Growth method for preferentially orienting NV color center ensemble in diamond

Abstract

The invention provides a rapid growth method for preferentially orienting an NV color center ensemble in diamond, which comprises the following steps: selecting a monocrystal diamond as a substrate, polishing the surface of the monocrystal diamond, cleaning and drying; the treated substrate is placed on a sample table of a microwave plasma chemical vapor deposition system for pretreatment, and the pretreatment comprises removal of residual gas on the substrate and hydrogen plasma etching to activate the surface of the substrate and removal of an oxide layer and impurities on the surface of the substrate; the sample growth process comprises a first stage, a second stage and a third stage; the prepared NV color center ensemble sample is high in growth rate which can reach 25.4 mu m / h, and the conversion rate of converting nitrogen into NV is as high as 6.58%; the problems of low growth speed and low NV conversion rate in the prior art are solved, large-scale mass production can be realized, and the production cost is reduced.

Description

Technical Field

[0001] This application relates to the field of quantum information material preparation technology, and in particular to a method for growing preferentially oriented NV color center ensembles in diamond. Background Technology

[0002] Solid-state spin systems are playing an increasingly important role in quantum science experiments, and diamond, with its dense carbon lattice, low-spin bath, and abundant color centers, has become a widely studied material. The negatively charged nitrogen-vacancy (NV) color centers in diamond exhibit excellent photoluminescence emission at 637 nm and possess superior spin properties. Due to their long spin coherence time at room temperature, high magnetic field sensitivity (down to sub-nanotesla levels), and nanometer-scale spatial resolution, they have attracted significant attention in the field of quantum sensing in recent years, enabling high-sensitivity quantum sensing experiments. The quantum spin states of NV color centers can be used to achieve high-precision measurements of external magnetic fields, electric fields, temperature, stress, and pH using optically detected magnetic resonance (ODMR) technology. Its applications have expanded to fields such as biomedical imaging, geological exploration, semiconductor defect detection, and quantum computing, forming scalable applications from the nanoscale to the macroscopic scale.

[0003] Despite the significant advantages of NV ensembles, their practical applications are limited by two key issues: low ODMR spectral contrast and the superposition of split spectra from four different crystal orientations of NV centers. In traditional methods, NV centers are randomly distributed across the four crystal faces of diamond, leading to interference between Zeeman split spectra from different orientations, significantly reducing the signal-to-noise ratio and magnetic field resolution. Furthermore, the superposition of fluorescence signals from multi-directional NV centers can mask the target magnetic field information, further limiting sensitivity. Therefore, shallow-surface NV ensembles are required, and these ensembles need to be perfectly aligned along one axis, as misaligned NV centers degrade the performance of quantum devices. To achieve high magnetic sensitivity in NV center quantum sensors, not only perfectly aligned NV axes but also high-density NV centers are necessary. NV formation methods using nitrogen ion implantation and accelerated beam irradiation can provide high-density NV ensembles up to 45 ppm; however, both methods result in random NV centers with four crystal orientations. Three-quarters of the NV center ensembles are not used for sensing, increasing the background signal, and the randomly oriented NV ensemble exhibits low signal contrast, only one-quarter of the ideal. Current research indicates that the conventional growth rate for preparing perfectly aligned NV ensembles with high contrast (≥27%) via CVD is less than 6.6 μm / h. Based on these growth rate values, a long growth time is required to achieve larger detection volumes. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in the related art. To this end, this application proposes a method for growing preferentially oriented NV center ensembles in diamond, which is a controllable growth method for diamond NV center ensembles based on microwave plasma chemical vapor deposition (MPCVD). This method achieves perfect alignment of NV centers along the <111> axis and enables high-speed growth, with a growth rate reaching 25.4 μm / h. The NV center layer has a uniform distribution, high density, excellent spin properties, and high magnetic field sensitivity, making it suitable for the fabrication of quantum sensing and quantum computing devices.

[0005] According to the first aspect of this application, a method for growing preferentially oriented NV color center ensembles in diamond is proposed, comprising the following steps:

[0006] Single-crystal diamond was selected as the substrate, and its surface was polished, cleaned, and dried.

[0007] The processed substrate is placed on the sample stage of a microwave plasma chemical vapor deposition system for pretreatment, including removing residual gas on the substrate and performing hydrogen plasma etching to activate the substrate surface and remove the oxide layer and impurities on the substrate surface.

[0008] The sample growth process includes a first stage and a second stage; wherein the first stage introduces a mixture of CH4 and H2 gas with a CH4 / H2 ratio of 1% and a nucleation induction time of 5.5 h; the second stage introduces 1000 ppm of high-purity nitrogen gas based on the first stage and the nitrogen doping time is 30 min.

[0009] In some embodiments, the substrate is HPHT Ib type (111) single crystal diamond;

[0010] And / or, the roughness of the substrate surface after polishing is less than 4 nm.

[0011] In some embodiments, the polished substrate is first cleaned with a mixed solution of concentrated sulfuric acid and H2O2 to remove metallic impurities; then it is ultrasonically cleaned for 15 minutes each with acetone, ethanol, and deionized water to remove organic contaminants and ion residues.

[0012] And / or, the volume ratio of concentrated sulfuric acid to H2O2 is 3:1;

[0013] And / or, the cleaned substrate is dried under a nitrogen gas flow.

[0014] In some embodiments, the microwave plasma chemical vapor deposition system is equipped with a microwave source, a reaction chamber, a gas control system, a vacuum system, a substrate heating platform, a gas supply and control system, and corresponding gases. The reaction chamber of the microwave plasma chemical vapor deposition system is made of high-purity quartz glass.

[0015] In some embodiments, a method for removing residual gas from the substrate includes mounting the substrate on a sample stage and evacuating it to 10°C. -5 Keep below Torr for 30 minutes;

[0016] And / or, the hydrogen plasma etching method includes introducing 300 sccm of high-purity hydrogen, using a microwave power of 3500 W, a gas pressure of 125 Torr, and etching at a temperature of 900 °C for 15 min.

[0017] In some embodiments, the first and second stages of the sample growth process are completed in a single mounting process;

[0018] And / or, the air pressure of the first and second stages is 125 Torr, which is initially set and then controlled by an automatic pressure feedback system.

[0019] In some embodiments, the distance between the substrate and the plasma is maintained at 8 mm in both the first and second stages, and the reflected power is less than 2%.

[0020] And / or, the growth temperature in the first and second stages is set to 900°C and the microwave power is 3.5kW.

[0021] In some embodiments, a mixture of CH4 and H2 gas is introduced in the first stage, wherein the CH4 is injected in a pulsed manner.

[0022] According to a second aspect of this application, a quantum information material is provided, which is prepared using the method described in any of the above embodiments.

[0023] In some embodiments, the NV of the quantum information material - The conversion efficiency reaches 6.58%, the RABI contrast ratio reaches 24%, the lateral relaxation time T2 is 2.8 μs, the decoherence time T2* is 54 ns, the longitudinal relaxation time T1 is 6.28 ms, and the magnetic field sensitivity is 3.15 nTμm. 3 / 2 Hz -1 / 2 .

[0024] Compared with related technologies, this application has the following advantages: Based on microwave plasma chemical vapor deposition (MPCVD), this application achieves crystal orientation control, uses a <111> oriented diamond substrate, and combines a stepped flow growth mode with a bias-enhanced orientation screening process to achieve an NV color center <111> orientation rate of nearly 100%; it achieves high-speed growth of the NV color center layer, and through two-stage gas dynamics control and pulsed methane injection technology, combined with nitrogen concentration control, the growth rate is increased to 25.4 μm / h; the NV conversion rate is as high as 6.58%, the RABI contrast ratio can reach 24%, the lateral relaxation time T2 is 2.8 μs, the decoherence time T2* is 54 ns, the longitudinal relaxation time T1 is 6.28 ms, and the magnetic field sensitivity is 3.15 nTμm3 / 2Hz-1 / 2.

[0025] Furthermore, this application eliminates the need for irradiation / annealing, avoiding the introduction of other defects or impurities, and yields a high-quality preferentially oriented NV center ensemble. This solves the problems of slow growth rate, long process cycle, and low NV conversion rate inherent in related technologies. By precisely controlling growth conditions, the density and orientation consistency of the NV centers are significantly improved, giving the NV center ensemble broader application prospects in quantum sensing and quantum computing. In addition, this application optimizes the spin properties of the NV centers and improves magnetic field sensitivity, providing strong support for realizing high-performance quantum devices.

[0026] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0027] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0028] Figure 1 This is a confocal scan image of a sample in the XY direction according to an embodiment of this application;

[0029] Figure 2 yes Figure 1 Confocal scan image of the sample in the YZ direction;

[0030] Figure 3 It is based on Figure 2 The matrix data was randomly extracted to show the variation of fluorescence values ​​at different Y positions with sample depth.

[0031] Figure 4 This is a continuous wave ODMR curve of a sample without a magnetic field, as proposed in one embodiment of this application;

[0032] Figure 5 yes Figure 4The continuous wave ODMR curve of the sample under a static magnetic field;

[0033] Figure 6 This is a Rabi oscillation spectrum of a diamond NV color center system according to an embodiment of this application; wherein Figure a is a Rabi measurement sequence diagram; Figure b is a Rabi measurement result diagram;

[0034] Figure 7 Figure 1 shows the measurement results of longitudinal relaxation time T1 according to an embodiment of this application; Figure 2a is a Rabi measurement sequence diagram; Figure 3b is a Rabi measurement result diagram.

[0035] Figure 8 yes Figure 7 Figure 1 shows the measurement results of the transverse relaxation time T2 of the sample; Figure 2a is the T1 measurement sequence; Figure 2b is the T1 measurement result.

[0036] Figure 9 yes Figure 7 The sample decoherence time T2* measurement results are shown in the figure; Figure a is the T2 measurement sequence; Figure b is the T2 measurement result.

[0037] Figure 10 This is the fluorescence saturation count of the sample proposed in one embodiment of this application;

[0038] Figure 11 This is a fluorescence image of a sample proposed in one embodiment of this application. Detailed Implementation

[0039] Embodiments of this application are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Rather, embodiments of this application include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0040] According to the first aspect of this application, a method for growing preferentially oriented NV color center ensembles in diamond is proposed, comprising the following steps:

[0041] S1: Single-crystal diamond is selected as the substrate, and its surface is polished, cleaned, and dried.

[0042] S2: The processed substrate is placed on the sample stage of the microwave plasma chemical vapor deposition system for pretreatment, including removing residual gas on the substrate and performing hydrogen plasma etching to activate the substrate surface and remove the oxide layer and impurities on the substrate surface.

[0043] S3: The sample growth process includes a first stage and a second stage; in the first stage, a mixture of CH4 and H2 gas is introduced with a CH4 / H2 ratio of 1%, and the nucleation induction time is 5.5 h; in the second stage, based on the first stage, 1000 ppm of high-purity nitrogen gas is introduced, and the nitrogen doping time is 30 min.

[0044] When the CH4 / H2 ratio is less than 0.5%, the generated NV color centers will exhibit non-(111) orientation; if the concentration of nitrogen gas introduced is too high (2000 ppm and above) or too low (100 ppm and below), the confocal scan image will show that the generated NV color centers are distributed very unevenly on the substrate.

[0045] In S1, single-crystal diamond is selected as the substrate, and the substrate is HPHT Ib type (111) single-crystal diamond. The surface of the substrate is polished so that the roughness of the substrate surface after polishing is less than 4nm. Then, the polished substrate is first cleaned with a mixed solution of concentrated sulfuric acid and H2O2 to remove metal impurities, wherein the volume ratio of concentrated sulfuric acid to H2O2 is 3:1. Then, it is ultrasonically cleaned with acetone, ethanol and deionized water for 15min each to remove organic pollutants and ion residues. The cleaned substrate is dried under nitrogen gas flow.

[0046] In step S2, the pretreated substrate is placed on the sample stage of a microwave plasma chemical vapor deposition (MPCVD) system for pretreatment. The MPCVD system is equipped with a microwave source, reaction chamber, gas control system, vacuum system, substrate heating platform, gas supply and control system, and corresponding gases. The reaction chamber of the MPCVD system is made of high-purity quartz glass. The pretreatment process involves removing residual gases from the substrate, for example, mounting the substrate on the sample stage and evacuating it to 10 °C. -5 Below Torr, maintain for 30 minutes; then perform hydrogen plasma etching to activate the substrate surface and remove the oxide layer and impurities on the substrate surface; for example, the hydrogen plasma etching method includes introducing 300 sccm of high-purity hydrogen, a microwave power of 3500W, a gas pressure of 125 Torr, and etching at a temperature of 900℃ for 15 minutes.

[0047] The sample growth process in S3 includes a first stage and a second stage; the first and second stages of the sample growth process are completed in one loading; in the first stage, a mixture of CH4 and H2 gas is introduced with a CH4 / H2 ratio of 1%, wherein CH4 is injected in a pulsed manner, the nucleation induction time is 5.5h, the gas pressure in the first stage is 125Torr, and after the initial setting, it is controlled by an automatic pressure feedback system; in the first stage, the distance between the substrate and the plasma is maintained at 8mm, and the reflection power is less than 2%; the growth temperature in the first stage is set at 900℃, and the microwave power is 3.5kW.

[0048] In the second stage, based on the first stage, 1000 ppm of high-purity nitrogen gas is introduced, and the nitrogen doping time is 30 minutes. The gas pressure in the second stage is 125 Torr, and after the initial setting, it is controlled by an automatic pressure feedback system. In addition, the distance between the substrate and the plasma is maintained at 8 mm throughout the second stage, and the reflection power is less than 2%. The growth temperature in the second stage is set to 900℃, and the microwave power is 3.5 kW.

[0049] According to a second aspect of this application, a quantum information material is prepared using the method described in any of the above embodiments.

[0050] In some embodiments, the NV of quantum information materials - The conversion efficiency reaches 6.58%, the RABI contrast ratio reaches 24%, the lateral relaxation time T2 is 2.8 μs, the decoherence time T2* is 54 ns, the longitudinal relaxation time T1 is 6.28 ms, and the magnetic field sensitivity is 3.15 nTμm. 3 / 2 Hz -1 / 2 .

[0051] Example 1

[0052] This embodiment provides a method for growing preferentially oriented NV color center ensembles in diamond. The first step involves substrate selection and preparation, using HPHT Ib type (111) single-crystal diamond with dimensions of 3×3×0.5mm. 3 The substrate is mechanically polished to achieve a surface roughness of less than 4 nm. Then, it undergoes pre-cleaning, first using Piranha solution (concentrated sulfuric acid: H2O2 = 3:1) to remove some metallic impurities; then, it is ultrasonically cleaned for 15 minutes each with acetone, ethanol, and deionized water to remove organic contaminants and ion residues. After drying, the substrate is rinsed with pure water and dried under a nitrogen gas flow before being placed in the MPCVD chamber to ensure a dry and contamination-free surface. The MPCVD system used is equipped with a microwave source, reaction chamber, gas control system, vacuum system, and substrate heating platform. The gas supply and control system provides high-purity hydrogen (H2), methane (CH4), nitrogen (N2), and oxygen. The reaction chamber is made of high-purity quartz glass.

[0053] Before sample growth, a vacuum pretreatment was performed. The cleaned <111> oriented diamond substrate was mounted on the sample stage, and a vacuum of 10 °C was applied. -5 Below Torr, maintain for 30 minutes to remove residual gas; then perform hydrogen plasma etching, introducing high-purity hydrogen at a flow rate of 300 sccm, setting the microwave power to 3500 W, maintaining the pressure at 125 Torr, and etching at 900℃ for 15 minutes. This is a key step in creating the hydrogen-terminated surface, providing a starting point for subsequent homoepitaxial growth, activating the substrate surface, removing oxide layers and impurities, and increasing nucleation density.

[0054] The following describes the sample growth process, which utilizes a two-stage gas dynamics control method. Both stages are completed in a single wafer loading to avoid air exposure and reduce the density of non-radiative centers. The first stage is nucleation induction, with a gas composition of CH4 / H2 = 1% and a nucleation induction time of 5.5 h. In this growth stage, the hydrogen etching process and the crystallization of the carbon precursor occur simultaneously. Therefore, we induce stepped flow growth by precisely controlling a low CH4 / H2 ratio, forming random nucleation hydrogen etching. It can be considered that at a low CH4 / H2 ratio, the high power density plasma generates a large number of atomic hydrogens to form active sites and adsorb carbon precursors on these sites, resulting in a high growth rate while maintaining stepped flow growth. This causes tensile stress on the <100> facet, promoting diamond growth along the <111> direction. The second stage is in-situ nitrogen-doped high-speed epitaxial growth of diamond. Based on the first stage, the CH4 / H2 ratio is changed to 0.05%, and 1000 ppm of high-purity nitrogen gas is introduced to incorporate nitrogen atoms into the lattice. The nitrogen doping time is 30 min. The air pressure during the two growth stages is maintained at around 125 Torr. After the initial setting, it is controlled by an automatic pressure feedback system. The growth temperature is set at 900℃ and the microwave power is 3.5kW.

[0055] Experimental Example

[0056] The sample obtained in Example 1 was tested, and the NV color centers were uniformly distributed and grew rapidly, such as... Figure 1 As shown, by Figure 1 The confocal scan images in the XY directions show that the luminescence intensity is consistent at different locations on the sample, indicating that the NV color centers are uniformly distributed. According to... Figures 2-3 The fluorescence intensity was determined to change with sample depth, and the thickness of the NV color centers in the sample was estimated accordingly, resulting in a growth rate of 25.4 μm / h. This achieved high-speed growth and solved the problem of low growth rate in previous studies.

[0057] ODMR test results as follows Figure 4As shown, the ODMR contrast can reach 23%. To confirm the preferential orientation of the NV ensemble along the 111 direction, a static magnetic field B of 89.3 Gauss was applied along the

[111] direction. In this configuration, the resonance line of the NV center along the

[111] direction should be observed at 2.87 ± (γ / 2π) B GHz, and the resonance lines along the other three directions are observed at 2.87 (γ / 2π)cos(109°) B GHz, where γ is the gyromagnetic ratio of the NV center and B is the bias magnetic field applied along the

[111] . Only two resonance lines were observed at all locations in the confocal scan image, indicating that the NV ensemble is perfectly aligned along the

[111] direction throughout the film, as shown. Figure 5 As shown.

[0058] like Figure 6 As shown, the Rabi contrast ratio can reach 24%, indicating that the NV color center has a high quality factor. Figure 7 As shown, the spin performance of the sample was tested. The longitudinal relaxation time T1 was 6.28 ms. The relatively long T1 has a significant advantage in applications such as quantum computing and quantum storage, which helps to realize fault-tolerant quantum computing and allows for the storage and processing of quantum information for a longer period of time. Figure 8 and Figure 9 The measurement results for the transverse relaxation time T2 (2.8 μs) and decoherence time T2* (54 ns) are respectively at an advantageous level, which is beneficial for some applications that require detection and measurement using free induction decay signals, such as magnetic resonance spectroscopy.

[0059] like Figure 10 As shown, the fluorescence count of the sample was measured as a function of laser power, using the formula... The fluorescence saturation value was fitted, and by comparing it with the fluorescence intensity of a single NV center (200 kHz) under the same confocal settings, the density of NV centers was estimated to be 0.75 ppm. The formula was then used. The calculated volume-normalized magnetic field sensitivity is 3.15 nT μm³ / 2 Hz⁻¹ / ². Here, V represents the focusing volume of our self-built confocal scanning system (4 / 3Π × 240 nm × 240 nm × 500 nm), γ is the gyromagnetic ratio, C is the ODMR contrast ratio, N is the number of NVs within the focusing volume, and τ is the decoherence time T²*. This magnetic field sensitivity is high, exceeding the previously reported highest sensitivity of 3.15 nT μm³ / 2 Hz⁻¹ / ². This result holds promise for applications in the development of materials for high-sensitivity quantum sensors with large sensor volumes.

[0060] like Figure 11 The emission spectrum of the sample is shown. A typical diamond NV center spectrum was obtained by exciting the sample with a 532 nm laser. The NV centers are located at 575 nm and 637 nm, respectively.0 The zero-phonon line of NV- was observed to have a significantly stronger ZPL than that of NV-. 0 This means that more 637nm photons can be collected under the same excitation conditions, which can improve the fidelity of spin state readout based on photon counting, and is particularly crucial for single-spin measurement, quantum state initialization and detection.

[0061] It should be noted that in the description of this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0062] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the function involved, as will be understood by those skilled in the art to which embodiments of this application pertain.

[0063] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0064] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for growing preferentially oriented NV color center ensembles in diamond, characterized in that, Includes the following steps: Single-crystal diamond was selected as the substrate, and its surface was polished, cleaned, and dried. The processed substrate is placed on the sample stage of a microwave plasma chemical vapor deposition system for pretreatment, including removing residual gas on the substrate and performing hydrogen plasma etching to activate the substrate surface and remove the oxide layer and impurities on the substrate surface. The sample growth process includes a first stage and a second stage; wherein the first stage introduces a mixture of CH4 and H2 with a CH4 / H2 ratio of 1% and a nucleation induction time of 5.5 h; the second stage introduces 1000 ppm of high-purity nitrogen gas based on the first stage and the nitrogen doping time is 30 min.

2. The growth method according to claim 1, characterized in that, The substrate is HPHT Ib type (111) single crystal diamond; And / or, the roughness of the substrate surface after polishing is less than 4 nm.

3. The growth method according to claim 2, characterized in that, After polishing, the substrate is first cleaned with a mixed solution of concentrated sulfuric acid and H2O2 to remove metallic impurities; then it is ultrasonically cleaned for 15 minutes each with acetone, ethanol and deionized water to remove organic contaminants and ion residues. And / or, the volume ratio of concentrated sulfuric acid to H2O2 is 3:1; And / or, the cleaned substrate is dried under a nitrogen gas flow.

4. The growth method according to any one of claims 1-3, characterized in that, The microwave plasma chemical vapor deposition system is equipped with a microwave source, reaction chamber, gas control system, vacuum system, substrate heating platform, gas supply and control system, and corresponding gas. The reaction chamber of the microwave plasma chemical vapor deposition system is made of high-purity quartz glass.

5. The growth method according to claim 4, characterized in that, The method for removing residual gas from the substrate includes mounting the substrate on a sample stage and evacuating it to 10°C. -5 Keep below Torr for 30 minutes; And / or, the hydrogen plasma etching method includes introducing 300 sccm of high-purity hydrogen, using a microwave power of 3500 W, a gas pressure of 125 Torr, and etching at a temperature of 900 °C for 15 min.

6. The growth method according to claim 4, characterized in that, The first and second stages of the sample growth process are completed in one slide loading. And / or, the air pressure of the first and second stages is 125 Torr, which is initially set and then controlled by an automatic pressure feedback system.

7. The growth method according to claim 4, characterized in that, In both the first and second stages, the distance between the substrate and the plasma is maintained at 8 mm, and the reflected power is less than 2%. And / or, the growth temperature in the first and second stages is set to 900°C and the microwave power is 3.5kW.

8. The growth method according to claim 7, characterized in that, In the first stage, a mixture of CH4 and H2 gas is introduced, wherein the CH4 is injected in a pulsed manner.

9. A quantum information material, characterized in that, It is prepared using the method described in any one of claims 1-8.

10. The quantum information material according to claim 9, characterized in that, Its NV - The conversion efficiency reaches 6.58%, the RABI contrast ratio reaches 24%, the lateral relaxation time T2 is 2.8 μs, the decoherence time T2* is 54 ns, the longitudinal relaxation time T1 is 6.28 ms, and the magnetic field sensitivity is 3.15 nTμm. 3 / 2 Hz -1 / 2 .

Images