WO2019200790A1

WO2019200790A1 - Metal cation-modified black phosphorus-based synapse device and preparation method therefor

Info

Publication number: WO2019200790A1
Application number: PCT/CN2018/101415
Authority: WO
Inventors: 张晗; 王慧德; 郭志男
Original assignee: 张晗
Priority date: 2018-04-17
Filing date: 2018-08-21
Publication date: 2019-10-24
Also published as: CN108987565B; CN108987565A

Abstract

A metal cation-modified black phosphorus-based synapse device, comprising a back gate electrode (1) as a synaptic front end; an isolation layer (2) and a functional layer (3) sequentially disposed on the back gate electrode (1); and a first electrode (4) as a reference electrode and a second electrode (5) as a synaptic rear end disposed on the functional layer (3) with a space therebetween. A portion of the functional layer (3) is exposed by a channel structure formed between the first electrode (4) and the second electrode (5). The material of the functional layer (3) comprises a metal cation-modified black phosphorous flake. The metal cation-modified black phosphorus-based synapse device has good environmental stability and excellent synaptic performance, and provides an important component support with high practical value for brain-like computation. The method for preparing the metal cation-modified black phosphorus-based synapse device is simple and easy to operate.

Description

Synaptic device based on metal cation modified black phosphorus and preparation method thereof

The present invention claims the application No. 201810340826.0 filed on Apr. 17, 2018, entitled "Synaptic device based on metal cation-modified black phosphorus and its preparation method", priority of the above-mentioned prior application. It is incorporated herein by reference.

Technical field

The invention relates to the field of artificial neural networks, in particular to a synaptic device based on metal cation modified black phosphorus and a preparation method thereof.

Background technique

With the rapid expansion of data information, modern von Neumann architecture-based computers are facing increasingly serious challenges, mainly in terms of slow processing speed and high power consumption. The human brain as a human information processing center has tremendous advantages such as ultra-fast, ultra-low power consumption, ultra-high fault tolerance, and the unparalleled advantages of traditional computers such as self-learning and programming. Therefore, especially with the advent of deep learning algorithms, brain-like computers that can learn, remember, and process information like human brains are the future direction and goals of computer development. Synapses are an important part of the human brain neural network and the neural molecular basis for brain memory and learning. Therefore, artificial simulation of synapses is an extremely important and effective way to implement brain-like computers.

There are many theories for simulating the synaptic-related properties with electrical devices, but the actual devices are few and the related performance needs to be further improved. Therefore, further development of artificial synaptic devices with high performance and high stability is of great significance for the development of brain-like computers.

Summary of the invention

In order to solve the above problems, the present invention provides a synaptic device based on metal cation-modified black phosphorus and a preparation method thereof, wherein the metal cation-modified black phosphorus synaptic device has good environmental stability and excellent synaptic performance.

A first aspect of the present invention provides a metal cation-modified black phosphorus synapse device comprising a back gate electrode as a synaptic front end, an isolation layer and a functional layer sequentially disposed on the back gate electrode, and an interval disposed in the function a first electrode as a reference electrode on the layer and a second electrode as a rear end of the synapse, a channel structure formed between the first electrode and the second electrode exposing a portion of the functional layer, the functional layer The material includes a metal cation-modified black phosphorus flake.

Wherein, the functional layer has a thickness of 5-30 nm.

Wherein the metal cation comprises at least one of silver ions, iron ions, gold ions, magnesium ions, mercury ions, and zinc ions.

Wherein the metal cation is adsorbed on the surface of the black phosphorus flake by a cation-π bond.

The length of the functional layer exposed between the first electrode and the second electrode in the first direction is 1-10 μm, and the length in the second direction is 1-15 μm.

Wherein, the black phosphorus flakes have a thickness of 5-30 nm.

Wherein, the black phosphorus flakes have a thickness of 20-30 nm.

Wherein, the black phosphor flakes have a thickness of 5-20 nm.

The back gate electrode is made of silicon, the back gate electrode has a thickness of 300-500 μm, and the resistivity is 1-10 Ω·cm; the isolation layer is made of silicon dioxide, and the thickness of the isolation layer is It is 200-500 nm.

The material of the first electrode and the second electrode is at least one of gold, titanium, aluminum, chromium, tungsten and nickel.

Wherein, the first electrode and the second electrode are both composite electrodes formed by laminating a chromium layer and a gold layer.

Wherein the chromium layer is in contact with the functional layer, the chromium layer has a thickness of 5-10 nm, and the gold layer has a thickness of 20-80 nm.

The metal cation-modified black phosphorus synaptic device provided by the invention has good environmental stability and excellent synaptic performance.

A second aspect of the present invention provides a method for preparing a synaptic device based on a metal cation-modified black phosphorus, comprising:

Providing a back gate electrode and an isolation layer disposed on the back gate electrode;

Transferring a black phosphor sheet to the isolation layer;

a photoresist is spin-coated over the black phosphor flakes and over the isolation layer not covered by the black phosphor flakes, and after exposure and development, an electrode pattern is formed;

Depositing an electrode material, and subsequently stripping the photoresist to form a first electrode and a second electrode to obtain a synapse device;

The synaptic device is immersed in a solution containing a metal cation for 0.2-2 h, and after taking out and drying, a synaptic device based on metal cation-modified black phosphorus is obtained.

Wherein the concentration of the metal cation in the metal cation-containing solution is 1×10 ⁻¹⁰ −1×10 ⁻⁴ mol/L.

Wherein the metal cation-containing solution is a metal salt-containing solution, and the metal salt includes a chlorinated salt, a metal nitrate or a metal sulfate.

Wherein the solvent in the metal cation-containing solution is an organic solvent.

Wherein the organic solvent is an organic solvent that does not contain -OH and -COOH.

Wherein the organic solvent comprises N-methylpyrrolidone.

Wherein the preparation method of the black phosphorus flakes comprises:

A black phosphorus single crystal block was provided, and a black phosphorus single crystal block was stuck on the tape, and repeatedly peeled 10-20 times to obtain a black phosphorus thin film.

The method for preparing a synaptic device based on metal cation-modified black phosphorus provided by the invention is simple and easy to operate, and a high-performance, environmentally stable synaptic device is obtained.

The operation or modulation process of a metal cation-modified black phosphorus-based synapse device as described above is:

(1) If a positive and negative scanning voltage is applied to the back gate electrode, the metal cation has a trapping effect on the electron injected into the back gate voltage, and a hysteresis phenomenon occurs;

(2) If a single voltage pulse is applied to the back gate electrode, the metal cation has a trapping effect on the electron injected into the back gate voltage pulse, and the second electrode current becomes larger or smaller before and after the pulse voltage injection, that is, The synapse device has synaptic weight characteristics;

(3) If a continuous voltage pulse is applied to the back gate electrode, the metal cation has a trapping effect on the electron injected into the back gate voltage pulse, and as the voltage pulse continues to be injected, the second electrode current continues to become larger or smaller. Synaptic device with synaptic long-term plasticity

In summary, the beneficial effects of the present invention include the following aspects:

1. The black phosphorus synaptic device based on metal cation-modified black phosphorus provided by the invention has good environmental stability and excellent synaptic performance.

2. The method for preparing a synaptic device based on metal cation-modified black phosphorus provided by the invention is simple and easy to operate, and a high-performance, environmentally stable synaptic device is obtained.

DRAWINGS

1 is a structural diagram of a synaptic device based on metal ion-modified black phosphorus according to an embodiment of the present invention;

2 is a flow chart of a method for preparing a synaptic device based on metal ion-modified black phosphorus according to an embodiment of the present invention;

3 is a graph showing hysteresis characteristics of a pure black phosphorus synaptic device and a silver ion-modified black phosphorus-based synapse device according to Embodiment 1 of the present invention;

4 is a diagram showing synaptic weights of a pure black phosphorus synaptic device and a silver ion-modified black phosphorus-based synapse device according to Embodiment 1 of the present invention;

5 is a long-term plasticity diagram of a synaptic device based on a pure black phosphorus synaptic device and a silver ion-modified black phosphorus according to Embodiment 1 of the present invention;

6 is a graph showing hysteresis characteristics of a pure black phosphorus synaptic device and a black phosphorus-based synaptic device based on iron ions according to Embodiment 2 of the present invention;

Figure 7 is a graph showing the hysteresis characteristic of a pure black phosphorus synaptic device and a gold ion-modified black phosphorus-based synapse device according to Example 3 of the present invention.

detailed description

The following is a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. It is the scope of protection of the present invention.

Referring to FIG. 1, a first aspect of an embodiment of the present invention provides a synapse device based on metal cation-modified black phosphorus, comprising a back gate electrode 1 as a synaptic front end, and an isolation layer sequentially disposed on the back gate electrode 1. 2 and a functional layer 3, and a first electrode 4 as a reference electrode and a second electrode 5 as a synaptic rear end, which are disposed on the functional layer 3, the first electrode 4 and the second electrode 5 The intervening channel structure exposes a portion of the functional layer 3, and the material of the functional layer 3 includes a metal cation-modified black phosphor flake.

In the embodiment of the present invention, the back gate electrode 1 is made of silicon, and the back gate electrode 1 has a thickness of 300-500 μm and a resistivity of 1-10 Ω·cm.

In the embodiment of the present invention, the material of the isolation layer 2 is silicon dioxide, and the thickness of the isolation layer 2 is 200-500 nm.

In an embodiment of the invention, the functional layer has a thickness of 5-30 nm.

In an embodiment of the invention, the black phosphor flakes are obtained by a method of tearing tape from a black phosphorus single crystal block.

In an embodiment of the invention, the functional layer is formed from a single piece of black phosphorous flakes. The black phosphor flakes have a thickness of 5 to 30 nm. Optionally, the black phosphor flakes have a thickness of 20-30 nm. Optionally, the black phosphor flakes have a thickness of 5-20 nm. Further optionally, the black phosphor flakes have a thickness of 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm. 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm or 30 nm.

In an embodiment of the invention, the metal cation comprises at least one of silver ions, iron ions, gold ions, magnesium ions, mercury ions, and zinc ions. Alternatively, the metal cation is adsorbed on the surface of the black phosphorus flake by a cation-π bond. The invention adopts a metal cation to modify the black phosphorus flakes, and the surface stability of the black phosphorus flakes can be improved on one side. On the other hand, due to the trapping effect of the metal cation layer on the electrons injected into the back gate voltage, hysteresis occurs, thereby improving the performance of the synapse device.

Optionally, the thickness of the metal cation adsorbed on the black phosphor flake is negligible, and therefore, the thickness of the metal cation-modified black phosphor flake is approximately equal to the thickness of the black phosphor flake.

In the embodiment of the present invention, the first electrode 4 (ie, corresponding to the source of the field effect transistor) and the second electrode 5 (ie, corresponding to the drain of the field effect transistor) are made of gold, copper, titanium, aluminum, At least one of chromium, tungsten and nickel. Optionally, the first electrode 4 and the second electrode 5 are composite electrodes formed by laminating a chrome layer and a gold layer, wherein the chrome layer is in contact with the functional layer, and the chrome layer has a thickness of 5 -10 nm, the gold layer has a thickness of 20-80 nm. The first electrode 4 and the second electrode 5 are connected to an external power source. Optionally, the first electrode 4 and the second electrode 5 are disposed at opposite ends of the black phosphor sheet layer. Alternatively, the first electrode 4 and the second electrode 5 may be in contact with the functional layer, and the area of the contact is not particularly limited. Optionally, a portion of the first electrode 4 and the second electrode 5 are in partial contact with the functional layer 3 and another portion is in contact with the isolation layer 2.

Referring to FIG. 1 , in the embodiment of the present invention, the length of the functional layer exposed between the first electrode 4 and the second electrode 5 in the first direction (ie, L in FIG. 1 ) is 1-10 μm along the second. The length of the direction (i.e., W in Fig. 1) is 1-15 μm. The first direction is a direction perpendicular to a direction in which the first electrode 4 and the second electrode 5 extend, and the second direction is a direction parallel to a direction in which the first electrode 4 and the second electrode 5 extend, that is, the first direction One direction is perpendicular to the second direction. Optionally, the functional layer exposed between the first electrode 4 and the second electrode 5 has a length L of 3 μm and a width W of 10 μm.

The working or modulation process of the synaptic device based on metal cation-modified black phosphorus provided by the invention is:

(1) If a positive and negative scanning voltage is applied to the back gate electrode, hysteresis may occur due to the trapping action of the electrons injected by the metal cation on the back gate voltage;

(2) If a single voltage pulse is applied to the back gate electrode (synaptic front end), the second electrode (synaptic back end) appears before and after the pulse voltage injection due to the trapping action of the metal cation on the electron injected by the back gate voltage pulse. The phenomenon that the current becomes larger or smaller, that is, the device has synaptic weight characteristics;

(3) If a continuous voltage pulse is applied to the back gate electrode (synaptic front end), due to the trapping action of the electrons injected by the metal cation on the back gate voltage pulse, the second electrode may appear as the voltage pulse continues to be injected. At the back end, the current continues to increase or decrease, that is, the device has synaptic long-term plasticity.

The synapse device provided by the invention is used for simulating a neuronal synaptic structure, since the device has the basic function of synapses, that is, a single voltage pulse-dependent pre- and post-current current changing characteristic (corresponding to short-term memory of the human brain) And a plurality of voltage pulse-dependent pre- and post-current currents continuously changing characteristics (corresponding to long-term memory of the human brain). Therefore, the device is expected to be used in future brain-like computing chips.

The synaptic device based on metal cation-modified black phosphorus provided by the invention has good environmental stability and excellent synaptic performance. This indicates that the synapse device can continue to work stably and efficiently in an air environment. That is, while improving the performance of the device, the process of device package protection that must be performed in order to prevent two-dimensional black phosphorus oxidation and the like can be omitted, and the actual production use of the device greatly simplifies the processing procedure and provides a pole for brain-like calculation. Supporting important components with practical value.

Referring to FIG. 2, a second aspect of an embodiment of the present invention provides a method for preparing a synaptic device based on a metal cation-modified black phosphorus, comprising:

S01, providing a back gate electrode 1 and an isolation layer 2 disposed on the back gate electrode 1;

S02, transferring the black phosphor sheet 31 onto the isolation layer 2;

S03, the photoresist layer 7 is spin-coated over the black phosphor sheet 31 and the spacer layer 2 not covered by the black phosphor sheet 31, after exposure and development, forming an electrode pattern 8;

S04, depositing an electrode material, and then stripping the photoresist to form a first electrode 4 and a second electrode 5 to obtain a synapse device;

S05, immersing the synaptic device in a solution containing a metal cation for 0.2-2 h, and taking out the drying to obtain a synaptic device based on metal cation-modified black phosphorus.

In the embodiment of the present invention, in step S01, a p-type or n-type doped silicon wafer having a silicon dioxide layer is provided, and the silicon wafer comprises two layers, respectively a silicon dioxide layer and a silicon layer, and the silicon layer The thickness is 300-500 μm, the resistivity is 1-10 Ω·cm, and the thickness of the silicon dioxide layer is 200-500 nm. The silicon layer serves as the back gate electrode 1 and the silicon dioxide layer serves as the isolation layer 2. Specifically, a commercial standard 4-inch p-type or n-type doped single-spray silicon oxide wafer was cut into a size of 1 × 1 cm ² using a silicon wafer cutter to obtain a silicon wafer to be used.

In the embodiment of the present invention, the step S01 further includes an operation of cleaning the silicon wafer, and the cleaning is performed according to the following method:

The silicon wafer to be used is sequentially ultrasonicated by acetone solution, isopropanol (or ethanol) for 3-5 minutes, ultrasonicated with deionized water for 3-8 min, and quickly dried with high purity nitrogen for use.

In the embodiment of the present invention, in the step S02, the preparation method of the black phosphor sheet 31 includes:

A black phosphorus single crystal block was provided, and a black phosphorus single crystal block was stuck to the tape, and repeatedly peeled 10-20 times to obtain a black phosphorus thin film 31.

In the embodiment of the present invention, the obtained black phosphorus flakes 31 are transferred onto the organic thin film 6, and then the black phosphorous flakes on the organic thin film 6 are transferred onto the separation layer 2.

Specifically, the tape is a Scotch tape. The organic film 6 comprises a polydimethylsiloxane (PDMS) film. A thinner black phosphor flake can be obtained by tearing off the tape, and the method is simple and easy to handle.

In the embodiment of the present invention, in step S03, a layer of photoresist 7 (PMMA) is applied over the black phosphor sheet 31 and the spacer layer 2 not covered by the black phosphor sheet 31 (model 950, A4). -A10), the rotation speed is 2000-4000 rpm, and is baked on a hot plate for 1-5 minutes, and the drying temperature is 50-180 °C. The photoresist-coated sample was subjected to electron beam exposure, and a specific electrode pattern 8 was obtained by a developing process. The electrode pattern 8 is two through holes that penetrate the photoresist and expose a portion of the black phosphor flakes.

In the embodiment of the present invention, in step S04, an electrode material is deposited over the via hole, the electrode material fills the through hole and is in contact with the black phosphor sheet to form the first electrode 4 and the second electrode 5 . Alternatively, the deposition is performed by a method such as thermal evaporation or magnetron sputtering. Alternatively, a chromium layer 9 having a thickness of 5-10 nm is first deposited, and then a gold layer 10 having a thickness of 20-80 nm is deposited to form a composite electrode. After the deposition is completed, the sample of the evaporated chromium/gold electrode is placed in an organic solvent such as acetone to be used for stripping the photoresist, and placed on a hot plate for heating for 10-30 minutes, wherein the temperature of the heating plate is set to 30-50. °C, finally take out the sample and quickly dry it with high purity nitrogen.

In the embodiment of the present invention, in the step S05, the molar concentration of the metal cation in the metal cation-containing solution is 1 × 10 ^-10 -1 × 10 ^-4 mol / L. Optionally, the metal cation-containing solution is a solution including at least one of silver ions, iron ions, gold ions, magnesium ions, mercury ions, and zinc ions. Optionally, the metal cation-containing solution is a metal salt-containing solution, such as a metal chloride salt, a metal nitrate, a metal sulfate, or the like. Optionally, the solvent in the metal cation-containing solution is an organic solvent. Further optionally, the organic solvent is an organic solvent that does not contain -OH and -COOH. Further optionally, the organic solvent comprises N-methylpyrrolidone (NMP). Optionally, after the end of the soaking, the synaptic device is taken out and quickly dried and dried with high-purity nitrogen gas to obtain a synaptic device based on metal cation-modified black phosphorus.

The invention adopts a method for modifying black phosphorus by metal cations, and adopts a field effect tube type device structure to obtain a high performance and environment stable synaptic device. The preparation method is simple and easy to operate. The method can significantly improve the synaptic characteristics of the synaptic device while solving the problem of black phosphorus environment stability, and has great practical value. The obtained synaptic device provides an important element for brain-like calculation. Device support.

Example 1

As shown in FIG. 1 , the present invention provides a silver ion-modified black phosphorus-based synapse device, which is a field effect tube type structure, and the functional layer is a silver ion modified black phosphorus sheet. The device has a p-type or n-type doped silicon layer 1, a silicon dioxide layer 2, a silver ion-modified black phosphor thin film 3, a first electrode 4, and a second electrode 5 in this order from bottom to top. The thickness of the silicon layer was 300 μm and the specific resistance was 1-10 Ω·cm. The thickness of the silicon dioxide layer was 300 nm. The silver ion-modified black phosphor flakes have a thickness of 20 nm. The first electrode and the second electrode are both chromium/gold materials, wherein the chromium layer has a thickness of 5 nm and the gold layer has a thickness of 40 nm. That is, the first electrode and the second electrode are respectively a composite electrode formed by laminating a chromium layer of 5 nm thick and a gold layer of 40 nm thick.

A method for preparing a synaptic device based on silver ion-modified black phosphorus, the method comprising the steps of:

(1) Clean the silicon wafer. Commercially available standard 4-inch p-type or n-type doped single-spray silicon oxide wafers using silicon wafer knives (silicon portion thickness 300 μm, resistivity 1-10 Ω·cm, silicon portion corresponding to back gate electrode, SiO ₂ Part of the thickness of 300nm, corresponding to the isolation layer) cut into 1 × 1cm ² size, respectively, by acetone solution, isopropanol for 5 minutes, respectively, and then ultrasonicated with deionized water for 5min and quickly dried with high purity nitrogen for use;

(2) Preparation of black phosphorus flakes. Take a small amount of black phosphorus single crystal block and stick it on the tape (such as Scotch tape), tear it 10-20 times, transfer the torn sample to polydimethylsiloxane (PDMS) film, and finally put it on PDMS film. Transfer the sample to the cleaned silicon wafer in step (1);

(3) Spin coating drying. a layer of photoresist PMMA (A4) is spin-coated on the surface of the above silicon wafer, the rotation speed is 3000 rpm, and baked on a hot plate for 5 minutes, the drying temperature is 120 ° C;

(4) Electron beam exposure and development. The photoresist coated sample is subjected to electron beam exposure, and a specific electrode pattern is obtained by a developing process;

(5) Coating. 5 nm of chromium and 40 nm of gold are successively evaporated by a method of thermal evaporation;

(6) Go to gold. The sample of the evaporated chromium/gold electrode is immersed in acetone, and placed on a hot plate for heating for 10 minutes, wherein the temperature of the heating plate is set to 50 ° C, and finally the sample is taken out and quickly dried with high-purity nitrogen;

(7) Performance test of pure black phosphorus synapse device. The device obtained in the step (6) was taken, and the performance test was performed using a semiconductor characteristic analyzer. Specifically: (a) use a silicon knife to cut the silicon dioxide layer at one corner of the silicon wafer; (b) place it on the probe platform matched with the semiconductor characteristic analyzer, and find the synapse through the matching CCD imaging system. The exact position of the device; (c) selecting two probes matched with the probe platform to contact the first electrode and the second electrode, respectively, and selecting another probe to contact the silicon layer exposed by slitting the silicon dioxide layer, when Used as a back gate electrode. The second electrode voltage was set to 1 V, and the first electrode voltage was 0 V. The back gate electrode inputs a bidirectional scan voltage of -60V-60V to obtain a hysteresis characteristic diagram; the back gate electrode inputs a single voltage pulse to obtain a synaptic weight characteristic map; the back gate electrode inputs 100 forward and 100 negative continuous voltage pulses, Obtaining synaptic long-term plasticity characteristics (see Figures 3, 4, 5);

(8) Silver ion modification. The device after the test in the step (7) was placed in a prepared 10 ^-6 mol/L silver nitrate solution (solvent N-methylpyrrolidone, NMP) for 0.5 h, and then quickly taken out and used with high purity nitrogen. Rapid drying to produce a synaptic device based on silver ion modified black phosphorus;

(9) Synaptic device performance test based on silver ion modified black phosphorus. Take the device obtained in step (8), perform the relevant performance test using the semiconductor characteristic analyzer, and obtain the relevant characteristic map in the same step (7) (see Figures 3, 4, and 5).

Example 2

As shown in FIG. 1, the present invention provides a synaptic device based on iron ion-modified black phosphorus, which is a field effect tube type structure, and the functional layer is an iron ion modified black phosphorus sheet. The device has a p-type or n-type doped silicon layer 1, a silicon dioxide layer 2, an iron ion-modified black phosphor thin film 3, a first electrode 4, and a second electrode 5 in this order from bottom to top. The silicon layer has a thickness of 500 μm and a specific resistance of 1-10 Ω·cm. The thickness of the silicon dioxide layer was 300 nm. The iron ion-modified black phosphorus flakes have a thickness of 20 nm. The first electrode and the second electrode are both chromium/gold materials in which the thickness of chromium is 5 nm and the thickness of gold is 40 nm. That is, the first electrode and the second electrode are respectively a composite electrode formed by laminating a chromium layer of 5 nm thick and a gold layer of 40 nm thick.

A method for preparing a synaptic device based on iron ion-modified black phosphorus, the method comprising the steps of:

(1) Clean the silicon wafer. Commercially available standard 4-inch p-type or n-type doped single-spray silicon oxide wafers using silicon wafer knives (silicon portion thickness 500 μm, resistivity 1-10 Ω·cm, silicon portion corresponding to back gate electrode, SiO ₂ Part of the thickness of 300 nm, corresponding to the isolation layer) was cut into 1 × 1 cm ² size, respectively, sonicated by acetone solution, isopropanol for 5 minutes, then ultrasonicated with deionized water for 5 min and quickly dried with high purity nitrogen for use.

(2) Preparation of black phosphorus flakes. Take a small amount of black phosphorus single crystal block and stick it on the tape (such as Scotch tape), tear it 10-20 times, transfer the torn sample to polydimethylsiloxane (PDMS) film, and finally put it on PDMS film. The sample is transferred to the cleaned wafer to be used in step (1).

(3) Spin coating drying. A layer of photoresist PMMA (A4) was spin-coated on the surface of the above silicon wafer at a rotation speed of 3000 rpm, and baked on a hot plate for 5 minutes at a drying temperature of 120 °C.

(4) Electron beam exposure and development. The photoresist-coated sample was subjected to electron beam exposure, and a specific electrode pattern was obtained by a developing process.

(5) Coating. 5 nm of chromium and 40 nm of gold were successively evaporated by a method of thermal evaporation.

(6) Go to gold. The sample of the evaporated chromium/gold electrode was immersed in acetone and placed on a hot plate for 30 minutes, wherein the temperature of the hot plate was set to 30 ° C, and finally the sample was taken out and quickly dried with high-purity nitrogen.

(7) Performance test of pure black phosphorus synapse device. The device obtained in the step (6) was taken, and the performance test was performed using a semiconductor characteristic analyzer. Specifically, the operations can be carried out in accordance with steps (a), (b), and (c) of the embodiment 1. The second electrode voltage was set to 1 V, and the first electrode voltage was 0 V. The back gate electrode inputs a bidirectional scan voltage of -60V-60V to obtain a hysteresis characteristic diagram; the back gate electrode inputs a single voltage pulse to obtain a synaptic weight characteristic map; the back gate electrode inputs 100 forward and 100 negative continuous voltage pulses, A synaptic long-term plasticity characteristic map is obtained (see Figure 6).

(8) Iron ion modification. The device after the test in the step (7) is placed in a prepared 10 ^-6 mol/L ferric chloride solution (the solvent is N-methylpyrrolidone, ie NMP), soaked for 0.5 h, and then quickly taken out and used in high purity. Rapid drying of nitrogen to produce a synaptic device based on iron ion-modified black phosphorus;

(9) Synaptic device performance test based on iron ion modified black phosphorus. Take the device obtained in step (8), perform the relevant performance test using the semiconductor characteristic analyzer, and obtain the relevant characteristic map in the same step (7) (see Figure 6).

Example 3

As shown in FIG. 1 , the present invention provides a gold ion-modified black phosphorus-based synapse device, which is a field effect tube type structure, and the functional layer is a gold ion modified black phosphorus sheet. The device has a p-type or n-type doped silicon layer 1, a silicon dioxide layer 2, a gold ion-modified black phosphor thin film 3, a first electrode 4, and a second electrode 5 in this order from bottom to top. The silicon layer has a thickness of 400 μm and a specific resistance of 1-10 Ω·cm. The thickness of the silicon dioxide layer was 300 nm. The gold ion-modified black phosphor flakes have a thickness of 20 nm. The first electrode and the second electrode are both chromium/gold materials in which the thickness of chromium is 5 nm and the thickness of gold is 40 nm.

A method for preparing a synaptic device based on gold ion-modified black phosphorus, the method comprising the steps of:

(1) Clean the silicon wafer. Commercially available standard 4-inch p-type or n-type doped single-spray silicon oxide wafers using a silicon wafer (silicon portion thickness 400 μm, resistivity 1-10 Ω·cm, silicon portion corresponding to back gate electrode, SiO ₂ Part of the thickness of 300 nm, corresponding to the isolation layer) was cut into 1 × 1 cm ² size, respectively, sonicated by acetone solution, isopropanol for 5 minutes, then ultrasonicated with deionized water for 5 min and quickly dried with high purity nitrogen for use.

(6) Go to gold. The sample of the evaporated chromium/gold electrode was immersed in acetone and placed on a hot plate for 20 minutes, wherein the temperature of the hot plate was set to 40 ° C, and finally the sample was taken out and quickly dried with high-purity nitrogen.

(7) Performance test of pure black phosphorus synapse device. The device obtained in the step (6) was taken, and the performance test was performed using a semiconductor characteristic analyzer. Specifically, the operations can be carried out in accordance with steps (a), (b), and (c) of the embodiment 1. The second electrode voltage was set to 1 V, and the first electrode voltage was 0 V. The back gate electrode inputs a bidirectional scan voltage of -60V-60V to obtain a hysteresis characteristic diagram; the back gate electrode inputs a single voltage pulse to obtain a synaptic weight characteristic map; the back gate electrode inputs 100 forward and 100 negative continuous voltage pulses, A synaptic long-term plasticity characteristic map is obtained (see Figure 7, where pure BP represents pure black phosphorus).

(8) Gold ion modification. The device after the test in the step (7) is placed in a prepared 10 ^-6 mol/L chloroauric acid solution (the solvent is N-methylpyrrolidone, ie, NMP), and then immersed for 0.5 hour, and then quickly taken out and used in high purity. Rapid drying of nitrogen gas to produce a synaptic device based on gold ion modified black phosphorus;

(9) Synaptic device performance test based on gold ion modified black phosphorus. Take the device obtained in step (8), perform the relevant performance test using the semiconductor characteristic analyzer, and obtain the relevant characteristic map in the same step (7) (see Figure 7).

Fig. 3 is a graph showing the hysteresis characteristics of synaptic devices before and after silver ion modification, wherein (a) and (b) are hysteresis characteristics of synaptic devices before and after silver ion modification, respectively. The results show that the hysteresis characteristics of the device are enhanced after silver ion modification.

Figure 4 is a graph showing the synaptic weight characteristics of synaptic devices before and after silver ion modification. Among them, (a) and (b) are the synapses before and after silver ion modification, and the synapse device stimulates the synaptic front end with a single positive pulse. The current corresponding to the back end increases the response; (c) and (d) are the current reduction response of the synaptic rear end of the synaptic device when the synaptic device stimulates the synaptic front end before and after the silver ion modification. The results show that after silver ion modification, the device synaptic weight (represented by ΔPSC/PSC quantitation) is significantly increased.

Figure 5 is a long-range plasticity characteristic of the synaptic device before and after silver ion modification; wherein (a) and (b) are long-ranges of the synaptic device before and after the silver ion modification, the synaptic device continues to train multiple positive and negative pulses. Plasticity characteristic diagram. The results show that long-term plasticity is enhanced after silver ion modification.

Fig. 6 is a graph showing the hysteresis characteristics of synaptic devices before and after iron ion modification, wherein (a) and (b) are hysteresis characteristics of synaptic devices before and after iron ion modification, respectively. The results show that the hysteresis characteristics are enhanced after the modification of iron ions.

Fig. 7 is a graph showing the hysteresis characteristics of synaptic devices before and after gold ion modification, wherein (a) and (b) are hysteresis characteristics of synaptic devices before and after gold ion modification, respectively. The results show that the hysteresis characteristics are enhanced after gold ion modification.

After the metal cations modify the black phosphorus flakes, they adhere to the black phosphorus surface layer by the action of the cation-π bond, which is equivalent to providing a positively charged metal cation layer for the black phosphor flakes. 1. If a positive and negative scanning voltage is applied to the back gate electrode, hysteresis may occur due to the trapping effect of the metal cation layer on the electrons injected into the back gate voltage. 2. If a single voltage pulse is applied to the back gate electrode (synaptic front end), the second electrode (synaptic back end) current will appear before and after the pulse voltage injection due to the trapping action of the metal cation layer on the electron injected by the back gate voltage pulse. The phenomenon of becoming larger or smaller, that is, the device has synaptic weight characteristics. 3. If a continuous voltage pulse is applied to the back gate electrode (synaptic front end), the second electrode (synapse) appears due to the continuous injection of the voltage pulse due to the metal cation layer trapping the electrons injected by the back gate voltage pulse. The back end) current continues to become larger or smaller, that is, the device has synaptic long-term plasticity. Therefore, the present invention improves the synaptic characteristics of the synaptic device by solving the black phosphorus environment stability problem by modifying the black phosphorus in the synaptic device, and provides practical value for brain-like calculation. Important component support.

The above-mentioned embodiments are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but is not to be construed as limiting the scope of the invention. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be determined by the appended claims.

Claims

A synapse device based on metal cation-modified black phosphorus, comprising: a back gate electrode as a synaptic front end, an isolation layer and a functional layer sequentially disposed on the back gate electrode, and a spacer layer disposed on the functional layer a first electrode as a reference electrode and a second electrode as a synaptic rear end, a channel structure formed between the first electrode and the second electrode exposing a portion of the functional layer, a material of the functional layer A black phosphorus flake comprising a metal cation modification.
The synapse device of claim 1, wherein the functional layer has a thickness of 5-30 nm.
The synapse device of claim 1, wherein the metal cation comprises at least one of silver ions, iron ions, gold ions, magnesium ions, mercury ions, and zinc ions.
The synapse device according to claim 1, wherein the metal cation is adsorbed on a surface of the black phosphorus sheet by a cation-π bond.
The synapse device of claim 1, wherein the functional layer exposed between the first electrode and the second electrode has a length in the first direction of 1-10 μm and a length in the second direction It is 1-15 μm.
The synapse device of claim 1, wherein the black phosphor flakes have a thickness of 5 to 30 nm.
The synapse device of claim 6, wherein the black phosphor flakes have a thickness of 20-30 nm.
The synapse device of claim 6, wherein the black phosphor flakes have a thickness of 5-20 nm.
The synapse device according to claim 1, wherein the back gate electrode is made of silicon, the back gate electrode has a thickness of 300-500 μm, and the resistivity is 1-10 Ω·cm; In the case of silicon dioxide, the separator has a thickness of 200 to 500 nm.
The synapse device according to claim 1, wherein the first electrode and the second electrode are made of at least one of gold, titanium, aluminum, chromium, tungsten, and nickel.
The synapse device of claim 10, wherein the first electrode and the second electrode are both composite electrodes formed by laminating a chromium layer and a gold layer.
The synapse device according to claim 11, wherein the chromium layer is in contact with the functional layer, the chromium layer has a thickness of 5 to 10 nm, and the gold layer has a thickness of 20 to 80 nm.
A method for preparing a synaptic device based on metal cation-modified black phosphorus, which comprises:

Providing a back gate electrode and an isolation layer disposed on the back gate electrode;

Transferring a black phosphor sheet to the isolation layer;

a photoresist is spin-coated over the black phosphor flakes and over the isolation layer not covered by the black phosphor flakes, and after exposure and development, an electrode pattern is formed;

Depositing an electrode material, and subsequently stripping the photoresist to form a first electrode and a second electrode to obtain a synapse device;

The synaptic device is immersed in a solution containing a metal cation for 0.2-2 h, and after taking out and drying, a synaptic device based on metal cation-modified black phosphorus is obtained.
The method of producing a synapse device according to claim 13, wherein the concentration of the metal cation in the metal cation-containing solution is 1 × 10 -10 -1 × 10 -4 mol/L.
The method of producing a synapse device according to claim 13, wherein the metal cation-containing solution is a metal salt-containing solution including a chlorinated salt, a metal nitrate or a metal sulfate.
The method of producing a synapse device according to claim 13, wherein the solvent in the metal cation-containing solution is an organic solvent.
The method of producing a synapse device according to claim 16, wherein the organic solvent is an organic solvent containing no -OH and -COOH.
The method of producing a synapse device according to claim 17, wherein the organic solvent comprises N-methylpyrrolidone.
The method of preparing a synapse device according to claim 13, wherein the method for preparing the black phosphor flakes comprises:

A black phosphorus single crystal block was provided, and a black phosphorus single crystal block was stuck on the tape, and repeatedly peeled 10-20 times to obtain a black phosphorus thin film.
The operation or modulation process of the metal cation-modified black phosphorus-based synapse device according to any one of claims 1 to 12 is:

(1) If a positive and negative scanning voltage is applied to the back gate electrode, the metal cation has a trapping effect on the electron injected into the back gate voltage, and a hysteresis phenomenon occurs;

(2) If a single voltage pulse is applied to the back gate electrode, the metal cation has a trapping effect on the electron injected into the back gate voltage pulse, and the second electrode current becomes larger or smaller before and after the pulse voltage injection, that is, The synapse device has synaptic weight characteristics;

(3) If a continuous voltage pulse is applied to the back gate electrode, the metal cation has a trapping effect on the electron injected into the back gate voltage pulse, and as the voltage pulse continues to be injected, the second electrode current continues to become larger or smaller. The phenomenon that the synapse device has synaptic long-term plasticity.