Amorphous gold-nickel alloy film and method thereof

Abstract

The present invention relates to the technical field of amorphous alloy materials, and provides an amorphous gold-nickel alloy film and a preparation method thereof. The present invention uses alkylthiols with a certain molecular coverage to orderly assemble on the surface of a gold film to form a molecular template, and uses the molecular template to regulate the structural characteristics of the gold-nickel alloy. The nickel atoms deposited on the molecular template can break the original Au-S chemical bonds of the system and directly contact the gold atoms. At the same time, the nickel atoms are regulated by the intermolecular interaction force in the template, and finally form a two-dimensional amorphous gold-nickel alloy film. The preparation method provided by the present invention has low cost and simple process. The obtained two-dimensional amorphous gold-nickel alloy film has relatively ideal amorphous degree and purity, and has broad application prospects in the fields of nanoelectronic devices, integrated circuit storage chips, and multiphase catalysis.

Description

Technical Field

[0001] The invention relates to the technical field of amorphous alloy materials, and in particular to an amorphous gold-nickel alloy film and a preparation method thereof. Background Art

[0002] Amorphous materials are ubiquitous in our daily lives, such as glass, lubricants, colloids, emulsions, and polymers. So far, four Nobel Prizes related to amorphous materials have been awarded. Amorphous alloys are an important type of amorphous materials. They are composed of metallic amorphous phases and nanocrystalline phases. Compared with conventional alloy materials, amorphous alloys have higher strength and good toughness, thus having important structural and functional applications. As early as 1960, Klement et al. discovered the first amorphous alloy. With the development of new technologies and new theories, researchers have developed some methods for obtaining amorphous alloys in the past few decades, providing some ways to prepare in-situ amorphous alloy materials.

[0003] At present, the research on amorphous gold-nickel alloys is mostly focused on bulk materials. A variety of amorphous alloys can be prepared by rapid cooling technology. Compared with bulk materials, the progress of low-dimensional nanomaterial growth technology has brought about a breakthrough in amorphous alloy materials. Due to the size effect, low-dimensional structures such as amorphous one-dimensional metal nanorods and two-dimensional films show better performance than bulk materials, such as better tensile ductility and plasticity. There are many methods to form low-dimensional nano amorphous alloys, including furnace or flash annealing, cold rolling, ball milling, and ultrasonic vibration. In principle, material crystallization is related to the nucleation and growth of crystals. These methods all have the shortcoming of in-situ growth observation at the atomic scale. It is worth noting that some researchers have directly deposited nickel atoms on the surface of gold films by combining ultra-high vacuum evaporation with in-situ observation technology, obtained gold-nickel alloy clusters and explored their nucleation rules [J.Phys.Chem.C 2016,120,13574-13580]. However, due to the high requirements for amorphousness in metallic glass components, the conventional two-dimensional gold-nickel alloy material directly deposited on the surface of the gold film lacks the structural characteristics of the amorphous alloy material, which may affect its functional application. Therefore, it is urgent to develop a method to grow two-dimensional amorphous gold-nickel alloy films at the atomic scale. Summary of the invention

[0004] In view of this, the present invention provides an amorphous gold-nickel alloy film and a preparation method thereof. The present invention utilizes alkylthiols to orderly assemble on the surface of the gold film to form a molecular template, and utilizes the molecular template to grow and control a two-dimensional amorphous gold-nickel alloy film at the atomic scale.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A method for preparing an amorphous gold-nickel alloy thin film comprises the following steps:

[0007] Using a chemical liquid phase method or a chemical vapor phase method, alkylthiol molecules are deposited on the surface of the gold film to form a molecular template; the molecular coverage of the molecular template on the surface of the gold film is 0.33ML;

[0008] Nickel atoms are evaporated and deposited on the surface of a gold film with a molecular template, and then a first annealing is performed to obtain an amorphous gold-nickel alloy film; the nickel atom coverage of the amorphous gold-nickel alloy film is 0.3-0.35ML.

[0009] Preferably, the chemical liquid phase method comprises: immersing the gold film in an alkylthiol molecular solution and then performing a second annealing to form a molecular template on the surface of the gold film; the concentration of the alkylthiol molecular solution is 5 to 20 mmol / L; the immersion time is 5 to 8 hours; the temperature of the second annealing is 50 to 55°C, and the time is 1 to 1.2 hours; the environmental vacuum degree of the second annealing is 3×10 -10 Below mbar.

[0010] Preferably, the chemical vapor method comprises: chemical vapor deposition of alkylthiol molecules on the surface of a gold film to form a molecular template; the molecular flux of the alkylthiol molecules is 0.3 to 0.35 mL / h; during the chemical vapor deposition, the temperature of the gold film is 280 to 300 K, and the deposition time is 1 to 1.2 h.

[0011] Preferably, the number of carbon atoms in the alkyl chain of the alkylthiol molecule is ≥8.

[0012] Preferably, the alkyl mercaptan molecule is one or more of octanethiol, decanethiol and dodecanethiol.

[0013] Preferably, the target material used in the evaporation deposition is a nickel target material, and the substrate is a gold film with a molecular template; during the evaporation deposition process, the temperature of the substrate is room temperature, and the temperature of the nickel target material is 1045-1050°C.

[0014] Preferably, the nickel target is preheated before the evaporation deposition, the preheating temperature is 1000-1020° C., and the preheating time is 25-30 minutes.

[0015] Preferably, the first annealing is performed at a temperature of 60 to 65° C. and for a time of 1 to 1.2 hours.

[0016] Preferably, the thickness of the gold film is 2 to 10 mm.

[0017] The present invention also provides an amorphous gold-nickel alloy film prepared by the preparation method described in the above scheme.

[0018] The present invention provides a method for preparing an amorphous gold-nickel alloy film, comprising the following steps: using a chemical liquid phase method or a chemical vapor phase method to deposit alkylthiol molecules on the surface of a gold film to form a molecular template; the molecular coverage of the molecular template on the surface of the gold film is 0.33ML; performing nickel atom evaporation deposition on the surface of the gold film with the molecular template, and then performing a first annealing to obtain an amorphous gold-nickel alloy film; the nickel atom coverage of the amorphous gold-nickel alloy film is 0.3ML. In the present invention, alkylthiols with a certain molecular coverage are orderly assembled on the surface of the gold film to form a molecular template, and the molecular template is used to regulate the structural characteristics of the gold-nickel alloy. The molecular template formed by alkylthiols can be regarded as a regulating medium, which can affect the diffusion nucleation process of the deposited nickel atoms on the gold surface; at the same time, under the intermolecular van der Waals interaction, the assembly configuration of the alkylthiol molecules can regulate the structure of the gold-nickel alloy film. Compared with the prior art, the method provided by the present invention can regulate the formation process of the alloy (from alloy nanodots / clusters to two-dimensional films) at the atomic scale, and the obtained alloy film has very high amorphous degree and purity. In addition, the alkylthiol molecule deposition method of the present invention can adopt chemical liquid phase method and chemical vapor phase method, which is easy to operate. Further, the alkylthiol molecule used in the present invention can be any thiol molecule with an alkyl chain length greater than octanethiol, and has a wide range of applications.

[0019] The preparation method provided by the present invention has low cost and simple process. The obtained two-dimensional amorphous gold-nickel alloy film has relatively ideal amorphous degree and purity, and has broad application prospects in the fields of nanoelectronic devices, integrated circuit storage chips, and multiphase catalysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The microstructure of the octanethiol molecular template prepared in Example 1 (image size is 42 nm) 2 );

[0021] Figure 2 The microstructure of the amorphous gold-nickel alloy film prepared in Example 1 (image size is 150 nm) 2 );

[0022] Figure 3 The microstructure of the gold-nickel alloy film prepared in Comparative Example 1 (image size is 7.5 nm) 2 ), the upper left illustration is a theoretical simulation of the gold-nickel alloy cluster;

[0023] Figure 4 The microscopic result of the gold-nickel alloy film prepared in Comparative Example 2 (image size is 280 nm) 2 ). DETAILED DESCRIPTION

[0024] The present invention provides a method for preparing an amorphous gold-nickel alloy thin film, comprising the following steps:

[0025] Using a chemical liquid phase method or a chemical vapor phase method, alkylthiol molecules are deposited on the surface of the gold film to form a molecular template; the molecular coverage of the molecular template on the surface of the gold film is 0.33ML;

[0026] Nickel atoms are evaporated and deposited on the surface of a gold film with a molecular template, and then a first annealing is performed to obtain an amorphous gold-nickel alloy film; the nickel atom coverage of the amorphous gold-nickel alloy film is 0.3-0.35ML.

[0027] The present invention uses a chemical liquid phase method or a chemical vapor phase method to deposit alkylthiol molecules on the surface of a gold film to form a molecular template. In the present invention, the thickness of the gold film is preferably 2 to 10 mm, more preferably 3 to 8 mm; before depositing the alkylthiol molecules, the side of the gold film to be deposited is preferably polished; the present invention has no special requirements for the polishing method, and a method familiar to those skilled in the art can be used; in a specific embodiment of the present invention, a single side surface of the gold film is polished, and then the alkylthiol molecular template is deposited on the polished surface, and then nickel atoms are evaporated on the side where the alkylthiol molecular template is deposited.

[0028] In the present invention, the chemical liquid phase method comprises: immersing the gold film in an alkylthiol molecular solution and then performing a second annealing to form a molecular template on the surface of the gold film; the concentration of the alkylthiol molecular solution is preferably 5 to 20 mmol / L, more preferably 10 to 15 mmol / L; the immersion time is preferably 5 to 8 hours, more preferably 6 to 7 hours, and the immersion temperature is preferably room temperature; the temperature of the second annealing is 50 to 55°C, and the time is 1 to 1.2 hours; the environmental vacuum degree of the second annealing is preferably 3×10 -10 mbar or less, more preferably 10 -11 ~3×10 -10 The present invention performs low-temperature annealing in an ultra-high vacuum environment, which can remove impurity molecules on the surface of the molecular template, thereby ensuring the purity of the molecular template and further obtaining an ideal alkylthiol molecular template.

[0029] In the present invention, the chemical vapor method preferably comprises: chemical vapor deposition of alkyl mercaptan molecules on the surface of a gold film to form a molecular template; the molecular flux of the alkyl mercaptan molecules is preferably 0.3 to 0.35 mL / h; in the chemical vapor deposition, the temperature of the gold film is preferably 280 to 300 K, more preferably 300 K, and the deposition time is preferably 1 to 1.2 h; the purity of the alkyl mercaptan molecules is preferably ≥ 98.5%; in the present invention, the alkyl mercaptan molecules are preferably first loaded into a glass test tube connected to an ultra-high vacuum device, degassed by 3 to 5 cycles of a freeze-thaw pump, and then the molecular flux is controlled within the above range by a micro-leak valve to perform chemical vapor deposition; the vacuum degree in the glass test tube is preferably 10 -10 mbar; alkyl mercaptan is liquid at room temperature. The present invention introduces it into a glass test tube in an ultra-high vacuum environment, evaporates the alkyl mercaptan into a molecular beam through the principle of air pressure difference, and then combines a micro-leak valve to control the flow of the molecular beam to evaporate it onto the surface of the gold film.

[0030] In the present invention, the number of carbon atoms in the alkyl chain of the alkyl mercaptan molecule is preferably ≥8, more preferably 8 to 12; specifically, the alkyl mercaptan molecule is preferably one or more of octanethiol, decanethiol and dodecanethiol, more preferably octanethiol.

[0031] The present invention deposits alkylthiol molecules on the surface of a gold film by a chemical liquid phase method or a chemical vapor phase method, and the alkylthiol molecules are orderly assembled on the surface of the gold film to form a molecular template; and the present invention controls the molecular coverage at 0.33ML (i.e., the full coverage layer of the molecule), which can ensure that an amorphous gold-nickel alloy film is obtained. If the molecular coverage is small, it is insufficient to provide enough gold atoms to form an alloy with nickel atoms, so that only a conventionally shaped two-dimensional metal film (such as Figure 4 shown).

[0032] After forming the molecular template, the present invention performs nickel atom evaporation deposition on the surface of the gold film with the molecular template, and then performs a first annealing to obtain an amorphous gold-nickel alloy film; the nickel atom coverage of the amorphous gold-nickel alloy film is 0.3-0.35ML, more preferably 0.3ML; in the present invention, if the nickel atom coverage is small, it is not enough to provide enough nickel atoms to form an alloy with the gold atoms, and it is more inclined to form regular alloy clusters (such as Figure 3 If the coverage of nickel atoms is large, it will lead to excess nickel atoms on the surface, thus forming a nickel film.

[0033] In the present invention, the target material used for the evaporation deposition is preferably a nickel target material, and the substrate is a gold film with a molecular template; the temperature of the substrate during the evaporation deposition process is preferably room temperature, and the temperature of the nickel target material is preferably 1045-1050°C; the present invention controls the temperature of the nickel target material at 1045-1050°C, which can ensure that the nickel in the nickel target material is sprayed onto the surface of the molecular template in the form of a single atom.

[0034] In the present invention, the nickel target material is preferably preheated before the evaporation deposition, the preheating temperature is preferably 1000-1020° C., and the time is preferably 25-30 min. The present invention removes impurities in the nickel target material by preheating.

[0035] In the present invention, the time of the evaporation deposition is preferably 18 to 20 minutes; after the nickel atoms are deposited on the surface of the molecular template, they can break the Au-S chemical bonds in the film and thus come into contact with the gold atoms. This process is accompanied by a partial loss of energy of the nickel atoms. At the same time, under the regulation of the intermolecular forces in the molecular template, the nickel atoms will first nucleate to form clusters of several or more than a dozen atoms. As the amount of nickel atom deposition gradually increases, the surface clusters gradually expand into a two-dimensional film.

[0036] In the present invention, the temperature of the first annealing is preferably 60-65°C, and the time is preferably 1-1.2h; since the deposition of nickel atoms breaks the Au-S chemical bond, the alkylthiol molecules adsorbed on the gold surface are transferred to the surface of the gold-nickel alloy film. In order to eliminate the possible influence of thiol molecules on the application of film performance, the present invention performs low-temperature annealing under the above conditions, which can desorb the thiol molecules on the surface of the film. At the same time, the relatively mild annealing parameters can ensure that the structural properties of the gold-nickel alloy film are not affected, thereby finally obtaining a high-quality two-dimensional amorphous gold-nickel alloy film.

[0037] The present invention also provides an amorphous gold-nickel alloy film prepared by the preparation method described in the above scheme; the two-dimensional amorphous gold-nickel alloy film provided by the present invention has relatively ideal amorphous degree and purity, and has broad application prospects in the fields of nanoelectronic devices, integrated circuit storage chips, and multiphase catalysis.

[0038] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Example 1

[0040] After polishing one side of a 2 mm thick gold film, the film was immersed in a 5 mmol / L octanethiol solution for 5 h at room temperature. -10 mbar) annealed for 1h at 50°C to form alkylthiol molecular templates on the surface of the gold film. The molecular coverage of alkylthiol on the surface of the gold film was 0.33ML. The molecular templates on the surface of the gold film were observed using a scanning probe microscope. The results are as follows Figure 1 As shown (image size is 42nm 2 ), Figure 1 The microstructure in is the molecular template used in the present invention.

[0041] The gold film with alkylthiol molecular template was used as the substrate, and nickel atoms were deposited on the side with the molecular template. Specifically, the nickel target was heated at 1000°C for 30 minutes, and then the temperature of the nickel target was increased to 1050°C for evaporation deposition of nickel atoms. The substrate temperature was controlled at room temperature throughout the process. The deposition time was 18 minutes, and the atomic coverage of nickel atoms on the surface of the gold-nickel alloy film was controlled to be 0.3ML. After annealing at 60°C for 1 hour, a two-dimensional amorphous gold-nickel alloy film was obtained. The obtained amorphous gold-nickel alloy film was observed by scanning probe microscopy, and the results are as follows: Figure 2 As shown (image size is 150nm 2 ). Figure 2 As shown in FIG. 1 , the amorphous gold-nickel alloy film exhibits a relatively dark appearance, which is consistent with the apparent light-dark characteristics of the conventional gold-nickel alloy clusters in Comparative Example 1, indicating that the alloy material obtained in Example 1 is a Figure 3 It can be seen that an amorphous alloy is obtained in Example 1, while a conventional alloy cluster is obtained in Comparative Example 1 without forming an amorphous structure.

[0042] Comparative Example 1

[0043] The other conditions were the same as those in Example 1, except that the coverage of the nickel atom deposition was changed to 0.08 ML. The obtained film was observed using a scanning probe microscope, and the results were as follows: Figure 3 As shown (image size is 4.5nm 2 ), Figure 3 The upper left corner is an illustration of the theoretical simulation. Figure 3 The dark spots in the figure are the gold-nickel alloy clusters measured under a scanning probe microscope. They have a regular apparent configuration and no amorphous structural features are observed. In addition, the theoretical simulation illustration on the upper left is consistent with the image features observed experimentally.

[0044] Comparative Example 2

[0045] The other conditions were the same as those in Example 1, except that the molecular coverage of alkylthiol in the molecular template was changed to 0.23 ML. The obtained film was observed using a scanning probe microscope, and the results were as follows: Figure 4 As shown (image size is 280nm 2 );according to Figure 4 It can be seen that the nickel atoms are in the form of regular metal islands, indicating that the nickel atoms form conventional two-dimensional materials on the surface of the molecular template, and the resulting film does not have the structural characteristics of an amorphous structure.

[0046] Example 2

[0047] The other conditions were the same as those in Example 1, except that octanethiol was replaced by decanethiol. The obtained gold-nickel alloy film was observed using a scanning probe microscope, and the results showed that the obtained gold-nickel alloy film had an amorphous structure.

[0048] Example 3

[0049] The other conditions were the same as those in Example 1, except that octanethiol was replaced by dodecanethiol. The obtained gold-nickel alloy film was observed using a scanning probe microscope, and the results showed that the obtained gold-nickel alloy film had an amorphous structure.

[0050] Example 4

[0051] Other conditions are the same as those in Example 1, except that the preparation method of the molecular template is changed to a chemical vapor deposition method, specifically: octanethiol with a purity ≥ 98.5% is placed in a glass test tube connected to an ultra-high vacuum device, and degassing is performed through three freeze-thaw pump cycles. The octanethiol molecules are evaporated into a molecular beam using the principle of air pressure difference, and the molecular beam flow is controlled to 0.3ML / h through a micro-leak valve. Chemical vapor deposition is performed on the surface of a 2mm thick, polished gold film. The temperature of the gold film is controlled to 300K, the deposition time is 1h, and the coverage of the alkylthiol molecular template on the gold film surface is 0.33ML.

[0052] The obtained gold-nickel alloy film was observed using a scanning probe microscope, and the results showed that the obtained gold-nickel alloy film had an amorphous structure.

[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an amorphous gold-nickel alloy thin film, characterized in that: The following steps are involved: Using a chemical liquid phase method or a chemical vapor phase method, alkylthiol molecules are deposited on the surface of the gold film to form a molecular template; The molecular coverage of the molecular template on the surface of the gold film is 0.33ML; Performing nickel atom evaporation deposition on the surface of the gold film with the molecular template, and then performing a first annealing to obtain an amorphous gold-nickel alloy film; the nickel atom coverage of the amorphous gold-nickel alloy film is 0.3-0.35ML; The number of carbon atoms in the alkyl chain of the alkylthiol molecule is ≥ 8; The target material used in the evaporation deposition is a nickel target material, and the substrate is a gold film with a molecular template; the temperature of the substrate during the evaporation deposition process is room temperature, and the temperature of the nickel target material is 1045-1050°C; The first annealing is performed at a temperature of 60 to 65° C. and for a time of 1 to 1.2 hours.

2. The preparation method according to claim 1, characterized in that: The chemical liquid phase method comprises: immersing the gold film in an alkylthiol molecular solution and then performing a second annealing to form a molecular template on the surface of the gold film; the concentration of the alkylthiol molecular solution is 5 to 20 mmol / L; the immersion time is 5 to 8 hours; the temperature of the second annealing is 50 to 55° C., the time is 1 to 1.2 hours; the environmental vacuum degree of the second annealing is 3×10 -10 Below mbar.

3. The preparation method according to claim 1, characterized in that: The chemical vapor method comprises: chemical vapor deposition of alkylthiol molecules on the surface of a gold film to form a molecular template; the molecular flux of the alkylthiol molecules is 0.3 to 0.35 mL / h; during the chemical vapor deposition, the temperature of the gold film is 280 to 300 K, and the deposition time is 1 to 1.2 hours.

4. The preparation method according to claim 1, characterized in that: The alkyl mercaptan molecules are one or more of octanethiol, decanethiol and dodecanethiol.

5. The preparation method according to claim 1, characterized in that: The nickel target material is preheated before the evaporation deposition, the preheating temperature is 1000-1020° C., and the preheating time is 25-30 minutes.

6. The preparation method according to claim 1, characterized in that: The thickness of the gold film is 2 to 10 mm.

7. The amorphous gold-nickel alloy thin film prepared by the preparation method according to any one of claims 1 to 6.

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