Strain-enhanced multi-sensory fusion photoelectric synapse device and preparation method and application thereof

Abstract

The invention belongs to the related technical field of two-dimensional material devices, and discloses a strain-enhanced multi-sensory fusion photoelectric synapse device and a preparation method and application thereof.The photoelectric synapse device comprises an insulating layer, an electrode and a functional layer which are arranged from bottom to top, and the functional layer is made of an in-plane polarization two-dimensional ferroelectric material; tensile strain is applied to the functional layer in the polar axis direction of the functional layer; the photoelectric synaptic device simulates the perception of visual information through the photoconductive effect of the functional layer, and simulates the tactile sense through the tensile strain. The synergistic effect of the photoconductive effect and the tensile strain significantly enhances the persistent photoconductivity (PPC) of the synaptic device, and the enhancement processing of a fingerprint image is realized through the characteristics of the device. Meanwhile, tensile strain is applied along a specific direction, so that the in-plane polarization intensity is remarkably improved, the restriction of a depolarization field is avoided, the stability and the performance of a ferroelectric device are improved, and a new way is provided for improving the performance of a photoelectric synapse device.

Description

Technical Field

[0001] The present invention belongs to the technical field related to two-dimensional material devices, and more specifically, relates to a strain-enhanced multi-sensory fusion optoelectronic synapse device and a preparation method and application thereof. Background Art

[0002] The human multisensory system achieves advanced cognitive learning and environmental perception by integrating visual, auditory and tactile information. The development of the multisensory fusion artificial nervous system mimics the operating mechanism of the biological nervous system, and its development is crucial to the advancement of bionic systems and human-computer interaction technology. Of all the information acquired by humans, visual information accounts for more than 80%, while touch contains multidimensional information related to contact with objects. The fusion of these two senses induces cross-modal synaptic plasticity, which is of great significance in the simulation of artificial intelligence.

[0003] In recent years, most of the research on multi-sensory fusion combining vision and touch is based on the integration of tactile sensors and artificial synapses. The physical separation of sensors and processors will lead to additional losses in the process of information transmission. Therefore, using advanced integrated design and methods to design a high-performance device with sensing and processing is becoming an urgent key direction for low-power neuromorphic sensing systems. In order to achieve the fusion perception of vision and touch while simplifying the structure, it is necessary to seek breakthroughs in material properties.

[0004] In order to realize the fusion sensing of vision and touch in multifunctional artificial systems, the functional layer materials need to not only have photoresponse and piezoelectricity, but also be able to memorize and process visual and tactile information. In this context, two-dimensional ferroelectric materials have become an ideal choice, which is expected to promote the development of visual-tactile integrated artificial synaptic devices in artificial intelligence systems. Summary of the invention

[0005] In response to the above defects or improvement needs of the prior art, the present invention provides a strain-enhanced multi-sensory fusion optoelectronic synapse device and a preparation method and application, which aims to achieve the fusion perception of vision and touch under the premise of simplifying the structure.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present invention, a strain-enhanced multi-sensory fusion optoelectronic synapse device is provided, wherein the optoelectronic synapse device comprises an insulating layer, an electrode and a functional layer arranged from bottom to top, wherein the material of the functional layer is an in-plane polarized two-dimensional ferroelectric material, and the functional layer is subjected to tensile strain along its own polar axis direction; the optoelectronic synapse device simulates the perception of visual information through the photoconductivity effect of the functional layer, and simulates the sense of touch through tensile strain.

[0007] Furthermore, the material of the functional layer is any one of mechanically stripped NbOI2, NbOCl2, and NbOBr2, and its thickness is 20nm-40nm.

[0008] Furthermore, the material of the insulating layer is any one of SiO2, Al2O3, HfO2, and ZrO2, and its thickness is 0nm-200nm.

[0009] Furthermore, the material of the electrode is gold, palladium or platinum, and its thickness is 60nm.

[0010] Furthermore, an insulating packaging layer is also arranged on the functional layer, and the material of the insulating packaging layer is a mechanically exfoliated two-dimensional layered material h-BN, and the thickness of the insulating packaging layer is 10nm-20nm.

[0011] Furthermore, the adjustment of the tensile strain is achieved by controlling the deposition thickness of the step structure composed of the insulating layer and the electrode and the channel width between the electrodes, the thickness of the step structure is 50nm-250nm, and the channel width is 1μm-5μm.

[0012] The present invention also provides a method for preparing the strain-enhanced multi-sensory fusion optoelectronic synaptic device as described above, the method comprising the following steps:

[0013] (1) Using electron beam lithography to prepare the desired pattern on the surface of a hard substrate;

[0014] (2) depositing the insulating layer and the electrode in sequence on the surface of the hard substrate;

[0015] (3) Using a low-dimensional transfer platform, the functional layer and the encapsulation layer are sequentially transferred onto the electrode to obtain the synaptic device.

[0016] Furthermore, during the transfer process, the functional layer is firstly attached to the electrode surface, and then pressure is gradually applied to the functional layer so that the bottom of the channel formed between the functional layer and the electrode is completely attached, thereby generating tensile strain.

[0017] The present invention also provides an application of the strain-enhanced multi-sensory fusion optoelectronic synapse device as described above in an artificial intelligence system.

[0018] In general, compared with the prior art, the strain-enhanced multi-sensory fusion optoelectronic synaptic device, preparation method and application provided by the present invention mainly have the following beneficial effects:

[0019] 1. The material of the functional layer is an in-plane polarized two-dimensional ferroelectric material, and tensile strain is applied along the polar axis direction of the functional layer. The perception of visual information is simulated by the photoconductivity effect of the functional layer, and the sense of touch is simulated by applying tensile strain in a specific direction of the functional layer. The synergistic effect of the photoconductivity effect and the tensile strain significantly enhances the persistent photoconductivity (PPC) of the synaptic device, and the fingerprint image enhancement processing is realized through the characteristics of the device. At the same time, by applying tensile strain along a specific direction, the in-plane polarization intensity is significantly improved, while avoiding the constraints of the depolarization field, improving the stability and performance of the ferroelectric device, and providing a new way to improve the performance of optoelectronic synaptic devices, especially in the fields of neuromorphic visual perception and visual information preprocessing, showing great application potential.

[0020] 2. Compared with the three-terminal floating gate, heterojunction and other device structures commonly used in current research, the present invention simplifies the structural design. By combining the ferroelectric, piezoelectric and photoelectric properties of the functional layer and using only a simple two-terminal structure, it successfully simulates the photoelectric synapse characteristics and effectively optimizes the synaptic performance.

[0021] 3. The present invention prepares the device by first evaporating the electrode and then transferring the two-dimensional material, which effectively avoids the damage of the metal atoms to the contact interface between the two when the electrode is directly evaporated on the two-dimensional material, avoids the Fermi level pinning effect, and helps to form good contact between the metal and the two-dimensional material interface, thereby facilitating the preparation of optoelectronic synapse devices with better performance.

[0022] 4. The present invention utilizes the synergistic effect of strain and light to effectively improve the photoelectric synapse properties such as PPF index and persistent photoconductance (PPC). By applying the characteristics of strain photoelectric synapse devices to the image processing of optical sensor fingerprints, the image quality can be greatly improved, demonstrating the application potential of multimodal sensory integration in multifunctional artificial nervous systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of a strain-enhanced multi-sensory fusion optoelectronic synaptic device provided by the present invention;

[0024] Figure 2 is an optical image of the device in Example 1 of the present invention;

[0025] Figure 3 is the P2 Raman peak of the strained and unstrained regions of the two-dimensional material NbOI2 in Example 1 of the present invention;

[0026] Figure 4 is a second harmonic total intensity diagram of the unstrained and strained regions of the two-dimensional material NbOI2 in Example 1 of the present invention;

[0027] Figure 5is the I of the non-strained device (upper) and the strained device (lower) in Example 1 of the present invention ds -V ds Cyclic hysteresis curve;

[0028] Figure 6 is the PPF exponential fitting function of the strained and unstrained NbOI2 devices in Example 1 of the present invention;

[0029] Figure 7 is the current response of the strained and unstrained NbOI2 devices to different numbers of 532nm light pulses in Example 1 of the present invention;

[0030] Figure 8 is the photocurrent fitting curve of the strained and unstrained NbOI2 devices in Example 1 of the present invention;

[0031] Fig. 9 It is the processing effect and gray value distribution statistics of the same original fingerprint image (ab) using the synaptic characteristics of strained (ef) and unstrained (cd) NbOI2 devices in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] The present invention provides a strain-enhanced multi-sensory fusion optoelectronic synapse device, which includes an insulating layer, an electrode, a functional layer and an insulating packaging layer arranged from bottom to top. The material of the functional layer is an in-plane polarized two-dimensional ferroelectric material, and the functional layer is subjected to tensile strain along its own polar axis direction; the optoelectronic synapse device simulates the perception of visual information through the photoconductivity effect of the functional layer, and simulates touch through tensile strain.

[0034] The material of the functional layer is any one of mechanically stripped NbOI2, NbOCl2, and NbOBr2, and its thickness is 20nm-40nm.

[0035] The material of the insulating layer is any one of SiO2, Al2O3, HfO2, and ZrO2, and its thickness is 0nm-200nm.

[0036] The electrode is made of gold, palladium or platinum, and has a thickness of 60 nm.

[0037] The material of the insulating encapsulation layer is a mechanically exfoliated two-dimensional layered material h-BN, and its thickness is 10nm-20nm. The insulating encapsulation layer is used to protect the functional layer that is sensitive to water and oxygen, and prevent the functional layer from reacting with moisture and oxygen in the environment. For a functional layer with environmental stability, there is no need to use the insulating encapsulation layer.

[0038] The adjustment of the tensile strain is achieved by controlling the deposition thickness of the step structure composed of the insulating layer and the electrode and the channel width between the electrodes. The thickness of the step structure is 50nm-250nm, and the channel width is 1μm-5μm.

[0039] The present invention also provides a method for preparing the strain-enhanced multi-sensory fusion optoelectronic synaptic device as described above, the preparation method mainly comprising the following steps:

[0040] (1) The desired pattern is prepared on the surface of a hard substrate using electron beam lithography.

[0041] (2) The insulating layer and the electrode are sequentially deposited on the surface of the hard substrate.

[0042] (3) Using a low-dimensional transfer platform, the functional layer and the encapsulation layer are sequentially transferred onto the electrode to obtain the synaptic device.

[0043] The insulating layer deposition method includes but is not limited to coating processes such as electron beam evaporation and magnetron sputtering. The electrode deposition method includes but is not limited to coating processes such as electron beam evaporation and thermal evaporation. In a glove box with extremely low oxygen and water content, a low-dimensional transfer platform is used to transfer the functional layer to the electrode surface in a specific direction to increase the non-central symmetry of the crystal structure. During the transfer process, the functional layer is first lightly adhered to the electrode surface, and then pressure is gradually applied to the PDMS to completely adhere the functional layer to the bottom of the channel, thereby generating tensile strain. If the functional layer is easily affected by the water and oxygen environment, the encapsulation layer is transferred to the electrode surface to protect the functional layer from environmental influences; if the functional layer is stable, there is no need to transfer the encapsulation layer.

[0044] The present invention also provides an application of the strain-enhanced multi-sensory fusion optoelectronic synapse device as described above in an artificial intelligence system.

[0045] The present invention is further described in detail below with reference to specific embodiments.

[0046] Example 1

[0047] This embodiment 1 provides a strain-enhanced multi-sensory fusion optoelectronic synaptic device, the device structure is as follows Figure 1 and Figure 2As shown, the material of the insulating layer is SiO2 with a thickness of 140nm; the material of the bottom electrode is Cr / Au with a thickness of 10 / 50nm; the material of the functional layer is NbOI2 with a thickness of 30nm; and the material of the encapsulation layer is h-BN with a thickness of 15nm.

[0048] The preparation method of a strain-enhanced multi-sensory fusion optoelectronic synaptic device provided in Example 1 is as follows:

[0049] (1) Photolithography pattern on a clean silicon oxide / silicon substrate: Spin-coat a layer of PMMA according to the parameters (rate: 600 r / min, time: 5 s; rate: 1000 r / min, time: 10 s; rate: 4000 r / min, time: 60 s), and then dry (5 min at 150 ° C). Expose the pattern using electron beam lithography, with a channel width of 3 μm. Dissolve the exposed PMMA with a developer to obtain the desired pattern;

[0050] (2) On the surface of the pattern prepared in step (1), an insulating layer SiO2 is deposited by electron beam evaporation process with a thickness of 140 nm and a rate of 0.05 nm / s; an electrode layer Cr is deposited by thermal evaporation process with a thickness of 10 nm and a rate of 0.03 nm / s; an electrode layer Au is deposited by thermal evaporation process with a thickness of 50 nm and a rate of 0.03 nm / s. Then, the excess PMMA is dissolved in acetone (60°C, 5 min);

[0051] (3) Sequentially transfer the functional layer and encapsulation layer to the step surface prepared in step (2): In a glove box with extremely low water and oxygen content, use a low-dimensional transfer platform to accurately transfer the two-dimensional material NbOI2 obtained by mechanical exfoliation to the electrode surface, and ensure that its polar axis remains in a specific direction perpendicular to the channel. First, NbOI2 is lightly attached to the electrode surface, and then gradually applies pressure to the PDMS to deform it downward so that NbOI2 is completely attached to the bottom of the channel. After this process is completed, the sample needs to be heated to 80°C and maintained for 5 minutes. Next, h-BN is transferred to the surface of NbOI2, the same as the previous step. It should be noted that the area of ​​h-BN should be larger than that of NbOI2 to protect NbOI2 from the influence of the water and oxygen environment.

[0052] Results Analysis

[0053] The strain characterization and performance characterization of the strain-enhanced multi-sensory fusion optoelectronic synaptic device prepared in Example 1 are as follows: Figure 3-Figure 8 shown.

[0054] Figure 3The P2 Raman peaks of the unstrained (light curve) and strained (dark curve) regions of the two-dimensional material NbOI2 are shown. Raman spectroscopy shows that the P2 Raman peak in the channel region exhibits a significant shift compared to the stress-free region, which proves the formation of strain. The tensile strain applied along the polar axis of NbOI2 increases the polar displacement of Nb atoms, exacerbates the non-centrosymmetry, and thus enhances the second harmonic signal. Figure 4 The total intensity of the second harmonic is shown to vary with the excitation beam (λ SHG =525nm) shows that the second harmonic intensity in the strained area is significantly higher than that in the unstrained area. The shift of the Raman peak and the enhancement of the second harmonic fully prove the generation of channel strain.

[0055] In order to study the synergistic effect of strain and light on device performance, a strain-free NbOI2 device was constructed by transferring electrodes for comparison. Figure 5 The I of the two devices in the dark state is shown. ds -V ds The curve shows a memristor curve of multiple cycles, indicating that the device has ferroelectric memristive behavior. Due to the tensile strain along the polar axis, the spontaneous polarization of NbOI2 is enhanced, so the strained NbOI2 device has a larger hysteresis window than the unstrained device. Figure 6 The relationship between the PPF index and the pulse interval obtained by fitting a double exponential function is shown. Compared with the unstrained device, the PPF index of the strained device is significantly improved from 116% to 180%. Figure 7 The current decay process of strained and unstrained NbOI2 devices in response to different numbers of light pulses under 532nm light pulses is demonstrated, indicating that strained devices have better photocurrent memory effect. In order to verify the superiority of multimodal perception in specific information processing fields compared to single-modal perception, the present invention conducts application research on optical fingerprint image processing.

[0056] Figure 8 The relationship between photocurrent and light intensity of NbOI2 devices in strained and unstrained states is demonstrated, and a power law fitting is performed on it. Fig. 9 The results show that the strain-free device ( Fig. 9 Compared with c and d in Figure 2, the strain device has a stronger Fig. 9 e) and part ( Fig. 9 f) shows better results in the fingerprint image, where the ridges and valleys of the fingerprint become more obvious.

[0057] Example 2

[0058] This Example 2 uses the same steps as Example 1 to prepare a strain enhanced ferroelectric polarization photoelectric synapse device. The difference from Example 1 is that the deposition of the insulating layer uses a magnetron sputtering process to deposit one of Al2O3, HfO2, ZrO2, etc.

[0059] Example 3

[0060] In this embodiment 2, a strain-enhanced ferroelectric polarization optoelectronic synapse device is prepared by using the same steps as in embodiment 1. The difference from embodiment 1 is that the functional layer uses one of the in-plane polarized two-dimensional ferroelectric materials such as NbOCl2 and NbOBr2.

[0061] Example 4

[0062] This Example 4 uses the same steps as Example 1 to prepare a strain-enhanced ferroelectric polarization photoelectric synapse device. The difference from Example 1 is that the magnitude of the tensile strain can be adjusted by changing the thickness of the insulating layer (0-200nm) and the channel width (1-5μm).

[0063] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A strain-enhanced multi-sensory fusion optoelectronic synaptic device, characterized in that: The photoelectric synapse device includes an insulating layer, an electrode and a functional layer arranged from bottom to top. The material of the functional layer is an in-plane polarized two-dimensional ferroelectric material, and the functional layer is subjected to tensile strain along its own polar axis direction; the photoelectric synapse device simulates the perception of visual information through the photoconductivity effect of the functional layer and simulates touch through tensile strain.

2. The strain-enhanced multi-sensory fusion optoelectronic synaptic device according to claim 1, characterized in that: The material of the functional layer is any one of mechanically stripped NbOI2, NbOCl2, and NbOBr2, and its thickness is 20nm-40nm.

3. The strain-enhanced multi-sensory fusion optoelectronic synaptic device according to claim 1, characterized in that: The material of the insulating layer is any one of SiO2, Al2O3, HfO2, and ZrO2, and its thickness is 0nm-200nm.

4. The strain-enhanced multi-sensory fusion optoelectronic synaptic device according to claim 1, characterized in that: The electrode is made of gold, palladium or platinum, and has a thickness of 60 nm.

5. The strain-enhanced multi-sensory fusion optoelectronic synaptic device according to claim 1, characterized in that: An insulating packaging layer is also arranged on the functional layer. The material of the insulating packaging layer is a mechanically exfoliated two-dimensional layered material h-BN, and the thickness thereof is 10nm-20nm.

6. The strain-enhanced multi-sensory fusion optoelectronic synaptic device according to any one of claims 1 to 5, characterized in that: The adjustment of the tensile strain is achieved by controlling the deposition thickness of the step structure composed of the insulating layer and the electrode and the channel width between the electrodes. The thickness of the step structure is 50nm-250nm, and the channel width is 1μm-5μm.

7. A method for preparing the strain-enhanced multi-sensory fusion optoelectronic synaptic device according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: (1) Using electron beam lithography to prepare the desired pattern on the surface of a hard substrate; (2) depositing the insulating layer and the electrode in sequence on the surface of the hard substrate; (3) Using a low-dimensional transfer platform, the functional layer and the encapsulation layer are sequentially transferred onto the electrode to obtain the synaptic device.

8. The strain-enhanced multi-sensory fusion optoelectronic synaptic device according to claim 7, characterized in that: During the transfer process, the functional layer is first adhered to the electrode surface, and then pressure is gradually applied to the functional layer so that the bottom of the channel formed between the functional layer and the electrode is completely adhered, thereby generating tensile strain.

9. Application of the strain-enhanced multi-sensory fusion optoelectronic synapse device according to any one of claims 1 to 6 in an artificial intelligence system.

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