Method for preparing atomic-scale multi-metal oxide film through laser ablation of liquid metal and atomic-scale multi-metal oxide film

Abstract

The invention provides a method for preparing an atomic-scale multi-metal oxide thin film through laser ablation of liquid metal and the atomic-scale multi-metal oxide thin film, and relates to the technical field of two-dimensional atomic-scale thin films. The method comprises the steps that liquid metal is smeared to a carrier, the carrier is placed in a container, and liquid sealing is conducted on the carrier through a metal precursor salt solution; performing laser ablation treatment on the liquid metal in the liquid seal to form a layer of metal oxide film on the surface of the liquid metal; and transferring the metal oxide film from the liquid metal surface layer to a substrate by using a Van der Waals transfer technology. According to the method, lattice matching of the substrate and the material does not need to be considered, the preparation steps of the two-dimensional multi-element metal oxide thin film are greatly simplified, and synthesis of the atomic-scale multi-element metal oxide thin film which is flat and uniform in morphology is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of two-dimensional atomic-level thin films, and in particular to a method for preparing an atomic-level multinary metal oxide thin film by laser ablation of liquid metal and an atomic-level multinary metal oxide thin film. Background Art

[0002] Liquid metal will form a natural oxide scale when exposed to air. The oxide scale has a weak interaction with the internal liquid metal. The separation of the oxide scale and liquid metal can be achieved through van der Waals exfoliation technology. Liquid metal has an electron-rich core, good fluidity, high surface tension, and can dissolve most metals, which can achieve the transfer of high-quality two-dimensional oxide films at the atomic level.

[0003] However, single-element liquid metal can only prepare monometallic metal oxide films, such as liquid Ga can only form Ga 2 O 3 However, liquid alloys are subject to thermodynamic constraints, and the surface oxides of liquid alloys will only form unit metal oxides with low Gibbs free energy (ΔGf), such as GaInSn liquid alloys, which can only prepare Ga 2 O 3 Therefore, this greatly limits the application of liquid metal in the synthesis of two-dimensional multinary metal oxides. Summary of the invention

[0004] In order to improve the current problem that liquid metal is difficult to synthesize two-dimensional multinary metal oxides, the present application provides a method for preparing an atomic-level multinary metal oxide film by laser ablation of liquid metal and an atomic-level multinary metal oxide film.

[0005] In a first aspect, the present application provides a method for preparing an atomic-level multi-element metal oxide film by laser ablation of liquid metal, which adopts the following technical solution: A method for preparing an atomic-level multi-element metal oxide film by laser ablation of liquid metal comprises the following steps: Step S1: applying liquid metal to a carrier, placing it in a container, and sealing it with a metal precursor salt solution; Step S2: performing laser ablation treatment on the liquid metal in the liquid seal so that a metal oxide film is formed on the surface of the liquid metal; Step S3: using van der Waals transfer technology to transfer the metal oxide film from the surface layer of the liquid metal to the substrate.

[0006] Optionally, the liquid metal includes a single metal or alloy containing gallium, bismuth, tin, germanium, indium, titanium, antimony, aluminum, cadmium, cerium, platinum, gold, palladium, iridium, ruthenium, rhodium, cesium, copper, chromium, iron, cobalt, nickel, zinc, manganese, vanadium, tantalum, tungsten, rhenium, osmium, hafnium, rubidium or strontium.

[0007] When the liquid metal is a liquid alloy, the atomic ratio of a single metal element in the liquid alloy will affect the tin content in the synthesized two-dimensional material.

[0008] Optionally, the metal element in the metal precursor salt solution is one or more of gallium, bismuth, tin, germanium, indium, titanium, antimony, aluminum, cadmium, cerium, platinum, gold, palladium, iridium, ruthenium, rhodium, cesium, copper, chromium, iron, cobalt, nickel, zinc, manganese, vanadium, tantalum, tungsten, rhenium, osmium, hafnium, rubidium or strontium.

[0009] Optionally, the metal precursor salt solution is selected from one of chloride, sulfate, phosphate and nitrate.

[0010] Optionally, the solvent in the metal precursor salt solution is selected from one or more of ethanol, n-hexane, methanol, water, acetone, and isopropanol.

[0011] The content of metal elements in the metal precursor salt solution will affect its diffusion degree in the liquid metal, and then affect the content of the metal element in the two-dimensional thin film material.

[0012] Since the pulse laser has energy output and energy stop output time in a single cycle, the local temperature of the liquid metal rises rapidly when the energy is output, which accelerates the diffusion of metal elements in the solution in the oxide layer and core of the liquid metal, and forms metastable multinary metal oxides on the surface; when the energy stops outputting, the sealed solution has a rapid cooling effect on the liquid metal, making the structure of the multinary metal oxide stable in a metastable state.

[0013] Optionally, the power density of the laser ablation process is 10 5 ~10 9 W / cm 2 , frequency is 1 Hz-80 kHz.

[0014] Optionally, the laser used in the laser ablation process is a nanosecond laser, a picosecond laser or a femtosecond laser.

[0015] Optionally, the laser ablation treatment lasts for 20-60 minutes.

[0016] Optionally, the laser ablation treatment lasts for 30 minutes.

[0017] The present application can further control the proportion of metal elements in the oxide film by controlling the time of laser ablation treatment. If the laser ablation treatment time is short, the diffusion amount of copper is small, and the proportion of copper elements in the formed two-dimensional oxide film is small; and as the laser ablation treatment time becomes longer, the proportion of copper elements in the two-dimensional oxide film will eventually stabilize and no longer change.

[0018] Optionally, the laser wavelength used in the laser ablation process covers ultraviolet, visible and near-infrared light.

[0019] Optionally, the carrier is selected from quartz, glass, sapphire, SiO 2 / Si wafer, TEM grid or any other one.

[0020] Optionally, the substrate is selected from quartz, glass, sapphire, SiO 2 / Si wafer, TEM grid or any other one.

[0021] Optionally, when the liquid metal is sealed in step S1, the same solvent as that in the metal precursor salt solution is used in advance for sealing, and then the metal precursor salt solution is added.

[0022] Optionally, the van der Waals transfer technique in step S3 is a direct touch lift-off method or a spin coating method.

[0023] The present application adopts the van der Waals transfer technology to transfer the multi-metal oxide film formed on the surface of the liquid metal. When touching, the van der Waals force between the substrate and the surface oxide of the liquid metal is greater than the van der Waals force between the surface oxide of the liquid metal and the liquid metal. The oxide on the surface of the liquid metal can be easily and completely transferred to the substrate. Therefore, the preparation method of the present application can realize large-scale production.

[0024] In a second aspect, the present application provides an atomic-level multinary metal oxide film, which is made by the method of preparing an atomic-level multinary metal oxide film by laser ablation of liquid metal.

[0025] In summary, the present application includes at least one of the following beneficial effects: 1. The present invention does not need to consider the lattice matching between the substrate and the material, greatly simplifies the preparation steps of the two-dimensional multinary metal oxide film, and realizes the synthesis of a smooth and uniform atomic-level multinary metal oxide film.

[0026] 2. This application uses laser ablation technology to achieve the preparation of large-area two-dimensional multi-metal oxides at room temperature and pressure. The operation is simple and inexpensive, and the reaction conditions are mild and pollution-free.

[0027] 3. The present application can achieve regulation of the ratio of metal elements by controlling the amount of liquid metal and the amount of metal precursor salt solution. For example, if the precursor solution contains copper ions, when the liquid gallium is laser ablated, copper will diffuse from the surface of the liquid metal to the inside, ultimately affecting the ratio of copper and gallium in the oxide film. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1It is a flow chart of the method for preparing atomic-level multinary metal oxide thin film by laser ablation of liquid metal provided in the present application; Figure 2 3. The two-dimensional (Cu, Ga) Ox film prepared in Example 1 of the present application and SEM images of the elements therein; wherein (a) is a SEM image of the two-dimensional (Cu, Ga) Ox film (scale bar: 30 µm), (b) is a distribution map of the Ga element on the two-dimensional (Cu, Ga) Ox film in (a) (scale bar: 30 µm), (c) is a distribution map of the O element on the two-dimensional (Cu, Ga) Ox film in (a) (scale bar: 30 µm), and (d) is a distribution map of the Cu element on the two-dimensional (Cu, Ga) Ox film in (a) (scale bar: 30 µm). DETAILED DESCRIPTION

[0029] The present application will be further described below in combination with the accompanying drawings and specific embodiments, but this should not be construed as limiting the scope of protection of the present application.

[0030] Example 1 Example 1 provides a method for preparing a synthetic two-dimensional (Cu, Ga)Ox film, see Figure 1 , the specific steps are as follows: (1) Ultrasonic cleaning of a 2 × 2 cm glass slide and a 1 × 1 cm SiO 2 / Si wafer 15 min.

[0031] (2) Take 50 µL of metallic Ga, heat it to 60°C and apply it on a glass slide. Place it in a beaker and seal it with 30 ml of anhydrous ethanol.

[0032] (3) Add 20 µL of 0.02 mol / L CuCl 2 The ethanol solution was added to the anhydrous ethanol in step (2), and the liquid metal Ga was ablated using a nanosecond pulse laser with a pulse width of 5 ns. The average laser power density was set to 2×10 5 W / cm 2 , the frequency is 20 kHz, the processing time is 30 min, and the laser wavelength belongs to the infrared band.

[0033] (4) Take out the glass slide coated with liquid gallium, heat it to 60°C, and evaporate the anhydrous ethanol to dryness. 2 / Si wafer touches liquid metal, transferring the oxide film on the surface of the liquid metal to SiO 2 / Si wafer, use a cotton swab to clean off most of the residual liquid metal on the oxide film in anhydrous ethanol at 80°C, and then use hot iodine ethanol solution to further remove the tiny liquid metal particles on the surface, ensuring that the structure of the oxide film is not destroyed while removing the residual liquid metal, ensuring that the oxide film is clean and smooth, and obtaining a two-dimensional (Cu,Ga)Ox film.

[0034] Figure 2 2 is a SEM image of the two-dimensional (Cu, Ga)Ox film prepared in Example 1 of the present application and the elements therein. Figure 2 It can be seen that the oxide film prepared in Example 1 is uniformly distributed with Cu, Ga, and O elements, indicating that the preparation method of Example 1 can prepare a multi-metal oxide film containing Cu and Ga.

[0035] Example 2 Example 2 provides a method for preparing a synthetic two-dimensional (Cu, Ga, In, Sn)Ox thin film, the specific steps are as follows: (1) Ultrasonic cleaning of a 2 × 2 cm glass sheet and a 1 × 1 cm SiO2 / Si sheet was performed using acetone, anhydrous ethanol, and deionized water, respectively, for 15 min.

[0036] (2) Apply 50 µL of liquid gallium-indium-tin alloy onto a glass slide, place it in a beaker, and seal it with 30 ml of anhydrous ethanol.

[0037] (3) Add 20 µL of 0.02 mol / L CuCl 2 The ethanol solution was added to the anhydrous ethanol in step (2), and the liquid gallium indium tin alloy was ablated using a nanosecond pulse laser with a pulse width of 5 ns. The average laser power density was set to 2×10 5 W / cm 2 , the frequency is 20 kHz, the processing time is 30 min, and the laser wavelength belongs to the infrared band.

[0038] (4) Take out the glass sheet coated with liquid gallium-indium-tin alloy, heat it to 60°C, and after the anhydrous ethanol is evaporated, use the SiO 2 / Si wafer touches liquid alloy, and most of the residual liquid metal on the oxide film is cleaned off with a cotton swab in anhydrous ethanol at 80 ℃, and then hot iodine ethanol solution is used to further remove tiny liquid metal particles on the surface, ensuring that the structure of the oxide film is not destroyed while removing the residual liquid metal, ensuring that the oxide film is clean and flat, and obtaining a two-dimensional (Cu,Ga,In,Sn)Ox film.

[0039] Example 3 Example 3 provides a method for preparing a synthetic two-dimensional (Cu, Sn, Ni, Pt, Ga)Ox thin film, the specific steps are as follows: (1) Ultrasonic cleaning of a 2 × 2 cm glass slide and a 1 × 1 cm SiO 2 / Si wafer 15 min.

[0040] (2) Take 50 µL of metallic gallium, heat it to 60 °C and apply it to a glass slide. Place it in a beaker and seal it with 30 ml of anhydrous ethanol.

[0041] (3) 20 μL of 0.02 mol / L copper chloride, tin chloride, nickel chloride, and chloroplatinic acid solutions were added to the anhydrous ethanol in step (2) respectively, and the liquid metal gallium was ablated using a nanosecond pulse laser with a pulse width of 5 ns. The average laser power density was set to 2×10 5 W / cm 2 , the frequency is 20 kHz, the processing time is 30 min, and the laser wavelength belongs to the infrared band.

[0042] (4) Take out the glass slide coated with liquid gallium, heat it to 60°C, and evaporate the anhydrous ethanol to dryness. 2 / Si wafer touches liquid metal, and most of the residual liquid metal on the oxide film is cleaned off with a cotton swab in anhydrous ethanol at 80°C, and then hot iodine ethanol solution is used to further remove tiny liquid metal particles on the surface, ensuring that the structure of the oxide film is not destroyed while removing the residual liquid metal, ensuring that the oxide film is clean and flat, and obtaining a two-dimensional (Cu, Sn, Ni, Pt, Ga)Ox film.

[0043] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing atomic-level multi-element metal oxide thin films by laser ablation of liquid metal, characterized in that: The following steps are involved: Step S1: applying liquid metal to a carrier, placing it in a container, and sealing it with a metal precursor salt solution; Step S2: performing laser ablation treatment on the liquid metal in the liquid seal so that a metal oxide film is formed on the surface of the liquid metal; Step S3: using van der Waals transfer technology to transfer the metal oxide film from the surface layer of the liquid metal to the substrate.

2. The method for preparing atomic-level multi-element metal oxide thin film by laser ablation of liquid metal according to claim 1, characterized in that: The liquid metal includes a single metal or alloy containing gallium, bismuth, tin, germanium, indium, titanium, antimony, aluminum, cadmium, cerium, platinum, gold, palladium, iridium, ruthenium, rhodium, cesium, copper, chromium, iron, cobalt, nickel, zinc, manganese, vanadium, tantalum, tungsten, rhenium, osmium, hafnium, rubidium or strontium.

3. The method for preparing atomic-level multi-element metal oxide thin film by laser ablation of liquid metal according to claim 1, characterized in that: The metal element in the metal precursor salt solution is one or more of gallium, bismuth, tin, germanium, indium, titanium, antimony, aluminum, cadmium, cerium, platinum, gold, palladium, iridium, ruthenium, rhodium, cesium, copper, chromium, iron, cobalt, nickel, zinc, manganese, vanadium, tantalum, tungsten, rhenium, osmium, hafnium, rubidium or strontium.

4. The method for preparing atomic-level multi-element metal oxide thin film by laser ablation of liquid metal according to claim 1, characterized in that: The metal precursor salt solution is selected from one of chloride, sulfate, phosphate and nitrate.

5. The method for preparing atomic-level multi-element metal oxide thin film by laser ablation of liquid metal according to claim 1, characterized in that: The solvent in the metal precursor salt solution is selected from one or more of anhydrous ethanol, n-hexane, methanol, water, acetone, and isopropanol.

6. The method for preparing atomic-level multi-element metal oxide thin film by laser ablation of liquid metal according to claim 1, characterized in that: The power density of the laser ablation process is 10 5 ~10 9 W / cm 2 , frequency is 1 Hz-80 kHz.

7. The method for preparing atomic-level multi-element metal oxide thin film by laser ablation of liquid metal according to claim 1, characterized in that: The substrate is selected from any one of a quartz plate, a glass plate, a sapphire, a SiO2 / Si plate, and a TEM grid.

8. The method for preparing atomic-level multi-element metal oxide thin film by laser ablation of liquid metal according to claim 1, characterized in that: When the liquid metal is sealed in the step S1, the same solvent as that in the metal precursor salt solution is used in advance for sealing, and then the metal precursor salt solution is added.

9. The method for preparing atomic-level multi-element metal oxide thin film by laser ablation of liquid metal according to claim 1, characterized in that: The van der Waals transfer technique in step S3 is a direct touch lift-off method or a spin coating method.

10. An atomic-level multinary metal oxide film, characterized in that: The film is prepared by the method for preparing an atomic-level multi-element metal oxide film by laser ablating liquid metal as described in any one of claims 1 to 9.

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