Metal oxide thin films, methods of making and using the same

Abstract

The present disclosure provides a method for preparing a metal oxide film, which comprises the following steps: placing a molten metal on a first substrate, forming a corresponding metal oxide layer on the surface of the molten metal; contacting the metal oxide layer with a second substrate, so that the metal oxide layer is attached to the second substrate; and separating the metal oxide layer from the surface of the molten metal by virtue of the difference between the force of action between the metal oxide layer and the second substrate and the force of action between the metal oxide layer and the molten metal. The preparation method has fewer overall preparation process procedures and does not have to rely on complex and precise large-scale equipment to achieve, and therefore also has the advantage of low cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin film materials, in particular to a two-dimensional metal oxide, a preparation method and application thereof. BACKGROUND

[0002] Transparent conductive oxide is a kind of semiconductor material with a wide gap, which not only has high transparency in the visible light range, but also has high conductivity, and is widely used as a transparent electrode in the fields of display devices and optoelectronic devices.

[0003] The transparent conductive oxide is mostly a metal oxide, among which indium tin oxide (ITO) is the most widely used, which has high light transmittance and low resistivity, which is beneficial to light transmission and carrier injection. However, indium tin oxide is mostly polycrystalline structure, which makes its micro-surface uniformity poor. Macroscopically, indium tin oxide not only has the problem of poor ductility, but also is easy to peel off, which makes it difficult to be applied in flexible devices. In contrast, amorphous metal oxide semiconductor can obtain a material with good uniformity and has many advantages such as ductility and flexibility. At present, the method for preparing metal oxide thin film is mostly deposition method, such as magnetron sputtering deposition or atomic layer deposition. This preparation method not only depends on complex and precise film coating equipment, but also needs to prepare target material meeting specific shape and performance in advance, and the preparation method is relatively complex and the preparation cost is relatively high. SUMMARY

[0004] Therefore, it is necessary to provide a preparation method of metal oxide thin film with simpler preparation process and lower cost.

[0005] According to some embodiments of the present disclosure, a preparation method of metal oxide thin film comprises the following steps:

[0006] Placing the molten metal on the first substrate, so that the surface of the molten metal forms a corresponding metal oxide layer;

[0007] Contacting the metal oxide layer with the second substrate, so that the metal oxide layer is attached to the second substrate, and using the difference between the action force between the metal oxide layer and the second substrate and the action force between the metal oxide layer and the molten metal to separate the metal oxide layer from the surface of the molten metal.

[0008] In some embodiments of the present disclosure, the step of separating the metal oxide layer from the surface of the molten metal comprises: moving the molten metal along a direction parallel to the surface of the second substrate by the first substrate, so that the molten metal and the metal oxide layer on the surface thereof are gradually separated, and the metal oxide layer is attached to the second substrate.

[0009] In some embodiments of the present disclosure, during the process of gradually separating the molten metal from the metal oxide layer on the surface thereof, the molten metal is continuously exposed to a gaseous environment containing oxidizing gas, so that the surface of the molten metal continuously forms the metal oxide layer.

[0010] In some embodiments of the present disclosure, after separating the metal oxide layer from the surface of the molten metal, the method further comprises: immersing the metal oxide layer in a boiling solvent, and then removing residual metal on the surface of the metal oxide layer.

[0011] In some embodiments of the present disclosure, the step of forming the corresponding metal oxide layer on the surface of the molten metal comprises: placing the molten metal in a gaseous environment containing oxidizing gas, so that the surface of the molten metal is oxidized and forms the metal oxide layer.

[0012] In some embodiments of the present disclosure, the step of placing the molten metal on the first substrate comprises: heating the metal to complete melting, and then transferring the molten metal material to the surface of the first substrate.

[0013] In some embodiments of the present disclosure, the thickness of the metal oxide layer is less than 9 nm.

[0014] In some embodiments of the present disclosure, the molten metal comprises indium, zinc and tin, and the material of the metal oxide layer comprises indium zinc tin oxide.

[0015] According to still another embodiment of the present disclosure, a metal oxide thin film is prepared by the method for preparing a metal oxide thin film according to any one of the above embodiments.

[0016] According to still another embodiment of the present disclosure, the metal oxide thin film according to the above embodiments is applied in the preparation of a transparent electrode, the preparation of a thin film transistor or the preparation of a photodetector.

[0017] In the method for preparing a metal oxide thin film of the present disclosure, a molten metal is first placed on a first substrate, and a corresponding metal oxide layer is formed on the surface of the molten metal. Then, a second substrate is used to contact the metal oxide layer, and the metal oxide layer is attached to the second substrate by virtue of the property that the interaction force between the metal oxide layer and the second substrate is stronger than the interaction force between the metal oxide layer and the molten metal, so as to separate the metal oxide layer from the surface of the molten metal. The present disclosure provides a method for preparing a metal oxide film layer which is different from the deposition method, and broadens the preparation approach of the metal oxide film layer. In the preparation method, the metal oxide layer is formed on the surface of the molten metal, and then the metal oxide layer is attached to the second substrate for separation. The overall preparation process has fewer procedures, and does not require complex and precise large-scale equipment, and therefore has the advantage of low cost.

[0018] In addition, due to the nature of the preparation process and the material itself, the deposition method cannot obtain a film layer with a thinner thickness when preparing certain metal oxides. In the preparation method of the metal oxide thin film provided by the present disclosure, the oxidation process of the surface of the molten metal is self-limiting, and the metal oxide layer formed in advance will limit the further oxidation of the molten metal inside, so that the preparation of a thinner metal oxide thin film can also be realized. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A schematic diagram of a preparation step of a metal oxide thin film;

[0020] Figure 2 A schematic diagram of the preparation process of step S1 in Figure 1

[0021] Figure 3 A schematic diagram of the preparation process of step S2 in Figure 1

[0022] Figure 4 A schematic diagram of the second substrate contacting the metal oxide layer in step S3 of Figure 1

[0023] Figure 5 A schematic diagram of the first substrate driving the molten metal to move along the surface of the second substrate in step S3 of Figure 1

[0024] Figure 6 A schematic diagram of the metal oxide layer adhering to the second substrate in step S3 of Figure 1

[0025] A schematic diagram of the element distribution of the indium zinc tin oxide thin film of Example 1; Figure 7

[0026] A test diagram of the atomic force microscope of the indium zinc tin oxide thin film of Example 1; Figure 8

[0027] A current-voltage relationship curve of the indium zinc tin oxide thin film of Example 1 before and after bending under lightless conditions and 255 nm wavelength light conditions; Figure 9 In the drawings, reference signs and their meanings are as follows:

[0028] 100, molten metal; 110, metal oxide layer; 200, first substrate; 300, second substrate.

[0029] DETAILED DESCRIPTION

[0030] ​​​​​For the purpose of promoting an understanding of the principles of the application, reference will now be made to the embodiments illustrated in the drawings. There is shown in the drawings, several embodiments of the application. It is understood that the application is not limited to the embodiments shown in the drawings. In fact, it is understood that the application is capable of assuming many different forms. Rather, the embodiments are provided for the purpose of illustration only.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. As used herein, "plurality" includes two and more than two. As used herein, "greater than or equal to" should be understood to include the number and the range greater than the number.

[0032] The present disclosure provides a method for preparing a metal oxide thin film, comprising the steps of: placing a metal material on a first substrate, controlling the temperature of the first substrate to keep the metal material as a molten metal; forming a corresponding metal oxide layer on the surface of the molten metal; contacting the metal oxide layer with a second substrate to make the metal oxide layer adhere to the second substrate, and separating the metal oxide layer from the surface of the molten metal by the difference between the force between the metal oxide layer and the second substrate and the force between the metal oxide layer and the molten metal.

[0033] In the method for preparing a metal oxide thin film of the present disclosure, the molten metal is first placed on a first substrate, and a corresponding metal oxide layer is formed on the surface of the molten metal. Then, the metal oxide layer is contacted with a second substrate to make the metal oxide layer adhere to the second substrate, and the metal oxide layer is separated from the surface of the molten metal by the property that the force between the metal oxide layer and the second substrate is stronger than the force between the metal oxide layer and the molten metal. The present disclosure provides a method for preparing a metal oxide film layer that is different from the deposition method, and broadens the preparation approach of the metal oxide film layer. In the preparation method, the metal oxide layer is formed on the surface of the molten metal, and then the metal oxide layer is adhered to the second substrate for separation. The overall preparation process has fewer procedures, and does not require complex and precise large-scale equipment, and therefore also has the advantage of low cost.

[0034] In addition, the traditional sputtering or atomic layer deposition coating method cannot obtain a film layer with a relatively thin thickness when preparing some metal oxides. In the method for preparing a metal oxide thin film of the present disclosure, the oxidation process on the surface of the molten metal has self-limiting property, and the metal oxide layer formed first will block the molten metal inside from being further oxidized, so that the preparation of a thinner metal oxide thin film can also be realized.

[0035] For the purpose of facilitating the understanding of the metal oxide thin film preparation method provided by the present disclosure, reference is made to Figure 1 Fig. 1 shows an embodiment of a metal oxide thin film preparation method, including steps S1-S4.

[0036] Reference is made to Figure 2 In step S1, a molten metal 100 is placed on a first substrate 200.

[0037] It can be understood that the metal material can be in a solid or liquid state at room temperature. If the metal material is in a liquid state at room temperature, it is itself the molten metal 100. If the metal material is in a solid state at room temperature, it can be heated to its melting point to form the molten metal 100.

[0038] The molten metal 100 forms a corresponding metal oxide on its surface in the subsequent preparation process. Therefore, the type of metal in the metal material corresponds to the metal element in the metal oxide. If the metal oxide contains only one metal element, the metal material can be a metal element. If the metal oxide contains multiple metal elements, the metal material can also be an alloy composed of multiple metals.

[0039] It can be understood that the metal material can form the molten metal 100 before being placed on the first substrate 200, and maintain the state of the molten metal 100 after being placed on the first substrate 200. In some examples of this embodiment, the step of placing the metal material on the first substrate 200 includes heating the metal material to complete melting, and then transferring the molten metal material to the surface of the first substrate 200. During the process of heating the metal material to complete melting, the metal material can be placed in an environment that does not react with it, for example, in a protective gas atmosphere or a vacuum environment. The metal material can also be directly placed in a gas environment containing oxidizing gas.

[0040] In some examples of this embodiment, the metal material can include one or more of indium, tin, zinc, and gallium.

[0041] In some examples of this embodiment, the purity of the metal raw material is above 99%. Alternatively, the purity of the metal raw material can be above 99.9%.

[0042] In some examples of this embodiment, the raw material of the molten metal 100 has a low melting point, for example, the melting point of the raw material of the molten metal 100 is below 200°C, so that the preparation can be completed in a relatively mild preparation environment. It can be understood that the melting point of the raw material can be adjusted by selecting a specific metal or controlling the composition of the metal. For example, the raw material of the molten metal 100 includes one or more of indium and gallium to obtain a lower melting point.

[0043] In some examples of this embodiment, the step of placing the molten metal 100 on the first substrate 200 further comprises a step of pre-heating the first substrate 200. In the step of pre-heating the first substrate 200, the first substrate 200 is heated to above the melting point of the metal material. The step of pre-heating the first substrate 200 serves to prevent the molten metal material from solidifying due to heat conduction from the first substrate 200 when the molten metal material is placed on the first substrate 200.

[0044] In some examples of this embodiment, the molten metal 100 can be placed on the first substrate 200 by drop casting. For example, the molten metal 100 in liquid form can be taken up by a glass pipette and sprayed onto the surface of the first substrate 200.

[0045] In some examples of this embodiment, the material of the first substrate 200 can comprise silicon dioxide, silicon or polyimide.

[0046] In some examples of this embodiment, after the metal material is placed on the first substrate 200, the first substrate 200 is continuously heated so that the temperature of the first substrate 200 is maintained above the melting point of the metal material, keeping the molten metal 100 in a molten state as a whole.

[0047] Referring to Figure 3 As shown, in step S2, a metal oxide layer 110 is formed on the surface of the molten metal 100.

[0048] In some examples of this embodiment, the molten metal 100 is placed in a gaseous environment containing an oxidizing gas, so that a corresponding metal oxide layer 110 is formed on the surface of the molten metal 100. When the molten metal 100 is exposed to the gaseous environment containing the oxidizing gas, the exposed part of the surface of the molten metal 100 will react with the oxidizing gas and form a corresponding metal oxide.

[0049] In some examples of this embodiment, the molten metal 100 is placed in a gaseous environment containing an oxidizing gas, so that a corresponding metal oxide layer 110 is formed on the surface of the molten metal 100. When the molten metal 100 is exposed to the gaseous environment containing the oxidizing gas, the exposed part of the surface of the molten metal 100 will react with the oxidizing gas and form a corresponding metal oxide.

[0050] In some examples of this embodiment, the oxidizing gas can be oxygen or other gases containing oxygen that can oxidize the molten metal 100 to form metal oxides. It is understood that the gaseous environment containing the oxidizing gas can be a pure oxidizing gas environment or a mixed gas environment containing the oxidizing gas and other gases. For example, this gaseous environment can be air. Furthermore, by appropriately controlling the concentration of the oxidizing gas in the gaseous environment, the reaction rate of the molten metal 100 can also be controlled.

[0051] In some examples of this embodiment, the temperature of the gas environment may be lower than the melting point of the molten metal 100. For example, the temperature of the gas environment is room temperature. Optionally, the temperature of the gas environment is 20°C to 30°C.

[0052] In some examples of this embodiment, in the step of placing the molten metal 100 in a gaseous environment containing an oxidizing gas, the molten metal 100 may first be placed on the first substrate 200 in an environment that does not react with the molten metal 100, and then the first substrate 200 may be transferred to the gaseous environment containing an oxidizing gas. Alternatively, the molten metal 100 and the first substrate 200 may be placed directly in the gaseous environment containing an oxidizing gas.

[0053] Step S3: The second substrate 300 is used to contact the metal oxide layer 110 to separate the metal oxide layer 110 from the surface of the molten metal 100.

[0054] Among them, reference Figure 4 As shown, a second substrate 300 is placed on the surface of the molten metal 100 away from the first substrate 200, so that the second substrate 300 contacts the metal oxide layer 110. Due to the attractive forces between atoms or molecules of the solid, the second substrate 300 can adsorb the metal oxide layer 110. Then, through the difference in the forces between the metal oxide layer 110 and the second substrate 300, and between the metal oxide layer 110 and the molten metal 100, the metal oxide layer 110 separates from the surface of the molten metal 100.

[0055] It is understood that atoms or molecules in a solid exhibit attractive forces. Therefore, when the second substrate 300 comes into contact with the metal oxide layer 110, adsorption can occur between the metal oxide layer 110 and the second substrate 300. Furthermore, the solid-solid interaction between the metal oxide layer and the second substrate 300 is stronger than the solid-liquid interaction between the metal oxide layer and the molten metal 100, making it easier for the metal oxide layer 110 to slip onto the molten metal 100. Utilizing this difference in forces, the formed metal oxide layer 110 can be separated from the molten metal 100, and the metal oxide layer 110 can be placed on the second substrate 300.

[0056] Reference Figure 4 andFigure 5 As shown, in some examples of this embodiment, the step of separating the metal oxide from the surface of the molten metal 100 includes gradually separating the molten metal 100 from the metal oxide layer 110 on the surface thereof by moving the molten metal 100 along a direction parallel to the surface of the second substrate 300 with the first substrate 200, the metal oxide layer 110 being attached to the second substrate 300. Since the solid-solid interaction force between the metal oxide layer and the second substrate 300 is stronger than the solid-liquid interaction force between the metal oxide layer and the molten metal 100, the metal oxide layer will remain on the second substrate 300 and gradually separate from the liquid alloy when the liquid alloy moves relative to the surface of the second substrate 300. Thus, the metal oxide layer attached to the second substrate 300 can be obtained.

[0057] In some examples of this embodiment, the first substrate 200 can be placed above the second substrate 300 during the process of moving the molten metal 100 along the surface of the second substrate 300 with the first substrate 200, and one side edge of the first substrate 200 is in close contact with the surface of the second substrate 300 and moves along the surface of the second substrate 300. In this way, the molten metal 100 is pushed by the first substrate 200 and gradually separates from the metal oxide layer 110 on the surface thereof, and the metal oxide layer on the surface of the molten metal 100 is transferred to the second substrate 300 as the molten metal 100 rolls on the surface of the second substrate 300.

[0058] In some examples of this embodiment, the molten metal 100 is continuously exposed to the gas environment containing the oxidizing gas during the process of gradually separating the molten metal 100 from the metal oxide layer 110 on the surface thereof, so that the surface of the molten metal 100 continuously forms a metal oxide layer 110. It can be understood that as the molten metal 100 gradually separates from the metal oxide layer 110 on the surface thereof, the interior of the molten metal 100 is also gradually exposed to the oxidizing gas and quickly re-forms a layer of metal oxide 110. Therefore, by the operation mode of this example, the surface of the molten metal 100 can continuously generate a new metal oxide layer 110, which is continuously transferred to the second substrate 300 during the movement of the molten metal 100. Thus, the size of the metal oxide layer 110 and the preparation efficiency are improved.

[0059] In some examples of this embodiment, the material of the second substrate 300 can include one or more of silicon dioxide, silicon, and polyimide.

[0060] In some examples of this embodiment, the thickness of the metal oxide layer 110 is less than 9 nm. For example, the thickness of the metal oxide layer 110 is 2 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, or a range between each of the thicknesses.

[0061] The conventional sputtering or atomic layer deposition coating method cannot obtain a thin film layer with a thin thickness when preparing some metal oxides. For example, a typical amorphous metal oxide semiconductor is indium zinc tin oxide (a-IZTO), which is composed of a multi-component mixed oxide and has a high crystallization energy, thus exhibiting obvious amorphous properties. In actual preparation, the thickness of the indium zinc tin oxide obtained by the sputtering method is usually in the range of 200 nm to 1000 nm, which cannot meet the requirements of flexible electronic devices. Even if the indium zinc tin oxide layer is manufactured by the atomic layer deposition method with high precision, the thickness of the indium zinc tin oxide can only be reduced to 40 nm. In the preparation method of the metal oxide thin film, the oxidation process of the surface of the molten metal 100 is self-limiting. The metal oxide layer 110 formed in advance blocks the contact between the oxidizing gas and the molten metal 100 in the interior, so that the preparation of a thinner metal oxide thin film can also be achieved.

[0062] Referring to Figure 6 After the metal oxide layer 110 is separated from the surface of the molten metal 100, the metal oxide layer 110 is temporarily attached to the second substrate 300. In actual use of the metal oxide layer 110, the metal oxide layer 110 can be separated from the second substrate 300 and transferred to a required device.

[0063] In step S4, the metal oxide layer 110 is soaked in a boiling solvent, and then the residual metal on the surface of the metal oxide layer 110 is removed.

[0064] The separation of the metal oxide layer 110 by attaching the metal oxide layer 110 to the second substrate 300 can cause a small amount of metal to remain on the surface of the metal oxide layer 110. Therefore, after the metal oxide layer 110 is separated from the surface of the molten metal 100, the metal oxide layer 110 can also be soaked in a boiling solvent to clean the surface of the metal oxide layer 110. Since the interaction between the metal and the metal oxide is an interfacial adsorption force, the adsorption force is weak, so that the small amount of metal attached to the surface of the metal oxide layer 110 can be effectively removed after soaking.

[0065] In some examples of the embodiment, the residual metal is removed by wiping. Alternatively, the wiping tool can be a wiping rod with a wiping end attached with fibers, such as a cotton swab.

[0066] The metal oxide thin film can be obtained by steps S1 to S4.

[0067] The disclosure also provides a metal oxide thin film prepared by the preparation method of the metal oxide thin film in the above embodiment.

[0068] It can be understood that the metal oxide film is formed by the reaction of molten metal with an oxidizing gas, and is separated from the surface of the molten metal by mechanical peeling.

[0069] The present disclosure also provides an application mode of the metal oxide film. Specifically, the metal oxide film has a relatively thin thickness, usually only several to tens of atoms thick, which can be less than 9 nm or even less than 5 nm, which makes the metal oxide film have a strong resistance to bending, and thus can be applied to the preparation of flexible devices.

[0070] The present disclosure also provides an application of the metal oxide film in the preparation of a transparent electrode or a semiconductor device.

[0071] For example, the present disclosure also provides a thin film transistor, which comprises a transparent electrode comprising the metal oxide film provided by the present disclosure. It can be understood that the metal oxide film comprises a conductive metal oxide. Optionally, the thin film transistor is a flexible thin film transistor.

[0072] For example, the present disclosure also provides a photodetector, which comprises the metal oxide film provided by the present disclosure. It can be understood that the metal oxide film is a semiconductor.

[0073] For example, the present disclosure also provides an electroluminescent device, which comprises a transparent electrode comprising the metal oxide film provided by the present disclosure. It can be understood that the metal oxide film comprises a conductive metal oxide. Optionally, the electroluminescent device is a flexible electroluminescent device.

[0074] For example, the present disclosure also provides a solar cell, which comprises a transparent electrode comprising the metal oxide film provided by the present disclosure. It can be understood that the metal oxide film comprises a conductive metal oxide.

[0075] In order to facilitate the understanding and implementation of the present disclosure, the following also provides more specific and detailed examples and comparative examples as a reference. Through the description and performance results of the following specific examples and comparative examples, the embodiments of the present disclosure and their advantages will also be apparent.

[0076] Unless otherwise specified, the raw materials used in the following examples can be commonly purchased on the market.

[0077] Example 1:

[0078] The purity of the metal indium is 99.995%, the purity of the metal zinc is 99.000%, and the purity of the metal tin is 99.999%.

[0079] The container is placed on the heating table for preheating, and the preheating temperature is 200°C.

[0080] The metal indium, the metal zinc and the metal tin are mixed in a container, heated for 30 min until the metal is completely melted, and a uniform molten metal alloy is obtained by stirring during the melting process.

[0081] The quartz sheet is used as the first substrate, preheated on a heating table, and the preheating temperature is 200℃. The molten metal is taken by a glass straw and dropped on the first substrate to spread naturally.

[0082] The molten metal on the quartz sheet is exposed to air, and after a layer of metal oxide layer is formed on the surface of the molten metal, a polyimide film is used as the second substrate and attached to the metal oxide layer from above the molten metal, and the second substrate is slid to separate the metal oxide layer from the molten metal, and the metal oxide layer is transferred to the second substrate.

[0083] The second substrate and the metal oxide layer are immersed in boiling ethanol for 1 min, and a cotton swab is used to gently wipe off a small amount of metal residue to obtain a metal oxide film.

[0084] Test 1: The element distribution diagram and atomic force microscope diagram of the indium zinc tin oxide film prepared in Example 1 are shown in Figure 7 and Figure 8 .

[0085] Test 2: The indium zinc tin oxide film prepared in Example 1 is bent at a bending angle of 60°, and repeated bending is performed 1000 times. The current-voltage relationship of the film under lightless condition and 255 nm wavelength light illumination condition before and after bending is tested, and the results are shown in Figure 9 . Among them, Figure 9 lightless 1 and light 1 in Figure 9 respectively represent the performance of the indium zinc tin oxide film before bending under lightless and light illumination conditions, and lightless 2 and light 2 respectively represent the performance of the indium zinc tin oxide film after bending under lightless and light illumination conditions.

[0086] Test 3: Based on the indium zinc tin oxide film prepared in this example, a thin film transistor and a photodetector are further prepared, the on-off ratio of the thin film transistor is tested, and the response speed and detection rate of the photodetector are tested, and the results are shown in Table 1 below.

[0087] In Table 1, Comparative Examples 1 through 6 are devices fabricated and tested based on known materials. Comparative Example 1 is an indium zinc tin oxide thin film, Comparative Example 2 is a nitrogen-doped indium zinc oxide / indium zinc tin oxide composite thin film, Comparative Example 3 is zinc oxide nanosheets, Comparative Example 4 is gallium oxide nanosheets, Comparative Example 5 is a thermally grown gallium oxide nanostructure, and Comparative Example 6 is an indium gallium zinc oxide thin film. “—” in Table 1 indicates that no relevant tests were performed.

[0088] Table 1

[0089] Thin film type Thickness (nm) On / Off ratio Responsivity (A / W) Detectivity (Jones) Example 1 4.99 10 6 ]] 7.57 x 10 4 ]]> 4.00 x 10 15 ]] Comparative Example 1 8+15 10 5 ]] — — Comparative Example 2 20 10 5 ]] — — Comparative Example 3 60-100 — 3386 — Comparative Example 4 10 — 3.3 4.0 x 10 12 ]] Comparative Example 5 2900 — 6.9 x 10 -3 ]] 4.25 x 10 11 ]]> Comparative Example 6 — — 5.4 3.3 x 10 12 ]]>

[0090] Reference Figure 6 As shown in the diagram, the distribution areas of indium, zinc, tin, and oxygen are basically overlapping and relatively uniform, indicating that the material of the thin film is indium zinc tin oxide. Figure 7 A schematic diagram of the indium zinc tin oxide thin film is shown in the atomic force microscope. Figure 7 The white line in the diagram represents the sampling test area, and the test results can be found in... Figure 7 The coordinate system in the diagram shows the distance from the sampling origin on the horizontal axis and the thickness on the vertical axis. Figure 7 It can be determined that the average thickness of this indium zinc tin oxide film is approximately 4.99 nm. (Combined with...) Figure 6 and Figure 7 It can be determined without any doubt that the preparation method provided in this disclosure can prepare metal oxide thin films with a thickness of less than 5 nm.

[0091] Reference Figure 8 As shown, before and after bending, the current-voltage curves of the metal oxide film under no-light conditions are almost completely overlapping, and the current-voltage curves under 255nm wavelength illumination conditions also show only a very small difference, indicating that bending 1000 times has basically no impact on the performance of the metal oxide film.

[0092] Referring to Table 1, compared to Comparative Examples 1 and 2, the on / off ratio of the thin-film transistor fabricated based on the indium zinc tin oxide thin film of Example 1 is an order of magnitude higher. Compared to Comparative Example 3, the responsivity of the photodetector fabricated based on the indium zinc tin oxide thin film of Example 1 is approximately 20 times higher. Compared to Comparative Examples 4-6, the responsivity of the photodetector fabricated based on the indium zinc tin oxide thin film of Example 1 is more than four orders of magnitude higher, and the detectivity is also three orders of magnitude higher. This is mainly due to the fact that the metal oxide thin film prepared by the method of preparing the metal oxide thin film provided in this disclosure is formed by the spontaneous oxidation of metal and has a significantly thinner thickness.

[0093] Any combination of the technical features in the above embodiments can be made, and for the sake of brevity, not all possible combinations are described above, however, as long as the combination of the technical features does not exist in contradiction, it shall be considered within the scope of the present disclosure.

[0094] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it shall not be understood as a limitation on the patent scope of the present application. It shall be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these shall be within the protection scope of the present application. Therefore, the protection scope of the present application patent shall be subject to the appended claims.

Claims

1. A method for producing a metal oxide thin film, characterized by, The method comprises the following steps: placing a molten metal on a first substrate to form a corresponding metal oxide layer on the surface of the molten metal; contacting the metal oxide layer with a second substrate to attach the metal oxide layer to the second substrate, and separating the metal oxide layer from the surface of the molten metal by the difference between the force between the metal oxide layer and the second substrate and the force between the metal oxide layer and the molten metal; the molten metal comprises indium, zinc and tin, and the material of the metal oxide layer comprises indium zinc tin oxide; the material of the first substrate comprises silicon dioxide or silicon; the material of the second substrate comprises polyimide; the step of separating the metal oxide layer from the surface of the molten metal comprises: placing the first substrate above the second substrate, and moving the side edge of the first substrate close to the surface of the second substrate along the surface of the second substrate, and moving the molten metal along a direction parallel to the surface of the second substrate by the first substrate to gradually separate the molten metal from the metal oxide layer on the surface of the molten metal, and the metal oxide layer is attached to the second substrate.

2. The method for producing a metal oxide thin film according to claim 1, characterized by, During the gradual separation of the molten metal from the metal oxide layer on the surface of the molten metal, the molten metal is continuously exposed to a gas environment containing oxidizing gas to continuously form the metal oxide layer on the surface of the molten metal.

3. The method of claim 1, wherein the metal oxide thin film is prepared by a method comprising: After separating the metal oxide layer from the surface of the molten metal, the method further comprises: immersing the metal oxide layer in a boiling solvent, and then removing the residual metal on the surface of the metal oxide layer.

4. The method for preparing a metal oxide thin film according to any one of claims 1 to 3, characterized in that, The step of forming a corresponding metal oxide layer on the surface of the molten metal comprises: placing the molten metal in a gas environment containing oxidizing gas to oxidize the surface of the molten metal and form the metal oxide layer.

5. The method of claim 1 to 3, wherein The step of placing the molten metal on the first substrate comprises: heating the metal material to complete melting, and then transferring the molten metal material to the surface of the first substrate.

6. The method of claim 1 to 3, wherein The thickness of the metal oxide layer is less than 9 nm.

7. A metal oxide thin film, characterized by, The metal oxide thin film is prepared by the method for preparing a metal oxide thin film according to any one of claims 1-6.

8. Use of the metal oxide thin film according to claim 7 in the preparation of a transparent electrode or a semiconductor device.

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