Optoelectronic synapse device and preparation method thereof

Abstract

The application discloses a kind of photoelectric synapse devices and preparation method thereof, method includes, provide the silicon-based substrate with dielectric layer deposited on surface;Perovskite quantum dot solution is deposited on the surface of the dielectric layer, to obtain perovskite quantum dot layer;Providing auxiliary film;Source electrode and drain electrode are set as metal electrode on the surface of the auxiliary film, channel is set between the source electrode and drain electrode;Channel layer is set at the opening of the channel, the channel layer includes first side and second side, the first side is connected with the source electrode and the drain electrode, the second side is provided with two-dimensional tunneling layer;The auxiliary film is stacked on the perovskite quantum dot layer, so that the two-dimensional tunneling layer is attached with the perovskite quantum dot layer, to obtain photoelectric synapse device.The scheme avoids the influence of water and oxygen in the photoetching process, and at the same time, the auxiliary film can further protect perovskite quantum dot.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of synaptic plasticity devices, in particular to a photoelectric synaptic device and a preparation method thereof. BACKGROUND

[0002] Moor's law has driven the information technology revolution since the 1960s, however, due to the short channel effect, the electronic devices based on silicon material are about to reach their physical limit, and Moor's law is approaching the end. The International Roadmap for Semiconductors proposes a new strategic roadmap: instead of large-scale expansion of silicon electronic devices, new materials and new devices (photoelectric synaptic devices) are introduced to obtain continuous performance improvement. Since graphene was discovered in 2004, a large number of two-dimensional materials have been reported, including hexagonal boron nitride, transition metal sulfide, black phosphorus, etc. These materials are formed by out-of-plane van der Waals force and can be mechanically exfoliated into single layers with a thickness of less than 1 nanometer. Unlike traditional bulk materials, two-dimensional semiconductor materials are not affected by the short channel effect due to their atomic thickness, and at the same time have a naturally uniform and dangling bond-free surface, which provides an opportunity for further reduction of device size.

[0003] In addition, when the bulk thickness is reduced to below 10 nanometers, the carrier mobility of silicon material is significantly reduced, while the carrier mobility of two-dimensional material only changes slightly. Due to the unique atomic structure and electrical and optical properties of two-dimensional materials, photoelectric synapses of two-dimensional materials have been widely studied, such as ionic liquid transistors, ferroelectric transistors, floating gate transistors, etc. In two-dimensional material floating gate transistors, the floating gate layer can be metal nanoparticles, graphene, etc., however, although metal nanoparticles and graphene exhibit charge trapping effect and can effectively adjust the channel carrier concentration, their photosensitivity is poor, which is not conducive to the multifunctionality of the device. SUMMARY

[0004] In view of the above deficiencies of the prior art, the purpose of the present application is to provide a photoelectric synaptic device and a preparation method thereof, aiming at solving the problem of poor photosensitivity of existing biological synapses.

[0005] A preparation method of a photoelectric synaptic device, comprising the following steps:

[0006] providing a silicon-based substrate with a dielectric layer deposited on the surface thereof;

[0007] depositing a perovskite quantum dot solution on the surface of the dielectric layer to obtain a perovskite quantum dot layer;

[0008] providing an auxiliary film;

[0009] providing a source electrode and a drain electrode as metal electrodes on the surface of the auxiliary film, and a channel is provided between the source electrode and the drain electrode;

[0010] A channel layer is arranged at the opening of the channel, the channel layer comprising a first side and a second side, the first side being in contact with the source electrode and the drain electrode, and the second side being provided with a two-dimensional tunneling layer;

[0011] The auxiliary film stack is arranged on the perovskite quantum dot layer, so that the two-dimensional tunneling layer is attached to the perovskite quantum dot layer, to obtain the optoelectronic synapse device.

[0012] Optionally, the method for preparing the optoelectronic synapse device, wherein the material of the perovskite quantum dot layer is ABX3, wherein A=C + , CH3NH3 + , CH(NH2)2 + ; B=Pb 2+ , Sn 2+ , Ge 2+ ; X=Br - , I - , Cl - .

[0013] Optionally, the method for preparing the optoelectronic synapse device, wherein the material of the channel layer is molybdenum disulfide, tungsten diselenide, tungsten disulfide or black phosphorus.

[0014] Optionally, the method for preparing the optoelectronic synapse device, wherein the material of the two-dimensional tunneling layer is hexagonal boron nitride.

[0015] Optionally, the method for preparing the optoelectronic synapse device, wherein the concentration of the perovskite quantum dot solution is 1-2 mg / mL.

[0016] Optionally, the method for preparing the optoelectronic synapse device, wherein the step of depositing the perovskite quantum dot solution on the surface of the dielectric layer to obtain the perovskite quantum dot layer comprises:

[0017] The perovskite quantum dot solution is spin-coated on the dielectric layer at a speed of 4500-5500 rpm for 30-45 s, and then annealed at a temperature of 110-130℃ for 20-40 min to obtain the perovskite quantum dot layer.

[0018] Optionally, the method for preparing the optoelectronic synapse device, wherein the material of the auxiliary film is selected from any one of polymethyl methacrylate, polyvinyl alcohol and polymethylethylene carbonate.

[0019] An optoelectronic synapse device, wherein the device is prepared by the above-mentioned method.

[0020] Optionally, the optoelectronic synapse device, wherein the thickness of the perovskite quantum dot layer is 15-25 nm.

[0021] Optionally, the optoelectronic synapse device, wherein the material of the dielectric layer is silicon dioxide; and the thickness of the channel layer is 0.7-10 nm.

[0022] Beneficial effects: Compared with the prior art, the present application successfully prepares a back-gate type two-dimensional material optoelectronic synapse transistor based on a perovskite quantum dot floating gate by means of full transfer, by adopting a transfer auxiliary film to directly transfer an electrode, a two-dimensional channel layer and a two-dimensional tunneling layer onto a perovskite quantum dot. This scheme avoids the influence of water and oxygen in the photoetching process, at the same time, the transfer auxiliary film can further protect the perovskite quantum dot, finally, by using the charge trapping effect and photosensitivity of the perovskite quantum dot, a variety of biological synapse functions can be simulated. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A structure schematic diagram of an optoelectronic synapse device provided by an embodiment of the present application is shown in the figure;

[0024] Figure 2 A flowchart for preparing an optoelectronic synapse device is shown in the figure;

[0025] Figure 3 Synaptic plasticity of an optoelectronic synapse device under light stimulation;

[0026] Figure 4 Current change of an optoelectronic synapse device under (a) single, (b) two, and (c) multiple gate voltage electric pulse stimulations;

[0027] Figure 5 Current change of an optoelectronic synapse device under (a) single, (b) two, and (c) multiple light pulse stimulations;

[0028] Figure 6 Current change of an optoelectronic synapse device under (a-b) different gate voltage electric pulse and (c-d) different frequency light pulse stimulations. DETAILED DESCRIPTION

[0029] The present application provides an optoelectronic synapse device and a preparation method thereof, in order to make the purpose, technical scheme and effects of the present application more clear and explicit, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0030] As Figure 1As shown, the photoelectric synapse device provided by the application comprises a silicon substrate 10, a dielectric layer 11 arranged on the surface of the silicon substrate 10, the material of the dielectric layer being silicon dioxide, a perovskite quantum dot layer 12 arranged on the surface of the dielectric layer 11, a two-dimensional tunneling layer 13 arranged on the surface of the perovskite quantum dot layer 12, a two-dimensional channel layer 14 arranged on the surface of the two-dimensional tunneling layer 13, a metal electrode 15 arranged on the two-dimensional channel layer, and an auxiliary film 16 arranged on the surface of the metal electrode.

[0031] In the embodiment, the charge capture effect and photosensitivity of the optical synapse device are improved by adopting the perovskite quantum dot layer as the floating gate, and the stability of the optical synapse device is improved by arranging the auxiliary film layer to further protect the perovskite quantum dot layer.

[0032] In the embodiment, the material of the perovskite quantum dot layer includes but is not limited to CsPbBr3, CH3NH3PbI3, CsSnI3, etc. The perovskite quantum dot has a high light absorption coefficient, and can generate a photoelectron-hole pair after being excited by light, thereby modulating the capture and release process of the carrier, which is conducive to realizing a multifunctional photoelectric synapse.

[0033] In the embodiment, the material of the channel layer includes but is not limited to molybdenum disulfide, tungsten diselenide, tungsten disulfide, black phosphorus, etc. The performance of the photoelectric synapse device can be optimized by changing the material of the channel layer. According to the energy band theory, the perovskite quantum dot and the channel material are selected to match the energy band structure. Due to the effect of the band gap and the built-in electric field, the light storage capacity of the perovskite quantum dot can be adjusted, thereby optimizing the performance of the photoelectric synapse device.

[0034] In the embodiment, the material of the two-dimensional tunneling layer is hexagonal boron nitride.

[0035] Based on the same inventive concept, the application further provides a preparation method of a photoelectric synapse device. Figure 2 The method comprises the following steps:

[0036] S10, providing a silicon-based substrate with a dielectric layer deposited on the surface thereof;

[0037] S20, depositing a perovskite quantum dot solution on the surface of the dielectric layer to obtain an ABX3 perovskite quantum dot layer, wherein A=C + , CH3NH3 + , CH(NH2)2 + ; B=Pb 2+ , Sn 2+ , Ge 2+ ; X=Br - , I - , Cl - ;

[0038] S30, providing an auxiliary film;

[0039] S40, providing a source electrode and a drain electrode on a surface of the auxiliary film as metal electrodes, a channel being provided between the source electrode and the drain electrode;

[0040] S50, providing a channel layer at an opening of the channel, the channel layer comprising a first side and a second side, the first side being connected to the source electrode and the drain electrode, and the second side being provided with a two-dimensional tunneling layer;

[0041] S60, stacking the auxiliary film on the perovskite quantum dot layer, so that the two-dimensional tunneling layer is attached to the perovskite quantum dot layer, to obtain a photoelectric synapse device.

[0042] In the embodiment, the silicon-based substrate serves as a back gate, and the silicon dioxide serves as a dielectric layer. The preparation of the perovskite quantum dot solution in step S20 includes synthesizing CsPbBr3 quantum dots by a hot injection method. First, a cesium oleate precursor is synthesized. 0.814 g of Cs2CO3, 30 ml of octadecene, and 2.5 ml of oleic acid are placed in a 100 mL double-necked flask. After degassing at 120°C for one hour, heating is performed in a nitrogen atmosphere until the oleic acid and Cs2CO3 completely react, and the heating temperature is 160°C. Subsequently, CsPbBr3 quantum dots are synthesized. 100 mL of octadecene, 10 mL of oleylamine, 10 mL of oleic acid, and 1.38 g of PbBr2 are placed in a 250 mL flask. After degassing at 120°C for one hour, heating is performed in a nitrogen atmosphere to 180°C. 8 mL of the cesium oleate precursor is quickly injected into the beaker, and after 5 seconds, the mixture is quickly cooled in ice water. The crude solution is centrifuged at a speed of 8000 rpm for 10 minutes, and the collected precipitate is dispersed in n-hexane, and the quantum dots are further purified by secondary centrifugation. Finally, the collected CsPbBr3 perovskite quantum dots are dispersed in n-hexane, and the prepared perovskite quantum dot solution has a concentration of 2 mg / mL. The prepared perovskite quantum dot solution is spin-coated on the dielectric layer by a spin coating method to obtain a perovskite quantum dot layer.

[0043] Exemplarily, the perovskite quantum dot solution is spin-coated on the dielectric layer at a speed of 5000 rpm for 40 s, and after spin coating, annealing is performed at a temperature of 120°C for 30 min to obtain a perovskite quantum dot layer. The thickness of the perovskite quantum dot layer can be 20 nm.

[0044] In the step S30, the auxiliary film includes, but is not limited to, polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), polymethylethylene carbonate (PPC), etc. In the step S40, a metal electrode, such as a gold electrode, is attached to the surface of the auxiliary film, and the two electrodes are arranged with a gap (channel) therebetween. A channel layer is attached on the channel, a two-dimensional tunneling layer is attached on the channel layer, and then the auxiliary film is placed on the substrate on which the perovskite quantum dots are spin-coated. It is easy to understand that the two-dimensional tunneling layer is in contact with the perovskite quantum dot layer.

[0045] In the present embodiment, in order to prepare a multifunctional two-dimensional material phototransistor (device) with a floating gate having a charge trapping effect and a light absorption effect, perovskite quantum dots are used as a floating gate layer, and a full transfer, no-lithography method is adopted. By transferring an auxiliary film, a metal electrode, a two-dimensional channel layer and a two-dimensional tunneling layer are directly transferred to a back gate substrate on which perovskite quantum dots are spin-coated, to obtain a two-dimensional material transistor type phototransistor device based on perovskite quantum dot floating gate. The device prepared by the full transfer method effectively avoids the influence of water and oxygen in the lithography process. At the same time, the transfer auxiliary film can further protect the perovskite quantum dots. In addition, the transfer electrode can effectively reduce the Fermi level pinning effect of the metal-two-dimensional semiconductor interface in the process of evaporating the electrode, which is conducive to the preparation of high-performance devices.

[0046] The preparation method of the phototransistor device and the performance test of the phototransistor device of the present application will be further explained and described below through specific embodiments:

[0047] Embodiment 1

[0048] 1. Preparation of electrode: laser direct writing is used to lithograph electrode patterns on a substrate on which photoresist (photoresist model LOL2000 / S1805) is spin-coated. After the development, pure gold evaporation and stripping process, electrode patterns are obtained, and the channel length is 3 μm.

[0049] 2. Two-dimensional material: mechanical exfoliation is used to obtain a single layer of molybdenum disulfide with a thickness of about 1 nm and hexagonal boron nitride with a thickness of about 10 nm.

[0050] 3. Spin-coating perovskite: CsPbBr3 perovskite quantum dot solution with a concentration of 2 mg / mL is spin-coated onto a highly doped silicon substrate with a 100 nm silicon oxide dielectric layer, with a rotation speed of 5000 rpm and a spin-coating time of 40 s. After spin-coating, annealing is performed at a temperature of 120°C for 30 min to obtain a perovskite quantum dot layer with a thickness of 20 nm.

[0051] 4. Full transfer device preparation: using PMMA transfer auxiliary film, electrode, single layer of molybdenum disulfide and hexagonal boron nitride with a thickness of about 10 nm are sequentially adhered, and the adhering process meets the following two points: 1. The electrode channel is located on both sides of the single layer of molybdenum disulfide; 2. The single layer of molybdenum disulfide is located at the center position of the hexagonal boron nitride and does not exceed the edge of the hexagonal boron nitride. Finally, the auxiliary film is placed on the substrate on which the perovskite quantum dot layer is spin-coated, and the device preparation is completed.

[0052] Example 2

[0053] 1. Preparation of electrode: laser direct writing is used to pattern the electrode on the substrate spin-coated with photoresist (photoresist model LOL2000 / S1805), and after the subsequent development, pure gold evaporation and stripping process, the electrode pattern with a channel length of 5 μm is obtained.

[0054] 2. Two-dimensional material: single layer of tungsten diselenide with a thickness of about 5 nm and hexagonal boron nitride with a thickness of about 13 nm are obtained by mechanical exfoliation.

[0055] 3. Spin-coating perovskite: CH3NH3SnI3 perovskite quantum dot solution with a concentration of 1.5 mg / mL is spin-coated onto a highly doped silicon substrate with a 100 nm silicon oxide dielectric layer, with a rotation speed of 4500 rpm and a spin-coating time of 30 s. After spin-coating, annealing is performed at a temperature of 110°C for 40 min to obtain a perovskite quantum dot layer with a thickness of 25 nm.

[0056] 4. Full transfer device preparation: using PMMA transfer auxiliary film, electrode, tungsten diselenide and hexagonal boron nitride with a thickness of about 13 nm are sequentially adhered, and the adhering process meets the following two points: 1. The electrode channel is located on both sides of the tungsten diselenide; 2. The tungsten diselenide is located at the center position of the hexagonal boron nitride and does not exceed the edge of the hexagonal boron nitride. Finally, the auxiliary film is placed on the substrate on which the perovskite quantum dot layer is spin-coated, and the device preparation is completed.

[0057] Example 3

[0058] 1. Preparation of electrode: laser direct writing is used to pattern the electrode on the substrate spin-coated with photoresist (photoresist model LOL2000 / S1805), and after the subsequent development, pure gold evaporation and stripping process, the electrode pattern with a channel length of 5 μm is obtained.

[0059] 2. Two-dimensional material: single layer of tungsten diselenide with a thickness of about 5 nm and hexagonal boron nitride with a thickness of about 13 nm are obtained by mechanical exfoliation.

[0060] 3. Spin-coating perovskite: CH(NH2)2GeCl3 perovskite quantum dot solution with a concentration of 1.5 mg / mL is spin-coated onto a high-doped silicon substrate with a 110 nm silicon oxide dielectric layer, where the rotation speed is 4500 rpm, the spin-coating time is 35 s, and the perovskite quantum dot layer with a thickness of 20 nm is obtained after annealing at a temperature of 110°C for 40 min.

[0061] 4. Full transfer device preparation: A PMMA transfer auxiliary film is used to sequentially stick the electrode, tungsten disulfide, and hexagonal boron nitride with a thickness of about 13 nm. The sticking process meets the following two points: 1. The electrode channel is located on both sides of the tungsten disulfide; 2. The tungsten disulfide is located at the center of the hexagonal boron nitride and does not exceed the edge of the hexagonal boron nitride. Finally, the auxiliary film is placed on the substrate with the spin-coated perovskite quantum dot layer, and the device preparation is completed.

[0062] The photoelectric synaptic performance of the device prepared in the above embodiment is tested: the synaptic plasticity of the photoelectric synaptic device under light stimulation is as shown in Figure 3 The electrical synaptic performance of the device is judged by testing the current change of the device under single, two, and multiple gate voltage electric pulse stimulations, and the results are as shown in Figure 4 The photoelectric synaptic performance of the device is judged by testing the current change of the device under single, two, and multiple light pulse stimulations, and the results are as shown in Figure 5 The multifunctionality of the biological synapse is simulated by changing the electric pulse, light pulse parameters, such as gate voltage size, pulse frequency, pulse width, light power density, etc., and the results are as shown in Figure 6

[0063] In summary, the present application provides a photoelectric synaptic device and a preparation method thereof. The method comprises: providing a silicon-based substrate with a dielectric layer deposited on the surface; depositing a perovskite quantum dot solution on the surface of the dielectric layer to obtain a perovskite quantum dot layer; providing an auxiliary film; setting a source electrode and a drain electrode as metal electrodes on the surface of the auxiliary film, and a channel is arranged between the source electrode and the drain electrode; a channel layer is arranged at the opening of the channel, the channel layer comprises a first side and a second side, the first side is connected to the source electrode and the drain electrode, and the second side is provided with a two-dimensional tunneling layer; and the auxiliary film is stacked on the perovskite quantum dot layer, so that the two-dimensional tunneling layer is attached to the perovskite quantum dot layer, to obtain a photoelectric synaptic device. By using a transfer auxiliary film to transfer the electrode, two-dimensional channel layer, and two-dimensional tunneling layer directly to the perovskite quantum dot, a back-gate type two-dimensional material photoelectric synaptic transistor based on the perovskite quantum dot floating gate is successfully prepared. This scheme avoids the influence of water and oxygen in the photoetching process, at the same time, the transfer auxiliary film can further protect the perovskite quantum dot, finally, by using the charge trapping effect and photosensitivity of the perovskite quantum dot, various biological synaptic functions can be simulated.

[0064] ​It is to be understood that the application is not limited to the examples described above, which can be modified or adapted in several ways by those skilled in the art without departing from the scope of the present application, as defined by the appended claims.

Claims

1. A method for fabricating a photoelectric synaptic device, characterized in that, The method comprises the following steps: providing a silicon substrate with a dielectric layer deposited on the surface thereof; depositing a perovskite quantum dot solution on the surface of the dielectric layer to obtain a perovskite quantum dot layer; providing an auxiliary film; providing a source electrode and a drain electrode as metal electrodes on the surface of the auxiliary film, with a channel arranged between the source electrode and the drain electrode; providing a channel layer at the opening of the channel, the channel layer comprising a first side and a second side, the first side being in contact with the source electrode and the drain electrode, and the second side being provided with a two-dimensional tunneling layer; stacking the auxiliary film on the perovskite quantum dot layer so that the two-dimensional tunneling layer is attached to the perovskite quantum dot layer to obtain a photoelectric synapse device, comprising: transferring the metal electrodes, the two-dimensional channel layer and the two-dimensional tunneling layer to the back gate substrate on which the perovskite quantum dots are spin-coated by transferring the auxiliary film to obtain a two-dimensional material transistor type photoelectric synapse device based on perovskite quantum dot floating gate.

2. The method of claim 1, wherein the method further comprises: The material of the perovskite quantum dot layer is ABX3, wherein A = Cs + , CH3NH3 + , CH(NH2)2 + ; B = Pb 2+ , Sn 2+ , Ge 2+ ; X = Br - , I - , Cl - .

3. The method of claim 1, wherein the method further comprises: The material of the channel layer is molybdenum disulfide, tungsten diselenide, tungsten disulfide or black phosphorus.

4. The method of claim 1, wherein the method further comprises: The material of the two-dimensional tunneling layer is hexagonal boron nitride.

5. The method of claim 1, wherein the method further comprises: The concentration of the perovskite quantum dot solution is 1-2 mg / mL.

6. The method of claim 2, wherein the method further comprises: The step of depositing the perovskite quantum dot solution on the surface of the dielectric layer to obtain a perovskite quantum dot layer comprises: spinning the perovskite quantum dot solution on the dielectric layer at a speed of 4500-5500 rpm for 30-45 s, and then annealing at a temperature of 110-130 DEG C for 20-40 min to obtain the perovskite quantum dot layer.

7. The method of claim 1, wherein the method further comprises: The material of the auxiliary film is selected from any one of polymethyl methacrylate, polyvinyl alcohol and polymethyl ethylene carbonate.

8. An optoelectronic synapse device, comprising: The preparation method is prepared by any one of claims 1-7.

9. The optoelectronic synaptic device of claim 8, wherein, The thickness of the perovskite quantum dot layer is 15-25 nm.

10. The optoelectronic synaptic device of claim 9, wherein, The material of the dielectric layer is silicon dioxide, and the thickness of the channel layer is 0.7-10 nm.

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