Preparation method of hexagonal boron nitride single photon source

Abstract

The invention provides a preparation method of a hexagonal boron nitride single photon source. The preparation method comprises the following steps: forming nanoparticles on the surface of a first substrate; mechanically stripping the hexagonal boron nitride sheet, transferring the hexagonal boron nitride sheet to a second substrate, performing plasma treatment on the hexagonal boron nitride sheet, and introducing a single photon source to the hexagonal boron nitride sheet; transferring the hexagonal boron nitride sheet into which the single photon source is introduced from the surface of the second substrate to the first substrate on which the nanoparticles are formed; and annealing the first substrate carrying the hexagonal boron nitride sheet introduced with the single-photon source and the nanoparticles to obtain the hexagonal boron nitride single-photon source, the nanoparticles being used for enhancing the brightness of the hexagonal boron nitride single-photon source. According to the preparation method, the preparation of the high-brightness hexagonal boron nitride single photon source can be realized.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of quantum communication, in particular to a preparation method of a hexagonal boron nitride single photon source. BACKGROUND

[0002] Solid-state quantum emitters are the key to drive the frontier technologies of quantum communication, computation, network architecture and sensing. As the cornerstone of quantum information technology, single photon sources are indispensable basic resources. Their carriers have been expanded from early single atoms / molecules to diamond point defects, silicon carbide point defects, semiconductor quantum dots and carbon nanotubes, etc.

[0003] Two-dimensional (2D) materials have attracted much attention due to their potential in hosting specific single photon emitters (SPEs) and excellent device integration and optical coupling characteristics. However, most SPEs in 2D transition metal dichalcogenides (TMDs) can only work at low temperatures, limiting their room-temperature applications. In contrast, the graphenelike layered material hexagonal boron nitride (hBN) exhibits significant advantages: the localized point defects in its wide band gap (~6 eV) can host room-temperature stable and strongly linearly polarized SPEs. The excellent chemical and thermal stability of hBN further ensures the long-term operation of the SPEs, making it an ideal platform for integrated quantum photonic devices.

[0004] Quantum emitters in hBN are often derived from defects randomly formed during its growth process or when it is exfoliated from bulk crystals. However, this randomness leads to ubiquitous and spatially disordered emitters, accompanied by low density and uneven optical properties. To overcome this problem, researchers have explored and adopted various post-processing methods, such as ion / electron irradiation, focused ion beam (FIB) treatment, plasma etching, femtosecond laser ablation, and atomic force microscope (AFM) tip nanoindentation, aiming to create high-density and uniformly characteristic quantum emitters. However, these methods require high costs, and the brightness of the generated emitters still has a long way to go. Therefore, how to prepare large-scale, high-brightness, and high-repetition quantum emitters at low cost is a problem that needs to be solved by those skilled in the art. SUMMARY

[0005] In view of the deficiencies of the prior art, the present disclosure provides a preparation method of a hexagonal boron nitride single photon source, which at least partially solves the problems of high cost and low brightness of hBN quantum emitter preparation in the prior art.

[0006] The preparation method of the hexagonal boron nitride single photon source provided by the present disclosure comprises the following steps: forming nanoparticles on a first substrate surface; mechanically exfoliating a hexagonal boron nitride flake and transferring the hexagonal boron nitride flake to a second substrate; performing plasma treatment on the hexagonal boron nitride flake to introduce a single photon source into the hexagonal boron nitride flake; transferring the hexagonal boron nitride flake with the introduced single photon source from the second substrate surface to the first substrate on which the nanoparticles are formed; and performing annealing on the first substrate carrying the hexagonal boron nitride flake with the introduced single photon source and the nanoparticles to obtain a hexagonal boron nitride single photon source, wherein the nanoparticles are used to enhance the brightness of the hexagonal boron nitride single photon source.

[0007] According to an embodiment of the present disclosure, the nanoparticles comprise metal nanoparticles or dielectric nanoparticles.

[0008] According to an embodiment of the present disclosure, when the nanoparticles comprise metal nanoparticles, the step of forming the nanoparticles on the first substrate surface comprises the following step: forming a metal thin film on the first substrate surface.

[0009] The step of forming the metal thin film on the first substrate surface comprises the following step: sputtering a metal thin film on the first substrate surface under the following conditions: an argon atmosphere as a sputtering atmosphere, a sputtering temperature of 450-550 DEG C, a sputtering gas pressure of 1.0 Pa, a sputtering power of 50-80 W, and a sputtering time of 3-5 s.

[0010] According to an embodiment of the present disclosure, the step of annealing the metal thin film to obtain metal nanoparticles comprises the following steps: annealing the metal thin film under the following conditions: an annealing temperature of 550-700 DEG C and an annealing time of 1-2 h, and then cooling the metal thin film to 400 DEG C at a speed of not more than 10 DEG C / min and naturally cooling the metal thin film to room temperature to obtain the metal nanoparticles.

[0011] According to an embodiment of the present disclosure, the step of mechanically exfoliating the hexagonal boron nitride flake and transferring the hexagonal boron nitride flake to the second substrate comprises the following steps: sticking the hexagonal boron nitride flake on a thermal release tape, and then slowly tearing the two thermal release tapes after the hexagonal boron nitride flake is stuck on another thermal release tape; repeating the above process until the thickness of the hexagonal boron nitride flake left on the thermal release tape is less than 100 nm; sticking the thermal release tape carrying the hexagonal boron nitride flake on the second substrate, heating the thermal release tape to a preset temperature and keeping the thermal release tape at the preset temperature for a preset period of time to slowly separate the thermal release tape from the second substrate, and transferring the hexagonal boron nitride flake to the second substrate; wherein the preset temperature is 90-120 DEG C, and the preset period of time is 5-15 min.

[0012] According to an embodiment of the present disclosure, the hexagonal boron nitride flakes are subjected to plasma treatment, and a single photon source is introduced into the hexagonal boron nitride flakes, including: placing a second substrate carrying the hexagonal boron nitride flakes in a radio frequency plasma generator for treatment, wherein the plasma treatment atmosphere includes at least one of argon, oxygen, hydrogen, methane and ammonia, the plasma treatment time is 1 min to 20 min, and the plasma treatment power is 20 W to 200 W.

[0013] According to an embodiment of the present disclosure, the hexagonal boron nitride flakes with the introduced single photon source are transferred from the surface of the second substrate to the first substrate with the formed nanoparticles, including: sequentially spin coating polyvinyl alcohol and polymethyl methacrylate on the second substrate carrying the hexagonal boron nitride flakes with the introduced single photon source, and then annealing on a 110°C to 120°C hot plate for 20 min to 30 min; soaking the second substrate after annealing in a potassium hydroxide solution until the second substrate and the hexagonal boron nitride flakes are separated, and using the second substrate to lift the hexagonal boron nitride flakes from the potassium hydroxide solution and transfer them to deionized water; using the first substrate with the formed nanoparticles to lift the hexagonal boron nitride flakes from the deionized water, and placing them on a 60°C to 80°C hot plate to heat until the water between the hexagonal boron nitride flakes and the first substrate is evaporated, and then increasing the temperature of the hot plate to 110°C to 120°C to anneal for 20 min to 30 min; soaking the first substrate carrying the hexagonal boron nitride flakes with the introduced single photon source and the nanoparticles in acetone for 30 min to 120 min, and repeating multiple times until the polyvinyl alcohol and the polymethyl methacrylate are completely washed out.

[0014] According to an embodiment of the present disclosure, the concentration of polyvinyl alcohol is 1% to 3%, the concentration of polymethyl methacrylate is 3% to 5%, the concentration of the potassium hydroxide solution is 15% to 25%, the temperature of the potassium hydroxide solution is 100°C to 120°C, the spin coating speed is 3000 rpm to 5000 rpm, and the spin coating time is 30 s to 60 s.

[0015] According to an embodiment of the present disclosure, the first substrate carrying the hexagonal boron nitride flakes with the introduced single photon source and the nanoparticles is annealed to obtain a hexagonal boron nitride single photon source, including: placing the first substrate carrying the hexagonal boron nitride flakes with the introduced single photon source and the nanoparticles into an annealing furnace for annealing, wherein the annealing atmosphere is one of nitrogen or air, the annealing temperature is 600°C to 900°C, and the thermal annealing time is 30 s to 60 s.

[0016] According to an embodiment of the present disclosure, the preparation method further comprises: placing the second substrate of the hexagonal boron nitride flake introduced into the single photon source into an annealing furnace for annealing, wherein the annealing atmosphere comprises one of air, oxygen, nitrogen or argon, the annealing temperature is 700-900 ℃, the annealing time is 30-60 min, and the temperature rising and falling rate is not more than 10 ℃ / min.

[0017] According to an embodiment of the present disclosure, the first substrate and the second substrate comprise a silicon dioxide / silicon substrate; before forming a layer of metal thin film on the surface of the first substrate, the method further comprises: sequentially placing the silicon dioxide / silicon substrate into acetone, isopropyl alcohol and ethanol for ultrasonic cleaning and drying with nitrogen.

[0018] The preparation method of the hexagonal boron nitride single photon source provided by the present disclosure has at least the following technical effects.

[0019] By plasma treatment process, the hexagonal boron nitride flake is treated by plasma, which can directly act on the material on the entire substrate, and can produce defects with optical activity by introducing lattice damage or introducing specific elements, so that large-scale single photon source preparation can be realized.

[0020] The hexagonal boron nitride flake introduced into the single photon source is transferred from the surface of the second substrate to the substrate formed with nanoparticles, so as to enhance the brightness of the hBN single photon source through the nanoparticles, and realize the low-cost preparation of high-repetition high-brightness single photon source. Specifically, due to the surface plasmon of the metal nanoparticles, near-field enhancement of the optical field can be realized, and the effect of the Bohr effect is further enhanced to enhance the local optical field; the dielectric nanoparticles can also further enhance the local optical field through Mie scattering. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0022] Figure 1 A flow chart of the preparation method of the hexagonal boron nitride single photon source according to an embodiment of the present disclosure is schematically shown.

[0023] Figure 2 A scanning electron microscope image of the nanoparticles according to an embodiment of the present disclosure is schematically shown.

[0024] Figure 3 A photoluminescence spectrum of the single photon source in the hexagonal boron nitride before wet transfer according to an embodiment of the present disclosure is schematically shown.

[0025] Figure 4 A schematic diagram of the second-order correlation characteristic test result of the single photon source in the hexagonal boron nitride before wet transfer according to an embodiment of the present disclosure is schematically shown.

[0026] Figure 5 A saturation emission rate curve of a single photon source in hexagonal boron nitride before wet transfer is schematically shown according to an embodiment of the present disclosure.

[0027] Figure 6 A photoluminescence spectrum of a single photon source of hexagonal boron nitride on silver nanoparticles after rapid thermal annealing is schematically shown according to an embodiment of the present disclosure.

[0028] Figure 7 A second-order correlation property test result diagram of a single photon source of hexagonal boron nitride on silver nanoparticles after rapid thermal annealing is schematically shown according to an embodiment of the present disclosure.

[0029] Figure 8 A saturation emission rate curve of a single photon source of hexagonal boron nitride on silver nanoparticles after rapid thermal annealing is schematically shown according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It is to be understood, however, that the description is merely exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description of embodiments of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. However, it would be apparent to those skilled in the art that the embodiments can be practiced without these specific details. In other instances, well-known structures and techniques have not been described in detail in order to avoid obscuring aspects of the present disclosure.

[0031] Figure 1 A flowchart of a method of preparing a single photon source of hexagonal boron nitride is schematically shown according to an embodiment of the present disclosure.

[0032] As shown in the present embodiment, the method of preparation may, for example, include operations S110-S150. Figure 1

[0033] In operation S110, nanoparticles are formed on a first substrate surface.

[0034] In operation S120, hexagonal boron nitride flakes are mechanically exfoliated and transferred onto a second substrate.

[0035] In operation S130, the hexagonal boron nitride flakes are subjected to plasma treatment to introduce single photon sources to the hexagonal boron nitride flakes.

[0036] In operation S140, the hexagonal boron nitride flakes to which the single photon sources are introduced are transferred from the second substrate surface to the first substrate on which the nanoparticles are formed.

[0037] ​At operation S150, the first substrate carrying the hexagonal boron nitride flakes and nanoparticles of the introduced single-photon source is annealed to obtain the hexagonal boron nitride single-photon source, wherein the nanoparticles are used to enhance the brightness of the hexagonal boron nitride single-photon source.

[0038] In some embodiments, the first substrate and the second substrate can include a silicon dioxide / silicon substrate. Before forming the metal thin film on the surface of the first substrate, the method further includes: sequentially placing the silicon dioxide / silicon substrate into acetone, isopropyl alcohol, and ethanol for ultrasonic cleaning and drying with nitrogen.

[0039] For example, two pieces of 1 cm x 1 cm silicon dioxide / silicon are prepared as the first substrate and the second substrate, and are sequentially placed into acetone, isopropyl alcohol, and ethanol for ultrasonic cleaning and drying with nitrogen.

[0040] For example, the cleaning is performed twice in each solvent, each time for 20 minutes, and the drying is performed with nitrogen having a purity of 99.9%.

[0041] In some embodiments, the nanoparticles include metal nanoparticles and dielectric nanoparticles. The metal nanoparticles may, for example, include gold nanoparticles, silver nanoparticles, aluminum nanoparticles, and the like.

[0042] In some embodiments, when the nanoparticles include metal nanoparticles, forming the nanoparticles on the surface of the first substrate includes: forming a metal thin film on the surface of the first substrate. The metal thin film is annealed to obtain the metal nanoparticles.

[0043] In some embodiments, forming the metal thin film on the surface of the first substrate can include: sputtering a metal thin film on the surface of the first substrate under the following conditions: an argon atmosphere as the sputtering atmosphere, a sputtering temperature of 500°C, a sputtering gas pressure of 1.0 Pa, a sputtering power of 50 W, and a sputtering time of 3 s-5 s.

[0044] For example, the silicon dioxide surface of the clean silicon dioxide / silicon substrate is fixed outward on a sample holder, and the sample holder is sent to a rotatable heating furnace in a magnetron sputtering chamber. The vacuum system is started to reduce the vacuum degree in the sputtering chamber to below 8.0 x 10 -5 Pa. The heating furnace is turned on for stage heating, and when the temperature of the first substrate rises to 500°C, the sample holder is rotated at a speed of 14 r / min. The vertical distance between the first substrate and the silver sputtering target is adjusted to 4.0 cm. The argon gas valve is opened, the vacuum system is adjusted to make the gas pressure in the chamber 1.0 Pa, the silver target cover is opened, the excitation power is adjusted to 50 W, and the capacitance is adjusted to make the glow normal. The sample holder is turned to above the target to start sputtering.

[0045] In some embodiments, annealing a metal film to obtain nanoparticles includes: annealing the metal film at an annealing temperature of 550°C to 700°C and an annealing time of 1 h to 2 h, then cooling it to 400°C at a rate not exceeding 10°C / min, and then naturally cooling it to room temperature to obtain nanoparticles.

[0046] For example, after sputtering a thin silver film onto the surface of the first substrate, no cooling is performed. The furnace temperature is adjusted to 550℃-700℃, and timing is started after the temperature stabilizes. The temperature is maintained for 1-2 hours. After the holding time is completed, the temperature is reduced to 400℃ at a rate not exceeding 10℃ / min. The argon gas valve is closed, and the vacuum system is adjusted to normal operation, allowing the silver to cool naturally to room temperature under high vacuum.

[0047] In some embodiments, mechanically peeling off the hexagonal boron nitride sheet and transferring it to a second substrate may include: adhering the hexagonal boron nitride sheet to a heat-release adhesive tape, adhering the sheet to another heat-release adhesive tape, and then slowly tearing the two tapes apart; repeating the above process until the thickness of the hexagonal boron nitride sheet remaining on the heat-release adhesive tape is less than 100 nm; adhering the heat-release adhesive tape carrying the hexagonal boron nitride sheet to the second substrate, heating it to a preset temperature and holding it at that temperature for a preset time period to allow the heat-release adhesive tape to slowly separate from the second substrate, thereby transferring the hexagonal boron nitride sheet to the second substrate; wherein the preset temperature is 90°C to 120°C, and the preset time period is 5 min to 15 min.

[0048] In some embodiments, plasma treatment of a hexagonal boron nitride sheet, introducing a single-photon source into the hexagonal boron nitride sheet, may include: placing a second substrate carrying the hexagonal boron nitride sheet in a radio frequency plasma generator for treatment, wherein the plasma treatment atmosphere includes at least one of argon, oxygen, hydrogen, methane and ammonia, the plasma treatment time is 1 min to 20 min, and the plasma treatment power is 20 W to 200 W.

[0049] For example, a second substrate carrying a hexagonal boron nitride sheet is placed into the chamber of an RF plasma generator. The chamber is then sealed, and a vacuum pump is used to evacuate the chamber pressure to below 0.5 Pa and maintain this pressure for 5 minutes. The vacuum pump is then turned off, and argon gas is introduced into the chamber to purge it. This evacuation and purging process is repeated 2-3 times. Depending on the desired treatment effect, gases such as argon, nitrogen, oxygen, hydrogen, methane, or ammonia are introduced into the chamber. The chamber pressure is adjusted to 20 Pa to 150 Pa by regulating the gas flow rate and the tightness of the chamber bypass valve. The plasma excitation power is adjusted to 20 W to 200 W. The plasma generator is then turned on, and the matching capacitor is adjusted so that the forward plasma power reaches the set excitation power, while the reverse power drops to 0. After the plasma glow in the chamber stabilizes, the hexagonal boron nitride sheet on the silicon dioxide / silicon substrate is processed for 1 to 20 minutes. After processing is complete, turn off the plasma generator power and gas valves, then turn off the vacuum pump and remove the processed second substrate.

[0050] In some embodiments, transferring a hexagonal boron nitride sheet with a single-photon source introduced from the surface of a second substrate to a first substrate with nanoparticles formed includes: sequentially spin-coating polyvinyl alcohol and polymethyl methacrylate onto the second substrate carrying the hexagonal boron nitride sheet with the single-photon source introduced, followed by annealing on a hot plate at 120°C for 20 min; immersing the annealed second substrate in a potassium hydroxide solution until the second substrate separates from the hexagonal boron nitride sheet, and using the second substrate to retrieve the hexagonal boron nitride sheet from the potassium hydroxide solution and transfer it to deionized water; using the first substrate with nanoparticles formed to retrieve the hexagonal boron nitride sheet from the deionized water, and heating it on a hot plate at 60°C~80°C until the moisture between the hexagonal boron nitride sheet and the first substrate evaporates, followed by annealing at 110°C~120°C for 20 min; immersing the first substrate carrying the hexagonal boron nitride sheet with the single-photon source introduced and the nanoparticles in acetone for 30 min~120 min. Repeat the process for 1 minute or more until polyvinyl alcohol and polymethyl methacrylate are completely washed away.

[0051] In some embodiments, the concentration of polyvinyl alcohol is 1% to 3%, the concentration of polymethyl methacrylate is 3% to 5%, the concentration of potassium hydroxide solution is 15% to 25%, the temperature of potassium hydroxide solution is 100℃ to 120℃, the spin coating speed is 3000 rpm to 5000 rpm, and the spin coating time is 30 s to 60 s.

[0052] In some embodiments, annealing a first substrate carrying a hexagonal boron nitride sheet and nanoparticles that introduce a single photon source to obtain a hexagonal boron nitride single photon source may include: placing the first substrate carrying the hexagonal boron nitride sheet and nanoparticles that introduce the single photon source into an annealing furnace for annealing, wherein the annealing atmosphere is either nitrogen or air, the annealing temperature is 600 ℃~900 ℃, and the thermal annealing time is 30 s~60 s.

[0053] In some embodiments, to further improve the quality of the hexagonal boron nitride single-photon source, the silicon dioxide / silicon substrate carrying the plasma-treated hexagonal boron nitride sheet can be annealed. The preparation method further includes: placing the second substrate containing the hexagonal boron nitride sheet with the single-photon source into an annealing furnace for annealing, wherein the annealing atmosphere includes one of air, oxygen, nitrogen, or argon, the annealing temperature is 700℃~900℃, the annealing time is 30min~60min, and the temperature rise and fall rate does not exceed 10℃ / min.

[0054] To more clearly illustrate the advantages of the preparation method of the hexagonal boron nitride single-photon source of this disclosure, some experimental data are listed below.

[0055] Figure 2 A scanning electron microscope image of silver nanoparticles according to an embodiment of the present disclosure is shown schematically.

[0056] like Figure 2 As shown, large-area silver nanoparticles were formed by high-temperature annealing under an argon atmosphere after magnetron sputtering of silver thin films.

[0057] Figure 3 The schematic illustration shows the photoluminescence spectrum of a single-photon source in hexagonal boron nitride prior to wet transfer according to an embodiment of the present disclosure.

[0058] like Figure 3 As shown, plasma processing can generate photoluminescence spectra on mechanically peeled hexagonal boron nitride sheets.

[0059] Figure 4 The diagram illustrates the test results of the second-order correlation characteristics of a single-photon source in hexagonal boron nitride before wet transfer according to an embodiment of the present disclosure.

[0060] like Figure 4 As shown, the second-order correlation of photoluminescence generated on mechanically stripped hexagonal boron nitride sheets by plasma treatment is much less than 0.5 at the position where the delay time is zero. This indicates that the processed material is a single-photon source with high single-photon purity.

[0061] Figure 5The diagram schematically illustrates the saturation emission rate curve of a single-photon source in hexagonal boron nitride before wet transfer according to an embodiment of the present disclosure.

[0062] like Figure 5 As shown, a single-photon source on a hexagonal boron nitride thin film after plasma processing was subjected to variable excitation power photoluminescence test, and the saturation emission rate curve was fitted.

[0063] Figure 6 The schematic illustration shows the photoluminescence spectrum of a hexagonal boron nitride single-photon source on silver nanoparticles after rapid thermal annealing according to an embodiment of the present disclosure.

[0064] like Figure 6 As shown, photoluminescence spectra conforming to the emission characteristics of a single-photon source can be obtained in hexagonal boron nitride on silver nanoparticles after rapid thermal annealing.

[0065] Figure 7 The illustration shows a schematic diagram of the second-order correlation characteristics test results of a hexagonal boron nitride single-photon source on silver nanoparticles after rapid thermal annealing according to an embodiment of the present disclosure.

[0066] like Figure 7 As shown, the second-order correlation of photoluminescence generated in hexagonal boron nitride on silver nanoparticles after rapid thermal annealing is less than 0.5 at the position where the delay time is zero. Therefore, it can be seen that the rapid thermal annealing treatment after wet transfer to silver nanoparticles still yields a single-photon source.

[0067] Figure 8 The diagram schematically illustrates the saturation emission rate curve of a hexagonal boron nitride single-photon source on silver nanoparticles after rapid thermal annealing according to an embodiment of the present disclosure.

[0068] like Figure 8 As shown, variable excitation power photoluminescence tests were performed on a hexagonal boron nitride thin film single-photon source on silver nanoparticles after rapid thermal annealing. The saturation emission rate curve was fitted, and the saturation emission rate was much higher than that of a hexagonal boron nitride single-photon source not on silver nanoparticles. The emitter brightness was significantly improved.

[0069] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A method for preparing a hexagonal boron nitride single-photon source, characterized in that, include: Nanoparticles are formed on the surface of the first substrate; A hexagonal boron nitride sheet is mechanically peeled off and transferred to a second substrate. The hexagonal boron nitride sheet is then subjected to plasma treatment to introduce a single-photon source into the sheet. A hexagonal boron nitride sheet with a single photon source is transferred from the surface of the second substrate to a first substrate on which nanoparticles are formed. Annealing a first substrate containing a hexagonal boron nitride thin film and nanoparticles that introduce a single photon source yields a hexagonal boron nitride single photon source, wherein the nanoparticles are used to enhance the brightness of the hexagonal boron nitride single photon source.

2. The preparation method according to claim 1, characterized in that, The nanoparticles include metal nanoparticles or dielectric nanoparticles.

3. The preparation method according to claim 1, characterized in that, When the nanoparticles include metal nanoparticles, forming the nanoparticles on the surface of the first substrate includes: A metal thin film is formed on the surface of the first substrate; The metal film was annealed to obtain metal nanoparticles.

4. The preparation method according to claim 3, characterized in that, The process of forming a metal thin film on the surface of the first substrate includes: Under the conditions of sputtering atmosphere of argon, sputtering temperature of 450℃~550℃, sputtering pressure of 1.0Pa, sputtering power of 50W~80W, and sputtering time of 3 s~5 s, a metal thin film is sputtered on the surface of the first substrate. The annealing of the metal thin film to obtain metal nanoparticles includes: The metal film was annealed at an annealing temperature of 550℃~700℃ for 1h~2h, and then cooled to 400℃ at a rate not exceeding 10℃ / min, and naturally cooled to room temperature to obtain the metal nanoparticles.

5. The preparation method according to claim 1, characterized in that, The mechanical stripping of the hexagonal boron nitride sheet and its transfer to the second substrate includes: Attach the hexagonal boron nitride sheet to the heat release tape, and then use another heat release tape to attach the sheet. Slowly peel the two tapes apart. Repeat the above process until the thickness of the hexagonal boron nitride sheet remaining on the heat release tape is less than 100 nm. A heat-release tape carrying a hexagonal boron nitride sheet is attached to a second substrate. The substrate is heated to a preset temperature and kept warm for a preset time period to allow the heat-release tape to slowly separate from the second substrate, thereby transferring the hexagonal boron nitride sheet onto the second substrate. The preset temperature is 90℃~120℃, and the preset time period is 5min~15min.

6. The preparation method according to claim 1, characterized in that, The plasma treatment of the hexagonal boron nitride sheet, introducing a single-photon source into the hexagonal boron nitride sheet, includes: The second substrate carrying the hexagonal boron nitride sheet is placed in a radio frequency plasma generator for processing. The plasma processing atmosphere includes at least one of argon, oxygen, hydrogen, methane, and ammonia. The plasma processing time is 1 min to 20 min, and the plasma processing power is 20 W to 200 W.

7. The preparation method according to claim 1, characterized in that, The step of transferring the hexagonal boron nitride sheet with a single-photon source introduced from the surface of the second substrate to the first substrate on which nanoparticles are formed includes: Polyvinyl alcohol and polymethyl methacrylate were sequentially spin-coated onto a second substrate carrying a hexagonal boron nitride thin film that introduced a single photon source, and then annealed on a hot plate at 110℃~120℃ for 20 min~30 min. After annealing, the second substrate is immersed in a potassium hydroxide solution until the second substrate separates from the hexagonal boron nitride sheet. The hexagonal boron nitride sheet is then retrieved from the potassium hydroxide solution using the second substrate and transferred to deionized water. Using a first substrate with nanoparticles, the hexagonal boron nitride sheet is scooped out from the deionized water and placed on a hot plate at 60°C to 80°C until the water between the hexagonal boron nitride sheet and the first substrate evaporates. Then, the hot plate temperature is raised to 110°C to 120°C for annealing for 20 min to 30 min. The first substrate, which carries a hexagonal boron nitride thin film and nanoparticles containing a single-photon source, is immersed in acetone for 30 min to 120 min, repeated multiple times until polyvinyl alcohol and polymethyl methacrylate are completely washed away; wherein the concentration of polyvinyl alcohol is 1% to 3%, the concentration of polymethyl methacrylate is 3% to 5%, the concentration of potassium hydroxide solution is 15% to 25%, the temperature of potassium hydroxide solution is 100℃ to 120℃, the spin coating speed is 3000 rpm to 5000 rpm, and the spin coating time is 30 s to 60 s.

8. The preparation method according to claim 1, characterized in that, The annealing of the first substrate, which carries the hexagonal boron nitride thin film and nanoparticles containing the introduced single-photon source, to obtain the hexagonal boron nitride single-photon source includes: The first substrate, which carries a hexagonal boron nitride thin film and nanoparticles that introduce a single photon source, is placed in an annealing furnace for annealing. The annealing atmosphere is either nitrogen or air, the annealing temperature is 600 ℃~900 ℃, and the thermal annealing time is 30 s~60 s.

9. The preparation method according to claim 1, characterized in that, The preparation method further includes: The second substrate, which carries a hexagonal boron nitride thin film containing a single-photon source, is placed in an annealing furnace for annealing. The annealing atmosphere includes one of air, oxygen, nitrogen, or argon. The annealing temperature is 700℃~900℃, the annealing time is 30min~60min, and the temperature rise and fall rate does not exceed 10℃ / min.

10. The preparation method according to claim 3, characterized in that, The first substrate and the second substrate comprise silicon dioxide / silicon substrates; Before forming a thin metal film on the surface of the first substrate, the method further includes: The silicon dioxide / silicon substrate was sequentially immersed in acetone, isopropanol, and ethanol for ultrasonic cleaning, and then dried with nitrogen gas.

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