Josephson junction device and method of making the same

Abstract

The application provides a Josephson junction device and a preparation method thereof. The preparation method comprises the following steps: preparing a first substrate and a single crystal thin film; forming a first electrode and a second electrode which are arranged at intervals on the first substrate; transferring the single crystal thin film to the first substrate and covering at least a part of the first electrode; performing annealing treatment on the first substrate to which the single crystal thin film is attached; performing cleavage on the single crystal thin film after the annealing treatment, so as to obtain a first thin film left on the first electrode and a second thin film separated from the first thin film; and transferring the second thin film to the first substrate and covering at least a part of the second electrode and a first part of the first thin film; wherein the first thin film and the second thin film have a first angle therebetween. The Josephson junction prepared by the application has good quality.

Description

Technical Field

[0001] This invention relates to the field of materials, and more specifically, to a Josephson junction device, its fabrication method, and its applications. Background Technology

[0002] Josephson junctions are an important tool for studying the intrinsic properties of superconducting materials. They are formed by weak coupling between two identical or different superconductors, enabling Cooper pair tunneling. In current techniques, Josephson junction fabrication typically involves first preparing a corner Josephson junction at low temperatures, followed by the deposition of metal electrodes. However, in this process, the high-temperature metal source or mask in the electron beam evaporation coating machine can affect the quality of the junction.

[0003] The content of the background section is merely the technology known to the inventor and does not necessarily represent the prior art in this field. Summary of the Invention

[0004] To address one of the aforementioned problems, a first aspect of the present invention provides a method for fabricating a Josephson junction device, comprising:

[0005] Prepare the first substrate and the single-crystal thin film;

[0006] A first electrode and a second electrode are formed on the first substrate at a distance from each other;

[0007] The single-crystal thin film is transferred onto the first substrate and covers at least a portion of the first electrode;

[0008] The first substrate with the attached single crystal thin film is subjected to annealing treatment;

[0009] The single-crystal thin film after the annealing treatment is cleaved to obtain a first thin film remaining on the first electrode and a second thin film separated from the first thin film; and

[0010] The second thin film is transferred onto the first substrate and covers at least a portion of the second electrode and a first portion of the first thin film; wherein the first thin film and the second thin film have a first angle between them.

[0011] In some embodiments of the present invention, the above preparation method further includes:

[0012] Separate the second thin film from the first substrate, the second electrode, and the first thin film; and

[0013] The second film is transferred back onto the first substrate, covering at least a portion of the second electrode and a second portion of the first film;

[0014] The second film and the first film have a second angle, which is not equal to the first angle.

[0015] In some embodiments of the present invention, separating the second thin film from the substrate, the second electrode, and the first thin film includes:

[0016] The second film is separated from the substrate, the second electrode, and the first film using a transfer medium at an ambient temperature below -60°C.

[0017] In some embodiments of the present invention, preparing a single-crystal thin film includes:

[0018] Prepare the single crystal sample and the second substrate;

[0019] The single crystal sample was dissected using adhesive tape, and the resulting sample film was transferred onto the second substrate; and

[0020] The sample film on the second substrate is dissociated using a transfer medium to obtain the single-crystal thin film.

[0021] In some embodiments of the present invention, forming a first electrode and a second electrode spaced apart on the first substrate includes:

[0022] Clean the first substrate;

[0023] A patterned first photoresist layer and a second photoresist layer are formed at intervals on the cleaned first substrate, respectively; and

[0024] The first electrode and the second electrode are formed by depositing films on the first photoresist layer and the second photoresist layer, respectively.

[0025] In some embodiments of the present invention, transferring the single-crystal thin film onto the first substrate and covering at least a portion of the first electrode includes:

[0026] The single-crystal thin film is transferred onto the first substrate using a transfer medium at an ambient temperature below -60°C, thereby bonding the single-crystal thin film to at least a portion of the first electrode; and

[0027] The ambient temperature is raised to above -40°C, causing the transfer medium to be released slowly, thereby leaving the single crystal film on at least a portion of the first electrode.

[0028] In some embodiments of the present invention, the annealing process is carried out in an oxygen environment with a pressure of at least 600 mbar, a temperature of 250°C-300°C, and a time of at least 10 min.

[0029] In some embodiments of the present invention, cleaving the single-crystal thin film after the annealing treatment includes:

[0030] The single-crystal thin film was dissociated using a transfer medium at an ambient temperature below -60°C.

[0031] In some embodiments of the present invention, transferring the second thin film onto the first substrate and covering at least a portion of the second electrode and a first portion of the first thin film includes:

[0032] The second thin film is transferred onto the first substrate using the transfer medium, such that the second thin film adheres to at least a portion of the second electrode and the first portion of the first thin film; and

[0033] The ambient temperature is raised to above -40°C, causing the transfer medium to be released slowly, thereby leaving the first film on at least a portion of the second electrode and on the first portion of the first film.

[0034] In some embodiments of the present invention, the thickness of the single-crystal thin film is 50nm-100nm.

[0035] In some embodiments of the present invention, the transfer medium is polydimethylsiloxane.

[0036] A second aspect of the present invention provides a Josephson junction device comprising:

[0037] Substrate;

[0038] The first electrode is located on the substrate;

[0039] The second electrode is located on the substrate and is disposed at a distance from the first electrode;

[0040] A first thin film is located on the substrate and covers at least a portion of the first electrode; and

[0041] A second thin film is located on the substrate and covers at least a portion of the second electrode and a first portion of the first thin film;

[0042] The first film and the second film have a first angle between them.

[0043] In some embodiments of the present invention, the second film can be separated from the substrate, the second electrode, and the first film, and can be transferred back onto the first substrate to cover at least a portion of the second electrode and a second portion of the first film, thereby creating a second angle between the first film and the second film, wherein the second angle is not equal to the first angle.

[0044] In some embodiments of the present invention, the thickness of the first film is 35nm-90nm.

[0045] In some embodiments of the present invention, the thickness of the second film is 10nm-15nm.

[0046] In some embodiments of the present invention, the first electrode and the second electrode are titanium-gold electrodes, wherein the thickness of the titanium layer of the titanium-gold electrode is 1nm-10nm and the thickness of the gold layer of the titanium-gold electrode is 30nm-50nm.

[0047] The Josephson junction fabrication process provided by this invention is conducted in a low-temperature, anhydrous, and oxygen-free environment. Furthermore, the method of pre-fabricating the electrodes before fabricating the junction avoids damage to the sample interface and surface, resulting in a high-quality Josephson junction. Moreover, because the first thin film is transferred to the first electrode first, and then the second thin film is transferred to the second electrode and the first thin film, the contact surface between the first and second thin films is a new interface generated by cleavage, which is beneficial for improving the quality of the Josephson junction.

[0048] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0049] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0050] Figure 1 This is a flowchart illustrating the fabrication process of a Josephson junction according to an embodiment of the present invention.

[0051] Figure 2 A flowchart illustrating the fabrication process of the Josephson junction according to another embodiment of the present invention.

[0052] Figure 3 This is a schematic diagram of the Josephson junction provided in an embodiment of the present invention.

[0053] Figure 4 This is a schematic diagram of the Josephson knot provided in another embodiment of the present invention. Detailed Implementation

[0054] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0055] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0056] In this invention, the terms "first," "second," and other ordinal numbers are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0057] It should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between the components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0058] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings and examples, so as to better understand the solution of the present invention and its advantages in various aspects. However, the specific embodiments and examples described below are for illustrative purposes only and are not intended to limit the present invention.

[0059] like Figure 1 As shown, the present invention provides a method for fabricating a Josephson junction device, comprising the following steps S110-S160. Optionally, the apparatus used in the present invention for fabricating a Josephson junction device includes a cantilever and a sample stage. The sample stage is used to place a substrate, etc., and sapphire with an attached transfer medium is mounted on the cantilever.

[0060] S110: Prepare the first substrate and single-crystal thin film.

[0061] Optionally, the substrate used in this invention may include, but is not limited to, silicon dioxide / silicon, gallium arsenide, glass, magnesium oxide, or strontium titanate. The type and size of the substrate can be selected according to actual needs. In one embodiment of this invention, the first substrate used is 4mm × 10mm silicon dioxide / silicon.

[0062] Optionally, the single-crystal thin film used in this invention may include, but is not limited to, Bi2Sr2CaCu2O8, Bi2Sr2CuO6, and Bi2Sr2Ca2Cu3O. 10 Or Bi2Sr2Ca3Cu4O 12 Two-dimensional materials, etc.

[0063] Optionally, in this invention, preparing a single-crystal thin film includes:

[0064] Prepare the single crystal sample and the second substrate;

[0065] The single-crystal sample was dissected using adhesive tape, and the resulting sample film was transferred onto a second substrate; and

[0066] The sample film on the second substrate was dissociated using a transfer medium to obtain a single-crystal thin film.

[0067] Optionally, the second substrate used is the same size and material as the first substrate. In other embodiments of the invention, the second substrate and the first substrate may be different in material and size. In one embodiment of the invention, the second substrate used is a 4mm × 10mm silicon dioxide / silicon substrate.

[0068] The obtained second substrate is ultrasonically cleaned in acetone and isopropanol for about 10 minutes to obtain a clean substrate surface. Optionally, to increase the adhesion between the sample film and the second substrate, after ultrasonication in acetone and isopropanol, the surface of the second substrate is cleaned with oxygen plasma. In one embodiment of the present invention, cleaning is performed at a power of about 100W, an oxygen pressure of about 0.1mbar, and a time of about 1 minute.

[0069] Optionally, the single-crystal sample is cleaved with adhesive tape inside a glove box to obtain a sample film. After cleaving, one side of the sample film is attached to the tape, and the other side is a fresh surface. This fresh surface is then attached to the surface of a second substrate, and after waiting for about 1 minute, the tape is peeled off, leaving the sample film on the second substrate.

[0070] Optionally, the sample film on the second substrate is cleaved using a low-temperature cleaving method. The transfer medium can be polydimethylsiloxane (PDMS). In one embodiment of the invention, PDMS is prepared by mixing a matrix and a curing agent in a 10:1 ratio using Dow Corning Sylgard 184 as the raw material. Optionally, the prepared PDMS is transferred to a clean sapphire glass slide and rapidly baked on a hot plate to approximately 120°C (approximately 10 min) to ensure sufficient adhesion between the PDMS and the sapphire glass slide. The sapphire slide with PDMS is then mounted on the cantilever of the transfer stage. When the ambient temperature cools to below -60°C, the sample film is cleaved using PDMS to obtain a single-crystal thin film of approximately 50 nm-100 nm. One side of the single-crystal thin film is attached to the PDMS, and the other side is a fresh surface.

[0071] S120: A first electrode and a second electrode are formed on a first substrate at a distance from each other.

[0072] Optionally, this step includes:

[0073] Clean the first substrate;

[0074] A first photoresist layer and a second photoresist layer, respectively, are formed on a first substrate after cleaning, with patterns spaced apart; and

[0075] The first electrode and the second electrode are formed by depositing films on the first photoresist layer and the second photoresist layer, respectively.

[0076] Optionally, after ultrasonically cleaning the first substrate in acetone and isopropanol for about 10 min, spin-coating with methyl methacrylate (PMMA) adhesive (spin-coating speed can be about 4 kr / min, spin-coating time can be about 1 min, spin-coating thickness can be about 200 nm) is performed, followed by baking on a hot plate at a temperature of about 180°C for about 2 min. Then, the PMMA adhesive is bombarded with an electron beam to expose and form an electrode pattern area. After that, it is developed with a developer (volume ratio can be methyl isopropanol: indolepropionic acid = 1:3) for about 1 min, and fixed with a fixer (isopropanol) for about 1 min. Through development and fixing, the PMMA adhesive in the electrode pattern area of ​​the electron beam bombardment area is removed, forming a patterned first photoresist layer and a second photoresist layer with spaced intervals.

[0077] Optionally, a titanium-gold electrode is deposited onto a first substrate with a patterned first and second photoresist layer spaced apart using electron beam evaporation. The thickness of the titanium layer of the titanium-gold electrode can be 1 nm-10 nm, and the thickness of the gold layer can be 30 nm-50 nm. After electrode deposition, the first substrate is immersed in acetone for at least three hours, then the metal film on the PMMA adhesive is blown off with a dropper, and finally cleaned with isopropanol to complete the electrode fabrication. It should be noted that the titanium-gold electrode can be replaced with other metals or superconducting electrodes.

[0078] S130: Transfer a single-crystal thin film onto a first substrate and cover at least a portion of the first electrode.

[0079] To increase the adhesion between the single-crystal thin film and the first substrate, the substrate surface can be cleaned with oxygen plasma before transfer. In one embodiment of the present invention, cleaning is performed at a power of approximately 60W, an oxygen pressure of approximately 0.3mbar, and a time of approximately 3 minutes.

[0080] Optionally, this step includes:

[0081] A single-crystal thin film is transferred onto a first substrate using a transfer medium at an ambient temperature below -60°C, thereby bonding the single-crystal thin film to at least a portion of the first electrode; and

[0082] The ambient temperature is raised to above -40°C, causing the transfer medium to be released slowly, thereby leaving the single crystal film on at least a portion of the first electrode.

[0083] Optionally, as described above, one side of the prepared single-crystal thin film is attached to PDMS, and the other side is a fresh surface. At an ambient temperature of -60°C, the fresh surface of the single-crystal thin film is rapidly transferred to the first substrate, so that the single-crystal thin film adheres to at least a portion of the first electrode. Then, the ambient temperature is raised to above -40°C, causing the PDMS to be slowly released, thereby leaving the single-crystal thin film on at least a portion of the first electrode.

[0084] S140: Annealing the first substrate with the single crystal thin film attached.

[0085] Annealing can enhance the adhesion between the single-crystal thin film and the first substrate. Optionally, annealing is performed in an annealing furnace under the following conditions: oxygen pressure of 600 mbar, temperature of 250°C-300°C, and annealing time of at least 10 min.

[0086] S150: The annealed single-crystal thin film is cleaved to obtain a first thin film remaining on the first electrode and a second thin film separated from the first thin film.

[0087] Optionally, in this step, a transfer medium is also used to dissociate the single-crystal thin film at an ambient temperature below -60°C. Optionally, when the ambient temperature drops below -60°C, the cantilever is moved to attach PDMS onto the single-crystal thin film, and the single-crystal thin film is dissociated to obtain a first thin film remaining on the first electrode and a second thin film separated from the first thin film. Optionally, the thickness of the first thin film is approximately 10nm-15nm. Because annealing is performed before dissociation, the first thin film will not separate from the first substrate. One side of the first thin film is attached to the first substrate, and the other side is a fresh surface. One side of the second thin film is attached to the PDMS, and the other side is a fresh surface.

[0088] S160: Transfer the second thin film onto the first substrate and cover at least a portion of the second electrode and a first portion of the first thin film.

[0089] Optionally, this step includes:

[0090] A second thin film is transferred onto a first substrate using a transfer medium, such that the second thin film adheres to at least a portion of the second electrode and a first portion of the first thin film; and

[0091] The ambient temperature is raised to above -40°C, causing the transfer medium to be released slowly, thereby leaving the first film on at least a portion of the second electrode and a first portion of the first film.

[0092] Optionally, as described above, one side of the fabricated second thin film is attached to PDMS, while the other side is a fresh surface. At an ambient temperature of -60°C, the sample stage is rotated at the desired angle, and then the fresh surface of the second thin film is rapidly transferred to the first substrate, causing the second thin film to adhere to at least a portion of the second electrode and a first portion of the first thin film, thereby forming a certain overlapping region (junction). Then, the ambient temperature is raised to above -40°C, causing the PDMS to slowly release, thus leaving the first thin film on at least a portion of the second electrode and the first portion of the first thin film. At this point, a first angle exists between the first and second thin films, forming a Josephson junction.

[0093] The Josephson junction fabrication process provided by this invention is conducted in a low-temperature, anhydrous, and oxygen-free environment. Furthermore, the method of pre-fabricating the electrodes before fabricating the junction avoids damage to the sample interface and surface, resulting in a high-quality Josephson junction. Moreover, because the first thin film is transferred to the first electrode first, and then the second thin film is transferred to the second electrode and the first thin film, the contact surface between the first and second thin films is a new interface generated by cleavage, which is beneficial for improving the quality of the Josephson junction.

[0094] Figure 2 The invention also illustrates a method for preparing a Josephson knot according to another embodiment of the invention, which includes steps S170 and S180 in addition to steps S110-S160.

[0095] S170: Separate the second thin film from the first substrate, the second electrode, and the first thin film.

[0096] Optionally, the Josephson junction obtained in step S160 is placed back into the glove box, and a vacuum environment is maintained throughout the process. The ambient temperature is lowered to below -60°C, and PDMS is used to bond it to the second thin film. The cantilever is moved to separate the second thin film from the first substrate, the second electrode, and the first thin film.

[0097] S180: Transfer the second thin film back onto the first substrate and cover at least a portion of the second electrode and a second portion of the first thin film.

[0098] The difference between this step and step S160 is that the overlapping portion of the second film and the first film is different (i.e., the second portion and the first portion of the first film are different), resulting in a different angle (i.e., the second angle) between them. The at least portion of the second electrode covered by the second film in step S180 may be the same as or different from the at least portion of the second electrode covered by the second film in S160. The specific process is similar to step S160 and will not be repeated here.

[0099] In this invention, steps S170 and S180 can be repeated multiple times. That is, in this invention, the lower superconducting film in the longitudinal Josephson junction can be kept in close contact with the substrate, and the upper superconducting film can be rotated repeatedly to realize a multi-angle Josephson junction device. After each rotation, the device is vacuum-sealed and transferred to the measurement device for cryogenic transport measurement. This greatly improves the utilization rate of the device and the measurement efficiency, and more directly reflects the dependence of the Josephson junction coupling strength on the torsion angle, eliminating the uncertainty of conclusions caused by the differences between different devices.

[0100] In this invention, during the electrical transport measurement of a Josephson junction, the prepared Josephson junction device can be transferred to the sample holder inside a glove box, and the electrodes are connected within the glove box. Then, a sample rod with a sealed cavity is inserted into the glove box, the sample holder is placed on the sample rod, a vacuum is drawn, and the sample rod is then inserted into a cryogenic measurement device for cryogenic transport measurement. Using a vacuum insertion method ensures that the sample is not affected by the external environment and is more conducive to repeated transfers and measurements.

[0101] Alternatively, the fabricated Josephson junction can be transferred to a measuring instrument for electrical transport measurement using a vacuum transfer method, or boron nitride can be cleaved and transferred as a protective layer onto the substrate to avoid interference from the external environment.

[0102] Figure 3 and Figure 4 This invention illustrates a Josephson junction. It includes a substrate 10 (i.e., the aforementioned first substrate), a first electrode 20, a second electrode 30, a first thin film 40, and a second thin film 50.

[0103] Optionally, the substrate 10 may include, but is not limited to, silicon dioxide / silicon, gallium arsenide, glass, magnesium oxide, or strontium titanate. Optionally, the first electrode 20 and the second electrode 30 may include, but are not limited to, titanium electrodes; metal and superconducting electrodes are also acceptable. Optionally, the first thin film 40 and the second thin film 50 are made of the same material, and may include, but are not limited to, Bi₂Sr₂CaCu₂O₈, Bi₂Sr₂CuO₆, and Bi₂Sr₂Ca₂Cu₃O₈. 10 Or Bi2Sr2Ca3Cu4O 12 Two-dimensional materials. A first thin film 40 is located on a substrate 10 and covers at least a portion of the first electrode 20. A second thin film 50 is located on a substrate 10 and covers at least a portion of the second electrode 30 and a first portion of the first thin film 40.

[0104] Figure 3 and Figure 4 In the illustrated embodiment, there are multiple first electrodes 20 and multiple second electrodes 30, both located on the substrate 10 and spaced apart. Optionally, the multiple first electrodes 20 and multiple second electrodes 30 are symmetrically arranged. A first angle α1 is formed between the first thin film 40 and the second thin film 50.

[0105] Optionally, the first electrode 20 and the second electrode 30 sequentially include a titanium layer and a gold layer in a direction away from the surface of the substrate 10. The thickness of the titanium layer can be 1 nm-10 nm, and the thickness of the gold layer can be 30 nm-50 nm. Optionally, the thickness of the first thin film is 35 nm-90 nm, and the thickness of the second thin film is 10 nm-15 nm.

[0106] Optionally, as described above, the second thin film 50 of the Josephson junction provided by the present invention can be separated from the substrate 10, the second electrode 30, and the first thin film 40, and can be transferred back onto the first substrate 10, covering at least a portion of the second electrode 30 and a second portion of the first thin film 40, thereby creating a second angle α2 between the first thin film 40 and the second thin film 50 (e.g., ...). Figure 4 (As shown). The second angle α2 and the first angle α1 are not equal.

[0107] In application, the Josephson junction device with a first angle α1 between the first and second thin films is first subjected to electrical transport measurements. Then, the second thin film is separated from the substrate, the second electrode, and the first thin film. Next, the second thin film is transferred back onto the first substrate, covering at least a portion of the second electrode and a second portion of the first thin film, so that a second angle α2 is formed between the first and second thin films. Electrical transport measurements are then performed again. Subsequently, the second thin film is separated and reattached, so that the angle between the first and second thin films is different each time, and electrical transport measurements are performed separately for each measurement.

[0108] As mentioned earlier, since the second thin film can be rotated repeatedly to change the angle between the first and second thin films, the Josephson junction can be utilized multiple times, which greatly improves the utilization rate and measurement efficiency of the device. Furthermore, it more directly reflects the dependence of the Josephson junction coupling strength on the torsion angle in terms of physics, eliminating the uncertainty in conclusions caused by differences between different devices.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for fabricating a Josephson junction device, characterized in that, include: Prepare the first substrate and the single-crystal thin film; A first electrode and a second electrode are formed on the first substrate at a distance from each other; The single-crystal thin film is transferred onto the first substrate and covers at least a portion of the first electrode; The first substrate with the attached single crystal thin film is subjected to annealing treatment; The single-crystal thin film after the annealing treatment is cleaved to obtain a first thin film remaining on the first electrode and a second thin film separated from the first thin film; as well as The second thin film is transferred onto the first substrate, covering at least a portion of the second electrode and a first portion of the first thin film; The first film and the second film have a first angle between them; Separate the second thin film from the first substrate, the second electrode, and the first thin film; as well as The second film is transferred back onto the first substrate, covering at least a portion of the second electrode and a second portion of the first film; The second film and the first film have a second angle, which is not equal to the first angle.

2. The preparation method according to claim 1, characterized in that, Separating the second thin film from the substrate, the second electrode, and the first thin film includes: The second film is separated from the substrate, the second electrode, and the first film using a transfer medium at an ambient temperature below -60°C.

3. The preparation method according to claim 1, characterized in that, Preparing single-crystal thin films includes: Prepare the single crystal sample and the second substrate; The single crystal sample was dissected using adhesive tape, and the resulting sample film was transferred onto the second substrate; and The sample film on the second substrate is dissociated using a transfer medium to obtain the single-crystal thin film.

4. The preparation method according to claim 1, characterized in that, Forming a first electrode and a second electrode spaced apart on the first substrate includes: Clean the first substrate; A patterned first photoresist layer and a second photoresist layer are formed at intervals on the cleaned first substrate, respectively; and The first electrode and the second electrode are formed by depositing films on the first photoresist layer and the second photoresist layer, respectively.

5. The preparation method according to claim 1, characterized in that, Transferring the single-crystal thin film onto the first substrate and covering at least a portion of the first electrode includes: The single-crystal thin film is transferred onto the first substrate using a transfer medium at an ambient temperature below -60°C, thereby bonding the single-crystal thin film to at least a portion of the first electrode; and The ambient temperature is raised to above -40°C, causing the transfer medium to be released slowly, thereby leaving the single crystal film on at least a portion of the first electrode.

6. The preparation method according to claim 1, characterized in that, The annealing process is carried out in an oxygen environment with a pressure of at least 600 mbar, a temperature of 250°C-300°C, and a time of at least 10 minutes.

7. The preparation method according to claim 1, characterized in that, Cleavage of the single-crystal thin film after the annealing treatment includes: The single-crystal thin film was dissociated using a transfer medium at an ambient temperature below -60°C.

8. The preparation method according to claim 7, characterized in that, Transferring the second thin film onto the first substrate and covering at least a portion of the second electrode and a first portion of the first thin film includes: The second thin film is transferred onto the first substrate using the transfer medium, such that the second thin film adheres to at least a portion of the second electrode and the first portion of the first thin film; and The ambient temperature is raised to above -40°C, causing the transfer medium to be released slowly, thereby leaving the first film on at least a portion of the second electrode and on the first portion of the first film.

9. The preparation method according to claim 1, characterized in that, The thickness of the single-crystal thin film is 50nm-100nm.

10. The preparation method according to claim 2, 3, 5 or 7, characterized in that, The transfer medium is polydimethylsiloxane.

11. A Josephson junction device, characterized in that, Prepared by the preparation method according to any one of claims 1-10, comprising: Substrate; The first electrode is located on the substrate; The second electrode is located on the substrate and is disposed at a distance from the first electrode; A first thin film is located on the substrate and covers at least a portion of the first electrode; and A second thin film is located on the substrate and covers at least a portion of the second electrode and a first portion of the first thin film; Wherein, the first film and the second film have a first angle; The second film is separable from the substrate, the second electrode, and the first film, and is transferable back onto the first substrate, covering at least a portion of the second electrode and a second portion of the first film, such that there is a second angle between the first film and the second film, wherein the second angle is not equal to the first angle.

12. The Josephson junction device according to claim 11, characterized in that, The thickness of the first film is 35nm-90nm, and the thickness of the second film is 10nm-15nm.

13. The Josephson junction device according to claim 11, characterized in that, The first electrode and the second electrode are titanium-gold electrodes, the titanium layer of the titanium-gold electrode has a thickness of 1nm-10nm, and the gold layer of the titanium-gold electrode has a thickness of 30nm-50nm.

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