A method for controlling the thermal relaxation path of superconducting nanostructures and its application

Abstract

This invention discloses a method for controlling the thermal relaxation path of superconducting nanostructures and its application. This method utilizes a van der Waals integration strategy to sequentially fabricate a molybdenum disulfide layer on a silicon / silicon oxide substrate using chemical solution deposition and a niobium nitride superconducting layer using magnetron sputtering, constructing a niobium nitride / molybdenum disulfide heterostructure with intrinsic anisotropic thermal conductivity. Superconducting nanodevices with specific geometric configurations are designed for this heterostructure. Leveraging the ultra-high in-plane thermal conductivity of molybdenum disulfide and its suppressed out-of-plane heat transfer characteristics, the method achieves directional control of the internal thermal relaxation path of the superconducting nanostructure, verifying its dual advantages of optimizing thermal management and enhancing superconducting performance. The control method of this invention is mature and controllable, effectively transforming disordered thermal relaxation into directional heat transfer, significantly improving the thermal stability and integration density of superconducting devices, and providing a core solution for the thermal management of nanocircuits in fields such as superconducting quantum computing and high-sensitivity quantum detection.

Description

Technical Field

[0001] This invention relates to a method and application for controlling the thermal relaxation path of superconducting nanostructures, belonging to the field of thermal management technology for superconducting nanocircuits and quantum devices. Background Technology

[0002] With the continuous increase in the integration density of superconducting nanocircuits, thermal relaxation has become a core technical bottleneck restricting their performance optimization and scalability. Specifically, heat accumulation inside the device not only suppresses the superconducting bandgap, generates excessive quasiparticles and accelerates quantum decoherence, but also induces thermal stress and leads to increased interfacial resistance. These factors collectively impair the long-term operational stability of superconducting devices. Solving this thermal relaxation problem is crucial for promoting the industrialization of quantum technologies such as quantum computing and quantum detection. However, existing thermal management methods mostly rely on isotropic passive heat dissipation strategies. These strategies have inherent limitations: they cannot achieve precise control of directional heat flow at the nanoscale and are prone to generating unnecessary thermal crosstalk between adjacent qubits, making them unsuitable for the application requirements of next-generation scalable superconducting quantum systems. Therefore, the industry urgently needs a technical solution that can actively control the thermal relaxation path, providing a core solution for improving the operational stability and integration density of superconducting nanodevices by guiding heat flow within the device in a directional and efficient manner.

[0003] Van der Waals integration technology overcomes the stringent requirements of lattice matching in heterostructure construction, allowing for free stacking to form heterojunctions as needed. This enables precise electronic and phonon engineering at the interface, demonstrating significant application potential in thermal management. These van der Waals materials generally possess intrinsic anisotropic thermal conductivity, providing feasibility for the design and construction of directional heat transport channels. By constructing directional thermal relaxation paths for devices, Joule heat generated during device operation can be efficiently guided and dissipated. This approach directly reduces the risk of device lock-up and thermal runaway caused by localized overheating, while eliminating the physical limitations imposed on circuit layout by thermal crosstalk. Currently, van der Waals integration-based thermal management methods have only been validated in semiconductor devices, and there have been no attempts to apply them to the thermal control of superconducting nanocircuits. The aforementioned research results provide valuable insights for the active control of heat flow in superconducting electronic devices and also raise new research topics for the cross-domain application of this technology. Summary of the Invention

[0004] Objective of this invention: The objective of this invention is to provide a method for controlling the thermal relaxation path of superconducting nanostructures. By constructing a niobium nitride / molybdenum disulfide van der Waals integrated heterostructure, intrinsic anisotropic thermal conductivity is introduced, enabling active and directional control of the thermal relaxation path of the superconducting nanostructure. This simultaneously improves the superconducting performance of niobium nitride, solves the thermal management bottleneck of superconducting nanocircuits, and provides a thermal relaxation control scheme for the large-scale development of superconducting quantum systems. Another objective of this invention is to provide applications of this method in the thermal management of superconducting nanocircuits, or in the fabrication of superconducting quantum computing devices or superconducting nanowire single-photon detectors.

[0005] Technical solution: The present invention provides a method for controlling the thermal relaxation path of superconducting nanostructures, comprising the following steps:

[0006] (1) A molybdenum disulfide layer was prepared on a silicon / silicon oxide substrate by chemical solution deposition;

[0007] (2) Niobium nitride superconducting thin film is deposited on the surface of the molybdenum disulfide layer prepared in step (1) by magnetron sputtering, and the magnetron sputtering process parameters are adjusted to form a niobium nitride / molybdenum disulfide van der Waals integrated heterostructure.

[0008] (3) The superconducting nanostructure patterning of the niobium nitride / molybdenum disulfide van der Waals integrated heterostructure in step (2) was fabricated by electron beam lithography and reactive ion etching. The directional control of thermal relaxation path was verified in the structure by utilizing the anisotropic thermal conductivity of molybdenum disulfide.

[0009] Furthermore, in step (1), the molybdenum disulfide layer is a wafer-level, polycrystalline structure, and the thickness of the molybdenum disulfide layer is adjusted by the rotation speed of the spin-coating precursor solution during the preparation process. The root mean square surface roughness of the molybdenum disulfide layer is ≤0.5 nm.

[0010] Furthermore, step (1) includes the following steps:

[0011] An ammonium tetrathiomolybdate-ethanolamine precursor solution was prepared, and after hydrophilic treatment of a silicon / silicon oxide substrate, the ammonium tetrathiomolybdate-ethanolamine solution was spin-coated. After two-step thermal decomposition and recrystallization, a polycrystalline molybdenum disulfide layer with wafer-level uniformity and anisotropic thermal conductivity was prepared.

[0012] Furthermore, the concentration of the ammonium tetrathiomolybdate-ethanolamine solution is 10-100 mM, and the spin coating speed is 3000-6000 r / s. These two parameters can affect the thickness of the prepared molybdenum disulfide layer, which is controlled within 3-10 layers. Immediately after spin coating, a post-baking treatment (150-180℃) is performed. Subsequently, the decomposition reaction of ammonium tetrathiomolybdate and the recrystallization reaction of molybdenum disulfide occur sequentially in a tube furnace.

[0013] Furthermore, in step (2), the niobium nitride superconducting layer film is a polycrystalline δ-phase niobium nitride. The niobium nitride superconducting layer film is prepared in a competing mode of magnetron sputtering to avoid damage to the underlying molybdenum sulfide layer during the sputtering process. A niobium nitride / molybdenum sulfide heterostructure is formed through van der Waals weak interface coupling. This heterostructure combines intrinsic anisotropic thermal conductivity with enhanced superconductivity.

[0014] Furthermore, during the magnetron sputtering preparation of niobium nitride, to prevent the underlying molybdenum disulfide layer from suffering significant damage and losing its original structure, thereby compromising its intrinsic anisotropic thermal conductivity, sputtering conditions need to be controlled. A competitive mode is preferred, with the sputtering current controlled within the range of 0.8–1 A, the argon gas flow rate at 100 sccm, the nitrogen gas flow rate at 4 sccm, the total gas pressure at 4.25 mTorr, and the target-substrate distance at 80 mm. Under these conditions, the sputtering rate is relatively slow, and the superconducting transition temperature of the prepared approximately 6 nm niobium nitride film is not lower than 7 K.

[0015] Furthermore, in step (3), deionized water is not used throughout the patterning process of the superconducting nanostructure to prevent cracking and delamination of the molybdenum disulfide layer. Electron beam lithography and reactive ion etching are used to fabricate the niobium nitride / molybdenum disulfide van der Waals integrated heterostructure into a superconducting nanostructure with a narrowed central geometry. The synergistic effect of the heating characteristics of this geometry and the anisotropic thermal conductivity of molybdenum disulfide enables directional relaxation of heat along the in-plane direction of molybdenum disulfide, while suppressing thermal crosstalk in the out-of-plane direction, thus achieving directional control of the thermal relaxation path.

[0016] Furthermore, for the designed nanostructure with a specific central geometric narrowing, the nanowire width in the central narrow region is set to 70–100 nm; the nanowire width in the two wider regions on both sides is set to 260–300 nm, and should not be less than three times the width of the narrow region. During reactive ion etching of this superconducting heterostructure, it is ensured that the etching completely penetrates the molybdenum disulfide layer. After etching, the sample is placed in a water bath in N-methylpyrrolidone (80°C, 10 min) to remove the surface electron beam resist PMMA. Excessive water bath time increases the risk of cracking in the molybdenum disulfide.

[0017] Furthermore, to verify the effect of adding molybdenum disulfide on heat flow path regulation, a method was adopted to obtain the internal thermal behavior of the device by measuring electrical parameters and calculating them using the thermal balance equation. This places certain technical requirements on high-precision electrical measurements, especially on the acquisition of the device's hysteresis current. The external electrical measurement circuit is mainly connected through a bias-Tee component, with a 50 Ω load connected to the component's RF port for impedance matching.

[0018] The thermal relaxation path modulation method for superconducting nanostructures described in this invention has applications in the thermal management of superconducting nanocircuits, or in the fabrication of superconducting quantum computing devices or superconducting nanowire single-photon detectors. This modulation method achieves directional and efficient dissipation of Joule heat within the device, suppresses thermal crosstalk between devices, improves the thermal stability, operational reliability, and integration density of superconducting devices, and solves the problem of heat accumulation during the large-scale integration of superconducting nanocircuits.

[0019] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0020] (1) This invention introduces van der Waals integration technology into the field of thermal relaxation path control in superconducting nanostructures for the first time, and proposes an active directional thermal relaxation control method. By actually constructing a niobium nitride / molybdenum disulfide heterostructure to introduce intrinsic anisotropic thermal conductivity, the traditional disordered thermal relaxation is transformed into controllable directional heat transfer, which effectively solves the defect that traditional thermal management schemes in superconducting nanostructures cannot achieve directional heat flow control, and can significantly suppress thermal crosstalk between superconducting devices.

[0021] (2) The control method of the present invention achieves the dual effects of thermal relaxation optimization and superconducting performance enhancement. The constructed niobium nitride / molybdenum disulfide heterostructure can not only achieve directional thermal relaxation, but also improve the superconducting transition temperature of niobium nitride due to the improved lattice matching between molybdenum disulfide and niobium nitride, and significantly improve the superconducting critical current density. At the same time, the robustness of the self-heating effect of the heterostructure is enhanced, which further improves the long-term operating stability of the superconducting device.

[0022] (3) The thermal relaxation path control method of the present invention adopts mature semiconductor processes such as chemical solution deposition, magnetron sputtering, electron beam lithography and reactive ion etching. The preparation process is controllable and highly repeatable. The molybdenum disulfide layer can achieve uniform preparation at the wafer level, and the thickness can be flexibly controlled by the solution concentration and spin coating speed, which is suitable for large-scale industrial production. Attached Figure Description

[0023] Figure 1 A schematic diagram comparing the thermal relaxation paths in traditional nanostructures and the van der Waals superconducting heterostructure constructed in this invention is shown; where a is a schematic diagram of the thermal relaxation path in a traditional superconducting nanostructure without a molybdenum disulfide layer, and b is a schematic diagram of the thermal relaxation path in the van der Waals superconducting heterostructure constructed in this invention.

[0024] Figure 2 A schematic diagram of the apparatus and process for the chemical preparation of molybdenum disulfide;

[0025] Figure 3 The images show optical photographs, AFM, and TEM characterization results of the molybdenum disulfide prepared in Example 1; where a is an optical photograph and b is a TEM image.

[0026] Figure 4 The images show the XRD and RT characterization results of two devices: one with a molybdenum disulfide layer and the other without (control group); where a is the XRD pattern and b is the RT result.

[0027] Figure 5 The images show the designed nanostructure layout and the SEM characterization results after actual fabrication.

[0028] Figure 6 The diagram shows the IV electrical test results and plateau current values ​​for two types of devices: niobium nitride nanostructure without molybdenum disulfide layer and niobium nitride / molybdenum disulfide heterostructure.

[0029] Figure 7 A comparison of the axial temperature gradients of two devices: a niobium nitride nanostructure without a molybdenum disulfide layer and a niobium nitride / molybdenum disulfide heterostructure.

[0030] Figure 8 The figures shown are for comparative example 1, which are the heterojunction quality characterization results under conventional niobium nitride preparation conditions. In the figures, a is an optical microscope image of niobium nitride of different thicknesses grown on molybdenum disulfide under conventional preparation conditions; b is a comparison of RT test results of 20 nm niobium nitride with and without molybdenum disulfide under conventional preparation conditions; and c is a comparison of RT test results of 20 nm niobium nitride with and without molybdenum disulfide under the improved preparation conditions of this invention. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are implemented based on the technical solution of the present invention and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0032] Example 1

[0033] A method for controlling the thermal relaxation path of superconducting nanostructures utilizes the intrinsic anisotropic heat dissipation properties of van der Waals materials, integrating them into superconducting nanostructures to achieve control of the heat flow path in the device. The overall control concept is as follows: Figure 1 As shown, it includes the following steps:

[0034] Step 1: Preparation of wafer-level polycrystalline molybdenum disulfide layer by chemical solution deposition

[0035] Approximately 26 mg of ammonium tetrathiomolybdate powder was weighed and added to 1 mL of ethanolamine reagent to prepare a 100 mM ammonium tetrathiomolybdate-ethanolamine precursor solution. The solution was sealed and stored at room temperature for later use. A clean silicon / silicon oxide substrate was pre-treated with a hydrophilic agent (operating conditions: oxygen flow rate 30 sccm, power 50 W, bombardment of the substrate surface for 3 min). The ammonium tetrathiomolybdate-ethanolamine precursor solution was then uniformly coated using a spin coater at 6000 r / s and a spin coating time of 30 s. Immediately after spin coating, the substrate was transferred to a 150°C constant-temperature hot plate for 5 min of post-coating annealing to remove the solvent from the ammonium tetrathiomolybdate-ethanolamine precursor solution and solidify the precursor solution film, resulting in a substrate coated with the ammonium tetrathiomolybdate-ethanolamine precursor solution.

[0036] Subsequently, as Figure 2 As shown, sufficient sulfur powder was placed in a ceramic boat, which was then placed in zone I of a tube furnace. A substrate coated with an ammonium tetrathiomolybdate-ethanolamine precursor solution was placed in zone II of the tube furnace. First, the tube furnace chamber was evacuated to below 1 Pa. Then, argon and hydrogen were introduced, with the gas flow rate adjusted to argon:hydrogen = 75:25 sccm, maintaining a chamber pressure of 100 Pa. The heating program for zone II of the tube furnace was started, raising the temperature from room temperature to 450℃ within 20 minutes and holding for 20 minutes to allow the ammonium tetrathiomolybdate in the ammonium tetrathiomolybdate-ethanolamine precursor solution to fully decompose under the strong reducing properties of hydrogen and low pressure. Simultaneously, the external heating mantle of zone I was opened to maintain the temperature of zone I at 150℃. After the decomposition reaction is complete, the hydrogen gas supply and the vacuum pump are immediately shut off, and argon gas is continuously introduced to raise the pressure inside the tube to 1 atm. Then, the temperature of zone II is raised to 850℃ over 20 minutes and held for 20 minutes for recrystallization. After the recrystallization reaction is complete, the heating section of the tube furnace is quickly removed, allowing the chamber to cool naturally and rapidly to room temperature under argon protection. Finally, a wafer-level, polycrystalline molybdenum disulfide layer is obtained on the silicon / silicon oxide substrate. This molybdenum disulfide layer is approximately 3.5 nm thick and has a root mean square surface roughness ≤0.17 nm. Figure 3 As shown.

[0037] Step 2: Fabrication of niobium nitride superconducting layers by magnetron sputtering to construct van der Waals integrated heterostructures.

[0038] A control group was designed, placing hydrophilically treated silicon / silicon oxide substrates prepared in step 1 with and without a molybdenum disulfide layer (control group) on the same tray to ensure that the niobium nitride grown in both devices was under the same conditions and from the same batch. The magnetron sputtering instrument was adjusted to competitive sputtering mode, and the core sputtering parameters were set as follows: sputtering current 1 A, argon flow rate 100 sccm, nitrogen flow rate 4 sccm, total chamber pressure 4.25 mTorr, target-substrate distance 80 mm, and the niobium nitride layer thickness was controlled to 6 nm.

[0039] The two structures were characterized by XRD and RT, and the results are as follows: Figure 4 As stated. Figure 4 As shown in Figure a, in the structure with a molybdenum disulfide layer, niobium nitride (6 nm, NbN-MoS2) is a polycrystalline δ phase, forming the required van der Waals integrated heterostructure with the molybdenum disulfide layer without disrupting the intrinsic anisotropic thermal conductivity of the molybdenum disulfide layer. Resistance-temperature (RT) measurements of niobium nitride on both devices show that the superconducting transition temperature of 6 nm niobium nitride without a molybdenum disulfide layer (control group, NbN) is approximately 7.5 K, while the superconducting transition temperature of the niobium nitride / molybdenum disulfide heterostructure with the molybdenum disulfide layer is increased by approximately 1 K. Figure 4 As shown in b.

[0040] Step 3: Patterning design and fabrication of heterogeneous structures

[0041] The preset pattern is a nanowire structure with a narrower center. The design concept behind this pattern is to add a lateral heat transfer term to the conventional nanowire structure, thereby evaluating the anisotropic heat dissipation capability. Figure 5As shown: the narrow central region is approximately 100 nm wide and 100 nm long, while the wide side regions are approximately 300 nm wide, with a total nanowire length of 10 μm. Before electron beam exposure, the sample was spin-coated with PMMA photoresist at a spin speed of 4000 rpm and a spin time of 60 s. Pre-baking was performed at 180 ℃ for 240 s to remove residual solvent. After electron beam exposure, the substrate was removed and developed in a MIBK:IPA ratio of 1:3 for 90 s, then fixed in pure IPA for 60 s. After fixing, the substrate was dried with a high-purity nitrogen gun to obtain a substrate with a PMMA mask. Subsequently, the substrate with the PMMA mask was placed in a reactive ion etching machine, and the etching parameters were set as follows: etching gas: trifluoromethane:sulfur hexafluoride = 20:40 sccm, etching pressure 4 Pa, RF power 80 W, and etching time 32 s, ensuring complete penetration of the niobium nitride layer and molybdenum disulfide layer. After etching, the substrate was placed in an 80°C constant temperature water bath in N-methylpyrrolidone for 10 min to remove the PMMA from the substrate surface. After the water bath, it was directly dried with a nitrogen gun, and the preset nanowire pattern was accurately transferred to the device. SEM observation showed that the actual fabricated nanowire width was slightly smaller than the design value, and met the condition that the width of the wide area nanowire was more than 3 times that of the narrow area nanowire. At the same time, the nanostructure size and width of the two devices with and without the molybdenum disulfide layer (niobium nitride / molybdenum disulfide heterostructure, NbN-MoS2) were nearly identical.

[0042] Step 4: Testing and Verification of the Effect of Thermal Relaxation Path Control on Superconducting Performance

[0043] The two devices prepared in step three—a niobium nitride / molybdenum disulfide heterostructure and a niobium nitride (without the molybdenum disulfide layer)—were placed in a GM cryostat, and an electrical testing system was built. A Keithley 2400 source meter was connected to the device via a bias-Tee element. The RF port of the bias-Tee element was connected to a 50 Ω load for impedance matching. After completing the circuit connection, the cryogenic chamber was evacuated and cooled to 2-6 K to test the superconducting performance and thermal relaxation modulation effect. The hysteresis current and plateau current were obtained by testing the IV characteristics of the device at different temperatures. Figure 6 As shown, the temperature gradient inside the device is calculated by combining the thermal balance equation and the effective boundary thermal conductivity obtained by fitting in the conventional nanowire structure beforehand. Referring to the phonon blackbody radiation model, the thermal balance equation is expressed as equation (1):

[0044]

[0045] In equation (1), K N and K SRepresents the thermal conductivity of the nanostructure in the normal and superconducting states, respectively; w represents the width of the nanodevice structure; d represents the thickness of the niobium nitride superconducting material; T b T represents the ambient temperature, I represents the internal temperature of the device, and R represents the hysteresis current of the device. □ The normal-state sheet resistance of niobium nitride, a superconducting material, is represented by x. N The boundary represents the resistive region, and β is the boundary thermal conductivity. In traditional nanowires with uniform linewidth, the transverse heat transfer term can be made equal to 0 through symmetry design, and then obtained by fitting through hysteresis current test.

[0046] Furthermore, based on COMSOL simulations of the axial temperature distribution of the designed nanostructure, a Gaussian function was used to mathematically approximate the temperature distribution of this structure for computational simplicity. Combined with the measured device plateau current, the internal temperature gradient of the device was then obtained. The results show that the overall temperature gradient of this niobium nitride / molybdenum disulfide superconducting nanostructure is reduced by 12.5 ± 2.5% compared to traditional devices without a molybdenum disulfide layer. Figure 7 As shown in the figure. Simultaneously, combining experimental data on the vertical temperature drop and axial temperature gradient of the device, parameter scanning was performed in COMSOL to obtain the effective thermal conductivity anisotropy ratio that satisfies the experimental results, yielding a ratio of approximately 3 at 4 K. These results confirm that this method achieves the directional and precise control of the internal thermal relaxation path of the niobium nitride / molybdenum disulfide superconducting nanostructure.

[0047] Comparative Example 1

[0048] In fabricating superconducting nanostructures based on van der Waals integration, a molybdenum disulfide layer was grown in the same manner as in Example 1. However, unlike Example 1, the superconducting niobium nitride layer was grown using conventional fabrication parameters: sputtering current 1.05 A, argon flow rate 70 sccm, nitrogen flow rate 10 sccm, total chamber pressure 4 mTorr, and target-substrate distance 30 mm. Based on these conventional niobium nitride fabrication conditions, optical microscope images of niobium nitride of different thicknesses grown on the molybdenum disulfide layer are shown below. Figure 8 As shown in Figure a, the electrical RT measurements of niobium nitride / molybdenum disulfide with a thickness of 20 nm are compared with those of niobium nitride with the same thickness prepared using conventional preparation parameters without a molybdenum disulfide layer. The results are as follows. Figure 8 As shown in Figure b, under these conditions, the thermal conductivity (RT) of niobium nitride with a molybdenum disulfide layer is not as good as that of niobium nitride with conventional preparation parameters without a molybdenum disulfide layer. This shows that under conventional niobium nitride preparation conditions, the structure of the molybdenum disulfide layer is severely damaged, and its intrinsic anisotropic thermal conductivity cannot be effectively utilized.

[0049] Meanwhile, a comparison of the electrical resistance (RT) tests of niobium nitride (20 nm) grown under the optimized sputtering conditions of Example 1 of this invention with and without a molybdenum disulfide layer revealed that the optimized conditions can perfectly construct a high-quality niobium nitride / molybdenum disulfide heterointerface. Furthermore, by utilizing the rapid in-plane thermal conductivity and out-of-plane thermal insulation properties of molybdenum disulfide, active directional control of the thermal relaxation path within the superconducting nanostructure was successfully achieved (see...). Figure 8 (c)

Claims

1. A method for controlling the thermal relaxation path of a superconducting nanostructure, characterized in that, Includes the following steps: (1) A molybdenum disulfide layer was prepared on a silicon / silicon oxide substrate by chemical solution deposition; (2) Niobium nitride superconducting thin film is deposited on the surface of the molybdenum disulfide layer prepared in step (1) by magnetron sputtering, and the magnetron sputtering process parameters are adjusted to form a niobium nitride / molybdenum disulfide van der Waals integrated heterostructure. (3) The superconducting nanostructure patterning of the niobium nitride / molybdenum disulfide van der Waals integrated heterostructure in step (2) was fabricated by electron beam lithography and reactive ion etching. The directional control of thermal relaxation path was verified in the structure by utilizing the anisotropic thermal conductivity of molybdenum disulfide.

2. The method for controlling the thermal relaxation path of superconducting nanostructures according to claim 1, characterized in that, In step (1), the molybdenum disulfide layer is a wafer-level, polycrystalline structure. The thickness of the molybdenum disulfide layer is adjusted by the rotation speed of the spin-coating precursor solution during the preparation process. The root mean square surface roughness of the molybdenum disulfide layer is ≤0.5 nm.

3. The method for controlling the thermal relaxation path of superconducting nanostructures according to claim 1, characterized in that, Step (1) includes the following steps: An ammonium tetrathiomolybdate-ethanolamine precursor solution was prepared, and after hydrophilic treatment of a silicon / silicon oxide substrate, the ammonium tetrathiomolybdate-ethanolamine solution was spin-coated. After a two-step thermal decomposition-recrystallization process, a polycrystalline molybdenum disulfide layer with wafer-level uniformity and anisotropic thermal conductivity was prepared.

4. The method for controlling the thermal relaxation path of superconducting nanostructures according to claim 1, characterized in that, In step (2), the niobium nitride superconducting layer film is a polycrystalline δ-phase niobium nitride.

5. The method for controlling the thermal relaxation path of superconducting nanostructures according to claim 1, characterized in that, In step (2), the preparation of the niobium nitride superconducting layer film is in a competitive mode of magnetron sputtering to avoid damage to the underlying molybdenum sulfide layer during the sputtering process.

6. The method for controlling the thermal relaxation path of superconducting nanostructures according to claim 1, characterized in that, In step (2), a niobium nitride / molybdenum sulfide heterostructure is formed through van der Waals weak interface coupling. This heterostructure has both intrinsic anisotropic thermal conductivity and enhanced superconductivity.

7. The method for controlling the thermal relaxation path of superconducting nanostructures according to claim 1, characterized in that, In step (3), deionized water is not used in the entire process of superconducting nano-heterogeneous structure patterning preparation to prevent the molybdenum sulfide layer from cracking and delamination.

8. The method for controlling the thermal relaxation path of superconducting nanostructures according to claim 1, characterized in that, In step (3), electron beam lithography and reactive ion etching are used to prepare a superconducting nanostructure with a narrowed middle geometry by using the niobium nitride / molybdenum disulfide van der Waals integrated heterostructure. The heating characteristics of this geometry and the anisotropic thermal conductivity of molybdenum disulfide work together to achieve directional relaxation of heat along the in-plane direction of molybdenum disulfide, while suppressing thermal crosstalk in the out-of-plane direction, thus completing the directional control of the thermal relaxation path.

9. The application of the superconducting nanostructure thermal relaxation path modulation method according to any one of claims 1-8 in the thermal management of superconducting nanocircuits, or in the fabrication of superconducting quantum computing devices or superconducting nanowire single-photon detectors.

10. The application according to claim 9, characterized in that, This control method enables the directional and efficient dissipation of Joule heat within the device, suppresses thermal crosstalk between devices, improves the thermal stability, operational reliability, and integration density of superconducting devices, and solves the problem of heat accumulation during the large-scale integration of superconducting nanocircuits.

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