Self-powered optoelectronic synapse device based on heterostructure and preparation method thereof
By using a self-powered opto-synaptic device with a heterostructure, utilizing an h-BN confinement layer and a CsPbBr3 quantum dot layer, the shortcomings of opto-synaptic devices in terms of non-volatility and power consumption are overcome, achieving long-term optical signal storage and self-powered performance, and supporting logic programming and Boolean logic gate applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- OCEAN UNIV OF CHINA
- Filing Date
- 2023-12-25
- Publication Date
- 2026-06-16
AI Technical Summary
Existing optical synaptic devices have low performance in terms of non-volatility and power consumption, which limits their application in high-performance computing circuits.
A self-powered opto-synaptic device with a heterostructure is developed. By introducing a two-dimensional confinement layer of hexagonal boron nitride (h-BN) and an asymmetric electrode, the rate-limiting effect of h-BN is used to improve the optical signal storage time. The self-powered performance is achieved through a CsPbBr3 quantum dot layer, and the storage state is controlled by adjusting the gate voltage signal and the optical signal.
It achieves long-term retention and non-volatile memory of optical signals, simulates biological synaptic memory, has self-powered capability, can realize photosynaptic performance without external voltage input, and supports logic relation programming and Boolean logic gate applications.
Smart Images
Figure CN117855302B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a self-powered opto-synaptic device based on a heterostructure and its fabrication method, belonging to the field of semiconductor device technology. Background Technology
[0002] Emerging neuromorphic computing technology integrates analog computing units and off-chip memory into a single device by simulating the parallel functions of neurons and synapses in the human brain. This enables complex memory processing to break through the von Neumann bottleneck, reduce data movement, improve computational efficiency, and promote the development of low-power computing architectures. As one of the candidate devices for next-generation digital memory, synaptic devices are characterized by fast switching speeds, wide scalability, and high integration.
[0003] Photosynaptic devices directly respond to and process optical signals, showing great potential in simulating human visual perception, memory, and environmental adaptation. The combination of photosensitivity and information processing in photosynaptic devices is essential for their development as artificial visual perception systems. Non-volatility is a crucial indicator for photosynaptic devices, but existing devices exhibit relatively low performance in this area. Furthermore, device power consumption has become one of the major bottlenecks restricting the future development of high-performance integrated circuits based on the von Neumann architecture. In the field of photosynaptic transistors, photothermoelectric heterojunction synaptic devices hold promise for providing new opportunities for the development of future low-power, high-performance computing circuits. Therefore, this invention is proposed. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a self-powered opto-synaptic device based on a heterostructure. By introducing a two-dimensional confinement layer of hexagonal boron nitride (h-BN), the rate-limiting effect of h-BN is utilized to improve the storage time of optical signals. Simultaneously, this opto-synaptic device achieves self-powered performance by introducing asymmetric electrodes, enabling optical signal storage and synaptic function without applying an external gate voltage. During logic programming, both the gate voltage signal and the incident light can be adjusted to regulate the storage state by regulating the charge carriers in the two-dimensional Te, CsPbBr3 quantum dot layer. Furthermore, the storage time of optical data can be changed by adjusting the gate voltage, allowing for complete data erasure.
[0005] The present invention also provides a method for fabricating the above-mentioned self-powered photoelectric synaptic device based on heterostructure.
[0006] The technical solution of the present invention is as follows:
[0007] A self-powered opto-synaptic device based on a heterostructure includes a substrate, a two-dimensional Te nanosheet, an h-BN nanosheet, and a CsPbBr3 quantum dot layer arranged sequentially from bottom to top. The two-dimensional Te nanosheet is connected to an active electrode and a drain electrode at its two ends, respectively. The two-dimensional Te nanosheet, h-BN nanosheet, and CsPbBr3 quantum dot layer are combined through van der Waals interactions.
[0008] The CsPbBr3 quantum dot layer serves as the photosensitive layer, the h-BN nanosheets as the confinement layer, and the two-dimensional Te nanosheets as the current transport layer. The substrate serves as the back gate electrode.
[0009] According to a preferred embodiment of the present invention, the source material comprises a metal electrode and multilayer graphene (MLG). The multilayer graphene is disposed on the upper side of the substrate, with a two-dimensional Te nanosheet connected to one end and a metal electrode disposed on the other end. The metal electrode is made of Cr / Au multilayer metal. The drain electrode is disposed at one end of the two-dimensional Te nanosheet, and the drain electrode is made of Cr / Au multilayer metal, with a Cr thickness of 7 nm and an Au thickness of 40 nm. The source and drain electrodes are made of two materials with different thermal conductivity. In the circuit composed of the two electrodes, illumination causes the two contact points to have different temperatures, forming a temperature gradient. CsPbBr3 quantum dots and Te are thermoelectric materials. That is, based on the temperature gradient, carrier diffusion is driven, and photovoltage is generated through the Seebeck effect, thereby achieving self-powered properties, that is, the performance of photosynaptic devices can be achieved without external voltage input.
[0010] The fabrication method of the above-mentioned self-powered photoelectric synaptic device based on heterostructure includes the following steps:
[0011] (1) Preparation of two-dimensional Te nanosheets;
[0012] (2) Two-dimensional Te nanosheets were transferred onto a silicon substrate using the LB process;
[0013] (3) Source and drain electrodes were fabricated at both ends of the two-dimensional Te nanosheet;
[0014] (4) Using a two-dimensional material transfer platform, h-BN nanosheets were vertically stacked onto two-dimensional Te nanosheets via dry transfer.
[0015] (5) Preparation of CsPbBr3 quantum dot layer.
[0016] According to a preferred embodiment of the present invention, in step (1), the two-dimensional Te nanosheets are prepared by dissolving 1g of polyvinylpyrrolidone and 0.2g of sodium tellurite in 50ml of deionized water, stirring evenly to obtain a reaction solution, and then adding a mixed solution of 6ml of hydrazine hydrate and 3ml of ammonia water to the reaction solution to carry out a hydrothermal reaction to obtain two-dimensional Te nanosheets.
[0017] According to a further preferred embodiment of the present invention, the hydrothermal reaction temperature is 160–200°C, and the reaction time is 20–40 hours.
[0018] According to a preferred embodiment of the present invention, in step (2), the specific method is to suspend the washed two-dimensional Te nanosheets in a mixed solvent, then drop the mixed solvent into deionized water, and after the mixed solvent evaporates, the two-dimensional Te nanosheets are assembled at the gas / water interface. Then, the two-dimensional Te nanosheets are transferred to the silicon substrate by a vertical lifting method, that is, the silicon substrate is vertically inserted into the water surface and moved up and down, and the two-dimensional Te nanosheets will be attached to the silicon substrate.
[0019] According to a further preferred embodiment of the present invention, the mixed solvent comprises N,N-dimethylformamide (DMF) and CHCl3, wherein the volume ratio of N,N-dimethylformamide and CHCl3 is 1:1.
[0020] According to a preferred embodiment of the present invention, in step (3), the drain is fabricated by electron beam lithography (EBL) and the metal contacts are thermally deposited Cr / Au.
[0021] The source electrode is fabricated using a dry transfer process. The specific steps are as follows: MLG nanosheets are adhered to the substrate using 3M tape, folded and peeled multiple times to achieve multilayer structure, and then the mechanically peeled MLG nanosheets are attached to a PDMS film. The contact points between the two-dimensional Te nanosheets and the substrate are located using a microscope. Under microscope observation, the MLG nanosheets on the PDMS film are aligned with the contact points, heated to 80°C, held for 20 minutes, and the PDMS film is slowly lifted. The MLG nanosheets on the PDMS film are transferred to the two-dimensional Te nanosheets to obtain multilayer graphene. Then, metal electrodes are fabricated on the multilayer graphene using electron beam lithography.
[0022] According to a preferred embodiment of the present invention, in step (4), the dry transfer method uses PDMS-assisted transfer method. The specific method is as follows: h-BN nanosheets are repeatedly picked up with 3M tape, folded and peeled to multiple layers, and the peeled h-BN nanosheets are pasted onto the PDMS film. Then, the target h-BN nanosheets are found through a microscope. The h-BN nanosheets other than the target h-BN nanosheets are removed by the PDMS film until the area around the target h-BN nanosheets is clean. Then, the h-BN nanosheets on the PDMS film are aligned with the two-dimensional Te nanosheets through a microscope. The film is heated to 80°C and held for 20 minutes. The PDMS film is then slowly lifted. The h-BN nanosheets on the PDMS film are transferred to the two-dimensional Te nanosheets, thus completing the dry transfer.
[0023] According to a preferred embodiment of the present invention, in step (5), the method for preparing the CsPbBr3 quantum dot layer is as follows: the target sample prepared in step (4) is placed in a PbBr2 dimethylformamide (DMF) solution. As the solution evaporates, a series of PbBr2 microfilaments (MWs) are formed on the surface of the target sample. The two-dimensional Te nanosheets and h-BN nanosheets of the target sample are immersed in a CsBr methanol solution to form CsPbBr3 quantum dots on the surface of the h-BN nanosheets. The samples are then heated for 30 minutes under ambient conditions to form a Te / h-BN / CsPbBr3 heterojunction photoelectric synapse device.
[0024] According to a further preferred embodiment of the present invention, the volume molar concentration of the PbBr2 dimethylformamide solution is 0.45 M, and the volume molar concentration of the CsBr methanol solution is 0.45 M.
[0025] The beneficial effects of this invention are as follows:
[0026] 1. The photoelectric synaptic device based on the Te / h-BN / CsPbBr3 quantum dot layered heterostructure of the present invention has a long residence time of the light pulse signal in the device due to the presence of the confinement layer, thus achieving excellent memory non-volatility and successfully simulating the biological synaptic memory function.
[0027] 2. This invention can simulate the excitatory and inhibitory synaptic activities by changing the reconfigurable internal potential of the pn junction by applying in-plane reverse voltage bias. Basic Boolean logic gate applications can be realized by controlling the optical and electrical inputs.
[0028] 3. This invention has designed a separate LB process for transferring two-dimensional Te nanosheets. Due to the inherent properties of tellurene crystals, dry transfer cannot produce relatively large and clean samples. However, the process of this invention can produce high-quality samples, thereby improving device performance.
[0029] 4. This invention has designed a dry transfer method to stack h-BN nanosheets on two-dimensional Te nanosheets. The dry transfer operation of this invention is simple, and non-target samples can be removed by repeated PDMS removal.
[0030] 5. The asymmetric electrode structure design of this invention achieves compatibility between device self-powering and photosynaptic performance under overall illumination. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of the structure of the present invention;
[0032] Figure 2 This is a three-dimensional structural schematic diagram of the present invention;
[0033] Figure 3 This is a schematic diagram illustrating the principle of improving optical storage time according to the present invention.
[0034] The components are: 1. Substrate; 2. Two-dimensional Te nanosheets; 3. h-BN nanosheets; 4. CsPbBr3 quantum dot layer; 5. Metal electrode; 6. Multilayer graphene; 7. Drain electrode; 8. Oxide insulating layer. Detailed Implementation
[0035] The present invention will be further described below with reference to the embodiments and accompanying drawings, but is not limited thereto.
[0036] Example 1:
[0037] like Figure 1-2 As shown, this embodiment provides a self-powered opto-synaptic device based on a heterostructure, including a substrate 1, a two-dimensional Te nanosheet 2, an h-BN nanosheet 3, and a CsPbBr3 quantum dot layer 4 arranged sequentially from bottom to top. The two-dimensional Te nanosheet 2 is connected to an active electrode and a drain electrode 7 at its two ends, respectively. The two-dimensional Te nanosheet 2, the h-BN nanosheet 3, and the CsPbBr3 quantum dot layer 4 are bonded together by van der Waals interactions.
[0038] The CsPbBr3 quantum dot layer serves as the photosensitive layer, the h-BN nanosheets as the confinement layer, and the two-dimensional Te nanosheets as the current transport layer. The substrate serves as the back gate electrode.
[0039] The source electrode material includes a metal electrode 5 and multilayer graphene 6. The multilayer graphene 6 is disposed on the substrate (the substrate has its own oxide insulating layer 8). One end of the multilayer graphene 6 is connected to a two-dimensional Te nanosheet 2, and the other end is disposed on the metal electrode 5. The metal electrode 5 is made of Cr / Au multilayer metal. The drain electrode 7 is disposed at one end of the two-dimensional Te nanosheet. The drain electrode 7 is made of Cr / Au multilayer metal, with a Cr thickness of 7 nm and an Au thickness of 40 nm. The source and drain electrodes are made of two materials with different thermal conductivity. In the circuit composed of the two electrodes, the temperature of the two contact points is different due to light illumination, forming a temperature gradient. CsPbBr3 quantum dots and Te are thermoelectric materials. Based on the temperature gradient, carrier diffusion is driven, and photovoltage is generated through the Seebeck effect, thereby achieving self-powered properties, that is, the performance of photosynaptic devices can be achieved without external voltage input.
[0040] The fabrication method of the above-mentioned self-powered photoelectric synaptic device based on heterostructure includes the following steps:
[0041] (1) Preparation of two-dimensional Te nanosheets 2: Dissolve 1g of polyvinylpyrrolidone and 0.2g of sodium tellurite in 50ml of deionized water and stir evenly to obtain a reaction solution. Then add a mixed solution of 6ml of hydrazine hydrate and 3ml of ammonia water to the reaction solution and carry out a hydrothermal reaction. The hydrothermal reaction temperature is 160-200℃ and the reaction time is 20-40 hours to obtain two-dimensional Te nanosheets.
[0042] (2) Two-dimensional Te nanosheets 2 are transferred to a silicon substrate by LB process: The washed two-dimensional Te nanosheets are suspended in a mixed solvent containing N,N-dimethylformamide (DMF) and CHCl3, with a volume ratio of N,N-dimethylformamide and CHCl3 of 1:1. The mixed solvent is then dropped into deionized water. After the mixed solvent evaporates, the two-dimensional Te nanosheets are assembled at the gas / water interface. Then, the two-dimensional Te nanosheets are transferred to the silicon substrate by vertical lifting method, that is, the silicon substrate is vertically inserted into the water surface and moved up and down. The two-dimensional Te nanosheets will then attach to the silicon substrate.
[0043] (3) Source and drain electrodes 7 were fabricated at both ends of the two-dimensional Te nanosheet 2: the drain electrode was fabricated by electron beam lithography (EBL) and the metal contacts were thermally deposited Cr / Au;
[0044] The source electrode is fabricated using a dry transfer process. The specific steps are as follows: MLG nanosheets are adhered to the substrate using 3M tape, folded and peeled multiple times to achieve multilayer structure, and the mechanically peeled MLG nanosheets are attached to a PDMS film. Then, the contact points between the two-dimensional Te nanosheets and the substrate are located using a microscope. Under microscope observation, the MLG nanosheets on the PDMS film are aligned with the contact points, heated to 80°C, held for 20 minutes, and the PDMS film is slowly lifted. The MLG nanosheets on the PDMS film are transferred to the two-dimensional Te nanosheets to obtain multilayer graphene. Then, metal electrodes are fabricated on the multilayer graphene using electron beam lithography.
[0045] (4) Using a two-dimensional material transfer platform, h-BN nanosheets 3 are vertically stacked on two-dimensional Te nanosheets 2 by dry transfer: h-BN nanosheets are repeatedly picked up with 3M tape, folded and peeled to multiple layers, and the peeled h-BN nanosheets are pasted onto the PDMS film. Then, the target h-BN nanosheet is found by microscopy. The h-BN nanosheets other than the target h-BN nanosheets are removed by PDMS film until the area around the target h-BN nanosheet is clean. Then, by microscopy, the h-BN nanosheets on the PDMS film are aligned with the two-dimensional Te nanosheets, heated to 80°C, held for 20 min, and the PDMS film is slowly lifted. The h-BN nanosheets on the PDMS film are transferred to the two-dimensional Te nanosheets, completing the dry transfer.
[0046] (5) Preparation of CsPbBr3 quantum dot layer 4: The target sample prepared in step (4) is placed in a PbBr2 dimethylformamide (DMF) solution with a volume molar concentration of 0.45M. As the solution evaporates, a series of PbBr2 microfilaments (MWs) are formed on the surface of the target sample. The two-dimensional Te nanosheets and h-BN nanosheets of the target sample are then immersed in a CsBr methanol solution with a volume molar concentration of 0.45M. CsPbBr3 quantum dots are formed on the surface of the h-BN nanosheets. The nanosheets are heated for 30 minutes under ambient conditions to form a Te / h-BN / CsPbBr3 heterojunction photoelectric synapse device.
[0047] The principle behind this embodiment for improving optical storage time is as follows: Figure 3 As shown, without a confinement layer, Te serves as the conductive channel. CsPbBr3 quantum dots are deposited on top of Te to form a junction region at the interface. Under illumination, electron-hole pairs generated on the CsPbBr3 quantum dots are separated by the built-in electric field at the heterojunction. Electrons are confined within the quantum dot layer, while holes are transported to the electrode through the Te channel. When the illumination is removed, electrons on the quantum dots can easily reach the Te layer, which has a lower conduction band. With a confinement layer, due to the high conduction band bottom of h-BN, electrons have difficulty reaching Te through the h-BN layer, thus extending the memory duration and achieving excellent non-volatility.
[0048] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A self-powered photoelectric synapse device based on a heterogeneous structure, characterized in that, The structure consists of a substrate, two-dimensional Te nanosheets, h-BN nanosheets, and a CsPbBr3 quantum dot layer arranged sequentially from bottom to top. The two-dimensional Te nanosheets are connected to the source and drain electrodes at their two ends, respectively. The two-dimensional Te nanosheets, h-BN nanosheets, and CsPbBr3 quantum dot layer are combined through van der Waals interactions. The source material includes a metal electrode and multilayer graphene (MLG). The multilayer graphene is disposed on the upper side of the substrate. One end of the multilayer graphene is connected to a two-dimensional Te nanosheet, and the other end is provided with a metal electrode. The metal electrode is made of Cr / Au multilayer metal. The drain electrode is disposed at one end of the two-dimensional Te nanosheet, and the drain electrode is made of Cr / Au multilayer metal.
2. The self-powered photoelectric synapse device based on a heterogeneous structure as described in claim 1, characterized in that, In the Cr / Au multilayer metal, the Cr thickness is 7 nm and the Au thickness is 40 nm.
3. The method for fabricating a self-powered photoelectric synaptic device based on a heterostructure as described in claim 2, characterized in that, The steps are as follows: (1) Preparation of two-dimensional Te nanosheets; (2) Two-dimensional Te nanosheets were transferred onto a silicon substrate using the LB process; (3) Source and drain electrodes were fabricated at both ends of the two-dimensional Te nanosheet, respectively; (4) Using a two-dimensional material transfer platform, h-BN nanosheets were vertically stacked on two-dimensional Te nanosheets by dry transfer; (5) Preparation of CsPbBr3 quantum dot layer.
4. The method for fabricating a self-powered photoelectric synaptic device based on a heterostructure as described in claim 3, characterized in that, In step (1), the two-dimensional Te nanosheets are prepared by dissolving 1g of polyvinylpyrrolidone and 0.2g of sodium tellurite in 50ml of deionized water, stirring evenly to obtain a reaction solution, and then adding a mixed solution of 6ml of hydrazine hydrate and 3ml of ammonia water to the reaction solution for hydrothermal reaction to obtain two-dimensional Te nanosheets.
5. The method for fabricating a self-powered photoelectric synaptic device based on a heterostructure as described in claim 4, characterized in that, The hydrothermal reaction temperature is 160~200˚C, and the reaction time is 20~40 hours.
6. The method for fabricating a self-powered photoelectric synaptic device based on a heterostructure as described in claim 5, characterized in that, In step (2), the specific method is to suspend the washed two-dimensional Te nanosheets in a mixed solvent, then drop the mixed solvent into deionized water. After the mixed solvent evaporates, the two-dimensional Te nanosheets are assembled at the gas / water interface, and then the two-dimensional Te nanosheets are transferred to the silicon substrate by vertical pulling method.
7. The method for fabricating a self-powered photoelectric synaptic device based on a heterostructure as described in claim 6, characterized in that, The mixed solvent contains N,N-dimethylformamide and CHCl3, with a volume ratio of 1:1 between N,N-dimethylformamide and CHCl3.
8. The method for fabricating a self-powered photoelectric synaptic device based on a heterostructure as described in claim 7, characterized in that, In step (3), the drain is fabricated using electron beam lithography, and the metal contacts are thermally deposited Cr / Au. The source electrode is fabricated using a dry transfer process. The specific steps are as follows: MLG nanosheets are adhered to the substrate using 3M tape, folded and peeled multiple times to achieve multilayer structure, and then the mechanically peeled MLG nanosheets are attached to a PDMS film. The contact points between the two-dimensional Te nanosheets and the substrate are located using a microscope. Under microscope observation, the MLG nanosheets on the PDMS film are aligned with the contact points, heated to 80˚C, held for 20 minutes, and the PDMS film is slowly lifted. The MLG nanosheets on the PDMS film are transferred to the two-dimensional Te nanosheets to obtain multilayer graphene. Then, metal electrodes are fabricated on the multilayer graphene using electron beam lithography.
9. The method for fabricating a self-powered photoelectric synaptic device based on a heterostructure as described in claim 8, characterized in that, In step (4), the dry transfer method uses PDMS-assisted transfer. The specific method is as follows: h-BN nanosheets are repeatedly picked up with 3M tape, folded and peeled to multiple layers, and the peeled h-BN nanosheets are pasted onto the PDMS film. Then, the target h-BN nanosheets are found through a microscope. The h-BN nanosheets other than the target h-BN nanosheets are removed through the PDMS film until the area around the target h-BN nanosheets is clean. Then, the h-BN nanosheets on the PDMS film are aligned with the two-dimensional Te nanosheets through a microscope. The film is heated to 80˚C and held for 20 min. The PDMS film is slowly lifted. The h-BN nanosheets on the PDMS film are transferred to the two-dimensional Te nanosheets, thus completing the dry transfer.
10. The method for fabricating a self-powered photoelectric synaptic device based on a heterostructure as described in claim 9, characterized in that, In step (5), the CsPbBr3 quantum dot layer is prepared as follows: the target sample prepared in step (4) is placed in a PbBr2 dimethylformamide solution. As the solution evaporates, a series of PbBr2 microfilaments are formed on the surface of the target sample. The two-dimensional Te nanosheets and h-BN nanosheets of the target sample are immersed in a CsBr methanol solution to form CsPbBr3 quantum dots on the surface of the h-BN nanosheets. The samples are heated for 30 minutes under ambient conditions to form a Te / h-BN / CsPbBr3 heterojunction photoelectric synapse device. The volumetric molar concentration of the PbBr2 dimethylformamide solution was 0.45 M, and the volumetric molar concentration of the CsBr methanol solution was 0.45 M.