YBCO (Yttrium Barium Copper Oxide) film for single-photon detector and deposition method of YBCO film

Abstract

The invention provides a YBCO (Yttrium Barium Copper Oxide) film for a single-photon detector and a deposition method thereof, and the deposition method comprises the following steps: S1, fixing a substrate on a substrate table of pulse laser deposition equipment, vacuumizing, and heating the substrate table to a deposition temperature; s2, oxygen is introduced into the deposition cavity until the oxygen pressure ranges from 0.25 Torr to 0.35 Torr; s3, adopting a YBCO target material, and carrying out pre-sputtering in a baffle closing state; s4, a baffle is opened, sputtering is conducted on the YBCO target material, and a YBCO film precursor is obtained; s5, oxygen is introduced into the deposition cavity, and meanwhile, the annealing temperature is reduced for in-situ annealing treatment; and S6, cooling to room temperature to obtain the YBCO film. According to the method, the high-quality ultrathin YBCO film with the thickness as low as 14 nm is prepared by accurately controlling the deposition parameters and the annealing process of the oxygen atmosphere, the prepared YBCO film still keeps excellent superconducting performance under the ultrathin condition, and the refrigeration cost is greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of superconducting thin film preparation, and particularly relates to a YBCO thin film for a single photon detector and a deposition method thereof. Background Art

[0002] A superconducting nanowire single photon detector (SNSPD) is a superconducting micro-nano device that converts an input single photon signal into an electrical pulse signal. It has performance advantages such as high detection efficiency, high count rate, low dark count, and extremely small time jitter. Therefore, SNSPD has a wide range of applications in multiple fields. Currently, the superconducting thin film materials used in the development of SNSPD include crystalline or polycrystalline niobium nitride (NbN) or niobium titanium nitride (NbTiN), and traditional superconductors such as completely disordered amorphous superconductors tungsten silicide (WSi) or molybdenum silicide (MoSi). Although these superconducting thin film materials have stable and reliable superconductivity, limited by their relatively low superconducting critical temperature, traditional SNSPD devices can only exhibit better single photon response performance at temperatures of 0.8K - 4.2K, which has become the key to restricting the detection performance and application of SNSPD. Compared with traditional superconducting thin film materials, YBCO (yttrium barium copper oxide) is a high-temperature superconducting material. The superconducting transition temperature (T C ) of YBCO is higher than the boiling point of liquid nitrogen (77K), usually around 90K, which enables it to achieve a superconducting state in a liquid nitrogen environment. The high-temperature superconducting material YBCO has a superconducting transition temperature (TC > 77K, liquid nitrogen temperature range) that cannot be compared with low-temperature superconductors. Using an ultrathin YBCO thin film to prepare SNSPD is a promising solution to increase its operating temperature.

[0003] However, due to the complex composition and structure of the YBCO superconducting thin film, the deposition of current ultrathin YBCO thin film materials still faces great challenges, especially for ultrathin YBCO thin film materials required for SNSPD preparation. Existing conventional YBCO thin film preparation methods, such as pulsed laser deposition (PLD), magnetron sputtering (MS), electron beam evaporation or thermal evaporation, metal organic deposition (MOD), metal organic chemical vapor deposition (MOCVD), etc., have problems in obtaining high-quality ultrathin YBCO thin films. For example, YBCO thin films prepared by metal organic deposition and metal organic chemical vapor deposition methods usually have a low density and it is difficult to obtain high-quality YBCO thin films; it is difficult to obtain single crystal thin films by magnetron sputtering, and reverse sputtering is likely to occur during sputtering, affecting the film morphology; when the thickness of the YBCO thin film decreases, it is difficult to release the residual stress of the film, resulting in a significant decrease in superconductivity. Therefore, the existing pulsed laser deposition method is mainly aimed at YBCO thin films with a thickness of more than one hundred nanometers, and there is no research on the deposition of ultrathin YBCO thin films for the field of single photon detection applications.

[0004] Therefore, it is necessary to provide an improved technical solution to address the deficiencies of the above-mentioned prior art. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a YBCO thin film for a single-photon detector and a deposition method thereof, which are used to solve the problem in the prior art that it is difficult to prepare a high-quality ultrathin YBCO thin film that can meet the requirements of superconducting single-photon detectors.

[0006] To achieve the above object and other related objects, the present invention provides a deposition method for a YBCO thin film used in a superconducting nanowire single-photon detector. The deposition method includes the following steps:

[0007] S1. Fix the substrate on the substrate stage of the pulsed laser deposition equipment, evacuate the deposition chamber, and heat the substrate stage to the deposition temperature.

[0008] S2. Introduce oxygen into the deposition chamber until the oxygen pressure is 0.25 Torr to 0.35 Torr.

[0009] S3. Use a YBCO target, and perform pre-sputtering on the YBCO target with pulsed laser in the state where the baffle is closed.

[0010] S4. Open the baffle between the YBCO target and the substrate, perform sputtering on the YBCO target with pulsed laser, and deposit the ejected substance on the substrate to obtain a YBCO thin film precursor.

[0011] S5. Introduce oxygen into the deposition chamber, and at the same time cool down to the annealing temperature to perform in-situ annealing treatment on the YBCO thin film precursor.

[0012] S6. After the in-situ annealing treatment, cool down to room temperature at a certain cooling rate to obtain a YBCO thin film.

[0013] Preferably, in step S1, the substrate includes a single crystal substrate of MgO or SrTiO3.

[0014] Preferably, in step S1, evacuate to a vacuum degree in the deposition chamber of 1×10 -7 Torr to 9.9×10 - 7 Torr.

[0015] Preferably, in step S1, the deposition temperature is 760 °C, and the heating rate is 20 to 30 °C / min.

[0016] Preferably, in step S3, the density of the YBCO target is not less than 94%, and calculated based on the atomic percentage of the YBCO stoichiometry, the copper element in the YBCO target is in excess of 2% to 5%.

[0017] Preferably, the pulsed laser frequency of the pre-sputtering in step S3 is 5 Hz to 10 Hz, and the time of the pre-sputtering is 300 s to 600 s.

[0018] Preferably, the pulsed laser frequency of the sputtering in step S4 is 2 Hz to 4 Hz, and the time of the sputtering is 150 s to 300 s.

[0019] Preferably, in step S5, oxygen is introduced into the deposition chamber until the pressure in the deposition chamber is 700 Torr to 760 Torr.

[0020] Preferably, the cooling rate for cooling to the annealing temperature in step S5 is 20 to 30 °C / min;

[0021] Preferably, the annealing temperature in step S5 is 620 to 680 °C, and the time of the in-situ annealing treatment is 25 to 35 min.

[0022] The present invention also provides a YBCO thin film prepared by using the above deposition method of the YBCO thin film for a superconducting nanowire single photon detector.

[0023] Preferably, the thickness of the YBCO thin film is 14 to 30 nm.

[0024] As described above, the YBCO thin film for a single photon detector and its deposition method of the present invention have the following beneficial effects:

[0025] Through the improved pulsed laser deposition process, by precisely controlling the deposition parameters and annealing process in an oxygen atmosphere, the present invention prepares a high-quality ultra-thin YBCO thin film with a thickness as low as 14 nm to meet the application requirements of a single photon detector; and the prepared YBCO thin film still maintains excellent superconducting properties under the ultra-thin condition, and the superconducting transition temperature reaches 78 K, greatly reducing the refrigeration cost; the present invention realizes the balance of the high-temperature superconducting properties and uniformity of the ultra-thin YBCO thin film with a low-complexity process, providing a material basis for the application of high-temperature superconducting single photon detectors. Description of the Drawings

[0026] Figure 1 It shows a schematic structural diagram of the pulsed laser deposition equipment used in the specific embodiment of the present invention.

[0027] Figure 2 It shows the resistance-temperature test curve of the YBCO thin film prepared in Example 1 of the present invention.

[0028] Figure 3 It shows the XRD test curve of the YBCO thin film prepared in Example 1 of the present invention.

[0029] Figure 4 Shown is the XRR test curve of the YBCO thin film prepared in Example 1 of the present invention.

[0030] Element number description

[0031] 10 Deposition chamber

[0032] 11 Substrate stage

[0033] 12 Target mounting position

[0034] 13 Baffle

[0035] 20 Oxygen inlet

[0036] 30 Pulsed laser emission device Detailed implementation manners

[0037] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0038] Before further describing the specific implementation manners of the present invention, it should be understood that the protection scope of the present invention is not limited to the specific specific implementation manners described below; it should also be understood that the terms used in the embodiments of the present invention are for describing specific specific implementation manners, rather than for limiting the protection scope of the present invention. The test methods without specific conditions noted in the following examples are generally carried out under conventional conditions or according to the conditions recommended by each manufacturer.

[0039] When the embodiments give a numerical range, it should be understood that unless otherwise specified in the present invention, any value between the two endpoints of each numerical range and any one of the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art of this technology. In addition to the specific methods, equipment, and materials used in the embodiments, according to the knowledge of those skilled in the art of this technology and the description of the present invention, any methods, equipment, and materials similar or equivalent to the methods, equipment, and materials described in the embodiments of the present invention can also be used to implement the present invention.

[0040] Please refer to Figure 1It should be noted that the illustrations provided in this embodiment only schematically illustrate the basic concept of the present invention. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0041] To meet the preparation and application requirements of single-photon detectors, the YBCO thin film used needs to be thin enough in thickness. However, the deposition methods in the prior art can only prepare thin films with a thickness of about one hundred nanometers or more. Therefore, the present invention can provide a high-quality ultra-thin YBCO thin film that can meet the requirements of superconducting single-photon detectors.

[0042] The present invention provides a deposition method for YBCO thin films for superconducting nanowire single-photon detectors, and the deposition method includes the following steps:

[0043] S1. Fix the substrate on the substrate stage 11 of the pulsed laser deposition equipment, evacuate the deposition chamber 10, and heat the substrate stage 11 to the deposition temperature.

[0044] S2. Introduce oxygen into the deposition chamber 10 until the oxygen pressure is 0.25 Torr to 0.35 Torr (such as 0.25 Torr, 0.26 Torr, 0.28 Torr, 0.3 Torr, 0.32 Torr, 0.34 Torr, 0.35 Torr, etc.); wherein, the oxygen pressure refers to the gas pressure generated by the introduced oxygen in the deposition chamber 10.

[0045] S3. Use a YBCO target and perform pre-sputtering on the YBCO target with pulsed laser in the state where the baffle 13 is closed.

[0046] S4. Open the baffle 13 between the YBCO target and the substrate, perform sputtering on the YBCO target with pulsed laser, and deposit the ejected substances on the substrate to obtain a YBCO thin film precursor.

[0047] S5. Introduce oxygen into the deposition chamber 10, and at the same time cool down to the annealing temperature to perform in-situ annealing treatment on the YBCO thin film precursor.

[0048] S6. After the in-situ annealing treatment, cool down to room temperature at a certain cooling rate to obtain a YBCO thin film.

[0049] Specifically, refer to Figure 1Schematic structural diagram of the pulsed laser deposition equipment used in the specific embodiment of the present invention. The pulsed laser deposition equipment includes a deposition chamber 10 and a pulsed laser emitting device 30. A substrate stage 11 is arranged in the deposition chamber 10, and the substrate stage 11 is used to fix the substrate. Above the substrate stage 11, a heating lamp is arranged, and the heating lamp is preferably a halogen lamp; a target mounting position 12 is correspondingly arranged on the substrate stage 11, and a baffle 13 is arranged between the target mounting position 12 and the substrate stage 11. The closed state of the baffle 13 is used to block the substances ejected from the target from depositing on the substrate; an oxygen inlet 20 is arranged on the deposition chamber 10, and oxygen is introduced into the deposition chamber 10 through the oxygen inlet 20; the deposition chamber 10 is also provided with an air extraction gas path (not shown in the figure), and the deposition chamber 10 is evacuated through the air extraction gas path. The air extraction gas path can be connected to a mechanical pump or a molecular pump; the pulsed laser beam emitted by the pulsed laser emitting device 30 is focused on the surface of the target, so that the surface atoms or molecules are excited and detached to form a plasma plume, and finally a thin film is deposited on the substrate.

[0050] As an example, in step S1, the substrate includes a single crystal substrate of MgO or SrTiO3 (strontium titanate).

[0051] Specifically, before the substrate is fixed on the substrate stage 11, it needs to be pretreated. The pretreatment specifically includes: ultrasonically cleaning the substrate with acetone and ethanol in sequence, and after drying, ensuring that there is no residual organic solvent; the MgO single crystal substrate is a single crystal wafer made of magnesium oxide, preferably with a (001) crystal plane orientation; the SrTiO3 single crystal substrate is an oxide single crystal material with a perovskite structure (ABO3 type), preferably the (001) crystal plane, and has a good lattice match with many functional materials (such as high-temperature superconductors).

[0052] As an example, in step S1, the deposition chamber 10 is evacuated to a vacuum degree of 1×10 -7 Torr~9.9×10 - 7 Torr.

[0053] Specifically, in step S1, a mechanical pump or a molecular pump is used to evacuate the deposition chamber 10 to a vacuum degree of 10 -7 Torr magnitude, such as 1×10 -7 Torr, 2×10 -7 Torr, 4×10 -7 Torr, 6×10 -7 Torr, 8×10 -7 Torr, 9×10 -7 Torr, 9.9×10 -7 Torr and any value within the range.

[0054] As an example, in step S1, the deposition temperature is 760° C., and the heating rate is 20-30° C. / min.

[0055] Specifically, in step S1, a halogen lamp is used to heat the substrate stage 11, and the heating rate may include any value within a range of 20°C / min, 22°C / min, 24°C / min, 26°C / min, 28°C / min, 30°C / min, etc. The deposition temperature has a great influence on the crystallization of the thin film and the superconducting properties of the thin film. Changes in the deposition temperature may cause the film to be unable to grow in the desired c-axis orientation, and may also cause a weakening of the superconducting performance and an increase in the surface roughness of the film.

[0056] As an example, the density of the YBCO target in step S3 is not less than 94%, and based on the atomic percentage calculation of the YBCO stoichiometric ratio, the copper element in the YBCO target is excessive by 2% to 5%.

[0057] Specifically, YBCO is yttrium barium copper oxide, and its chemical formula is Yba2Cu3O 7-x , where x is usually between 0 and 1; the density of the YBCO target is the ratio of the actual density of the target to the theoretical density, which reflects the size of the pores inside the target, and the high-density YBCO target can produce uniform plasma plume and reduce film defects; in the process of pulsed laser deposition, the Cu element is easily lost due to its strong volatility, and excess Cu can make up for the Cu loss to maintain the stoichiometric ratio.

[0058] In a specific embodiment of the present invention, the density of the YBCO target is at least 94%, and the higher the better, without any excessive restriction. Based on the atomic percentage calculation of the YBCO stoichiometric ratio, the copper element in the YBCO target is in excess of 2%, 3%, 4%, 5%, etc., wherein the chemical formula of YBCO is YBa2Cu3O 7-x , that is, the atomic ratio of Y:Ba:Cu is 1:2:3. The 4% excess of copper means that the actual atomic number of Cu is 4% more than the ideal value of 3, that is, the actual Cu atomic number is 3×(1+4%)=3.12.

[0059] As an example, the pulse laser frequency of the pre-sputtering in step S3 is 5 Hz to 10 Hz, and the pre-sputtering time is 300 s to 600 s.

[0060] Specifically, the pre-sputtering in step S3 is to bombard the surface of the target material with a laser before formally depositing the thin film to clean the target material and remove surface contaminants or oxide layers to ensure the stability of the subsequent deposition process and the quality of the thin film; the pulse laser frequency may include 5Hz, 6Hz, 7Hz, 8Hz, 9Hz, 10Hz, etc., and the pre-sputtering time may include any value within a range of 300s, 400s, 500s, 600s, etc.

[0061] As an example, in step S4, the pulsed laser frequency for sputtering is 2 Hz to 4 Hz, and the sputtering time is 150 s to 300 s.

[0062] Specifically, sputtering is to bombard the YBCO target with pulsed laser, so that the surface atoms or molecules are excited and detached, and the ejected substances are deposited on the substrate. The pulsed laser frequency during sputtering can include any value within a range such as 2 Hz, 2.5 Hz, 3 Hz, 3.5 Hz, 4 Hz, etc., and the sputtering time can include any value within a range such as 150 s, 160 s, 170 s, 180 s, 190 s, 200 s, etc. In a specific embodiment of the present invention, for example, the pulsed laser frequency for sputtering is set in advance to 2 Hz, and the sputtering time is 300 s. At this time, the number of sputtering pulses should be 600. However, in the actual experimental process, the shutter 13 is closed when there are 8 - 12 remaining pulses, otherwise the deposited YBCO thin film will have an uneven whitening phenomenon.

[0063] As an example, in step S5, oxygen is introduced into the deposition chamber 10 until the pressure in the deposition chamber 10 is 700 Torr to 760 Torr.

[0064] Specifically, a large amount of oxygen is introduced into the deposition chamber 10, and the pressure in the deposition chamber 10 after introducing oxygen is approximately in the atmospheric pressure state, such as 700 Torr, 710 Torr, 720 Torr, 740 Torr, 760 Torr, etc.

[0065] As an example, in step S5, the cooling rate to the annealing temperature is 20 - 30 °C / min.

[0066] As an example, the annealing temperature is 620 - 680 °C, and the in-situ annealing treatment time is 25 - 35 min.

[0067] Specifically, in step S5, the cooling rate can include any value within a range such as 20 °C / min, 22 °C / min, 24 °C / min, 26 °C / min, 28 °C / min, 30 °C / min, etc.; the annealing temperature can include 620 °C, 640 °C, 660 °C, 680 °C, etc., and the in-situ annealing treatment time can include 25 min, 26 min, 28 min, 30 min, 32 min, 34 min, 35 min, etc. Additionally, in step S6, the cooling rate for cooling the substrate stage 11 to room temperature is preferably 30 °C / min.

[0068] The present invention also provides a YBCO thin film prepared by using the above deposition method for YBCO thin film for superconducting nanowire single photon detectors.

[0069] As an example, the thickness of the YBCO thin film is 14 - 30 nm.

[0070] Specifically, the thickness of the YBCO thin film can include values within any range such as 14 nm, 15 nm, 16 nm, 20 nm, 25 nm, 28 nm, 30 nm, etc.

[0071] To better understand the YBCO thin film for superconducting nanowire single photon detectors and its deposition method in the present invention, the YBCO thin film for superconducting nanowire single photon detectors and its deposition method in the present invention will be described below with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0072] Example 1

[0073] This example provides a deposition method for a YBCO thin film for superconducting nanowire single photon detectors. The deposition method includes the following steps:

[0074] S1. Take the required MgO substrate with a (001) crystal phase, ultrasonically clean the substrate with acetone and ethanol in sequence for 5 minutes, dry it, and then fix it on the substrate stage 11 of the pulsed laser deposition equipment using clips (the clips should firmly press the substrate to prevent it from sliding, and try to ensure that the force of each clip is similar. A heat conducting sheet is provided between the substrate and the substrate stage 11 to ensure stable heat conduction between the substrate and the substrate stage 11), evacuate the deposition chamber 10 to 4.18×10 -7 Torr, and use a halogen lamp to heat the substrate stage 11 to the deposition temperature of 760 °C at a heating rate of 30 °C / min;

[0075] S2. Introduce oxygen into the deposition chamber 10 to make the oxygen pressure in the deposition chamber 10 stable at 0.3 Torr;

[0076] S3. After the oxygen pressure and the temperature of the substrate stage 11 are stable, keep the baffle 13 between the substrate stage 11 and the target closed, use a YBCO target (the density is 94%, and the copper element content is 4% in excess of the stoichiometric ratio), and pre-sputter the YBCO target with pulsed laser for 3000 pulses in the closed state of the baffle 13. The pulsed laser frequency is 10 Hz, that is, the pre-sputtering time is 300 s;

[0077] S4. Open the baffle 13 between the YBCO target and the substrate, sputter the YBCO target with pulsed laser for 600 pulses, the pulsed laser frequency is 2 Hz, and close the baffle 13 when there are about 10 pulses remaining to obtain a YBCO thin film precursor;

[0078] S5. After sputtering is completed, close the pumping gas path, and quickly introduce a large amount of oxygen into the deposition chamber 10 until the pressure in the deposition chamber 10 reaches atmospheric pressure. The oxygen pressure at the end of actual oxygen filling is 710 Torr. Cool down at a cooling rate of 30 °C / min to 650 °C for in-situ annealing treatment for 30 min;

[0079] S6. After in-situ annealing treatment, cool down to room temperature at a cooling rate of 30 °C / min, and then open the deposition chamber 10 to remove the thin film sample to obtain a YBCO thin film.

[0080] This embodiment also provides a YBCO thin film, which is deposited by using the deposition method of the YBCO thin film for superconducting nanowire single photon detectors in this embodiment.

[0081] Adopt the four-wire method to perform resistance-temperature (RT) testing on the deposited YBCO thin film in the PPMS system; perform XRD testing on the deposited YBCO thin film; use X-ray reflectivity testing (XRR) instrument to perform X-ray reflectivity testing on the deposited YBCO thin film.

[0082] Refer to Figure 2 is the resistance-temperature test curve of the YBCO thin film prepared in this embodiment. It can be seen from the figure that the critical transition temperature of this YBCO thin film is 78 K; refer to Figure 3 is the XRD test curve of the YBCO thin film prepared in this embodiment. The diffraction peaks of YBCO (001) to (0010) are clear and there are no other impurity phase peaks, indicating that the deposited YBCO thin film grows along the c-axis, and T C is usually relatively high; refer to Figure 4 is the XRR test curve of the YBCO thin film prepared in this embodiment. After fitting the curve, it is obtained that the thickness of the YBCO thin film is 14 nm.

[0083] In summary, through the improved pulsed laser deposition process, by precisely controlling the deposition parameters and annealing process of the oxygen atmosphere, the present invention prepares a high-quality ultra-thin YBCO thin film with a thickness as low as 14 nm to meet the application requirements of single photon detectors; and the prepared YBCO thin film still maintains excellent superconducting properties under ultra-thin conditions, with a superconducting transition temperature of 78 K, greatly reducing the refrigeration cost; the present invention realizes the balance of high-temperature superconducting properties and uniformity of the ultra-thin YBCO thin film with a low-complexity process, providing a material basis for the application of high-temperature superconducting single photon detectors. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0084] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for depositing a YBCO thin film for a single-photon detector, characterized in that: The deposition method comprises the following steps: S1, fixing the substrate on a substrate stage of a pulsed laser deposition device, evacuating the deposition chamber, and heating the substrate stage to a deposition temperature; S2, introducing oxygen into the deposition chamber until the oxygen pressure reaches 0.25 Torr to 0.35 Torr; S3, using a YBCO target material, and pre-sputtering the YBCO target material using a pulsed laser with the baffle closed; S4, opening the baffle between the YBCO target and the substrate, sputtering the YBCO target with a pulsed laser, and depositing the ejected material on the substrate to obtain a YBCO thin film precursor; S5, introducing oxygen into the deposition chamber and cooling the chamber to an annealing temperature, and performing in-situ annealing on the YBCO thin film precursor; S6. After in-situ annealing treatment, the temperature is lowered to room temperature at a certain cooling rate to obtain a YBCO thin film.

2. The method for depositing a YBCO thin film for a single photon detector according to claim 1, characterized in that: The substrate in step S1 includes a MgO or SrTiO3 single crystal substrate.

3. The method for depositing a YBCO thin film for a single photon detector according to claim 1, characterized in that: In step S1, the vacuum in the deposition chamber is evacuated to a vacuum degree of 1×10 -7 Torr~9.9×10 -7 Torr.

4. The method for depositing a YBCO thin film for a single photon detector according to claim 1, characterized in that: In step S1, the deposition temperature is 760° C., and the heating rate is 20-30° C. / min.

5. The method for depositing a YBCO thin film for a single-photon detector according to claim 1, characterized in that: The density of the YBCO target in step S3 is not less than 94%, and based on the atomic percentage calculation of the YBCO stoichiometric ratio, the copper element in the YBCO target is excessive by 2% to 5%.

6. The method for depositing a YBCO thin film for a single photon detector according to claim 1, characterized in that: The pulse laser frequency of the pre-sputtering in step S3 is 5 Hz to 10 Hz, and the time of the pre-sputtering is 300 s to 600 s.

7. The method for depositing a YBCO thin film for a single photon detector according to claim 1, characterized in that: The pulse laser frequency of the sputtering in step S4 is 2 Hz to 4 Hz, and the sputtering time is 150 s to 300 s.

8. The method for depositing a YBCO thin film for a single photon detector according to claim 1, characterized in that: Step S5 includes one or a combination of the following conditions: The oxygen gas is introduced into the deposition chamber until the pressure in the deposition chamber is 700 Torr to 760 Torr; The cooling rate from the temperature down to the annealing temperature is 20 to 30°C / min; The annealing temperature is 620-680° C., and the in-situ annealing treatment time is 25-35 minutes.

9. A YBCO thin film prepared by the deposition method of a YBCO thin film for a single-photon detector according to any one of claims 1 to 8.

10. The YBCO thin film for single-photon detector according to claim 9, characterized in that: The thickness of the YBCO film is 14-30 nm.

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