A method for preparing a nickel-copper alloy single crystal thin film and a nickel-copper alloy single crystal thin film obtained thereby

Abstract

The present application relates to a kind of preparation methods of nickel copper (111) alloy single crystal film, comprising the following steps: S1, provide sapphire substrate;S2, on the crystal face Al2O3 (0001) of sapphire substrate, deposit 50-5000nm thick metal film, obtain the sapphire substrate of nickel copper alloy deposition, wherein, the metal film is the alloy film of nickel atom and copper atom by nickel atom 1-40% of total number of atoms;S3, sapphire substrate is placed into chemical vapor deposition furnace, carries out annealing treatment in the gas atmosphere of argon and hydrogen, obtains (111) crystal direction single crystal film.The present application also relates to a kind of nickel copper (111) alloy single crystal film obtained according to the preparation method described above.According to the preparation method of the present application, the performance of graphene is greatly improved, which lays the foundation for the application of graphene in the field of microelectronics.

Description

TECHNICAL FIELD

[0001] The present application relates to alloy single crystal thin film, more particularly to a preparation method of nickel-copper (111) alloy single crystal thin film and the nickel-copper (111) alloy single crystal thin film obtained therefrom. BACKGROUND

[0002] Graphene material has excellent photoelectric performance, and has important application in the future in the fields of microelectronics, energy, biological detection and the like, causing widespread attention of all circles. At present, the growth material of graphene is mainly copper foil material. Since the surface of copper foil is rough, undulating and has weak catalytic ability, the quality of graphene grown on the surface of copper foil substrate is low, which seriously limits the application of graphene in the field of microelectronics in the future. SUMMARY

[0003] In order to solve the problem of low quality of graphene caused by the growth material of graphene in the prior art, the present application aims to provide a preparation method of nickel-copper (111) alloy single crystal thin film and the nickel-copper (111) alloy single crystal thin film obtained therefrom.

[0004] The present application provides a preparation method of nickel-copper (111) alloy single crystal thin film, comprising the following steps: S1, providing a sapphire substrate; S2, depositing a 50-5000nm thick metal thin film on the crystal face Al2O3(0001) of the sapphire substrate to obtain a sapphire substrate with nickel-copper alloy deposited thereon, wherein the metal thin film is an alloy thin film composed of nickel atoms and copper atoms, and the content of nickel atoms in the alloy thin film is 1-40% of the total number of atoms; S3, placing the sapphire substrate into a chemical vapor deposition furnace and performing annealing treatment in an argon and hydrogen gas atmosphere to obtain a (111) crystal direction single crystal thin film.

[0005] The sapphire substrate in the preparation method of the present application can be matched with the epitaxy of alloy atoms of the metal thin film; the metal thin film in the preparation method of the present application is selected to have a specific nickel-copper atom ratio, which can ensure the catalytic performance of the alloy thin film; the metal thin film in the preparation method of the present application is selected to have a specific thickness, which can ensure that the metal thin film will not be damaged during the annealing treatment while ensuring the single crystallization of the alloy thin film; the chemical vapor deposition in the preparation method of the present application is selected to have a specific gas atmosphere, which can ensure the single crystallization of the alloy thin film, and in particular, can protect the alloy thin film from oxidation during the annealing process and can also increase the kinetic energy of nickel-copper atom movement.

[0006] Among them, Al2O3(0001) refers to the C face of sapphire, also known as sapphire (0001). Experiments show that neither the R face nor the A face of sapphire can realize the single crystallization of the alloy thin film.

[0007] The purity of the nickel and copper atoms in the metal thin film is 99.999%. That is, the total number of copper and nickel atoms accounts for 99.999% of the total number of atoms in the metal thin film.

[0008] The step S1 comprises: providing a sapphire wafer; cleaning the sapphire wafer; and placing the cleaned sapphire wafer into a muffle furnace for high-temperature annealing, thereby obtaining a sapphire substrate. Preferably, the sapphire wafer is a wafer with a diagonal length of 2-6 inches.

[0009] The temperature of the high-temperature annealing in the muffle furnace is 1100℃.

[0010] The step S2 comprises: depositing at a rate of 0.1 nm / min-100 nm / min while heating the sapphire substrate to 100℃-900℃. Preferably, the heating of the sapphire substrate is by radiation heating or resistance heating.

[0011] The step S2 specifically comprises: depositing by magnetron sputtering, thermal evaporation, electron beam evaporation, or molecular beam epitaxy.

[0012] The step S2 specifically comprises: simultaneously depositing nickel and copper atoms; or first depositing nickel atoms and then depositing copper atoms; or first depositing copper atoms and then depositing nickel atoms.

[0013] The annealing treatment in the chemical vapor deposition furnace comprises a holding stage, an annealing stage, and a cooling stage. Preferably, the holding stage greatly improves the crystalline quality of the thin film, and the annealing stage ensures the realization of single crystallization of the thin film.

[0014] The temperature range of the holding stage is 200℃-600℃, and the holding time is 10 min-240 min; the temperature range of the annealing stage is 600℃-1100℃, and the annealing time is 10 min-240 min.

[0015] The heating rate from room temperature to the holding stage is 0.1℃ / min-50℃ / min; the heating rate from the holding stage to the annealing stage is 0.1℃ / min-50℃ / min; and the cooling rate from the annealing stage to room temperature is 0.01℃ / min-100℃ / min.

[0016] The ratio of argon gas to hydrogen gas in the temperature rising stage is (10-1000sccm):(1-500sccm); the ratio of argon gas to hydrogen gas in the temperature maintaining stage is (10-1000sccm):(1-300sccm); the ratio of argon gas to hydrogen gas in the temperature rising stage from the temperature maintaining stage to the annealing stage is (10-1000sccm):(1-300sccm); the ratio of argon gas to hydrogen gas in the annealing stage is (10-1000sccm):(1-100sccm); and the ratio of argon gas to hydrogen gas in the temperature falling stage is (10-1000sccm):(1-50sccm).

[0017] The application further provides a nickel-copper (111) alloy single crystal thin film prepared by the preparation method.

[0018] According to the preparation method, the nickel-copper single crystal thin film is prepared by the sapphire epitaxy method, the obtained nickel-copper (111) alloy single crystal thin film has an atomic level flatness (the fluctuation degree is not higher than 0.5 nm), so that the grown graphene cannot be wrinkled through the flat substrate, and the electrical, magnetic and thermal conductive properties of the graphene cannot be reduced due to the existence of the wrinkles, and the graphene quality is improved. In addition, the nickel-copper (111) alloy single crystal thin film obtained by the preparation method has a high catalytic ability to decompose organic gases such as methane, ethane and acetylene at a low temperature through the nickel atoms in the alloy, so that the graphene is catalytically grown efficiently. In particular, the growth of the graphene on the nickel-copper (111) alloy single crystal thin film obtained by the preparation method can be carried out at 800℃ or below, which is lower than the lowest growth temperature of copper, i.e. 900℃. In summary, the nickel-copper (111) alloy single crystal thin film obtained by the preparation method greatly improves the performance of the graphene, and lays a foundation for the application of the graphene in the microelectronic field. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 FIG. 1 is a photo of a nickel-copper (111) alloy single crystal thin film obtained according to the first embodiment of the application;

[0020] Figure 2 FIG. 2 is a scanning optical microscope photo of the nickel-copper (111) alloy single crystal thin film obtained according to the first embodiment of the application;

[0021] Figure 3 FIG. 3 is a scanning electron microscope photo of the nickel-copper (111) alloy single crystal thin film obtained according to the first embodiment of the application;

[0022] Figure 4 FIG. 4 is an atomic force microscope photo of the nickel-copper (111) alloy single crystal thin film obtained according to the first embodiment of the application;

[0023] Figure 5is an out-of-plane X-ray diffraction pattern of a nickel-copper (111) alloy single crystal thin film obtained according to the first embodiment of the present application;

[0024] Figure 6 is an in-plane X-ray diffraction pattern of a nickel-copper (111) alloy single crystal thin film obtained according to the first embodiment of the present application;

[0025] Figure 7 is a photograph of a nickel-copper (111) alloy single crystal thin film obtained according to the second embodiment of the present application;

[0026] Figure 8 is a photograph of a nickel-copper (111) alloy single crystal thin film obtained according to the third embodiment of the present application. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present application will be described below in detail with reference to the accompanying drawings.

[0028] The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified.

[0029] Example 1

[0030] Step a: a 2-inch sapphire wafer was selected.

[0031] Step b: the sapphire wafer was cleaned and placed in deionized water for ultrasonic treatment for 30 min, and then cleaned with a high-purity nitrogen gun; the sapphire wafer was placed in an acetone solution for ultrasonic treatment for 30 min, and then cleaned with a high-purity nitrogen gun.

[0032] Step c: the sapphire wafer was placed in a muffle furnace for high-temperature annealing, the annealing temperature was 1100℃, the annealing time was 12 hours, and the sapphire wafer was naturally cooled to room temperature to obtain a sapphire substrate.

[0033] Step d: a 600-nm-thick metal thin film was deposited on the crystal surface Al2O3(0001) of the sapphire substrate by a magnetron sputtering method, the sapphire substrate was heated to a temperature of 200℃, the sputtering rate (deposition rate) was 20 nm / min, the argon gas was 0.5 pa, and the power was 400 w, to obtain a sapphire substrate with a nickel-copper alloy deposited thereon (nickel-copper / sapphire).

[0034] Step e: annealing treatment of nickel copper / sapphire. The sapphire substrate is placed in a chemical vapor deposition furnace for annealing treatment. The temperature is raised to 600 DEG C at a rate of 10 DEG C / min, the ratio of argon and hydrogen is 500 sccm:40 sccm; the temperature is kept at 600 DEG C for 60 min, the ratio of argon and hydrogen is 500 sccm:20 sccm; the temperature is raised to 1000 DEG C at a rate of 10 DEG C / min from 600 DEG C, the ratio of argon and hydrogen is 500 sccm:20 sccm; the temperature is kept at 1000 DEG C for 60 min, the ratio of argon and hydrogen is 500 sccm:10 sccm; after annealing, the temperature is lowered to room temperature at a rate of 4 DEG C / min, the ratio of argon and hydrogen is 500 sccm:5 sccm, and a nickel copper (111) alloy single crystal thin film is obtained.

[0035] The morphology is characterized as follows:

[0036] The morphology of the obtained nickel copper (111) alloy single crystal thin film is characterized, wherein, Figure 1 is a photo of the obtained nickel copper (111) alloy single crystal thin film; Figure 2 is a scanning optical microscope photo of the obtained nickel copper (111) alloy single crystal thin film, and it can be seen from the photo that the surface of the substrate is very smooth in a large range; Figure 3 is a scanning electron microscope photo of the obtained nickel copper (111) alloy single crystal thin film, and it can be seen from the photo that the surface of the alloy thin film is very smooth and no grain boundary is found under high magnification; Figure 4 is an atomic force microscope photo of the obtained nickel copper (111) alloy single crystal thin film, and it can be seen from the photo that the alloy substrate is smooth and the surface roughness is 0.5 nm.

[0037] Therefore, the nickel copper (111) alloy single crystal thin film obtained by the preparation method has atomic level smoothness, so that the grown graphene cannot be wrinkled by using the smooth substrate, and the electrical properties of the graphene cannot be reduced due to the existence of wrinkles, and the quality of the graphene is improved.

[0038] The single crystal property is characterized as follows:

[0039] The single crystal property of the obtained nickel copper (111) alloy single crystal thin film is characterized, wherein, Figure 5 is an out-of-plane X-ray diffraction pattern of the obtained nickel copper (111) alloy single crystal thin film, and the peak at 43.5 DEG in the pattern is a nickel copper (111) alloy orientation peak, indicating that the alloy thin film is a (111) oriented film, wherein the (111) surface is the most closely packed surface in the hexagonal close-packed structure of the nickel alloy, the mismatch of the atomic arrangement lattice thereof with the graphene lattice is low, and the graphene can be well epitaxially grown; and the catalytic property thereof is stronger than that of other surfaces; Figure 6is the in-plane X-ray diffraction pattern of the obtained nickel-copper (111) alloy single crystal thin film. Three peaks can be seen in the figure, which are 120° apart from each other, and are triple symmetric, thus indicating that the alloy thin film is a single crystal nickel-copper (111) thin film, and the surface of the thin film is (111) surface.

[0040] Example 2

[0041] Step a: select a 2-inch sapphire wafer.

[0042] Step b: clean the sapphire wafer, put it in deionized water for ultrasonic cleaning for 30 min, and blow it clean with a high-purity nitrogen gun; put it in an acetone solution for ultrasonic cleaning for 30 min, and blow it clean with a high-purity nitrogen gun.

[0043] Step c: place the sapphire wafer in a muffle furnace for high-temperature annealing, with an annealing temperature of 1100°C, annealing for 12 hours, and naturally cooling to room temperature to obtain a sapphire substrate.

[0044] Step d: using the method of molecular beam epitaxy (MBE), deposit a 50 nm thick metal thin film on the crystal surface Al2O3(0001) of the sapphire substrate, wherein the proportion of nickel atoms in the total number of atoms is 1%, the sapphire substrate is heated to a temperature of 100°C, the sputtering rate is 0.1 nm / min, and a sapphire substrate deposited with a nickel-copper alloy (nickel-copper / sapphire) is obtained.

[0045] Step e: annealing treatment of nickel-copper / sapphire. Place the sapphire substrate in a chemical vapor deposition furnace for annealing treatment. Increase the temperature to 200°C at a rate of 0.1°C / min, with an argon and hydrogen ratio of 10 sccm:1 sccm; maintain the temperature at 200°C for 10 min, with an argon and hydrogen ratio of 10 sccm:1 sccm; increase the temperature from 200°C to 600°C at a rate of 0.1°C / min, with an argon and hydrogen ratio of 10 sccm:1 sccm; anneal at 600°C for 10 min, with an argon and hydrogen ratio of 500 sccm:10 sccm; after annealing, decrease the temperature to room temperature at a rate of 0.01°C / min, with an argon and hydrogen ratio of 10 sccm:50 sccm, to obtain a nickel-copper (111) alloy single crystal thin film.

[0046] Figure 7 is a photograph of the obtained nickel-copper (111) alloy single crystal thin film, in which the surface of the substrate can be seen to be very smooth.

[0047] Example 3

[0048] Step a: select a 6-inch sapphire wafer.

[0049] Step b: clean the sapphire wafer, put it into deionized water and ultrasonic for 30 min, clean it with high purity nitrogen gun; put it into acetone solution and ultrasonic for 30 min, clean it with high purity nitrogen gun.

[0050] Step c: put the sapphire wafer into the muffle furnace for high temperature annealing, the annealing temperature is 1100℃, annealing for 12 hours, natural cooling to room temperature, to get the sapphire substrate.

[0051] Step d: use the method of magnetron sputtering to deposit 5000nm thick metal film on the crystal surface Al2O3(0001) of the sapphire substrate, the proportion of nickel atoms in the total number of atoms is 40%, the sapphire substrate is heated to a temperature of 900℃, the sputtering rate is 100nm / min, the argon is 0.5pa, the power is 50w, to get the sapphire substrate deposited with nickel copper alloy (nickel copper / sapphire).

[0052] Step e: annealing treatment of nickel copper / sapphire. Put the sapphire substrate into the chemical vapor deposition furnace for annealing treatment. Increase the temperature to 600℃ at a rate of 50℃ / min, the proportion of argon and hydrogen is 1000sccm:500sccm; keep the temperature at 600℃ for 240min, the proportion of argon and hydrogen is 1000sccm:300sccm; increase the temperature from 600℃ to 1100℃ at a rate of 50℃ / min, the proportion of argon and hydrogen is 1000sccm:300sccm; annealing at 1100℃ for 240min, the proportion of argon and hydrogen is 1000sccm:100sccm; after annealing, decrease the temperature to room temperature at a rate of 100℃ / min, the proportion of argon and hydrogen is 1000sccm:50sccm, to get the nickel copper (111) alloy single crystal thin film.

[0053] Figure 8 The photo of the obtained nickel copper (111) alloy single crystal thin film, the surface of the substrate can be seen in the figure is very smooth.

[0054] The above described, only for the preferred embodiments of the present application, not to limit the scope of the present application, the above embodiments of the present application can also be made various changes. That is, according to the present application, the claims and the contents of the specification of the simple, equivalent changes and modifications, all fall within the scope of the present application patent claims. The present application is not described in detail, all are conventional technical content.

Claims

1. A method for preparing a nickel-copper alloy single-crystal thin film, characterized in that, Includes the following steps: S1, provide a sapphire sheet, clean the sapphire sheet, and place the cleaned sapphire sheet in a muffle furnace for high-temperature annealing at 1100℃ to obtain a sapphire substrate; S2, simultaneously depositing nickel and copper atoms, depositing a 50-5000nm thick metal film on the Al2O3(0001) crystal plane of the sapphire substrate to obtain a sapphire substrate with deposited nickel-copper alloy, wherein the metal film is an alloy film composed of nickel atoms and copper atoms, with nickel atoms accounting for 1-40% of the total number of atoms. S3, the sapphire substrate is placed in a chemical vapor deposition furnace and annealed in an argon and hydrogen atmosphere. The temperature is increased to 600℃ at a rate of 10℃ / min, with an argon to hydrogen ratio of 500 sccm:40 sccm; it is then held at 600℃ for 60 min, with an argon to hydrogen ratio of 500 sccm:20 sccm; finally, the temperature is increased from 600℃ to 1000℃ at a rate of 10℃ / min, with an argon to hydrogen ratio of 500 sccm. m: 20 sccm; annealed at 1000℃ for 60 min, with an argon to hydrogen ratio of 500 sccm: 10 sccm; after annealing, cooled to room temperature at a rate of 4℃ / min, with an argon to hydrogen ratio of 500 sccm: 5 sccm, to obtain a nickel-copper alloy single crystal thin film with a (111) crystal orientation. The out-of-plane X-ray diffraction pattern of the single crystal thin film has a (111) alloy orientation peak, and the in-plane X-ray diffraction pattern of the single crystal thin film has a triplet symmetric peak.

2. The preparation method according to claim 1, characterized in that, Step S2 includes: depositing sapphire substrate at a rate of 0.1 nm / min to 100 nm / min while heating the sapphire substrate to 100°C to 900°C.

3. The preparation method according to claim 2, characterized in that, Step S2 specifically involves deposition via magnetron sputtering, thermal evaporation, electron beam evaporation, or molecular beam epitaxy.

4. A nickel-copper alloy single-crystal thin film obtained by the preparation method according to any one of claims 1-3, wherein the nickel-copper alloy single-crystal thin film has a (111) alloy orientation.

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