Preparation method of two-dimensional amorphous gallium oxide film

Abstract

The invention discloses a preparation method of a two-dimensional amorphous gallium oxide film. The amorphous gallium oxide is prepared by taking gallium selenide as a substrate and adopting the steps of stripping-transferring, heating and oxidizing in air and the like. The thickness of the obtained amorphous gallium oxide thin film is within ten nanometers, and the prepared amorphous gallium oxide thin film is uniform in structure thickness and smooth in surface. The method is simple to operate, short in time consumption, environment-friendly in production, adjustable in preparation size and configuration and suitable for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the field of material preparation, and particularly relates to a method for preparing a two-dimensional amorphous gallium oxide thin film. Background Art

[0002] As a newly emerging two-dimensional ultra-wide bandgap semiconductor material, it has attracted wide attention in the field of advanced electronic devices in recent years. Its background technology can be summarized as the following key points: a bandgap width significantly higher than that of traditional silicon oxide, which can effectively inhibit the quantum tunneling effect and is suitable for devices with nodes below 5 nm; having a high dielectric constant, with both gate control efficiency and interface compatibility; the amorphous structure has no long-range order, and its sensitivity to point defects (such as oxygen vacancies) is lower than that of the crystal phase, which is beneficial to reducing the interface state density. Its special physical, chemical, and mechanical properties have shown great potential in the manufacture and development of electronic and optoelectronic devices.

[0003] Common preparation methods of amorphous gallium oxide include controlled oxidation method, chemical vapor deposition (CVD), atomic layer deposition (ALD), magnetron sputtering (MS), laser pulse deposition (PLD), etc. Existing synthesis technologies have relatively strict requirements for equipment and environment. For example, Fan Yang (Cui S, Mei Z, Zhang Y, Liang H and Du X 2017 Adv. Opt. Mater. 5 1700454) et al. prepared large-area uniform thin films by magnetron sputtering in 2017. Although the process is mature and suitable for industrial production, the quality of the prepared thin films is greatly affected by the purity of the target and sputtering conditions, and high-temperature annealing during the preparation process may cause the transformation from amorphous to crystalline state. Li Xing (Li X, Yang J G, Ma H P, Liu Y H, Ji Z G, Huang W, Ou X, Zhang D W and Lu H L 2020 ACS Appl. Mater. Interfaces 12 30538) et al. used ALD technology to prepare amorphous gallium oxide thin films with different thicknesses for electronic devices in 2020, but the deposition rate of this method is slow and not suitable for large-scale production. Therefore, it is necessary to explore a new preparation method to achieve an efficient and simple synthesis method, especially for the controllable preparation of two-dimensional amorphous gallium oxide. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a two-dimensional amorphous gallium oxide thin film in view of the deficiencies of the prior art. Using gallium selenide as the substrate, amorphous gallium oxide is prepared by heating and oxidizing in air. The thickness of the obtained amorphous gallium oxide thin film is within 10 nanometers, and the prepared amorphous gallium oxide thin film has a uniform structure thickness, a smooth surface, simple operation, short time consumption, and can be applied on a large scale.

[0005] The present invention is realized through the following technical solutions.

[0006] A method for preparing a two-dimensional amorphous gallium oxide according to the present invention includes the following steps.

[0007] (1) First, the SiO 2 / Si substrate is ultrasonically cleaned with acetone, isopropyl alcohol, and deionized water in sequence to remove impurities on its surface, and then is dried with an ear syringe.

[0008] (2) Prepare a piece of tape, dissociate the gallium selenide crystal through the tape and directly peel it onto the PDMS film. Observe and position the uniform gallium selenide flakes under a microscope, then flip the PDMS film, accurately align it with the substrate using a transfer stage, and at room temperature, make the gallium selenide on the PDMS adhere to the target substrate. After slowly lifting the PDMS film, the sample is transferred onto the target substrate.

[0009] (3) Heat up the heating stage to a stable temperature, place the obtained substrate with gallium selenide on the heating stage, and after waiting for the oxidation to complete, an amorphous gallium oxide thin film can be obtained.

[0010] Preferably, the gallium selenide described in step (2) is a single crystal gallium selenide prepared by chemical vapor deposition.

[0011] Preferably, the thickness of the PDMS film described in step (2) is 50 um - 300 um.

[0012] Preferably, the maximum temperature of the heating stage used in step (3) can reach 500 °C.

[0013] Preferably, the time and temperature for placing the substrate on the heating stage in step (3) depend on the thickness of the selected material. The applicable heating stage temperature for the gallium selenide flakes is 400 °C - 450 °C, and the heating time is 1 min - 30 min.

[0014] The technical effects of the present invention.

[0015] (1) The present invention successfully changes the structure of the material through thermal oxidation on the heating stage and prepares an amorphous gallium oxide thin film with good quality.

[0016] (2) Different from the existing methods for preparing amorphous gallium oxide, the present invention provides a new method and idea, that is, using gallium selenide as the substrate, with the help of low-cost equipment (heating stage), changing the material structure by heating and oxidizing in the air, and then generating amorphous gallium oxide.

[0017] (3) Good controllability, the oxidation temperature and oxidation time can be well controlled through the heating stage.

[0018] (4) Compared with chemical vapor deposition, magnetron sputtering, laser pulse deposition, etc., the operation of the present invention is simple, time-consuming is short, the cost is low, the prepared size and configuration are adjustable, and the prepared gallium oxide film has uniform thickness and smooth surface. The mechanical peeling and transfer method and the heating oxidation method adopted in the present invention are very simple and easy to operate, and can quickly complete the preparation of the two-dimensional amorphous gallium oxide film.

[0019] (5) The materials involved in the present invention are safe, environmentally friendly, and will not produce substances harmful to the environment. Description of the Drawings

[0020] Figure 1 For the comparison diagram of the gallium selenide flake and the oxidized amorphous gallium oxide on the SiO 2 / Si 2 substrate in Example 2 of the present invention, where the left figure is gallium selenide and the right figure is amorphous gallium oxide.

[0021] Figure 2 For the Raman spectrum change diagram of the gallium selenide flake and the oxidized amorphous gallium oxide in Example 2 of the present invention.

[0022] Figure 3 For the thickness change diagram of the gallium selenide flake and the oxidized amorphous gallium oxide in Example 2 of the present invention.

[0023] Figure 4 For the comparison diagram of the crystal structure diagrams of the gallium selenide flake and the oxidized amorphous gallium oxide in Example 2 of the present invention, where the left figure is gallium selenide and the right figure is amorphous gallium oxide. Among them, the large figure is the surface topography at high resolution, and the inset in the large figure is the electron diffraction pattern. Specific Embodiments

[0024] The present invention will be further described below in conjunction with examples. Example 1

[0025] First, the SiO 2 / Si substrate was ultrasonically cleaned with acetone, isopropanol, and deionized water in sequence to remove the impurities on its surface, and then dried with an ear syringe. The substrate was placed on the transfer table. A piece of tape was prepared, and gallium selenide was directly peeled onto the PDMS film through the tape. The uniformly located gallium selenide flakes with a thickness of 8 nm were observed under a microscope, and then the PDMS film was turned over. The transfer table was used to accurately align the silicon wafer so that the gallium selenide on the PDMS was attached to the silicon wafer. After slowly lifting the PDMS film, the sample was successfully transferred to the target position on the silicon wafer. The heating table was adjusted to 400 °C. After the surface temperature of the heating table was stable, the silicon wafer substrate with gallium selenide was placed on it. After standing and heating for 20 min, the substrate was removed, and amorphous gallium oxide could be obtained. Example 2

[0026] First, the SiO2 The SiO2 / Si substrate was successively ultrasonically cleaned with acetone, isopropyl alcohol, and deionized water to remove impurities on its surface, and then dried with an ear syringe. The substrate was placed on a transfer stage. A piece of tape was prepared, and gallium selenide was directly peeled onto the PDMS film through the tape. Uniform gallium selenide flakes with a thickness of 9.5 nm were observed and positioned under a microscope. Then, the PDMS film was flipped, and the silicon wafer was precisely aligned using the transfer stage so that the gallium selenide on the PDMS was attached to the silicon wafer. After slowly lifting the PDMS film, the sample was successfully transferred to the target position on the silicon wafer. The heating stage was adjusted to 450 °C. After the surface temperature of the heating stage was stabilized, the silicon wafer substrate with gallium selenide was placed on it. After standing and heating for 20 min, the substrate was removed, and amorphous gallium oxide could be obtained. Example 3

[0027] First, the SiO2 / Si substrate was successively ultrasonically cleaned with acetone, isopropyl alcohol, and deionized water to remove impurities on its surface, and then dried with an ear syringe. The substrate was placed on a transfer stage. A piece of tape was prepared, and gallium selenide was directly peeled onto the PDMS film through the tape. Uniform gallium selenide flakes with a thickness of 12 nm were observed and positioned under a microscope. Then, the PDMS film was flipped, and the silicon wafer was precisely aligned using the transfer stage so that the gallium selenide on the PDMS was attached to the silicon wafer. After slowly lifting the PDMS film, the sample was successfully transferred to the target position on the silicon wafer. The heating stage was adjusted to 450 °C. After the surface temperature of the heating stage was stabilized, the silicon wafer substrate with gallium selenide was placed on it. After standing and heating for 30 min, the substrate was removed, and amorphous gallium oxide could be obtained.

[0028] From Figure 1 It can be seen the change in the optical images of the gallium selenide thin film before and after thermal oxidation. Due to the change in the optical bandgap of the material, it can be observed under an optical microscope that the film peeled on the SiO2 / Si substrate becomes more transparent in color after oxidation.

[0029] From Figure 2 It can be seen that gallium selenide has Raman characteristic peaks at 58.7 cm -1 , 134.2 cm -1 , 212.7 cm -1 , 252.6 cm -1 , 308.2 cm -1 . After the thermal oxidation transforms into amorphous gallium oxide, the Raman characteristic peaks disappear.

[0030] From Figure 3 It can be seen that after the gallium selenide thin film is thermally oxidized to amorphous gallium oxide, the film thickness decreases from 9.5 nm to 5 nm.

[0031] From Figure 4The regular arrangement of gallium selenide atoms can be seen, and the electron diffraction pattern shows symmetry. After undergoing thermal oxidation, it transforms into amorphous gallium oxide, and the crystal characteristics disappear, and no information can be observed.

Claims

1. A method for preparing two-dimensional amorphous gallium oxide, characterized in that The following steps are involved: (1) The SiO2 / Si substrate was first ultrasonically cleaned with acetone, isopropanol, and deionized water to remove impurities on its surface, and then dried with an ear bulb; (2) preparing a piece of tape, dissociating the GaSe crystals through the tape and directly peeling them onto the PDMS film; observing the uniformly positioned GaSe flakes under a microscope, then flipping the PDMS film over, accurately aligning the substrate using a transfer table, and making the GaSe on the PDMS fit the target substrate at room temperature, slowly lifting the PDMS film, and transferring the sample onto the target substrate; (3) The heating platform is heated to a stable temperature, and the obtained substrate with gallium selenide is placed on the heating platform. After the oxidation is completed, an amorphous gallium oxide film is obtained.

2. The method for preparing a two-dimensional amorphous gallium oxide according to claim 1, characterized in that The gallium selenide described in step (2) is a gallium selenide single crystal prepared by chemical vapor deposition.

3. A method for preparing two-dimensional amorphous gallium oxide, characterized in that The thickness of the PDMS film described in step (2) is 50um-300um.

4. A method for preparing two-dimensional amorphous gallium oxide, characterized in that The maximum temperature of the heating stage used in step (3) can reach 500°C.

5. A method for preparing two-dimensional amorphous gallium oxide, characterized in that The time and temperature at which the substrate is placed on the heating platform in step (3) depend on the thickness of the selected material. The heating platform temperature suitable for gallium selenide wafers is 400°C-450°C, and the heating time is 1 min-30 min.

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