阅读说明：本技术 一种英寸级单晶薄膜的制备方法及单晶薄膜 (Preparation method of inch-grade single crystal film and single crystal film ) 是由 潘孟春 彭俊平 胡悦国 李裴森 胡佳飞 邱伟成 张琦 于 2020-05-26 设计创作，主要内容包括：本发明公开了一种英寸级单晶薄膜的制备方法及单晶薄膜,本发明制备方法的实施步骤包括：将单晶基片进行预处理,预处理包括清洗、高温灼烧；在预处理后的单晶基片的外延面上沉积铁磁金属薄膜；将沉积有铁磁金属薄膜的单晶基片退火处理得到(111)或(0001)取向的单晶薄膜。单晶薄膜为基于前述制备方法制备得到的单晶薄膜。本发明能够实现英寸级单晶薄膜的制备,制备得到的单晶薄膜在英寸级范围内具有原子级平整度、超高洁净度和单一晶化特征,能够为实现大面积石墨烯生长以及高性能石墨烯自旋电子器件研制提供技术基础。(The invention discloses a preparation method of an inch-grade single crystal film and the single crystal film, and the implementation steps of the preparation method comprise: pretreating the single crystal substrate, wherein the pretreatment comprises cleaning and high-temperature burning; depositing a ferromagnetic metal film on the epitaxial surface of the pretreated single crystal substrate; annealing the single crystal substrate deposited with the ferromagnetic metal film to obtain the (111) or (0001) oriented single crystal film. The single crystal thin film is a single crystal thin film produced based on the foregoing production method. The preparation method can realize the preparation of inch-grade single crystal films, the prepared single crystal films have the characteristics of atomic-grade flatness, ultrahigh cleanliness and single crystallization in an inch-grade range, and a technical basis can be provided for realizing the growth of large-area graphene and the development of high-performance graphene spinning electronic devices.)

1. A method for preparing an inch-scale single crystal thin film is characterized by comprising the following implementation steps:

1) pretreating the single crystal substrate, wherein the pretreatment comprises cleaning and high-temperature burning;

2) depositing a ferromagnetic metal film on the epitaxial surface of the pretreated single crystal substrate;

3) annealing the single crystal substrate deposited with the ferromagnetic metal film to obtain the (111) or (0001) oriented single crystal film.

2. The method for producing an inch-scale single crystal thin film according to claim 1, wherein the single crystal substrate used in step 1) is a hexagonal close-packed crystal having an epitaxial surface of (0001) or a cubic close-packed crystal having an epitaxial surface of (111).

3. The method for preparing an inch-scale single crystal thin film according to claim 2, wherein the detailed step of cleaning in step 1) comprises: putting the mixture into an acetone solution for ultrasonic cleaning for 5-10 minutes in an ultraclean room, putting the mixture into an isopropanol solution for ultrasonic cleaning for 5-10 minutes, putting the mixture into deionized water for ultrasonic cleaning for 5-10 minutes, and blowing the mixture clean by a high-purity nitrogen gun; repeating the steps until the epitaxial surface of the single crystal substrate is free from obvious particle impurities and water stains when the epitaxial surface of the single crystal substrate is observed by a microscope.

4. The method for preparing an inch-scale single crystal thin film according to claim 3, wherein the detailed step of high-temperature firing in step 1) comprises: putting the single crystal substrate into a tube furnace for high-temperature burning, introducing oxygen-argon mixed gas in the atmosphere at the temperature of 1000-1300 ℃, and naturally cooling to normal temperature after burning for specified time; repeating the steps until the atomic level flatness of the epitaxial surface is confirmed when the atomic force microscope is used for carrying out random multipoint characterization on the epitaxial surface of the single crystal substrate, wherein the atomic level flatness means that the undulation degree of the epitaxial surface of the single crystal substrate is not higher than 0.5 nm.

5. The method for preparing an inch-scale single crystal thin film according to claim 4, wherein the deposition process used in the step 2) for depositing the ferromagnetic metal thin film on the epitaxial surface of the pretreated single crystal substrate is electron beam evaporation, magnetron sputtering, or molecular beam epitaxy, and the purity of the metal source material used is higher than 99.99%.

6. The method for preparing an inch-scale single crystal thin film according to claim 5, wherein the deposition process parameters used in the step 2) for depositing the ferromagnetic metal thin film on the epitaxial surface of the pretreated single crystal substrate are as follows: the deposition rate is 0.05-0.5 nm/s, and the temperature of the single crystal substrate is 200-500 ℃.

7. The method for producing an in-inch single crystal thin film according to claim 6, wherein the metal source material used in depositing the ferromagnetic metal thin film in step 2) is a ferromagnetic metal or an alloy material of a ferromagnetic metal having a cubic close-packed structure or a hexagonal close-packed structure.

8. The method for preparing an inch-scale single crystal thin film according to claim 7, wherein the detailed annealing treatment of the single crystal substrate deposited with the ferromagnetic metal thin film in the step 3) comprises the steps of placing the single crystal substrate deposited with the ferromagnetic metal thin film in a vacuum chamber of a heating device under a vacuum annealing furnace or an ultrahigh vacuum condition, heating to 300-500 ℃ to degas the surface of the single crystal substrate to eliminate gas molecules adsorbed on the surface of the ferromagnetic metal thin film, uniformly heating to 750-1000 ℃ and maintaining for 0.5-2 hours, and uniformly cooling to room temperature, wherein the background vacuum pressure of the vacuum chamber is less than 5 × 10^-5Pa。

9. A single crystal thin film characterized by being a (111) or (0001) oriented single crystal thin film produced by the method for producing an inch-scale single crystal thin film according to any one of claims 1 to 8.

Technical Field

The invention relates to the technology of spintronics and the preparation of thin film materials, in particular to a preparation method of an inch-grade single crystal thin film and the single crystal thin film.

Background

Graphene, as a novel two-dimensional material, has a wide application prospect in the aspects of electronics, photonics, composite materials, energy and the like due to excellent physicochemical characteristics. The device formed by the ferromagnetic material and the graphene shows novel spin transport characteristics, and brings new activity to the spintronics. For example, graphene/nickel has a novel interface spin filtering effect, and a graphene-based magnetic tunnel junction formed by the graphene/nickel has great magnetoresistance.

The graphene spintronics device needs to prepare high-quality graphene on a nickel single crystal film substrate, but the currently prepared nickel film has a large domain boundary and cannot reach the consistency of inch-level single crystals, so that the thickness of the grown graphene is not uniform.

Disclosure of Invention

The technical problems to be solved by the invention are as follows: aiming at the problems in the prior art, the invention provides a preparation method of an inch-grade single crystal film and the single crystal film, the preparation method can realize the preparation of the inch-grade single crystal film, the prepared single crystal film has the characteristics of atomic-grade flatness, ultrahigh cleanliness and single crystallization in an inch-grade range, and a technical basis can be provided for realizing the growth of large-area graphene and the development of high-performance graphene spintronic devices.

In order to solve the technical problems, the invention adopts the technical scheme that:

a preparation method of an inch-scale single crystal thin film comprises the following implementation steps:

1) pretreating the single crystal substrate, wherein the pretreatment comprises cleaning and high-temperature burning;

2) depositing a ferromagnetic metal film on the epitaxial surface of the pretreated single crystal substrate;

3) annealing the single crystal substrate deposited with the ferromagnetic metal film to obtain the (111) or (0001) oriented single crystal film.

Alternatively, the single crystal substrate used in step 1) is a hexagonal close-packed crystal having an epitaxial face of (0001) or a cubic close-packed crystal having an epitaxial face of (111).

Optionally, the detailed steps of washing in step 1) include: putting the mixture into an acetone solution for ultrasonic cleaning for 5-10 minutes in an ultraclean room, putting the mixture into an isopropanol solution for ultrasonic cleaning for 5-10 minutes, putting the mixture into deionized water for ultrasonic cleaning for 5-10 minutes, and blowing the mixture clean by a high-purity nitrogen gun; repeating the steps until the epitaxial surface of the single crystal substrate is free from obvious particle impurities and water stains when the epitaxial surface of the single crystal substrate is observed by a microscope.

Optionally, the detailed step of high-temperature burning in step 1) comprises: putting the single crystal substrate into a tube furnace for high-temperature burning, introducing oxygen-argon mixed gas in the atmosphere at the temperature of 1000-1300 ℃, and naturally cooling to normal temperature after burning for specified time; repeating the steps until the atomic level flatness of the epitaxial surface is confirmed when the atomic force microscope is used for carrying out random multipoint characterization on the epitaxial surface of the single crystal substrate, wherein the atomic level flatness means that the undulation degree of the epitaxial surface of the single crystal substrate is not higher than 0.5 nm.

Optionally, the deposition process adopted in the step 2) for depositing the ferromagnetic metal thin film on the epitaxial surface of the pretreated single crystal substrate is electron beam evaporation, magnetron sputtering or molecular beam epitaxy, and the purity of the adopted metal source material is higher than 99.99%.

Optionally, the deposition process parameters adopted in depositing the ferromagnetic metal thin film on the epitaxial surface of the pretreated single crystal substrate in the step 2) are as follows: the deposition rate is 0.05-0.5 nm/s, and the temperature of the single crystal substrate is 200-500 ℃.

Optionally, the metal source material used in depositing the ferromagnetic metal thin film in step 2) is a ferromagnetic metal or an alloy material of a ferromagnetic metal in a cubic close-packed structure or a hexagonal close-packed structure.

Optionally, in step 3) a ferromagnetic material is depositedThe detailed steps of the annealing treatment of the single crystal substrate of the metal film comprise that the single crystal substrate deposited with the ferromagnetic metal film is placed into a vacuum chamber of a vacuum annealing furnace or a heating device under the condition of ultrahigh vacuum, the temperature is firstly raised to 300-500 ℃ to degas the surface of the single crystal substrate so as to eliminate gas molecules adsorbed on the surface of the ferromagnetic metal film, then the temperature is raised to 750-1000 ℃ at a constant speed and maintained for 0.5-2 hours, then the temperature is lowered to the room temperature at a constant speed, the background vacuum pressure of the vacuum chamber is less than 5 × 10^-5Pa。

In addition, the invention also provides a monocrystalline film which is a (111) or (0001) oriented monocrystalline film prepared by the preparation method of the inch-scale monocrystalline film.

Compared with the prior art, the invention has the following advantages:

1. the invention utilizes the lattice symmetry of the epitaxial surface of the single crystal substrate to induce the crystal face of the ferromagnetic metal film to grow epitaxially, and improves the crystallization quality of the film through a vacuum high-temperature annealing process, thereby ensuring the realization of the single crystallization of the film.

2. After the single crystal substrate is fully cleaned in an ultraclean room and is burnt at high temperature for enough time, the whole inch-level epitaxial surface has ultrahigh cleanliness and atomic-level flatness, so that the prepared ferromagnetic metal single crystal film has the characteristics of atomic-level flatness, ultrahigh cleanliness and single crystallization in an inch-level range, and is very suitable to be used as a metal substrate for growing high-quality graphene (or other two-dimensional materials). The method is compatible with the modern semiconductor process, and can be used for preparing large-size array graphene spin electronic devices.

Drawings

FIG. 1 is a basic flow diagram of a method according to an embodiment of the present invention.

FIG. 2 is a schematic flow chart of a Ni (111) single crystal thin film manufacturing process according to a first embodiment of the present invention.

FIG. 3 is an atomic force microscope representation of a Ni (111) single crystal thin film prepared in accordance with a first embodiment of the present invention.

FIG. 4 is an X-ray diffraction chart of a Ni (111) single crystal thin film produced in the first example of the present invention.

FIG. 5 is a diagram showing the characteristics of an α -Al2O3(0001) substrate and a Ni (111) single crystal thin film in accordance with one embodiment of the present invention.

FIG. 6 is a representation of a nickel film prepared with a single crystal substrate having a cleanliness that does not meet the requirements of the present invention.

Detailed Description

The invention is further described below with reference to the drawings and specific preferred embodiments of the description, without thereby limiting the scope of protection of the invention.