A two-dimensional layered-non-layered van der waals heterostructure, a preparation method and application thereof

Abstract

The application relates to the technical field of inorganic semiconductors, in particular to a two-dimensional layered-non-layered van der Waals heterostructure and a preparation method and application thereof. The preparation method of the two-dimensional layered-non-layered van der Waals heterostructure provided by the application comprises the following steps: a layered molybdenum disulfide nanosheet is prepared on a substrate by using a mechanical stripping method or a gas phase deposition method; a non-layered lead selenide nanosheet is prepared on a mica substrate by using a gas phase deposition method; polymethyl methacrylate is suspended and coated on the mica substrate and heated to form a polymethyl methacrylate supporting film; the mica substrate is removed, and the lead selenide nanosheet is adhered to the polymethyl methacrylate supporting film; the lead selenide nanosheet is placed on the molybdenum disulfide nanosheet, and the polymethyl methacrylate supporting film is dissolved by using an organic solvent, so that the two-dimensional layered-non-layered van der Waals heterostructure is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inorganic semiconductor, in particular to a two-dimensional layered-non-layered van der Waals heterostructure and a preparation method and application thereof. BACKGROUND

[0002] Two-dimensional materials have an atomic-level ultra-thin thickness and are highly compatible with silicon-based technology, so they have attracted more and more attention from researchers. Heterostructures assembled from two-dimensional materials, i.e. van der Waals heterostructures, have gradually emerged and provide a new platform to realize functions that cannot be realized by a single material, such as tunnel transistors, light-emitting diodes and solar cells. The current two-dimensional van der Waals heterostructure is mainly based on the combination of two-dimensional layered materials. Compared with two-dimensional layered materials, two-dimensional non-layered materials have a more abundant material system and more outstanding physical properties in some aspects, and have a strong complementarity with layered materials. For example, III-V semiconductors have a direct bandgap structure and a higher carrier mobility than silicon, and metal chalcogenides have outstanding optoelectronic and photovoltaic properties. If these non-layered materials can be two-dimensionalized and combined with two-dimensional layered materials to form a two-dimensional layered material-two-dimensional non-layered material van der Waals heterostructure, the problem of multi-physical mismatch limitation in the integration of two-dimensional layered materials and non-layered materials can be solved, and their unique functions can be organically combined together. By means of band engineering and interface engineering, the performance of the heterostructure can be precisely regulated, and novel electronic and optoelectronic properties can be realized. SUMMARY

[0003] The embodiment of the present application provides a two-dimensional layered-non-layered van der Waals heterostructure and a preparation method. The two-dimensional layered-non-layered van der Waals heterostructure provided by the present application combines layered materials and non-layered materials, and can realize the complementary advantages of material properties.

[0004] In a first aspect, the present application provides a preparation method of a two-dimensional layered-non-layered van der Waals heterostructure, comprising the following steps:

[0005] Prepared layered molybdenum disulfide nanosheets on a substrate by a mechanical exfoliation method or a vapor deposition method;

[0006] Prepared non-layered lead selenide nanosheets on a mica substrate by a vapor deposition method;

[0007] Formed a polymethyl methacrylate support film by suspending polymethyl methacrylate on the mica substrate and heating;

[0008] Removed the mica substrate, and the lead selenide nanosheets adhered to the polymethyl methacrylate support film;

[0009] The lead selenide nanosheet is placed on the molybdenum disulfide nanosheet, and the poly(methyl methacrylate) supporting film is dissolved by using an organic solvent, so as to obtain a two-dimensional layered-non-layered van der Waals heterostructure.

[0010] In some embodiments, the substrate is a Si / SiO2 substrate.

[0011] In some embodiments, the thickness of SiO2 in the Si / SiO2 substrate is 100-300 nm.

[0012] In some embodiments, the thickness of the layered molybdenum disulfide nanosheet is 0.7-10 nm, and the lateral size of the layered molybdenum disulfide nanosheet is 5-20 μm. In some preferred embodiments, the thickness of the layered molybdenum disulfide nanosheet is 3-8 nm.

[0013] In some embodiments, the thickness of the non-layered lead selenide nanosheet is 5-100 nm, and the lateral size of the non-layered lead selenide nanosheet is 20-50 μm. In some preferred embodiments, the thickness of the non-layered lead selenide nanosheet is 30-50 nm.

[0014] In some embodiments, the heating mode is baking at 120°C.

[0015] In some embodiments, the organic solvent is acetone or chloroform.

[0016] In a second aspect, the application further provides a two-dimensional layered-non-layered van der Waals heterostructure prepared by using the above preparation method.

[0017] In some embodiments, the lead selenide nanosheet and the molybdenum disulfide nanosheet partially overlap.

[0018] In a third aspect, the application further provides an application of the two-dimensional layered-non-layered van der Waals heterostructure, and the two-dimensional layered-non-layered van der Waals heterostructure is used for preparing a transistor, a rectifier, and a photodetector.

[0019] The technical scheme provided by the application has the beneficial effects including: the layered molybdenum disulfide nanosheet and the non-layered lead selenide nanosheet are artificially stacked by using the positioning transfer technology, the two-dimensional layered material and the two-dimensional non-layered material are combined to prepare the van der Waals heterostructure, the problem of multi-physical mismatch limitation in the integration of the two-dimensional layered material and the two-dimensional non-layered material is solved, the advantages of the material characteristics are complementary, and the super-high current on-off ratio (~10 8 ), the current rectification ratio (~10 6 ), and the excellent photoelectric performance can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative effort based on these drawings.

[0021] Figure 1 A schematic diagram of the two-dimensional layered-non-layered van der Waals heterostructure provided by the embodiments of the present application;

[0022] Figure 2 A flowchart of the preparation method of the two-dimensional layered-non-layered van der Waals heterostructure provided by the embodiments of the present application;

[0023] Figure 3 An optical microscope picture of the two-dimensional layered-non-layered van der Waals heterostructure device obtained in Embodiment 1;

[0024] Figure 4 The current-gate voltage transfer curve of the two-dimensional layered-non-layered van der Waals heterostructure device obtained in Embodiment 1 when the device works as a transistor under different bias conditions;

[0025] Figure 5 The current-bias output curve of the two-dimensional layered-non-layered van der Waals heterostructure device obtained in Embodiment 1 when the device works as a rectifier under different gate voltage conditions;

[0026] Figure 6 The device properties of the two-dimensional layered-non-layered van der Waals heterostructure device obtained in Embodiment 1 when the device works as a photodetector under 473 nm incident laser;

[0027] Figure 7 The photo-on photo change diagram of the two-dimensional layered-non-layered van der Waals heterostructure device obtained in Embodiment 1 under 473 nm incident laser and different gate voltage conditions;

[0028] Figure 8 The current-gate voltage transfer curve of the two-dimensional layered-non-layered van der Waals heterostructure device obtained in Embodiment 2 when the device works as a transistor under different bias conditions;

[0029] Figure 9 The current-bias output curve of the two-dimensional layered-non-layered van der Waals heterostructure device obtained in Embodiment 2 when the device works as a rectifier under different gate voltage conditions. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] This application provides a two-dimensional layered-non-layered van der Waals heterostructure, which combines layered and non-layered materials to achieve complementary advantages in material properties.

[0032] Figure 1 This is a schematic diagram of a two-dimensional layered-non-layered van der Waals heterostructure provided in an embodiment of this application, with reference to... Figure 1 The two-dimensional layered-non-layered van der Waals heterostructure provided in this application includes layered molybdenum disulfide nanosheets and non-layered lead selenide nanosheets arranged sequentially from bottom to top on a Si / SiO2 substrate. The layered molybdenum disulfide nanosheets are N-type semiconductors, and the non-layered lead selenide nanosheets are P-type semiconductors. The layered molybdenum disulfide nanosheets and non-layered lead selenide nanosheets have both overlapping and non-overlapping regions.

[0033] The thickness of SiO2 in the Si / SiO2 substrate is 100-300 nm, the thickness of layered molybdenum disulfide nanosheets is 0.7-10 nm, and the thickness of non-layered lead selenide nanosheets is 5-100 nm.

[0034] refer to Figure 2 This application also provides a method for preparing a two-dimensional layered-non-layered van der Waals heterostructure, comprising the following steps:

[0035] Step S101: Layered molybdenum disulfide nanosheets are prepared on a Si / SiO2 substrate by mechanical exfoliation or vapor deposition, and the thickness of SiO2 is selected by optical microscopy, with the thickness being 100-300 nanometers.

[0036] Step S102: Non-layered lead selenide nanosheets are prepared on a mica substrate by vapor deposition and selected by optical microscopy.

[0037] Step S103: Polymethyl methacrylate is suspended on a mica substrate with lead selenide nanosheets on its surface and baked at 120°C for 10 minutes with a heating plate to form a polymethyl methacrylate support film.

[0038] In step S104, the polymethyl methacrylate support film is separated from the mica substrate in deionized water, the mica substrate is removed, and lead selenide nanosheets adhere to the polymethyl methacrylate support film.

[0039] Step S105, under the assistance of an optical microscope, manually place the lead selenide nanosheet on the molybdenum disulfide nanosheet, and dissolve the polymethyl methacrylate support film by using an organic solvent, i.e., acetone or chloroform, to obtain a two-dimensional layered-non-layered van der Waals heterostructure.

[0040] The two-dimensional layered-non-layered van der Waals heterostructure can be connected with two metal electrodes to prepare a heterostructure device, referring to Figure 1 One of the metal electrodes is placed on the layered molybdenum disulfide nanosheet as a drain electrode, and the other metal electrode is placed on the non-layered lead selenide nanosheet as a source electrode. The metal electrodes are prepared by standard electron beam exposure or photolithography and metal deposition methods. The metal electrodes are made of one or more of gold, silver, copper, chromium, palladium, platinum, iridium, and nickel. In some preferred embodiments, the deposition sequence of the metal electrodes is chromium and gold. The thickness of the chromium layer is 5-15 nm, and the thickness of the gold layer is 40-80 nm.

[0041] The heterostructure device can be used to prepare a transistor, a rectifier, and a photodetector.

[0042] The two-dimensional layered-non-layered van der Waals heterostructure and the preparation method thereof provided by the present application will be described in detail below in conjunction with examples.

[0043] Example 1

[0044] The present application provides a preparation method of a two-dimensional layered-non-layered van der Waals heterostructure, which comprises the following steps:

[0045] Step S101, mechanically peel off a bulk molybdenum disulfide material by using a tape to prepare a two-dimensional layered molybdenum disulfide nanosheet on a Si / SiO2 substrate, wherein the thickness of SiO2 is 300 nm. The thickness of the molybdenum disulfide nanosheet is 6.2 nm, which is selected by an optical microscope and an atomic force microscope.

[0046] Step S102, synthesize a two-dimensional non-layered lead selenide nanosheet on a mica substrate by using a chemical vapor deposition method, and select the thickness of the lead selenide nanosheet by an optical microscope and an atomic force microscope, which is 43 nm.

[0047] Step S103, suspend polymethyl methacrylate on the mica substrate with the lead selenide nanosheet on the surface, and bake the polymethyl methacrylate at 120°C for 10 minutes by using a heating plate to form a polymethyl methacrylate support film.

[0048] Step S104, separate the polymethyl methacrylate support film from the mica substrate in deionized water, remove the mica substrate, and adhere the lead selenide nanosheet to the polymethyl methacrylate support film.

[0049] Step S105, under the assistance of optical microscope, the lead selenide nanosheet is manually placed on the molybdenum disulfide nanosheet, and after the transfer, the polymethyl methacrylate support film is dissolved with acetone, i.e. a two-dimensional layered-non-layered van der Waals heterostructure is prepared on the Si / SiO2 substrate.

[0050] The obtained two-dimensional layered-non-layered van der Waals heterostructure is connected with two metal electrodes to form a van der Waals heterostructure device, one of the metal electrodes is placed on the layered molybdenum disulfide nanosheet as a drain electrode, and the other metal electrode is placed on the non-layered lead selenide nanosheet as a source electrode. The metal electrodes are prepared by a standard electron beam exposure process and a metal plating process, and the metal deposition sequence of the metal electrodes is chromium and gold, the thickness of the chromium layer is 10 nm, and the thickness of the gold layer is 50 nm.

[0051] In Example 1, the specific process of synthesizing the two-dimensional non-layered lead selenide nanosheet on the mica substrate by the chemical vapor deposition method is as follows: the selenium powder and the lead selenide powder are respectively placed in the center of the front temperature zone and the rear temperature zone of the double-temperature-zone tube furnace, and the mica substrate is placed directly above the lead selenide powder as the growth substrate of the material; the hydrogen-argon mixed gas is continuously introduced into the double-temperature-zone tube furnace as the carrier gas, the selenium vapor and the lead selenide vapor react and grow on the mica substrate, and after growing for 10 minutes, the natural cooling to room temperature is performed, i.e. the two-dimensional non-layered lead selenide nanosheet is obtained on the surface of the mica.

[0052] Figure 3 The optical microscope picture of the two-dimensional layered-non-layered van der Waals heterostructure device obtained in Example 1.

[0053] Figure 4 The current-gate voltage transfer curve of the two-dimensional layered-non-layered van der Waals heterostructure device obtained in Example 1 when the device works as a transistor under different bias conditions, as shown in FIGS. 4a and 4b. Figure 4 As can be seen from FIGS. 4a and 4b, the device exhibits an ultra-high current on-off ratio, and the maximum current on-off ratio can be up to ~ 10 8 . The current on-off ratio of the transistor is defined as the ratio of the on-state current to the off-state current.

[0054] Figure 5 The current-bias output curve of the two-dimensional layered-non-layered van der Waals heterostructure device obtained in Example 1 when the device works as a rectifier under different gate voltage conditions. As can be seen from FIGS. 5a and 5b, Figure 5 the device exhibits obvious rectification effect, and the maximum current rectification ratio can be up to ~ 10 6 . The current rectification ratio of the rectifier is defined as the ratio of the current under the reverse bias (set to -3 volts in Example 1) to the current under the forward bias (set to 3 volts in Example 1).

[0055] Figure 6Device properties of the two-dimensional layered-non-layered van der Waals heterostructure obtained in Example 1 when working as a photodetector under 473 nm incident laser light. Wherein, Figure 6 a is the relationship between the device current and the gate voltage under different laser powers, Figure 6 b is the relationship between the device responsivity and the gate voltage under different laser powers. From Figure 6 It can be seen that the maximum device responsivity can reach ~ 10 3 Ampere per watt, showing excellent photoelectric performance.

[0056] Figure 7 The optical on-off light change diagram of the two-dimensional layered-non-layered van der Waals heterostructure obtained in Example 1 under 473 nm incident laser light and different gate voltages. From Figure 7 It can be seen that the device has obvious switching current and does not decay with time, and has good stability.

[0057] Example 2:

[0058] The embodiment 2 of the present application provides a preparation method of a two-dimensional layered-non-layered van der Waals heterostructure, comprising the following steps:

[0059] Step S101, using a chemical vapor deposition method to synthesize molybdenum disulfide nanosheets directly on a Si / SiO2 substrate, the thickness of SiO2 is 300 nm, and the thickness of the molybdenum disulfide nanosheet is 0.7 nm selected by an optical microscope and an atomic force microscope;

[0060] Step S102, using a chemical vapor deposition method to synthesize two-dimensional non-layered lead selenide nanosheets on a mica substrate, and selecting the thickness of 43.7 nm by an optical microscope and an atomic force microscope;

[0061] Step S103, suspending poly methyl methacrylate on the mica substrate with lead selenide nanosheets, and baking at 100℃ for 20 minutes with a heating plate to form a poly methyl methacrylate support film;

[0062] Step S104, separating the poly methyl methacrylate support film from the mica substrate in deionized water, removing the mica substrate, and adhering the lead selenide nanosheet to the poly methyl methacrylate (PMMA) support film;

[0063] Step S105, placing the lead selenide nanosheet on the molybdenum disulfide nanosheet manually under the assistance of an optical microscope, and dissolving the poly methyl methacrylate (PMMA) support film with acetone after transfer, that is, a two-dimensional layered-non-layered van der Waals heterostructure is prepared on the Si / SiO2 substrate.

[0064] The obtained two-dimensional layered-non-layered van der Waals heterostructure is connected with two metal electrodes to form a van der Waals heterojunction device, in which one metal electrode is placed on the layered molybdenum disulfide nanosheet as a drain electrode, and the other metal electrode is placed on the non-layered lead selenide nanosheet as a source electrode. Among them, the metal electrode is prepared by a photoetching process and a metal plating process, and the metal deposition sequence of the metal electrode is chromium, gold, the thickness of the chromium layer is 6 nm, and the thickness of the gold layer is 60 nm.

[0065] The process of synthesizing two-dimensional non-layered lead selenide nanosheets in Example 2 is the same as that in Example 1.

[0066] Figure 8 For the two-dimensional layered-non-layered van der Waals heterostructure device obtained in Example 2 to work as a transistor, the current-gate voltage transfer curve of the device under different bias conditions. From Figure 8 It can be seen that the device exhibits an ultra-high current on-off ratio, and the maximum current on-off ratio can be up to ~ 10 5 . Among them, the current on-off ratio of the transistor is defined as the ratio of the on-state current to the off-state current.

[0067] Figure 9 For the two-dimensional layered-non-layered van der Waals heterostructure device obtained in Example 2 to work as a rectifier, the current-voltage output curve of the device under different gate voltage conditions. From Figure 9 It can be seen that the device exhibits obvious rectification effect, and the maximum current rectification ratio can be up to ~ 10 3 . Among them, the current rectification ratio of the rectifier is defined as the ratio of the current under reverse bias (set to -2 volts in Example 2) to the current under forward bias (set to 2 volts in Example 2).

[0068] In the description of the present specification, the description of the terms "one embodiment / way", "some embodiments / ways", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / way or example are included in at least one embodiment / way or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment / way or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments / ways or examples. In addition, the skilled in the art can combine and combine the different embodiments / ways or examples described in the present specification and the features of the different embodiments / ways or examples without contradiction.

[0069] It has to be noted that, in the present application, terms like "first", "second", and the like in the description and in the claims are used to distinguish between similar elements and not necessarily to describe a sequential or chronological order. Furthermore, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element. The term "plurality" denotes two or more, for example two, three or four unless expressly specified otherwise.

[0070] The foregoing is considered as illustrative only of the principles of the application. Numerous modifications and changes will readily occur to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Accordingly, the scope of the application is indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.

Claims

1. A method for preparing a two-dimensional layered-non-layered van der Waals heterostructure, characterized in that, Includes the following steps: Layered molybdenum disulfide nanosheets with a thickness of 0.7-10 nm were prepared on a substrate by mechanical exfoliation or vapor deposition. Non-layered lead selenide nanosheets with a thickness of 5-100 nm were prepared on a mica substrate by vapor deposition. Polymethyl methacrylate (PMMA) is suspended and coated on the mica substrate and heated to form a PMMA support film. When the mica substrate is removed, the lead selenide nanosheets adhere to the polymethyl methacrylate support film. Lead selenide nanosheets are placed on molybdenum disulfide nanosheets, and polymethyl methacrylate supporting films are dissolved using organic solvents to obtain two-dimensional layered-non-layered van der Waals heterostructures. The organic solvent is acetone or chloroform.

2. The method for preparing a two-dimensional layered-non-layered van der Waals heterostructure according to claim 1, characterized in that, The substrate is a Si / SiO2 substrate.

3. The method for preparing a two-dimensional layered-non-layered van der Waals heterostructure according to claim 2, characterized in that, The thickness of SiO2 in the Si / SiO2 substrate is 100-300 nm.

4. The method for preparing a two-dimensional layered-non-layered van der Waals heterostructure according to claim 1, characterized in that, The heating method is baking at 120 ℃.

5. A two-dimensional layered-non-layered van der Waals heterostructure, characterized in that, It is prepared by the preparation method according to any one of claims 1-4.

6. The two-dimensional layered-non-layered van der Waals heterostructure according to claim 5, characterized in that, The lead selenide nanosheets and molybdenum disulfide nanosheets partially overlap.

7. The application of the two-dimensional layered-non-layered van der Waals heterostructure according to claim 5, characterized in that, The two-dimensional layered-non-layered van der Waals heterostructure is used to fabricate transistors, rectifiers, and photodetectors.

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