Preparation method of large-area hexagonal boron nitride ultraviolet single-photon source

Abstract

The application discloses a preparation method of a large-area hexagonal boron nitride ultraviolet single-photon source. ‑3 The system is first vacuumized to 10 ‑3 Pa below, and then heated to the reaction temperature and kept for a period of time; then, BCl3 and NH3 or BF3 and NH3 are introduced as two kinds of raw gas, and the graphite clamp is slightly decomposed by the high-temperature environment to provide a carbon source; the gas is mixed and chemically reacted to grow a large-area hexagonal boron nitride film with carbon defects; and the film peeled from the substrate is the hexagonal boron nitride ultraviolet single-photon source. The application successfully prepares the large-area hexagonal boron nitride ultraviolet single-photon emission source, characterizes the emission center with potential single-photon source characteristics, paves the way for the practical application of the hexagonal boron nitride material in quantum communication and optoelectronic application, and shows the stability and high-efficiency single-photon emission capacity of the material at room temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of single photon source, in particular to a preparation method of a large-area hexagonal boron nitride ultraviolet single photon source. BACKGROUND

[0002] In the development of future quantum computing and information processing technologies, optical applications with single photons play a crucial role. In order to achieve effective application of these technologies, single photon source systems need to have long-term stability, easy to set up, and preferably composed of low-cost materials. Current research focuses on finding new single photon sources with different emission wavelengths and higher emission rates, and which can be excited by means other than laser light, such as electric current (electroluminescence) or fast electrons (cathodoluminescence, CL).

[0003] At present, semiconductor quantum dots and color centers in diamond and silicon carbide have provided solid-state platforms for optically stable room-temperature single photon emitters in the visible range. In recent years, low-dimensional layered semiconductors have attracted attention as a promising new optical material. Single photon sources have also been described recently in transition metal dichalcogenides and hexagonal boron nitride (h-BN). Quantum communication is usually achieved by transmitting (single) photons in optical fibers, but free-space links are also considered a viable alternative. One advantage of the ultraviolet spectral range is that its background solar radiation is very limited, so that optical communication can be carried out during the day. However, due to the technical difficulties of preparing wide-bandgap nanostructures with single photon source characteristics, there have been few reports on ultraviolet single photon sources so far. Although ultraviolet single photon sources operating at 200K have been achieved using GaN and InGaN quantum dots, synthesizing such color centers in wide-bandgap materials may be a more viable way to achieve room-temperature ultraviolet single photon sources.

[0004] h-BN has recently become a promising candidate for optoelectronic applications due to its strong ultraviolet radiation that is stable at room temperature. The luminescence of high-quality crystals is mainly characterized by a sharp line at 5.75eV in the deep ultraviolet. In addition, other strong features in the ultraviolet spectral region are associated with extrinsic defects, but the quantum nature of these emissions has not been fully explored so far. And in previous studies, people have not been able to effectively obtain large-area h-BN with ultraviolet single photon emission. SUMMARY

[0005] The present application provides a preparation method of a large-area hexagonal boron nitride ultraviolet single photon source, which successfully realizes a large-area (6 inches) h-BN ultraviolet single photon emission source. This breakthrough paves the way for the practical application of h-BN materials in quantum communication and optoelectronic applications. The present application demonstrates the stability and high-efficiency single photon emission capability of the material at room temperature, which will provide important support for the development of future quantum technologies.

[0006] In order to achieve the above object, the technical scheme adopted by the present application is:

[0007] In a first aspect, the present application provides a preparation method of a large-area hexagonal boron nitride ultraviolet single-photon source, comprising the following steps:

[0008] Step S1, in a vapor deposition furnace, a silicon carbide substrate is fixed by using a graphite clamp, and vacuum is extracted to 10 -3 Pa below;

[0009] Step S2, then the system temperature is raised to the reaction temperature by using resistance heating and is kept warm; in a high-temperature environment, BCl3 and NH3, or BF3 and NH3 two kinds of raw gas are introduced, high temperature makes the graphite clamp slightly decompose to provide a small amount of carbon source, in the middle of the deposition cavity, the gas is mixed and chemically reacts, and a large-area hexagonal boron nitride film with carbon defects is grown;

[0010] Step S3, then power is turned off, the hexagonal boron nitride film and the substrate are cooled to room temperature in the furnace, the hexagonal boron nitride film is peeled off from the substrate, and a large-area hexagonal boron nitride single-photon source is prepared.

[0011] Further, the growth time of the hexagonal boron nitride film in step S2 is 80-120 min.

[0012] Further, in step S2, the system is raised to 1500-1700 DEG C and kept warm.

[0013] Further, in step S2, the volume ratio of BCl3 and NH3, or BF3 and NH3 two kinds of raw gas is 1:0.9.

[0014] Further, in step S2, the two kinds of raw gas BCl3 and NH3, or BF3 and NH3 enter the deposition cavity from the bottom.

[0015] In a second aspect, the present application provides a large-area hexagonal boron nitride ultraviolet single-photon source, which is prepared by the above preparation method of a large-area hexagonal boron nitride ultraviolet single-photon source.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] Hexagonal boron nitride becomes a promising candidate for optoelectronic applications due to its strong ultraviolet radiation stable at room temperature. Although there are many sharp spectral features in the ultraviolet region, the single-photon source characteristics of these features have not been clearly studied. The present application successfully realizes a large-area h-BN ultraviolet single-photon emission source, and characterizes potential single-photon source emission centers (including 4.08 eV, 3.93 eV, and 3.74 eV centers). This breakthrough paves the way for the practical application of h-BN materials in quantum communication and optoelectronic applications. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 a is a real photo of the 6-inch hexagonal boron nitride film after peeling in the present application embodiment 1;

[0019] Figure 1 b is a CL spectrum of the hexagonal boron nitride film in the present application embodiment 2, Figure 1 c is a second-order time correlation function;

[0020] Figure 2 is a high-resolution TEM image of the hexagonal boron nitride film in the present application embodiment 3. DETAILED DESCRIPTION

[0021] The specific embodiments of the present application are further described below. It should be noted that the description of these embodiments is used to help understand the present application, but does not constitute a limitation on the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0022] The experimental methods in the following examples are all conventional methods unless otherwise specified. The test materials used in the following examples are all commercially available unless otherwise specified.

[0023] Example 1, Preparation method of large-area hexagonal boron nitride single-photon source

[0024] This embodiment is used to provide a preparation method of a large-area hexagonal boron nitride single-photon source of the present application. The preparation method uses chemical vapor deposition to grow a large-area hexagonal boron nitride film, and selects a 6-inch silicon carbide (SiC) single crystal as a substrate material, which includes the following steps:

[0025] Step S1, in a vapor deposition furnace, the SiC substrate is fixed using a graphite clamp, and vacuumed to below 10 -3 Pa gas pressure;

[0026] Step S2, the system temperature is raised to 1600℃ by resistance heating and kept for a while. In the high temperature environment, BCl3 and NH3 (or BF3 and NH3) two kinds of raw gas are introduced at a volume ratio of 1:0.9, so that BCl3 and NH3 (or BF3 and NH3) two kinds of raw gas enter the deposition cavity from the bottom.

[0027] Step S3, power off, the hexagonal boron nitride film and the substrate are cooled to room temperature and taken out of the furnace, the hexagonal boron nitride film is peeled off from the substrate, and a large-area hexagonal boron nitride single photon source of the present application is obtained.

[0028] In step S2 of the present embodiment, high temperature causes the graphite clamp to slightly decompose to provide a small amount of carbon source. In the middle of the deposition cavity, the gas mixture reacts chemically to grow a large-area hexagonal boron nitride film with carbon defects. The growth time of the hexagonal boron nitride film is about 90 min.

[0029] In the present application, through reaction growth, the hexagonal boron nitride material can be uniformly deposited on the surface of the SiC substrate to form a large-area high-quality h-BN film. The actual photo of the 6-inch h-BN film peeled off from the substrate is shown in Figure 1 a. The thickness of the h-BN film of the present application can reach microns, making peeling simple. Therefore, using the method of the present application can not only synthesize a uniform h-BN layer on a large-area substrate, but also control the thickness and crystalline quality of the h-BN film by controlling the reaction conditions, providing a reliable preparation technology for its application in electronic devices and other high-performance materials.

[0030] Example 2, CL spectrum analysis of large-area hexagonal boron nitride single photon source

[0031] The CL spectrum of the large-area hexagonal boron nitride single photon source of the present application was analyzed using a scanning electron microscope, and the results are shown in Figure 1 b~ Figure 1 c. Figure 1 b is the CL spectrum of the hexagonal boron nitride film, Figure 1 c is the second-order time correlation function.

[0032] The results show that the unique way of electron-excited optical materials produces a special fingerprint in the photon statistics of the emitted cathodoluminescence (CL) light. By measuring the CL spectrum, it can be seen that the sample has sharp peaks at 4.08 eV, 3.93 eV, 3.74 eV and 3.56 eV at room temperature, and a larger broad peak at 3.19 eV (see Figure 1 b). These spectral features indicate that there are multiple energy levels and recombination centers in the material, which can emit photons of specific energy under electron excitation. For the 4.08 eV emission line, studies have shown that it is related to the nitrogen site (C N ​The carbon impurities on the surface of the substrate are related to the carbon substitution impurities. It is worth mentioning that the graphite clamp is specially customized in the deposition cavity to fix the substrate. The surface of the graphite clamp is slightly decomposed at high temperature to provide a small amount of carbon source during the growth of h-BN.

[0033] In order to further study the luminescence characteristics, the luminescence characteristics in the range of 3.6-4.1 eV were measured using Hanbury Brown-Twiss (HBT) correlator. By measuring the second-order correlation function The statistical properties of photons and the quantum properties of light field can be analyzed. In particular, it is observed that g (2) (0) satisfies 0≤g (2) (0)<1, which means that the photon statistics at zero delay time exist sub-Poisson distribution. After further deducting the background noise, g (2) (0)~0.2 is observed. This result is a clear sign of the anti-bunching of photons in the quantum light field, reflecting that the photons in the light field are anti-correlated in time, that is, the probability of emitting two or more photons at the same time is very low (see Figure 1 c). This anti-bunching phenomenon is an important feature that distinguishes it from classical light field, indicating that the luminescent center in the sample has the ability of single photon emission, which has potential application value as a single photon source.

[0034] Example 3, TEM crystal structure analysis of large-area hexagonal boron nitride single photon source

[0035] The crystal structure of the large-area hexagonal boron nitride single photon source of the present application was analyzed using a transmission electron microscope (TEM), and the cross-sectional high-resolution TEM image of the h-BN film is shown in Figure 2 .

[0036] Figure 2 As can be seen from the cross-sectional h-BN layered atomic arrangement in the middle, the (002) crystal plane is displayed. This indicates that the film grows along the c-axis. This smooth surface and clear atomic-level structure show that the sample has good crystal quality and uniformity. High-quality crystal structure is crucial for the performance of h-BN samples in electronic and photoelectron applications.

[0037] In summary, the present application uniformly deposits large-area high-quality h-BN films on SiC substrates by precisely controlling the chemical vapor deposition process conditions, not only ensuring the high crystalline quality and large-area uniformity of h-BN materials, but also systematically studying their optical and quantum properties. CL spectral measurements show that at room temperature, h-BN materials exhibit sharp emission peaks at 4.08 eV, 3.93 eV and 3.74 eV, which correspond to specific emission centers within the material, indicating its potential for single-photon emission. To further confirm the single-photon properties of these emission centers, a HBT correlator was used to measure the luminescence characteristics in the range of 3.6-4.1 eV. By calculating the second-order correlation function g (2) (τ), especially the value g (2) (0) at zero delay time, it was found that g (2) (0) ~ 0.2, much smaller than the lower limit of 1 for classical light fields. This result indicates that these emission centers in h-BN exhibit obvious photon anti-bunching properties, confirming their ability as ultraviolet single-photon sources.

[0038] Therefore, the present application not only demonstrates the feasibility of synthesizing high-quality h-BN films on large-area substrates by chemical vapor deposition, but also reveals the great potential of h-BN materials in the field of quantum optics. As ultraviolet single-photon emission sources, h-BN materials are expected to play an important role in future quantum communication, quantum computing and advanced optoelectronic devices. Such single-photon sources have irreplaceable application value in quantum information processing, quantum key distribution and photonic quantum computing, marking a major advance in the application of h-BN materials in quantum technology.

[0039] The above describes the embodiments of the present application in detail, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the present application, and still fall within the scope of protection of the present application.

Claims

1. A method for preparing a large-area hexagonal boron nitride ultraviolet single-photon source, characterized in that, The method comprises the following steps: Step S1, in a vapor deposition furnace, a silicon carbide substrate is fixed using a graphite clamp, and vacuumed to 10 -3 below Pa gas pressure; Step S2, the system temperature is raised to the reaction temperature by resistance heating and kept constant; in the high temperature environment, BCl3 and NH3, or BF3 and NH3, two kinds of raw gas are introduced, the high temperature makes the graphite clamp slightly decompose to provide a small amount of carbon source, the gas mixes and reacts in the middle of the deposition cavity, and a large-area hexagonal boron nitride film with carbon defects is grown; Step S3, the power is turned off, the hexagonal boron nitride film and the substrate are cooled to room temperature and taken out of the furnace, the hexagonal boron nitride film is peeled off from the substrate, and a large-area hexagonal boron nitride single-photon source is prepared.

2. The method of claim 1, wherein the method is performed at a temperature of 1000 °C or less. The growth time of the hexagonal boron nitride film in step S2 is 80-120 min.

3. The method of claim 1, wherein the method is performed at a temperature of 1000 °C or less. The system temperature is raised to 1500-1700℃ and kept constant in step S2.

4. The method of claim 1, wherein the method is performed at a temperature of 1000 °C or less. The volume ratio of BCl3 and NH3, or BF3 and NH3, two kinds of raw gas in step S2 is 1:0.

9.

5. The method of claim 1, wherein the method is performed at a temperature of 1000 °C or less. The two kinds of raw gas BCl3 and NH3, or BF3 and NH3 in step S2 enter the deposition cavity from the bottom.

6. A large area hexagonal boron nitride ultraviolet single photon source, characterized in that, The large-area hexagonal boron nitride ultraviolet single-photon source is prepared by the method of any one of claims 1-5.

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