CN109326711B

CN109326711B - Metal nanocluster-doped memristor and preparation method thereof

Info

Publication number: CN109326711B
Application number: CN201810906794.6A
Authority: CN
Inventors: 刘向阳; 史晨阳
Original assignee: Xiamen University
Current assignee: Xiamen University
Priority date: 2018-08-10
Filing date: 2018-08-10
Publication date: 2021-06-22
Anticipated expiration: 2038-08-10
Also published as: CN109326711A

Abstract

The invention provides a metal nanocluster doped memristor and a preparation method thereof, and relates to the technical field of microelectronics. The metal nanocluster-doped memristor comprises an upper electrode, a resistance change layer and a lower electrode, wherein the resistance change layer is located between the upper electrode and the lower electrode, and the resistance change layer is a resistance change material film doped with metal nanoclusters. The preparation method comprises the following steps: s1, cleaning the lower electrode; s2, forming the resistance change layer on the surface of the cleaned lower electrode in a pulling coating mode; and S3, growing the upper electrode on the resistance change layer by adopting a magnetron sputtering method. The corresponding metal nano-cluster composite film is prepared by doping the metal nano-clusters into the resistance change material film material, and under the action of an electric field, the metal nano-clusters can play a role in strengthening a local electric field and improve the resistance conversion characteristic. And the resistance change memory has stable performance and high switching speed, and lays a foundation for the design and further development of the memristor.

Description

Metal nanocluster-doped memristor and preparation method thereof

Technical Field

The invention relates to the technical field of microelectronics, in particular to a metal nanocluster-doped memristor and a preparation method thereof.

Background

The memristor realizes data storage by utilizing two or more different resistance states which are expressed by a resistance change layer material under the action of an external electric field, is a novel nonvolatile memory which is widely concerned in recent years, and brings about a hot research in the industry and academia. The memristor is formed by a simple sandwich structure of an upper electrode, a resistance change layer and a lower electrode, wherein a resistance change layer material is a carrier for resistance change of the memristor, the memristor is caused to have different storage window values, retention characteristics, erasing and writing speeds and the like by different types of resistance change materials, and all performance parameters of the memristor are closely related to the properties of the resistance change layer material. The resistance change layer material is generally a semiconductor material or an insulating material, and the currently reported resistance change layer materials are widely classified into inorganic materials, organic materials and the like according to basic properties. Inorganic materials such as binary oxides (titanium dioxide, zinc dioxide, hafnium dioxide and the like), chalcogenide solid electrolytes and the like, the inorganic materials generally show more stable and faster memristive effects with better tolerance as the resistance change layer materials, and organic materials such as PVK, P3HT, PI, PVP and the like also have typical memristive switching effects and are characterized by high flexibility, low cost and simpler preparation. However, practical memristor products are not released late, because various excellent performances reported at present are realized in different memristors, and the problems of high operating voltage, large power consumption, poor retention characteristics, poor cyclic tolerance, low erasing speed and the like of the existing memristors generally exist. In order to solve the problems, various performances of the memristor need to be further improved from multiple aspects such as material modification and structure optimization.

Disclosure of Invention

The invention aims to provide a metal nano-cluster-doped memristor, which takes a technical nano-cluster as a doping body, can play a role in strengthening a local electric field and obtains more excellent resistance change switching performance.

The invention also aims to provide a preparation method of the metal nanocluster-doped memristor, wherein the resistance change layer is formed in a pulling coating mode, the preparation method is simple, the cost is low, the plasticity is strong, and the doping amount of the metal nanocluster is adjustable.

The technical problem to be solved by the invention is realized by adopting the following technical scheme.

The metal nanocluster-doped memristor comprises an upper electrode, a resistance change layer and a lower electrode, wherein the resistance change layer is located between the upper electrode and the lower electrode, and the resistance change layer is a resistance change material film doped with metal nanoclusters.

A preparation method of the metal nanocluster-doped memristor comprises the following steps:

s1, cleaning the lower electrode;

s2, forming the resistance change layer on the surface of the cleaned lower electrode in a pulling coating mode;

and S3, growing the upper electrode on the resistance change layer by adopting a magnetron sputtering method.

The metal nanocluster-doped memristor and the preparation method thereof have the beneficial effects that:

the metal nano-cluster is a relatively stable nano-structure formed by a plurality of to dozens of metal atoms, the size of the nano-cluster is generally a plurality of nanometers, and the nano-cluster has special electrochemical performance and quantum size effect. The memory-resistance switching circuit has better memory-resistance switching effect, better cycle stability and retention characteristic, low switching voltage, low energy consumption and extremely high erasing speed which reaches the level of 10 ns. Meanwhile, the manufacturing process is simple, the cost is low, and the plasticity is strong. By adjusting the doping type and degree of the metal cluster, the flexibility of memristive energy regulation is increased.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a flow chart of a method of fabricating a metal nanocluster doped memristor of an embodiment of the present invention;

FIG. 2 is a model schematic of a memristor fabricated in an embodiment of the present disclosure;

FIG. 3 is a morphology of the silk fibroin film in example 1;

in fig. 4, a is a topography of the silk fibroin film in example 2, and b is a corresponding surface potential scanning map of a;

FIG. 5 is surface potential data for the corresponding marker positions of FIGS. 4a and 4 b;

fig. 6 is a current-voltage cyclic scan diagram of a memristor cycled 1 time between a high resistance state and a low resistance state as provided in example 1;

fig. 7 is a current-voltage cyclic scan diagram of 50 cycles of the memristor provided in example 1 between high and low resistance states;

fig. 8 is a current-voltage cyclic scan diagram of 100 cycles of the memristor provided in example 1 between high and low resistance states;

FIG. 9 is an erase speed performance diagram of the memristor of example 1;

FIG. 10 is a comparison graph of the on-off ratio and operating voltage of memristors of example 2(Ag NCs fraction 30%), example 3(Ag NCs fraction 10%), example 4(Ag NCs fraction 20%), example 5(Ag NCs fraction 40%), and comparative example 1(Ag NCs fraction 0%).

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The metal nanocluster-doped memristor and the preparation method thereof according to the embodiments of the present invention are specifically described below.

Further, in the preferred embodiment of the present invention, the upper electrode is a metal element electrode or an alloy electrode, and the lower electrode is an oxide electrode or a nitride electrode. More preferably, the upper electrode is a simple metal electrode, such as an Ag electrode, a Cu electrode, or the like. The lower electrode is preferably an oxide electrode, such as an Indium Tin Oxide (ITO) electrode, an F-doped tin oxide (FTO) electrode, or the like.

Further, in a preferred embodiment of the present invention, the resistive material film is selected from one of a metal oxide film, a high molecular polymer film, and a natural protein film. The metal oxide can be selected from titanium dioxide, zinc dioxide, hafnium dioxide, etc. The polymer can be PVK, P3HT, PI, PVP, etc. The natural protein can be selected from albumin, silk fibroin, sericin, bovine serum albumin, wool keratin, etc.

Further preferably, in this embodiment, the resistive material film is a silk fibroin film. Silk fibroin is a natural protein, has typical hindered state transition characteristics, and compared with inorganic materials and organic materials, the protein material has better biocompatibility and biodegradation controllability, so that the protein material has greater application potential in the field of wearable implantable electronic devices in the future.

Further, in a preferred embodiment of the present invention, the metal nanoclusters are selected from one of gold nanoclusters, silver nanoclusters and copper nanoclusters. More preferably, the metal nanoclusters are silver nanoclusters (Ag NCs). The Ag NCs are selected to obtain a smoother composite morphology and a more prominent surface potential difference area.

Further, in the preferred embodiment of the present invention, the thickness of the upper electrode is 60 to 80nm, the thickness of the resistance change layer is 30 to 40nm, and the thickness of the lower electrode is 160 to 200 nm. More preferably, the upper electrode has a thickness of 70nm and the lower electrode has a thickness of 180 nm. The thicknesses of the upper electrode, the resistance change layer and the lower electrode are regulated and controlled, so that the memristor is endowed with a more lasting retention characteristic, and the retention time reaches 10⁴s is more than s.

Further, in the preferred embodiment of the invention, the doping amount of the metal nanoclusters in the resistive material thin film is 10-40%. Namely, the metal nanoclusters account for 10-40% of the mass of the resistance change material film. More preferably, the doping amount of the metal nanoclusters is 30%. With the increase of the doping amount, the on-off ratio of the memristor is effectively improved, the value of the storage window is increased, and the peripheral circuit is facilitated to recognize the state stored by the device.

The invention also provides a preparation method of the metal nanocluster-doped memristor, which comprises the following steps:

s1, cleaning the lower electrode;

In step S1, the cleaning with the ITO conductive glass refers to performing decontamination treatment on the ITO conductive glass, for example, immersing the ITO conductive glass in an organic solution such as acetone for ultrasonic cleaning.

In step S2, the step of forming the resistance change layer on the surface of the cleaned lower electrode by using a pull-coating method includes:

and S21, preparing a natural protein solution. The method comprises the following specific steps:

(1) placing natural silkworm cocoons into a weak base solution (such as a sodium bicarbonate solution with the concentration of 3-5 g/L), heating and boiling for 20-40 min, and repeating for 2 times to obtain the degummed silk.

(2) And (3) dissolving the degummed silk by using 8-10 mol/L LiBr solution, and heating for 3-5 h at 50 ℃ to obtain silk fibroin mixed solution.

(3) And dialyzing the silk fibroin mixed solution for 20-50 h by using a dialysis bag to obtain a silk fibroin solution. It is understood that the silk fibroin solution obtained by dialysis can be concentrated or diluted to obtain a silk fibroin solution with a certain concentration.

S22, preparing the metal nanocluster by using bovine serum albumin as a template and adopting an in-situ reduction method.

Specifically, in one embodiment of the present invention, the metal nanoclusters are gold nanoclusters, and the preparation steps are: mixing 40-60 mg/mL bovine serum albumin solution and 9-11 mM chloroauric acid solution, introducing nitrogen after stirring, adding 1mol of sodium hydroxide solution for reaction for 10-15 h after stirring for 1-5 min at 35-40 ℃, and dialyzing for 2-4 days by using a dialysis bag after the reaction is finished to prepare the gold nanoclusters. Preferably, the volume ratio of the bovine serum albumin solution to the chloroauric acid solution is 1:1, the dialysis bag is solarbio MD80, and the molecular weight cut-off is 8000.

In another embodiment of the present invention, the metal nanoclusters are silver nanoclusters, and the preparation steps are: mixing a bovine serum albumin solution with the concentration of 70-80 mg/ml and a silver nitrate solution with the concentration of 6-8 mmol, introducing nitrogen after stirring, adding 1mol of a sodium hydroxide solution after stirring for 20-40 min at the temperature of 35-40 ℃, adding a sodium borohydride solution with the concentration of 110-130 mM after reacting for 50-80 min, and dialyzing for 2-4 days through a dialysis bag after the reaction is finished to obtain the silver nanocluster. Preferably, the volume ratio of the bovine serum albumin solution to the silver nitrate solution is 1: 2. The dialysis bag was solarbio MD80 with a molecular weight cut-off of 8000.

According to different characteristics of the gold nanoclusters and the silver nanoclusters, the bovine serum albumin template is used for regulating and controlling different using amounts of bovine serum albumin and different reaction parameters to obtain the high-stability metal nanoclusters, and particularly for the silver nanoclusters, when the silver nanoclusters are prepared by taking the bovine serum albumin as a reducing agent, sodium borohydride is further used for reduction, so that the silver nanoclusters with more stable structures are obtained.

S23, adding the metal nanoclusters into the natural protein solution, and mixing to obtain a doped solution. Specifically, in the doping process, the metal nanoclusters and the natural protein solution are adjusted to be 20mg/L, and then the metal nanoclusters are doped into the natural protein solution according to the volume ratio of 10-40% to obtain the doped solution.

S24, immersing the lower electrode in the doping solution for a period of time, and then pulling to form a natural protein film doped with metal nanoclusters on the surface of the lower electrode. Specifically, the process of pulling the coating film comprises the following steps: the method is characterized in that a lower electrode, such as ITO conductive glass, is immersed in a doping solution, preferably, the immersion time is 260-330 s, the pulling speed is 0.05-0.2 mm/s, and the pulling height is 18-24 mm. The thickness of the prepared natural protein film is controlled to be 30-40nm by regulating and controlling the parameters of the pulling coating film.

Further included after step S24 is: s25, soaking the natural protein film prepared by pulling in glycerol for 20-30 h, cleaning and drying. The natural protein film is soaked in the glycerol solution, so that protein crystallization can be promoted, and the stability of the natural protein film is facilitated.

According to the invention, bovine serum albumin is wrapped on the metal nanoclusters prepared by taking bovine serum albumin as a template, the bovine serum albumin wrapped metal nanoclusters have lower surface potential under the action of an electric field, particularly the surface potential of the silver nanoclusters is lower than that of the gold nanoclusters, the bovine serum albumin wrapped metal nanoclusters are doped into the silk fibroin film to serve as a bipolar electrode, the growth process of the conductive wire is regulated and controlled to be more regular, and more excellent resistance change switching performance can be obtained, including higher erasing and writing speed, larger on-off ratio and the like. In addition, the bovine serum albumin wraps the metal nano-clusters, so that the bovine serum albumin and the silk fibroin are more favorably mixed, the obtained resistive material film is smoother in appearance, and the surface potential difference area is more prominent.

In step S3, magnetron sputtering is performed on the surface of the obtained natural protein film doped with the metal nanocluster to obtain an upper electrode. The size, shape and thickness of the upper electrode are controlled by masking plate and controlling sputtering current parameters.

The features and properties of the present invention are described in further detail below with reference to examples.

Example 1

The embodiment provides a gold nanocluster doped memristor, which is prepared according to the following steps:

(1) cleaning of the lower electrode:

and (3) sequentially immersing the ITO conductive glass (the specification is 1 x 4cm, the thickness is 180nm) in ultrapure water, acetone and isopropanol solution, respectively carrying out ultrasonic treatment for 10min, and drying by using nitrogen to obtain a clean lower electrode.

(2) Preparing a silk fibroin solution:

collecting 10g Bombyx Bombycis, cutting, removing impurities, adding into prepared weak base solution (10g sodium bicarbonate dissolved in 2L deionized water), heating to boil, maintaining for 30min, and repeating for 2 times. Taking out silk, soaking in distilled water for 1 hr, and changing water once. And then placing the silk in an oven at 60 ℃ for drying to obtain the degummed silk. Taking 5g of degummed silk, adding 35ml of LiBr solution (9.3mol/L) for dissolving, standing and heating at 60 ℃ for 4h to prepare silk fibroin mixed solution. Weighing dialysis bags (solarbio MD34, molecular weight cut-off 3500) in proportion, heating the dialysis bags in boiling water for 15min, washing the dialysis bags with distilled water, introducing the mixed solution of silk fibroin, placing the dialysis bags in a dialysis bucket filled with distilled water, changing the water at intervals of 2h, and dialyzing for 2d to obtain the silk fibroin solution.

(3) Preparing metal nano-clusters:

measuring 50mL of bovine serum albumin solution (50mg/mL), dissolving chloroauric acid powder with ultrapure water to prepare 50mL of chloroauric acid solution (10mM), mixing and stirring the two solutions, introducing nitrogen, controlling the temperature to be 37 ℃, stirring for 2 minutes, adding 5mL of sodium hydroxide solution (1M), timing to react for 12 hours, and dialyzing for three days by using a dialysis bag (solarbio MD80, molecular weight cut-off 8000) after the reaction is finished to prepare the gold nanocluster.

(4) Preparation of a doping solution:

the concentration of the metal nano-cluster is adjusted to be 20mg/mL, the concentration of the silk fibroin is adjusted to be 20mg/mL, and the metal nano-cluster and the silk fibroin solution are mixed according to the volume ratio of 3:7 to obtain a doped solution with the doping amount of 30%.

(5) Preparing a silk fibroin film:

and (3) immersing the ITO conductive glass in the step (1) in the doping solution in the step (4) for 300s, wherein the pulling speed is 0.1mm/s, and the pulling height is 20mm, so that the silk fibroin film (with the thickness of about 35nm) doped with the metal nanoclusters is obtained. Soaking the silk fibroin film in glycerol for 24h, taking out, rinsing with ultrapure water, and finally drying in an incubator at 25 ℃.

(6) Preparing an upper electrode:

and (5) carrying out magnetron sputtering on the surface of the silk fibroin film obtained in the step (5) to obtain an Ag electrode, wherein the size of the Ag electrode is 90 mu m, and the thickness of the Ag electrode is 70 nm.

A memristor model schematic is shown in fig. 2. The protein memristor is formed by a typical sandwich structure of an upper electrode (Ag), a resistance layer (silk fibroin film) and a lower electrode (ITO), wherein the thickness of the resistance layer is preferably 30-40nm, the thickness of the Ag electrode is 70nm, and the thickness of the ITO electrode is 180 nm.

Fig. 3 is a scanning electron microscope image of the silk fibroin film coated with gold nanoclusters and doped with bovine serum of this embodiment, and it can be seen from fig. 3 that a doped region shown as a white circle appears on the surface of the film, and the surface of the film is flat.

Example 2

The present embodiment provides a silver nanocluster doped memristor, which is different from embodiment 1 in that: in the step (3):

weighing 24mL of bovine serum albumin solution (74mg/mL), preparing 48mL of silver nitrate solution (7.5mM), mixing and stirring the two solutions, stirring at the rotation speed of 1000rpm, introducing nitrogen, controlling the temperature at 37 ℃, adding 2.4mL of sodium hydroxide solution (1M) after stirring for 2 minutes, adding 1.8mL of sodium borohydride solution (112mM) after timing reaction for half an hour, continuing the reaction for 1 hour, and dialyzing for three days by using a dialysis bag (solarbio MD80, molecular weight cut-off 8000) after the reaction is finished to prepare the silver nanocluster.

Fig. 4a is an atomic force scanning electron microscope image of the silk fibroin film coated with gold nanoclusters and doped with bovine serum of the present embodiment, and fig. 4b is a corresponding surface potential scanning image of fig. 4 a. Fig. 5 is surface potential data for the corresponding marker positions of fig. 4a and 4 b. Fig. 4 shows that the surface of the film is flat, and the doped area on the surface of the film is more than that of the film in example 1, the potential difference on the surface of the sample is very outstanding, and the potential of the doped area is obviously lower than that of the matrix material.

Example 3

The present embodiment provides a silver nanocluster doped memristor, which is different from embodiment 2 in that: in the step (4), the metal nano-clusters and the silk fibroin solution are mixed according to the volume ratio of 1:9 to obtain a doping solution with the doping amount of 10%.

Example 4

The present embodiment provides a silver nanocluster doped memristor, which is different from embodiment 2 in that: in the step (4), the metal nano-clusters and the silk fibroin solution are mixed according to the volume ratio of 2:8 to obtain a doping solution with the doping amount of 20%.

Comparative example 1

This comparative example provides a memristor, which was prepared according to the following steps:

(1) cleaning of the lower electrode: same as in example 1.

(2) Preparing a silk fibroin solution: same as in example 1.

(3) Measuring 50mL of bovine serum albumin solution (50mg/mL), controlling the temperature at 37 ℃, stirring for 2 minutes, adding 5mL of sodium hydroxide solution (1M), standing for 12 hours, and dialyzing for three days by using a dialysis bag (solarbio MD80, molecular weight cut-off 8000) after the reaction is finished to prepare the bovine serum albumin solution without doping the metal nanoclusters.

(4) And (4) adjusting the concentration of the bovine serum albumin solution obtained in the step (3) to be 20mg/mL and the concentration of the silk fibroin to be 20mg/mL, and mixing the bovine serum albumin solution and the silk fibroin solution according to the volume ratio of 3:7 to obtain a mixed solution.

(5) Preparing a silk fibroin film:

and (3) immersing the ITO conductive glass in the step (1) in the mixed solution in the step (4) for 300s, wherein the pulling speed is 0.1mm/s, and the pulling height is 20mm, so that the silk fibroin film (the thickness is about 35nm) is obtained. Soaking the silk fibroin film in glycerol for 24h, taking out, rinsing with ultrapure water, and finally drying in an incubator at 25 ℃.

(6) Preparing an upper electrode: same as in example 1.

Comparative example 2

(1) cleaning of the lower electrode: same as in example 1.

(2) Preparing a silk fibroin solution: same as in example 1.

(3) Preparing metal nano particles: 50mL of wool keratin solution (50mg/mL) was measured, chloroauric acid powder was dissolved in ultrapure water to prepare 50mL of chloroauric acid solution (10mM), the two solutions were mixed and stirred for 2min, 5mL of sodium hydroxide solution (1M) was added, and the mixture was left to stand for 12h, thereby obtaining gold nanoparticle-doped wool keratin solution.

(4) Adjusting the concentration of the wool keratin solution obtained in the step (3) to be 20mg/mL and the concentration of the silk fibroin to be 20mg/mL, and mixing the bovine serum albumin solution and the silk fibroin solution according to the volume ratio of 1:4 to obtain a mixed solution.

(5) Preparing a silk fibroin film:

and (3) immersing the ITO conductive glass in the step (1) in the mixed solution in the step (4) for 300s, wherein the pulling speed is 0.1mm/s, and the pulling height is 20mm, so that the silk fibroin film (the thickness is about 25nm) is obtained.

(6) Preparing an upper electrode: same as in example 1.

Test examples

The performance parameters of the memristor such as cycle tolerance, operating voltage and erasing speed are tested in a laboratory. Testing an instrument: keithley2400 semiconductor tester.

Fig. 6-8 show the cycle tolerance of the gold nanocluster doped protein memristor, the cycle tolerance refers to the number of times that the memristor can be cyclically converted between a high resistance state and a low resistance state, namely the number of times that the device can be repeatedly erased and written, and a current-voltage cyclic scanning test result shows that the protein memristor can be stably cycled for more than 100 times, and shows good cycle stability.

Fig. 9 shows the erasing speed performance of the gold nanocluster doped memristor of embodiment 1, the erasing speed reflecting whether the memristor realizes the capability of fast operation. It can be seen from FIG. 9 that the memristor erasure speed reaches 12ns, indicating the great potential of the memristor as a high speed memory. The erasing and writing speed performance of the memristors provided by the embodiment 2, the comparative example 1 and the comparative example 2 is tested at the same time, and the results are shown in the table 1.

TABLE 1

Fig. 10 shows that the performance of the silver nanocluster doped memristor changes along with the improvement of the doping amount of the silver nanocluster, and it can be seen from the graph that the addition of the silver nanocluster reduces the switching voltage of the protein memristor, shows that the energy consumption of the device is low, and meanwhile, the switching ratio is remarkably improved, which indicates that the value of the storage window is increased, and is beneficial to the peripheral circuit to identify the state stored by the device.

The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Claims

1. The metal nanocluster-doped memristor is characterized by comprising an upper electrode, a resistance change layer and a lower electrode, wherein the resistance change layer is located between the upper electrode and the lower electrode, the resistance change layer is a resistance change material film doped with the metal nanoclusters, the thickness of the upper electrode is 60-80 nm, the thickness of the resistance change layer is 30-40nm, the thickness of the lower electrode is 160-200 nm, the metal nanoclusters are silver nanoclusters, bovine serum albumin is used as a template, and the metal nanoclusters are prepared by an in-situ reduction method.

2. The metal nanocluster-doped memristor according to claim 1, wherein the resistive material film is selected from one of a metal oxide film, a high polymer film, and a natural protein film.

3. The metal nanocluster-doped memristor according to claim 2, wherein the natural protein film is selected from one or more of silk fibroin film, sericin film, bovine serum albumin film, and wool keratin film.

4. The metal nanocluster-doped memristor according to claim 1, wherein the upper electrode is a elemental metal electrode or an alloy electrode, and the lower electrode is an oxide electrode or a nitride electrode.

5. The metal nanocluster-doped memristor according to claim 1, wherein the mass fraction of the metal nanoclusters in the resistive material thin film is 10-30%.

6. A preparation method of the metal nanocluster-doped memristor according to any one of claims 1 to 5, characterized by comprising the following steps:

s1, cleaning the lower electrode;

s3, growing the upper electrode on the resistance change layer by adopting a magnetron sputtering method;

the step of forming the resistance change layer on the surface of the cleaned lower electrode in a pull coating mode comprises the following steps:

s21, preparing a natural protein solution;

s22, preparing a metal nano-cluster by using bovine serum albumin as a template and adopting an in-situ reduction method;

s23, adding the metal nanoclusters into the natural protein solution, and mixing to obtain a doped solution;

s24, immersing the lower electrode in the doping solution for a period of time, and then pulling to form a natural protein film doped with metal nanoclusters on the surface of the lower electrode.

7. The method according to claim 6, further comprising, after step S24:

s25, soaking the natural protein film prepared by pulling in glycerol for 20-30 h, cleaning and drying.

8. The method according to claim 6, wherein in step S22, the metal nanoclusters are silver nanoclusters, and the method comprises: mixing a bovine serum albumin solution with the concentration of 70-80 mg/mL and a silver nitrate solution with the concentration of 6-8 mmol, introducing nitrogen after stirring, adding 1mol of a sodium hydroxide solution after stirring for 20-40 min at the temperature of 35-40 ℃, adding a sodium borohydride solution with the concentration of 110-130 mM after reacting for 20-40 min, reacting for 50-80 min, and dialyzing for 2-4 days through a dialysis bag after the reaction is finished to obtain the silver nanocluster.