CN113235049A

CN113235049A - Transition metal sulfide thin film and preparation method and application thereof

Info

Publication number: CN113235049A
Application number: CN202110458369.7A
Authority: CN
Inventors: 成会明; 唐磊; 农慧雨; 滕长久; 刘碧录
Original assignee: Tsinghua-Berkeley Shenzhen Institute Preparation Office
Current assignee: Tsinghua-Berkeley Shenzhen Institute Preparation Office
Priority date: 2021-04-27
Filing date: 2021-04-27
Publication date: 2021-08-10

Abstract

The invention discloses a transition metal sulfide thin film and a preparation method and application thereof, wherein the preparation method comprises the following steps: preparing a transition metal precursor film with the thickness of more than or equal to 100 nm; and then placing the transition metal precursor film at 700-850 ℃ and adding the transition metal precursor film into the film at a volume flow ratio of (1-2): and (2) carrying out a sulfurization reaction for 60-120 min under the action of the mixed gas of the hydrogen and the hydrogen sulfide of 1. By the method, the effective control of the sulfur content in the product film along the direction vertical to the surface of the film can be realized by controlling the process parameters in the preparation process, so that the preparation and component control of the wafer-level transition metal sulfide film are realized.

Description

Transition metal sulfide thin film and preparation method and application thereof

Technical Field

The invention relates to the technical field of preparation of transition metal sulfide thin films, in particular to a transition metal sulfide thin film and a preparation method and application thereof.

Background

Since the unimorph graphene is separated by a Geim research group at Manchester university in the United kingdom in 2004, two-dimensional materials with unique physical properties attract the attention of researchers, wherein transition metal chalcogenide compounds (such as molybdenum disulfide and tungsten disulfide) have excellent electrical properties, photoelectric properties and adjustable band gaps, and have great potential in the fields of micro-nano electronic devices, optical devices, chemical biosensors, electrocatalysis and the like. In order to meet the application requirements of large-scale preparation and high integration, a preparation method of a large-area uniform thin film of a two-dimensional transition metal chalcogenide needs to be developed, and chemical components of the two-dimensional transition metal chalcogenide can be regulated and controlled.

Chemical vapor deposition is an important method for preparing two-dimensional transition metal chalcogenides. Taking molybdenum disulfide as an example, molybdenum disulfide can be prepared by depositing molybdenum disulfide on a substrate through chemical vapor deposition by using molybdenum trioxide powder and sulfur powder as precursors, but the concentration distribution of a vapor source deposited on the substrate is not uniform in the preparation process, so that a large-scale uniform film is difficult to obtain; meanwhile, the traditional laboratory growth process is difficult to be compatible with the actual industrial large-scale production line. In order to achieve large-scale controllable production of two-dimensional materials, researchers have made extensive efforts to select appropriate precursors (liquids or gases), precursor and gas supply means, additives, substrates, and the like.

For example, currently, researchers have proposed a method for preparing a molybdenum disulfide thin film by a magnetron sputtering method, in which molybdenum disulfide sintered palladium is used as a target, argon is used as a working gas, a molybdenum sulfide thin film is obtained by sputtering in a magnetron sputtering chamber, and the obtained thin film is two-dimensional molybdenum disulfide or bulk molybdenum disulfide. In addition, researchers have proposed a chemical vapor deposition method for preparing disulfide, which specifically comprises the steps of taking tungsten oxide powder and sulfur powder as precursors, placing the sulfur powder at the upstream, placing the tungsten oxide precursor at the center of a heating zone of a tube furnace, and obliquely putting a silicon wafer bottom on a tungsten oxide precursor quartz boat for chemical vapor deposition. However, the above methods are difficult to adjust the distribution of the components, particularly the sulfur concentration in the disulfide.

In summary, the large-scale uniform transition metal chalcogenide thin film is prepared and the chemical components of the thin film are still difficult to control, and the controllability, the repeatability and the process compatibility of the preparation process need to be further improved.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a transition metal sulfide thin film and a preparation method and application thereof.

In a first aspect of the present invention, a method for preparing a transition metal sulfide thin film is provided, which includes the following steps:

s1, preparing a transition metal precursor film with the thickness of more than or equal to 100 nm;

s2, placing the transition metal precursor film at 700-850 ℃, and carrying out a sulfurization reaction for 60-120 min under the action of a mixed gas of hydrogen and hydrogen sulfide with a volume flow ratio of (1-2): 1.

The preparation method of the transition metal sulfide provided by the embodiment of the invention has at least the following beneficial effects: the preparation method comprises the steps of preparing a transition metal precursor film with a specific thickness, and then carrying out a vulcanization reaction under the action of hydrogen and hydrogen sulfide mixed gas with a specific volume flow ratio at a specific temperature, wherein the hydrogen can promote the decomposition of the hydrogen sulfide, so that the inward vulcanization reaction of the transition metal precursor film from the surface is realized, transition metal sulfide is formed, and the sulfur content of the prepared product film is reduced along with the increase of the inward extension depth of the surface of the film. Through the mode, the effective control of the gradient distribution of the sulfur content in the product film along the direction vertical to the surface of the film can be realized by controlling the technological parameters of the preparation process including the thickness of the film, the temperature and the time of the vulcanization reaction and the volume flow ratio of the introduced hydrogen and the hydrogen sulfide in the reaction process, so that the preparation and the component control of the wafer-level transition metal sulfide film are realized, and the method has the advantages of simple process, easiness in operation, controllability, repeatability and process compatibility, and is suitable for industrial production.

In some embodiments of the present invention, in step S1, a transition metal precursor is deposited on the substrate by a deposition method to prepare a transition metal precursor film with a thickness greater than or equal to 100 nm. The transition metal precursor film can be completely covered on the substrate, and can also be designed into planar patterns such as characters, geometric figures, animal and plant images and the like, and the transition metal precursor film is not particularly limited; in addition, the pattern structure can be firstly constructed into a pattern template through methods such as mask assistance, photoetching, 3D printing and the like, and then deposited on the substrate through a deposition method.

In some embodiments of the invention, the deposition process is a physical vapor deposition process; preferably, the physical vapor deposition method is at least one selected from electron beam evaporation, thermal evaporation, atomic layer deposition, magnetron sputtering, spin coating and imprinting; more preferably, electron beam evaporation is used. The metal precursor is deposited on the substrate by adopting a physical vapor deposition method, so that large-area uniform supply of a metal source can be realized, the controllable preparation of the transition metal sulfide thin film with the sulfur content distributed in a gradient manner through a vulcanization reaction is further ensured, and the uniformity and the reliability of the transition metal sulfide thin film are improved.

In some embodiments of the invention, the transition metal precursor is selected from at least one of molybdenum, platinum, niobium, ruthenium, palladium, tungsten, tantalum. Typical but non-limiting combinations among these are: combinations of molybdenum and platinum, combinations of platinum and niobium, ruthenium and palladium, tungsten and tantalum, ruthenium, palladium, tungsten and tantalum, and the like.

In some embodiments of the present invention, in step S1, the substrate is at least one selected from a silicon substrate, a sapphire substrate, a glass substrate, and a quartz substrate.

In some embodiments of the present invention, step S2 specifically includes: placing the transition metal precursor film in a closed container, and introducing inert gas to remove air in the closed container; introducing hydrogen and inert gas serving as carrier gas into the closed container, and raising the temperature in the closed container to 700-850 ℃; and then, adding the mixture into the closed container according to the volume flow ratio of (1-2): 1, introducing hydrogen and hydrogen sulfide, and carrying out a vulcanization reaction on the transition metal precursor film for 60-120 min at the temperature of 700-850 ℃. In the above way, the air is discharged before the temperature of the closed container is raised, so that the residual air in the closed container can be prevented from contacting with hydrogen in the subsequent reaction, and potential safety hazards are generated. The inert gas can be selected from nitrogen, helium, neon, argon, xenon, etc., and preferably argon and/or nitrogen is used. In the process of introducing carrier gas hydrogen and inert gas, the introduction rate of the hydrogen can be controlled to be 5-50 sccm, preferably 15-25 sccm; the inert gas is introduced at a rate of 1 to 1000sccm, preferably 400 to 600 sccm.

In some embodiments of the invention, the closed vessel is a vertical tube furnace, and the lower end of the vertical tube furnace has a gas inflow port; the surface of the transition metal precursor film is arranged towards the direction of the gas inflow port; preferably, the flow direction of the carrier gas is perpendicular to the surface of the transition metal precursor film, i.e., the flow direction of the carrier gas is parallel to the normal direction of the transition metal precursor film. In addition, the vertical tube furnace can be 1.5-foot vertical tube furnace, and the metal precursor film can be placed in the heating central area of the tube furnace during preparation.

In some embodiments of the invention, in step S2, the temperature rise speed of the closed container in the temperature rise process is 10 to 40 ℃/min; preferably, after the temperature in the closed container is increased to 700-850 ℃, the temperature in the closed container is increased to the following value according to the volume flow ratio (1-2): 1, in the process of introducing hydrogen and hydrogen sulfide, the introduction rate of the hydrogen is 5-50 sccm (preferably 15-25 sccm), and the introduction rate of the hydrogen sulfide is 5-25 sccm (preferably 8-12 sccm). Further preferably, the temperature rise speed of the closed container in the temperature rise process is controlled to be 25-35 ℃/min. Wherein, the volume flow ratio of the mixture to the inside of the closed container is (1-2): 1, introducing hydrogen and hydrogen sulfide, which is beneficial to realizing the controllable adjustment of the prepared transition metal sulfide film component. After the completion of the vulcanization reaction, the temperature may be further decreased under an inert gas.

In step S2, the transition metal precursor thin film prepared in step S1 is placed in a closed container together with the substrate to undergo a sulfurization reaction, so as to prepare a transition metal sulfide thin film on the substrate; the sulfur content of the prepared transition metal sulfide thin film is reduced along with the increase of the extending depth of the surface of the thin film towards the substrate direction, the corresponding sulfur vacancy is increased along with the increase of the depth, and the structure is favorable for the modulation of the switch state of the memristor.

Measuring the sulfur content of different depths of the prepared transition metal sulfide thin film from the surface to the substrate direction by adopting X-ray photoelectron spectroscopy (XPS), wherein the relative intensity value of sulfur in the XPS on the surface is 0.25-0.21; the XPS relative intensity value at the etching depth of 1min is 0.20-0.16; the XPS relative intensity value at the etching depth for 4min is 0.15-0.14; the XPS relative intensity value at the etching depth of 9min is 0.13-0.12, and the XPS relative intensity value at the etching depth of 19min is less than or equal to 0.11.

In a second aspect of the present invention, a transition metal sulfide thin film is provided, which is obtained by any one of the methods for producing a transition metal sulfide thin film according to the first aspect of the present invention, wherein the sulfur content in the transition metal sulfide thin film is distributed in a gradient manner in a direction perpendicular to the surface of the transition metal sulfide thin film. The transition metal sulfide thin film can be applied to preparation of memristors, and good linearity and large-area array data processing can be achieved.

The third aspect of the invention provides an application of the transition metal sulfide thin film in preparation of a memristor

Drawings

The invention is further described with reference to the following figures and examples, in which:

FIG. 1 is a schematic flow chart of a process for preparing a transition metal sulfide thin film according to example 1;

FIG. 2 is an optical photograph of a transition metal sulfide thin film obtained in example 1;

FIG. 3 is a Raman spectrum of a transition metal sulfide thin film obtained in example 1 with a laser at 532 nm;

FIG. 4 is a Raman spectral line scan of a transition metal sulfide thin film obtained in example 1 under a laser of 532 nm;

FIG. 5 is an XPS plot of the sulfur content at different depths from the surface toward the substrate for the transition metal sulfide thin films prepared in example 1;

FIG. 6 is a secondary ion mass spectrum of the sulfur content of the transition metal sulfide thin film prepared in example 1 at different depths from the surface toward the substrate;

FIG. 7 is a current-voltage curve of a memristor constructed by the transition metal sulfide thin film prepared in example 1, after 12 consecutive scans;

FIG. 8 is a current-cycle number fitting graph of a memristor constructed using the transition metal sulfide thin film prepared in example 1;

FIG. 9 is a large-area array device test diagram of a memristor constructed by using the transition metal sulfide thin film prepared in example 1;

fig. 10 is a current-voltage graph of a memristor constructed using the transition metal sulfide thin film prepared in comparative example 7 under a continuous scanning state for 5 times.

Detailed Description

The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.

Example 1

The present embodiment prepares a transition metal sulfide thin film, and the preparation process flow thereof is shown in fig. 1, and specifically includes the following steps:

s1, depositing the transition metal platinum on a 1-inch single-polished silicon wafer substrate by adopting an electron beam coating method to prepare a transition metal platinum film with the thickness of 100 nm;

s2, placing the transition metal platinum film in a heating central area of a 1.5-inch vertical tube furnace, and introducing argon for 30min at an introduction rate of 500sccm to discharge air in the tube furnace; then introducing hydrogen (with the introduction rate of 20sccm) and argon (with the introduction rate of 500sccm) as carrier gases, wherein the flow rate of the carrier gases is parallel to the normal direction of the transition metal platinum film; raising the temperature in the tube furnace to 700 ℃ at a temperature raising rate of 30 ℃/min under the atmosphere of carrier gas; then, the mixture is added into a tube furnace according to the volume flow ratio of 2:1, introducing hydrogen (the introduction rate is 20sccm) and hydrogen sulfide (the introduction rate is 10sccm), wherein the gas flow direction is parallel to the normal direction of the transition metal platinum film, and the transition metal platinum film is subjected to a vulcanization reaction for 60min at the temperature of 700 ℃; and then cooling the silicon wafer substrate under argon to form a transition metal sulfide film, namely a platinum sulfide film, on the single polished silicon wafer substrate, wherein an optical photo of the platinum sulfide film is shown in figure 2.

The platinum sulfide thin film prepared above was measured and analyzed by a raman spectrometer under 532nm laser, and the obtained results are shown in fig. 3 and 4. According to the test results, 25 data points were uniformly collected in the horizontal direction of the film surface, and it can be seen that the prepared platinum sulfide film was uniformly distributed on the substrate.

The sulfur content at different depths of the platinum sulfide thin film prepared above was measured from the surface toward the substrate by X-ray photoelectron spectroscopy (XPS), and the results of the measurement are shown in fig. 5. According to the detection: the XPS relative strength value of the surface of the platinum sulfide film is 0.24; the XPS relative intensity value at the etching depth of 1min is 0.17; the XPS relative intensity value at the etching depth after 4min is 0.15; the XPS relative intensity value at the etching depth of 9min is 0.12; the XPS relative intensity value at 19min etch depth was 0.11. It was thus shown that the sulfur content of the platinum sulfide thin film produced above decreased with increasing depth of extension of the surface toward the substrate, and the sulfur content of the platinum sulfide thin film was distributed in a gradient in the direction perpendicular to the surface of the thin film.

Further, the sulfur content of the platinum sulfide thin film obtained above at different depths from the surface toward the substrate was measured and analyzed by a secondary ion mass spectrometer, and the results are shown in fig. 6. As can be seen from fig. 6, the sulfur content in the platinum sulfide thin film is distributed in a gradient manner from the surface to be bonded to the substrate.

The platinum sulfide film is transferred to a conductive substrate from a single polished silicon wafer substrate by adopting a polymethyl methacrylate auxiliary transfer method, and a 5 × 5 memristor array is constructed on the platinum sulfide film by using an electron beam evaporation and mask technology.

The current-voltage curve of the memristor constructed by the platinum sulfide thin film of the embodiment from 1 to 12 is sequentially shown from top to bottom in fig. 7, and the current component of the device is increased and presents a low-resistance state.

Fig. 8 is a current-cycle number fitting graph of the memristor constructed above, and it can be seen from fig. 8 that the current linearly increases with the increase of the cycle number.

FIG. 9 is a large-area array device test chart of the memristor constructed above, and it can be found that the conductance of the device gradually increases along with the increase of the cycle number in a large-area range, and the device shows good uniformity and consistency.

Example 2

The embodiment prepares the transition metal sulfide thin film, and the specific process comprises the following steps:

s1, depositing transition metal palladium on a 1-inch sapphire substrate by adopting an electron beam plating method, and preparing a transition metal palladium film with the thickness of 100 nm;

s2, placing the transition metal palladium film in a heating central area of a 1.5-inch vertical tube furnace, and introducing argon of 500sccm for 30min to exhaust air in the tube furnace; then introducing hydrogen (with the introduction rate of 5sccm) and argon (with the introduction rate of 500sccm) as carrier gases, wherein the flow rate of the carrier gases is parallel to the normal direction of the transition metal palladium film; under the atmosphere of carrier gas, the temperature in the tube furnace is increased to 800 ℃ at the temperature increasing rate of 10 ℃/min; then introducing hydrogen (with the introduction rate of 5sccm) and hydrogen sulfide (with the introduction rate of 5sccm) into the tubular furnace according to the volume flow ratio of 1:1, wherein the gas flow direction is parallel to the normal direction of the transition metal palladium film, and the transition metal palladium film is subjected to a sulfurization reaction for 120min at the temperature of 800 ℃; and then cooling under argon gas to form a transition metal sulfide film, namely a palladium sulfide film, on the sapphire substrate.

And measuring the sulfur content at different depths of the prepared palladium sulfide film from the surface to the direction of the sapphire substrate by adopting X-ray photoelectron spectroscopy (XPS), so that the sulfur content of the palladium sulfide film is reduced along with the increase of the extension depth of the surface to the direction of the sapphire substrate, and the sulfur content of the palladium sulfide film is distributed in a gradient manner along the direction vertical to the surface of the film.

Example 3

s1, depositing the transition metal tungsten on a 1-inch quartz plate substrate by adopting an electron beam plating method, and preparing a transition metal tungsten film with the thickness of 100 nm;

s2, placing the transition metal tungsten film in a heating central area of a 1.5-inch vertical tube furnace, and introducing argon of 500sccm for 30min to exhaust air in the tube furnace; then introducing hydrogen (with the introduction rate of 50sccm) and argon (with the introduction rate of 500sccm) as carrier gases, wherein the flow rate of the carrier gases is parallel to the normal direction of the transition metal tungsten film; raising the temperature in the tube furnace to 850 ℃ at a temperature raising rate of 40 ℃/min under the atmosphere of carrier gas; then introducing hydrogen (with the introduction rate of 50sccm) and hydrogen sulfide (with the introduction rate of 25sccm) into the tubular furnace according to the volume flow ratio of 2:1, wherein the gas flow direction is parallel to the normal direction of the transition metal tungsten film, and the transition metal tungsten film is subjected to a vulcanization reaction for 80min at the temperature of 850 ℃; and then cooling under argon gas to form a transition metal sulfide film, namely a tungsten sulfide film, on the quartz piece substrate.

And measuring the sulfur content at different depths of the prepared tungsten sulfide film from the surface to the direction of the quartz plate substrate by adopting X-ray photoelectron spectroscopy (XPS), so as to obtain that the sulfur content of the tungsten sulfide film is reduced along with the increase of the extension depth of the surface to the direction of the quartz plate substrate, and the sulfur content of the tungsten sulfide film is in gradient distribution along the direction vertical to the surface of the film.

Example 4

This example prepared a transition metal sulfide thin film, and differs from example 1 in that: the transition metal platinum thin film prepared in step S1 was 100nm thick and in a butterfly pattern, and the other operations were the same as in example 1 to obtain a transition metal sulfide thin film, i.e., a platinum sulfide thin film.

The sulfur content at different depths of the platinum sulfide film prepared in the embodiment is measured from the surface towards the substrate direction of the single polished silicon wafer by adopting X-ray photoelectron spectroscopy (XPS), so that the sulfur content of the platinum sulfide film in the embodiment is reduced along with the increase of the extension depth of the surface towards the substrate direction of the single polished silicon wafer, and the sulfur content of the platinum sulfide film is in gradient distribution along the direction vertical to the surface of the film.

Example 5

This example prepared a transition metal sulfide thin film, and differs from example 1 in that: in step S1, the transition metal platinum was replaced with the transition metal niobium, and the other operations were performed in the same manner as in example 1 to obtain a transition metal sulfide thin film, i.e., a niobium sulfide thin film.

Example 6

This example prepared a transition metal sulfide thin film, and differs from example 1 in that: in step S1, the transition metal platinum was replaced with the transition metal ruthenium, and the other operations were performed in the same manner as in example 1 to obtain a transition metal sulfide thin film, i.e., a ruthenium sulfide thin film.

Example 7

This example prepared a transition metal sulfide thin film, and differs from example 1 in that: in step S1, the transition metal platinum was replaced with the transition metal tantalum, and the other operations were the same as in example 1 to obtain a transition metal sulfide thin film, i.e., a tantalum sulfide thin film.

The sulfur content at different depths of the transition metal sulfide thin films prepared in examples 5 to 7 was measured from the surface toward the single-polished silicon wafer substrate by X-ray photoelectron spectroscopy (XPS), and it was found that the sulfur content in each transition metal sulfide thin film decreased with increasing depth of extension of the surface toward the single-polished silicon wafer substrate, and the sulfur content in the transition metal sulfide thin film was distributed in a gradient manner along a direction perpendicular to the surface of the thin film.

Comparative example 1

This comparative example, which prepared a transition metal sulfide thin film, differs from example 1 in that: in step S2, the temperature in the tube furnace was raised to 650 ℃ and the vulcanization reaction was carried out under the temperature conditions, and the other operations were the same as in example 1.

Comparative example 2

This comparative example, which prepared a transition metal sulfide thin film, differs from example 1 in that: in step S2, the temperature in the tube furnace was raised to 900 ℃ and the vulcanization reaction was carried out under the temperature conditions, and the other operations were the same as in example 1.

Comparative example 3

This comparative example, which prepared a transition metal sulfide thin film, differs from example 1 in that: the time for the sulfurization reaction in step S2 was 50min, and the other operations were the same as in example 1.

Comparative example 4

This comparative example, which prepared a transition metal sulfide thin film, differs from example 1 in that: the time for the sulfurization reaction in step S2 was 140min, and the other operations were the same as in example 1.

Comparative example 5

This comparative example, which prepared a transition metal sulfide thin film, differs from example 1 in that: after the temperature in the tube furnace is raised to 700 ℃ in step S2, the tube furnace is charged with a gas at a volume flow rate ratio of 0.8: 1 hydrogen gas (flow rate of 8sccm) and hydrogen sulfide (flow rate of 10sccm) were introduced, and the other operations were the same as in example 1.

Comparative example 6

This comparative example, which prepared a transition metal sulfide thin film, differs from example 1 in that: after the temperature in the tube furnace is raised to 700 ℃ in step S2, the tube furnace is charged with a gas at a volume flow rate ratio of 2.2: 1 hydrogen gas (at a flow rate of 22sccm) and hydrogen sulfide (at a flow rate of 10sccm) were introduced, and the other operations were the same as in example 1.

Respectively measuring the sulfur content of the transition metal sulfide thin films prepared in the comparison ratio of 1-6 from the surface to the direction of the single polished silicon wafer substrate by adopting X-ray photoelectron spectroscopy (XPS), wherein the test results show that: the trend that the sulfur content in each transition metal sulfide film is reduced along with the increase of the extension depth of the surface in the direction of the single polished silicon wafer substrate is not obvious, and the sulfur content in the transition metal sulfide film is distributed in a gradient mode along the direction vertical to the surface of the film. From the above, in the preparation process of the transition metal sulfide thin film, the temperature of the vulcanization reaction needs to be controlled to be 700-850 ℃, the reaction time needs to be controlled to be 60-120 min, and the volume flow ratio of the introduced hydrogen and the hydrogen sulfide in the reaction process is controlled to be (1-2): 1, so that the effective control of the sulfur content gradient distribution in the transition metal sulfide thin film is realized by regulating and controlling the process parameters under the above conditions.

Comparative example 7

This comparative example, which prepared a transition metal sulfide thin film, differs from example 1 in that: the thickness of the transition metal platinum thin film to be prepared in step S1 was 5nm, and the other operations were the same as in example 1.

The sulfur content at different depths of the transition metal sulfide thin film prepared in this comparative example was measured from the surface toward the substrate direction by X-ray photoelectron spectroscopy (XPS), and the test results showed that: the sulfur content in the transition metal sulfide thin film is basically kept unchanged along with the increase of the extending depth of the surface towards the substrate direction, and the sulfur content in the transition metal sulfide thin film is not distributed in a gradient way.

And transferring the transition metal sulfide thin film of the comparative example onto a conductive substrate from a single polished silicon wafer substrate by adopting a polymethyl methacrylate auxiliary transfer method, and constructing a 5 multiplied by 5 memristor array on the transition metal sulfide thin film by using an electron beam evaporation and mask technology. The change of current with voltage was measured for the constructed memristor under 5 consecutive scan conditions, and the results are shown in fig. 10. As can be seen from the test results shown in fig. 10, the resistance of the constructed memristor is basically unchanged after 5 consecutive scans. From the above, in the above process for preparing the transition metal sulfide thin film, the transition metal precursor thin film needs to be thick enough, and the thickness thereof is generally controlled to be greater than or equal to 100nm, so that the effective control of the gradient distribution of the sulfur content in the transition metal sulfide thin film can be realized by regulating and controlling the process parameters including the thickness of the thin film, the temperature and time of the sulfidation reaction, and the volume flow ratio of the hydrogen gas introduced into the reaction process and the hydrogen sulfide.

From the above, the invention prepares the transition metal precursor film with the thickness of more than or equal to 100nm, then carries out the sulfuration reaction for 60-120 min under the condition of 700-850 ℃ and the action of the mixed gas of hydrogen and hydrogen sulfide with the volume flow ratio of (1-2): 1, wherein, the hydrogen can promote the decomposition of the hydrogen sulfide, the sulfuration reaction of the transition metal precursor film from the surface to the inside is realized, the transition metal sulfide is formed, the sulfur content in the prepared transition metal sulfide film is reduced along with the increase of the inward extension depth of the film surface, the sulfur content in the transition metal sulfide film is distributed in a gradient way along the direction vertical to the film surface, the effective control of the gradient distribution of the sulfur content in the film can be realized by controlling the technological parameters comprising the film thickness, the sulfuration reaction temperature, the time and the volume flow ratio of the hydrogen and the hydrogen sulfide introduced in the reaction process, the preparation and component control of the wafer-level transition metal sulfide film are realized, the process is simple and easy to operate, and the method has controllability, repeatability and process compatibility and is suitable for industrial production.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.

Claims

1. A method for preparing a transition metal sulfide thin film, comprising the steps of:

2. The method of claim 1, wherein in step S1, the transition metal precursor is deposited on the substrate by a deposition method to form a transition metal precursor film with a thickness greater than or equal to 100 nm.

3. The method for producing a transition metal sulfide thin film according to claim 2, wherein the deposition method is a physical vapor deposition method; preferably, the physical vapor deposition method is at least one selected from the group consisting of electron beam evaporation, thermal evaporation, atomic layer deposition, magnetron sputtering, spin coating, and imprinting.

4. The method for producing a transition metal sulfide thin film according to claim 2, wherein the transition metal precursor is at least one selected from molybdenum, platinum, niobium, ruthenium, palladium, tungsten, and tantalum.

5. The method for producing a transition metal sulfide thin film according to claim 2, wherein in step S1, the substrate is at least one selected from a silicon substrate, a sapphire substrate, a glass substrate, and a quartz substrate.

6. The method for producing a transition metal sulfide thin film according to any one of claims 1 to 5, wherein the step S2 specifically includes: placing the transition metal precursor film in a closed container, and introducing inert gas to remove air in the closed container; introducing hydrogen and inert gas serving as carrier gas into the closed container, and raising the temperature in the closed container to 700-850 ℃; and then, adding the mixture into the closed container according to the volume flow ratio of (1-2): 1, introducing hydrogen and hydrogen sulfide, and carrying out a vulcanization reaction on the transition metal precursor film for 60-120 min at the temperature of 700-850 ℃.

7. The method for producing a transition metal sulfide thin film according to claim 6, wherein the closed vessel is a vertical tube furnace, and a gas inflow port is provided at a lower end of the vertical tube furnace; the surface of the transition metal precursor film is arranged towards the direction of the gas inflow port; preferably, the flow direction of the carrier gas is perpendicular to the surface of the transition metal precursor thin film.

8. The method for producing a transition metal sulfide thin film according to claim 6, wherein in step S2, the temperature rise rate of the closed container in the temperature rise process is 10 to 40 ℃/min; preferably, after the temperature in the closed container is increased to 700-850 ℃, the temperature in the closed container is increased to the following value according to the volume flow ratio (1-2): 1, in the process of introducing hydrogen and hydrogen sulfide, the introduction rate of the hydrogen is 5-50 sccm, and the introduction rate of the hydrogen sulfide is 5-25 sccm.

9. A transition metal sulfide thin film produced by the method for producing a transition metal sulfide thin film according to any one of claims 1 to 8, wherein a sulfur content in the transition metal sulfide thin film is distributed in a gradient in a direction perpendicular to a surface of the transition metal sulfide thin film.

10. Use of the transition metal sulfide thin film of claim 9 in the preparation of a memristor.