two-dimensional materials and a preparation method thereof. Background Art

[0002] With the continued development of artificial intelligence, the demand for efficient data access and massive data storage poses increasing challenges to the traditional von Neumann architecture, which separates computing modules from storage units. At the same time, semiconductor technology development is approaching the limits of Moore's Law, making it increasingly difficult to improve the performance of the von Neumann architecture through process improvements. Neuromorphic computing, which simulates the neurons and synapses in the biological brain for data processing, has become a key direction in the development of high-performance computing due to its advantages such as low energy consumption, adaptive learning, and high parallel computing. At the device level, the preparation of artificial synaptic devices that mimic the synaptic functions of the biological brain has become a very important research direction.

[0003] Compared to traditional bulk materials, two-dimensional materials offer superior properties in thickness, interface, and mobility. A diverse range of materials and the ability to stack materials with diverse properties enable diverse device structures and achieve a wide range of device functions. Their atomic-level thickness also offers significant advantages in the miniaturization and integration of future devices, and holds broad application value in the post-Moore era of semiconductor technology.

[0004] Traditional CMOS-based artificial synaptic devices require multiple transistors to simulate a single synaptic behavior, making it difficult to achieve high integration density and posing difficulties and challenges in establishing high-density artificial neural networks. However, novel structural synaptic devices with non-volatile memory capabilities can achieve synaptic functionality in a single device, offering broad prospects for the development and application of artificial neural networks. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a multifunctional photosensitive synaptic device based on two-dimensional materials and a preparation method thereof.

[0006] In order to solve the above technical problems, the present invention is solved by the following technical solutions:

[0007] A multifunctional photosensitive synaptic device based on two-dimensional materials, comprising:

[0008] substrate;

[0009] A gate, a source, a drain and a stacked structure are arranged above the substrate, and the stacked structure includes a first two-dimensional material layer, a second two-dimensional material layer and a third two-dimensional material layer. The gate is arranged above the substrate, and the first two-dimensional material layer, the second two-dimensional material layer and the third two-dimensional material layer are sequentially covered above the gate. The source and the drain are respectively covered above the third two-dimensional material layer, and a channel is formed between the source and the drain, wherein the second two-dimensional material layer includes defective hexagonal boron nitride, the first two-dimensional material layer serves as a light absorption layer, the second two-dimensional material layer serves as an isolation layer, and the third two-dimensional material layer serves as a readout layer.

[0010] As an embodiment, the defective hexagonal boron nitride in the second two-dimensional material layer is obtained by:

[0011] The growth is carried out under the conditions of a temperature of 1200° C. to 1450° C. and a pressure of 10 Pa, and 0.6% of carbon is introduced during the growth process to obtain defective hexagonal boron nitride.

[0012] As an embodiment, the first two-dimensional material layer comprises a two-dimensional semiconductor material having a light absorption function;

[0013] The first two-dimensional material layer includes a plurality of transition metal sulfide layers or a plurality of transition metal selenide layers or a mixture of the two.

[0014] As an implementation method, the third two-dimensional material layer includes a conductive and light-transmitting two-dimensional material;

[0015] The third two-dimensional material layer includes a single layer or 5 layers or less of graphene, a single layer or 5 layers or less of transition metal sulfide, or a single layer or 5 layers or less of transition metal selenide.

[0016] As an implementation method, the substrate is an insulating material substrate or the top layer of the substrate is an insulating material layer;

[0017] The insulating material is any one of glass, silicon oxide wafer, ceramic, PET and PI.

[0018] As an implementation method, it includes two gates and two first two-dimensional material layers, a first channel is formed between the two gates, the two first two-dimensional material layers respectively cover the two gates, a second channel is provided between the two first two-dimensional material layers, the first channel and the second channel are interconnected, the upper surface of the substrate is exposed below the first channel, and the lower surface of the second two-dimensional material layer is exposed above the second channel.

[0019] As an implementation method, when the amplitude of the positive pulse signal applied to the gate is 1 to 5V, the pulse width is 0.5 to 3s, and the amplitude of the negative pulse applied is -1 to -5V, and the pulse width is 0.5 to 3s, the synaptic enhancement function or inhibition function is achieved.

[0020] A method for preparing a multifunctional photosensitive synaptic device based on two-dimensional materials, comprising the following steps:

[0021] Providing a substrate, wherein the substrate is an insulating material substrate or the top layer of the substrate is an insulating material layer;

[0022] forming a gate above the top layer of the substrate;

[0023] The gate is sequentially covered with a stacked structure, wherein the stacked structure includes a first two-dimensional material layer, a second two-dimensional material layer, and a third two-dimensional material layer;

[0024] A source and a drain are respectively formed above the third two-dimensional material layer, and a channel is formed between the source and the drain, wherein the second two-dimensional material layer contains defective hexagonal boron nitride, the first two-dimensional material layer serves as a light absorption layer, the second two-dimensional material layer serves as an intermediate isolation layer, and the third two-dimensional material layer serves as a readout layer.

[0025] As an embodiment, the defective hexagonal boron nitride in the second two-dimensional material layer is obtained by:

[0026] The growth is carried out under the conditions of a temperature of 1200° C. to 1450° C. and a pressure of 10 Pa, and 0.6% of carbon is introduced during the growth process to obtain defective hexagonal boron nitride.

[0027] As an implementation method, the following steps are further included before covering the second two-dimensional material layer:

[0028] Two gates are formed above the top layer of the substrate, with a first channel provided between the two gates, wherein the depth of the first channel is the same as the thickness of the gates;

[0029] A first two-dimensional material layer is stacked above each gate, and a second channel is formed between the two first two-dimensional material layers. The position of the second channel corresponds to the first channel, and the depth of the second channel is the same as the thickness of the first two-dimensional material layer.

[0030] The present invention has significant technical effects due to the adoption of the above technical solutions:

[0031] 1. The device of the present invention has a simple structure, a concise and easy-to-understand working principle, a simple preparation process, and is easy to use.

[0032] 2. The device of the present invention is based on vertical stacking of pure two-dimensional thin film materials and has a small size, which is conducive to the needs of high density and high integration.

[0033] 3. The device of the present invention can realize dual working modes of electrical modulation / optical-electrical hybrid modulation. The dual-gate device has optical switching logic function, diverse working methods, and wide application scenarios.

[0034] 4. The light absorption layer and the readout layer of the device of the present invention are separated, and in the optical-electrical hybrid modulation working mode, it can have the advantages of high light response and high-speed readout.

[0035] 5. The first two-dimensional material layer of the absorption layer of the present invention can arbitrarily select a suitable two-dimensional material according to the actual application wavelength requirements, and has application flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 A three-dimensional schematic diagram of the structure of a single-gate multifunctional photosensitive synaptic device based on two-dimensional materials provided by an embodiment of the present invention;

[0038] Figure 2 A cross-sectional view of the structure of a single-gate multifunctional photosensitive synaptic device based on two-dimensional materials provided by an embodiment of the present invention;

[0039] Figure 3 This is a transfer characteristic curve diagram of a device according to an embodiment of the present invention;

[0040] Figure 4 This is a graph showing the LTP / LTD characteristic curve of the device in the electrical modulation mode according to an embodiment of the present invention;

[0041] Figure 5 This is a graph showing the LTP / LTD characteristic curve of the device in the optical-electrical hybrid modulation mode according to an embodiment of the present invention;

[0042] Figure 6 A three-dimensional schematic diagram of the structure of a dual-gate multifunctional photosensitive synaptic device based on two-dimensional materials provided by an embodiment of the present invention;

[0043] Figure 7 A cross-sectional view of the structure of a dual-gate multifunctional photosensitive synaptic device based on two-dimensional materials provided by an embodiment of the present invention;

[0044] Figure 8 and 9Schematic diagram of a device implementing "AND" and "OR" logic functions under dark and light conditions according to an embodiment of the present invention.

[0045] The symbols in the accompanying drawings are:

[0046] 1. Substrate; 2. Gate; 3. Source; 4. Drain; 5. First two-dimensional material layer; 6. Second two-dimensional material layer; 7. Third two-dimensional material layer; 8. First channel; 9. Second channel. DETAILED DESCRIPTION

[0047] The present invention will be further described in detail below with reference to the examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0048] Example 1:

[0049] A multifunctional photosensitive synaptic device based on two-dimensional materials, such as Figure 1-2 Shown, including:

[0050] Substrate 1;

[0051] A gate 2, a source 3, a drain 4 and a stacked structure are arranged above the oxide layer of the substrate 1, and the stacked structure includes a first two-dimensional material layer 5, a second two-dimensional material layer 6 and a third two-dimensional material layer 7. The gate 2 is arranged above the substrate 1, and the first two-dimensional material layer 5, the second two-dimensional material layer 6 and the third two-dimensional material layer 7 are sequentially covered above the gate 2. The source 3 and the drain 4 are respectively covered above the third two-dimensional material layer 7, and a channel is formed between the source 3 and the drain 4, wherein the second two-dimensional material layer 6 includes defective hexagonal boron nitride, the first two-dimensional material layer 5 serves as a light absorption layer, the second two-dimensional material layer 6 serves as an isolation layer, and the third two-dimensional material layer 7 serves as a readout layer.

[0052] In one embodiment, the defective hexagonal boron nitride in the second two-dimensional material layer is obtained by:

[0053] The growth is carried out under the conditions of a temperature of 1200° C. to 1450° C. and a pressure of 10 Pa, and 0.6% of carbon is introduced during the growth process to obtain defective hexagonal boron nitride.

[0054] Specifically, the first two-dimensional material layer 5 contains a two-dimensional semiconductor material with light absorption function; the first two-dimensional material layer 5 can be a plurality of transition metal sulfide layers or a plurality of transition metal selenide layers or a mixture of the two; such as tungsten diselenide, etc. The specific materials are not repeated here.

[0055] In addition, the third two-dimensional material layer 7 includes a conductive and light-transmitting two-dimensional material; the third two-dimensional material layer 7 includes a single layer or 5 layers or less of graphene, a single layer or 5 layers or less of transition metal sulfide, or a single layer or 5 layers or less of transition metal selenide.

[0056] In addition, the substrate 1 in this solution is an insulating material substrate or the top layer of the substrate is an insulating material layer; more specifically, the insulating material is any one of glass, silicon oxide wafer, ceramic, PET and PI. Of course, other materials can also be selected, which will not be repeated here.

[0057] In one embodiment, when the amplitude of the positive pulse signal applied to the gate 2 is 1 to 5V and the pulse width is 0.5 to 3s, the amplitude of the negative pulse applied is -1 to -5V and the pulse width is 0.5 to 3s, the synaptic enhancement function or inhibition function is achieved.

[0058] Example 2:

[0059] The following is an example process:

[0060] A method for preparing a multifunctional photosensitive synaptic device based on two-dimensional materials, comprising the following steps:

[0061] S100, providing a substrate 1, wherein the substrate 1 is an insulating material substrate or the top layer of the substrate 1 is an insulating material layer;

[0062] S200, forming a gate 2 above the oxide layer of the substrate 1;

[0063] S300, a stacked structure is sequentially covered on the gate 2, the stacked structure comprising a first two-dimensional material layer 5, a second two-dimensional material layer 6, and a third two-dimensional material layer 7, wherein the second two-dimensional material layer 6 comprises defective hexagonal boron nitride, the first two-dimensional material layer 5 serves as a light absorption layer, the second two-dimensional material layer 6 serves as an intermediate isolation layer, and the third two-dimensional material layer 7 serves as a readout layer;

[0064] S400 , a source electrode 3 and a drain electrode 4 are formed on the third two-dimensional material layer 7 , and a channel is formed between the source electrode 3 and the drain electrode 4 .

[0065] In the actual preparation process, the material of the substrate 1 and the material of the stacking structure are selected, and the following preparation methods can be used:

[0066] A silicon oxide wafer with a top oxide layer of 100 nm is used as substrate 1;

[0067] A three-terminal electrode pattern was fabricated on the oxide layer of substrate 1 using photolithography, and 5 nm of chromium and 40 nm of gold were grown as electrode materials using magnetron sputtering technology.

[0068] Transfer tungsten diselenide to the electrode surface as a bottom layer material by PVA and PDMS assisted transfer, so that the tungsten diselenide covers the gate 2 while not contacting the source and drain electrodes. This tungsten diselenide is prepared by mechanical stripping.

[0069] By means of PVA and PDMS-assisted transfer, defective hexagonal boron nitride is transferred and stacked on top of tungsten diselenide as a second two-dimensional material layer 6 so as to cover the effective area. The defective hexagonal boron nitride used is prepared by mechanical exfoliation. The defective hexagonal boron nitride of the second two-dimensional material layer is obtained by growing at a temperature of 1200° C. to 1450° C. and a pressure of 10 Pa, and introducing 0.6% carbon during the growth process to obtain defective hexagonal boron nitride.

[0070] By means of PVA and PDMS-assisted transfer, stacked graphene is transferred on top of the defective hexagonal boron nitride as the third two-dimensional material layer 7, so that the graphene covers the effective area, ensuring that the graphene contacts the source 3 and the drain 4 to form a channel while not contacting the gate 2. The graphene is a single layer or 5 layers or less of graphene prepared by mechanical exfoliation.

[0071] Based on the structure of Example 1 and the structure prepared by the preparation method of Example 2, the following tests were performed:

[0072] In electrical modulation mode, a constant voltage is applied to both source 3 and drain 4, respectively, and the current in the channel formed by the third material layer is read in real time. When a negative pulse is applied to gate 2, the conductance of the channel increases, leading to an increase in current, thus stimulating the synapse. When a positive pulse is applied to gate 2, the conductance of the channel decreases, leading to a decrease in current, thus inhibiting the synapse. Therefore, the weight of the photosensitive synaptic device can be adjusted by controlling the number and polarity of the applied pulses.

[0073] In the photoelectric hybrid modulation working mode, that is, not only pulses are applied but also light is applied, and light is applied to the device surface, when a negative pulse is applied to gate 2, the channel conductance increases significantly compared to the dark state, and the current rises, thereby further realizing information encoding; and when a positive pulse is applied to gate 2, consistent with the electrical modulation mode, the channel conductance decreases, and the synapse is inhibited, thereby realizing the photosensitive synaptic device with light-driven information encryption function.

[0074] Based on this, the control principles are summarized as follows:

[0075] When a negative pulse signal is applied to the gate 2, a top-down electric field is generated in the vertical direction of the multifunctional photosensitive synaptic device, and the charges move under the action of the electric field. Since the second two-dimensional material layer 6 contains defective hexagonal boron nitride, the moving charges are captured, and charges of opposite polarity are coupled out in the channel formed by the third material layer, thereby increasing the conductivity. When the gate voltage is 0V, due to the capture effect of the second two-dimensional material layer 6, the captured charges will not be released immediately, so the conductivity of the channel will not be reset immediately.

[0076] When a positive pulse signal is applied to the gate 2, an electric field is generated from bottom to top in the vertical direction of the multifunctional photosensitive synaptic device. The charges captured by the defective hexagonal boron nitride in the second two-dimensional material layer 6 will gradually break free from the constraints under the action of the electric field, so the channel conductance will also gradually reset. When the gate voltage is 0V, the electric field force is not sufficient to help all the charges break free immediately, so the channel conductance will not be reset immediately.

[0077] When the photosensitive synaptic device is illuminated, the incident light is mainly absorbed by the first two-dimensional material layer 5, so the incident photons will excite the generation of electron-hole pairs. Under the action of the electric field, the electron-hole pairs are separated, so photogenerated charges are generated and captured by the defective hexagonal boron nitride in the second two-dimensional material layer 6, and the channel conductance is significantly increased; when there is no light, no photogenerated charges are generated and the channel conductance does not increase significantly.

[0078] The above test is to apply a 10mV constant bias between the source 3 and the drain 4, and apply a -5~5V bidirectional scanning voltage to the gate 2. The transfer characteristic curve observed is as follows Figure 3 From the bidirectional scanning curve, it can be concluded that due to the capture of charge by the hexagonal boron nitride containing defect states, the transfer curve shows obvious hysteresis.

[0079] In addition, long-term synaptic plasticity (i.e., long-term potentiation (LTP) and long-term depression (LTD)) was tested under the electrical modulation working mode. The test process and procedures are as follows:

[0080] A constant bias of 10mV is applied between the source 3 and the drain 4. 50 negative pulse signals with a pulse width of 500ms and a pulse interval of 500ms are first applied to the gate 2, with a pulse amplitude of -4V. Then, 50 positive pulse signals with a pulse width of 500ms and a pulse interval of 500ms are applied, with a pulse amplitude of 2V. The LTP / LTD characteristic curve obtained by the test is shown as follows: Figure 4The response to the number and polarity of pulses is directly reflected in the change in current. With the continuous application of negative pulse signals, the conductance continues to increase, and the current shows a gradually increasing trend, achieving the LTP function. With the subsequent application of positive pulse signals, the conductance continues to decrease, and the current trend changes from rising to falling, eventually returning to a near-original state, achieving the LTD function.

[0081] We also conducted a long-term synaptic plasticity test under the optical-electrical hybrid modulation working mode, applying the same source-drain voltage and gate voltage configuration as in the electrical modulation working mode, and tested the LTP / LTD characteristics of the device under 532nm laser illumination conditions of different light intensities and in dark conditions. The results are as follows Figure 5 As shown in the figure, in the LTP segment, in addition to the original LTP characteristics, the current magnitude shows a clear difference between light and dark, while in the LTD segment, the current magnitude has no obvious difference between light and dark. This shows that the function of optical signal encoding and information encryption can be realized in the LTP segment.

[0082] Example 3:

[0083] A multifunctional photosensitive synaptic device based on two-dimensional materials, such as Figure 6-7 Shown, including:

[0084] Substrate 1, wherein the substrate 1 is an insulating material substrate or the top layer of the substrate is an insulating material layer;

[0085] A gate 2, a source 3, a drain 4 and a stacked structure are arranged above the oxide layer of the substrate 1, and the stacked structure includes a first two-dimensional material layer 5, a second two-dimensional material layer 6 and a third two-dimensional material layer 7. The gate 2 is arranged above the substrate 1, and the first two-dimensional material layer 5, the second two-dimensional material layer 6 and the third two-dimensional material layer 7 are sequentially covered above the gate 2, and the gate 2 includes two gates 2 and two first two-dimensional material layers 5. A first channel 8 is formed between the two gates 2, and the two first two-dimensional material layers 5 are respectively arranged above the two gates 2. A second channel 9 is provided between the two first two-dimensional material layers 5, and the first channel 8 and the second channel 9 are mutually connected. The first two-dimensional material layer 6 is connected, the upper surface of the substrate 1 is exposed below the first channel 8, the lower surface of the second two-dimensional material layer 6 is exposed above the second channel 9, the upper surface of the substrate 1 is exposed below the first channel 8, the lower surface of the second two-dimensional material layer is exposed above the second channel 9, and the source 3 and the drain 4 are respectively covered above the third two-dimensional material layer 7, and a channel is formed between the source 3 and the drain 4, wherein the second two-dimensional material layer 6 includes defective hexagonal boron nitride, the first two-dimensional material layer 5 serves as a light absorption layer, the second two-dimensional material layer 6 serves as an isolation layer, and the third two-dimensional material layer 7 serves as a readout layer.

[0086] In one embodiment, the defective hexagonal boron nitride in the second two-dimensional material layer 6 is obtained by:

[0087] The growth is carried out under the conditions of a temperature of 1200° C. to 1450° C. and a pressure of 10 Pa, and 0.6% of carbon is introduced during the growth process to obtain defective hexagonal boron nitride.

[0088] Specifically, the first two-dimensional material layer 5 contains a two-dimensional semiconductor material with light absorption function; the first two-dimensional material layer 5 includes a plurality of transition metal sulfide layers or a plurality of transition metal selenide layers or a mixture of the two.

[0089] The third two-dimensional material layer 7 includes a conductive and light-transmitting two-dimensional material; the third two-dimensional material layer 7 includes a single layer or 5 layers or less of graphene, a single layer or 5 layers or less of transition metal sulfide, or a single layer or 5 layers or less of transition metal selenide.

[0090] In one embodiment, the substrate 1 is an insulating material substrate or the top layer of the substrate is an insulating material layer; the insulating material is any one of glass, silicon oxide wafer, ceramic, PET and PI.

[0091] Specifically, when the amplitude of the positive pulse signal applied to the gate 2 is 1 to 5V and the pulse width is 0.5 to 3s, and the amplitude of the negative pulse signal applied is -1 to -5V and the pulse width is 0.5 to 3s, the synaptic enhancement or inhibition function is achieved.

[0092] Example 4:

[0093] The following is an exemplary preparation method:

[0094] A method for preparing a multifunctional photosensitive synaptic device based on two-dimensional materials, comprising the following steps:

[0095] S100, providing a substrate 1, wherein the top layer of the substrate 1 is an insulating layer;

[0096] S200, forming two gates 2 above the top layer of the substrate 1, with a first channel 8 provided between the two gates 2, the depth of the first channel 8 being the same as the thickness of the gate 2; a first two-dimensional material layer 5 being stacked above each gate 2, a second channel 9 being formed between the two first two-dimensional material layers 5, the position of the second channel 9 corresponding to the first channel 8, the depth of the second channel 9 being the same as the thickness of the first two-dimensional material layer 5, the first two-dimensional material layer 5 being sequentially covered with a second two-dimensional material layer 6 and a third two-dimensional material layer 7, the defective hexagonal boron nitride of the second two-dimensional material layer 6 being obtained by: growing at a temperature of 1200°C to 1450°C and a pressure of 10 Pa, and introducing 0.6% carbon during the growth process, thereby obtaining defective hexagonal boron nitride, the first two-dimensional material layer 5 being used as a light absorption layer, the second two-dimensional material layer 6 being used as an intermediate isolation layer, and the third two-dimensional material layer 7 being used as a readout layer;

[0097] S400 , forming a source 3 and a drain 4 on the third two-dimensional material layer 7 , and forming a channel between the source 3 and the drain 4 , wherein the second two-dimensional material layer 6 comprises defective hexagonal boron nitride.

[0098] Specifically, in the actual preparation process, the material of the substrate 1 and the material of the stacking structure are selected, and the following preparation methods can be used:

[0099] A silicon oxide wafer with a top oxide layer of 100 nm is used as substrate 1;

[0100] A four-terminal electrode pattern was fabricated on the oxide layer of substrate 1 using photolithography, and 5 nm chromium and 40 nm gold were grown as electrodes using magnetron sputtering technology.

[0101] Tungsten diselenide is transferred twice to the electrode surface as the bottom layer material through PVA and PDMS assisted transfer. The tungsten diselenide transferred twice is arranged in parallel and independently, covering the two gate electrodes respectively. The parallel arranged tungsten diselenide does not touch each other, and does not touch the source and drain electrodes. The tungsten diselenide used is prepared by mechanical stripping;

[0102] By means of PVA and PDMS-assisted transfer, a defective hexagonal boron nitride material is transferred and stacked on top of the tungsten diselenide as the second two-dimensional material layer 6, so that the parallel tungsten diselenide is effectively covered. The defective hexagonal boron nitride used is prepared by mechanical exfoliation. The defective hexagonal boron nitride of the second two-dimensional material layer is obtained by growing at a temperature of 1200° C. to 1450° C. and a pressure of 10 Pa, and introducing 0.6% carbon during the growth process to obtain the defective hexagonal boron nitride.

[0103] Through PVA and PDMS-assisted transfer, stacked graphene is transferred as the top layer material on top of the defective hexagonal boron nitride, so that the graphene covers the effective area of ​​the device, ensuring that the graphene contacts the source and drain to form a channel while not contacting the gate 2 electrode. The graphene is a single layer or a few layers of graphene with 5 layers or less prepared by mechanical exfoliation.

[0104] In the single electrical modulation working mode, the same functions as those of the multifunctional synaptic device prepared by the preparation method of Example 1 and Example 2 were achieved. In the optical-electrical hybrid modulation working mode, it was also found that:

[0105] In dark conditions, the device can realize the "AND" logic function, and in light conditions, the device can realize the "OR" logic function, such as Figure 8 and 9 shown.

[0106] Under dark and light conditions, an electric pulse is applied to any gate 2 or both gates 2 at the same time for testing. After normalizing the channel current, under dark conditions, when only the two gates 2 are simultaneously pulsed, the channel current is greater than the threshold value of 0.5;

[0107] Under light conditions, when an electric pulse is applied to any gate 2 or to both gates 2 at the same time, the channel current is greater than the threshold value 0.5;

[0108] That is, in the optical-electrical hybrid modulation mode, the optical switch logic function can be realized. In dark conditions, only when both gates are subjected to an electrical pulse signal, the channel current can be higher than the threshold current, thus realizing the "AND" logic function. Under light conditions, when either one of the gates or both of them are subjected to an electrical pulse signal, the channel current can be higher than the threshold voltage, thus realizing the "OR" logic function. In other words, the logical "OR" and "AND" functions can be realized by light or no light, and the "OR" and "AND" switching can be performed according to the light conditions.

[0109] Furthermore, it should be noted that the specific embodiments described in this specification may vary in the shapes and names of their components. Any equivalent or simple variations based on the structure, features, and principles described in the patented concept of this invention are included within the scope of protection of this patent. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments, and these modifications, as long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, shall fall within the scope of protection of this invention.

Claims

1. A multifunctional photosensitive synaptic device based on two-dimensional materials, characterized in that: include: substrate; A gate, a source, a drain, and a stacked structure are provided above the substrate, wherein the stacked structure includes a first two-dimensional material layer, a second two-dimensional material layer, and a third two-dimensional material layer. The gate is provided above the substrate, and the first two-dimensional material layer, the second two-dimensional material layer, and the third two-dimensional material layer are sequentially covered above the gate. The source and the drain are respectively covered above the third two-dimensional material layer, and a channel is formed between the source and the drain. The second two-dimensional material layer includes defective hexagonal boron nitride, the first two-dimensional material layer serves as a light absorption layer, the second two-dimensional material layer serves as an isolation layer, and the third two-dimensional material layer serves as a readout layer. Among them, it includes two gates and two first two-dimensional material layers, a first channel is formed between the two gates, the two first two-dimensional material layers respectively cover the top of the two gates, a second channel is provided between the two first two-dimensional material layers, the first channel and the second channel are interconnected, the upper surface of the substrate is exposed below the first channel, and the lower surface of the second two-dimensional material layer is exposed above the second channel.

2. The multifunctional photosensitive synaptic device based on two-dimensional materials according to claim 1, characterized in that: The defective hexagonal boron nitride of the second two-dimensional material layer is obtained by the following method: The growth is carried out at a temperature of 1200℃~1450℃ and a pressure of 10Pa, and 0.6% carbon is introduced during the growth process to obtain defective hexagonal boron nitride.

3. The multifunctional photosensitive synaptic device based on two-dimensional materials according to claim 1, characterized in that: The first two-dimensional material layer comprises a two-dimensional semiconductor material having a light absorption function; The first two-dimensional material layer includes a plurality of transition metal sulfide layers or a plurality of transition metal selenide layers or a mixture of the two.

4. The multifunctional photosensitive synaptic device based on two-dimensional materials according to claim 1, characterized in that: The third two-dimensional material layer includes a conductive and light-transmitting two-dimensional material; The third two-dimensional material layer includes a single layer or 5 layers or less of graphene, a single layer or 5 layers or less of transition metal sulfide, or a single layer or 5 layers or less of transition metal selenide.

5. The multifunctional photosensitive synaptic device based on two-dimensional materials according to claim 1, characterized in that: The substrate is an insulating material substrate or the top layer of the substrate is an insulating material layer; The insulating material is any one of glass, silicon oxide wafer, ceramic, PET and PI.

6. The multifunctional photosensitive synaptic device based on two-dimensional materials according to claim 1, characterized in that: When the amplitude of the positive pulse signal applied to the gate is 1~5V, the pulse width is 0.5~3s, and the amplitude of the negative pulse signal applied is -1~-5V, and the pulse width is 0.5~3s, the synaptic enhancement function or inhibition function is achieved.

7. A method for preparing a multifunctional photosensitive synaptic device based on two-dimensional materials, characterized in that: The following steps are involved: Providing a substrate, wherein the substrate is an insulating material substrate or the top layer of the substrate is an insulating material layer; forming a gate above the top layer of the substrate; The gate is sequentially covered with a stacked structure, wherein the stacked structure includes a first two-dimensional material layer, a second two-dimensional material layer, and a third two-dimensional material layer; A source electrode and a drain electrode are respectively formed on the third two-dimensional material layer, and a channel is formed between the source electrode and the drain electrode, wherein the second two-dimensional material layer comprises defective hexagonal boron nitride, the first two-dimensional material layer serves as a light absorption layer, the second two-dimensional material layer serves as an intermediate isolation layer, and the third two-dimensional material layer serves as a readout layer; Among them, it includes two gates and two first two-dimensional material layers, a first channel is formed between the two gates, the two first two-dimensional material layers respectively cover the top of the two gates, a second channel is provided between the two first two-dimensional material layers, the first channel and the second channel are interconnected, the upper surface of the substrate is exposed below the first channel, and the lower surface of the second two-dimensional material layer is exposed above the second channel.

8. The method for preparing a multifunctional photosensitive synaptic device based on two-dimensional materials according to claim 7, characterized in that: The defective hexagonal boron nitride of the second two-dimensional material layer is obtained by the following method: The growth is carried out at a temperature of 1200℃~1450℃ and a pressure of 10Pa, and 0.6% carbon is introduced during the growth process to obtain defective hexagonal boron nitride.

9. The method for preparing a multifunctional photosensitive synaptic device based on two-dimensional materials according to claim 7 or 8, characterized in that: Before covering the second two-dimensional material layer, the following steps are also included: Two gates are formed above the top layer of the substrate, with a first channel provided between the two gates, wherein the depth of the first channel is the same as the thickness of the gates; A first two-dimensional material layer is stacked above each gate, and a second channel is formed between the two first two-dimensional material layers. The position of the second channel corresponds to the first channel, and the depth of the second channel is the same as the thickness of the first two-dimensional material layer.

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