Micron-size diamond particle with NV color center as well as preparation method and application of micron-size diamond particle

Abstract

The invention provides micron-sized diamond particles with NV color centers and a preparation method and application of the micron-sized diamond particles with the NV color centers. The preparation method comprises the following steps that cleaned diamond seed crystals are placed in a microwave chemical vapor deposition chamber, CH4, H2 and N2 are introduced, and nitrogen-doped monocrystal diamond grows; the nitrogen-doped single crystal diamond is sequentially subjected to electron irradiation and vacuum annealing treatment, and the single crystal diamond with the NV color center is obtained; and the single crystal diamond with the NV color center is polished, cut and annealed, and the micron-sized diamond particles with the NV color center are obtained. The prepared micron-sized diamond particles are high in NV color center concentration and can be used for preparing a magnetic detection probe.

Description

Technical Field

[0001] The present invention relates to the technical field of diamond NV center preparation, and particularly to a micron-sized diamond particle with an NV center, a preparation method thereof, and an application thereof. Background Art

[0002] At present, for the nitrogen-containing diamond powder directly grown by the CVD method, although the nitrogen content in the powder is high, most of the nitrogen therein is aggregated nitrogen and cannot form an NV center. Moreover, for the magnetic detection probe made of diamond powder, the magnetic detection sensitivity is low, and it is not convenient to prepare the required microstructures. Summary of the Invention

[0003] The present invention provides a micron-sized diamond particle with an NV center, a preparation method thereof, and an application thereof. The prepared micron-sized diamond particle has a high NV center concentration and can be used to prepare a magnetic detection probe.

[0004] The technical solution of the present invention is realized as follows: A preparation method of a micron-sized diamond particle with an NV center includes the following steps:

[0005] (1) Place the cleaned diamond seed crystal in a microwave chemical vapor deposition chamber, and introduce CH 4 , H 2 and N 2 to grow nitrogen-doped single-crystal diamond.

[0006] (2) Perform electron irradiation and vacuum annealing treatments on the nitrogen-doped single-crystal diamond in sequence to obtain a single-crystal diamond with an NV center;

[0007] (3) Perform polishing, cutting, and annealing treatments on the single-crystal diamond with an NV center to obtain a micron-sized diamond particle with an NV center.

[0008] Through the electron irradiation treatment of the present invention, vacancies are generated inside the diamond. The diamond itself is doped with nitrogen during the growth process, and the nitrogen content is relatively high, but there are fewer internal vacancies. The irradiated vacancies can move inside the diamond during the annealing process and be captured by single substituted nitrogen atoms to form NV centers, which is equivalent to increasing the NV center concentration.

[0009] After laser cutting, graphite will be generated at the cutting position due to high temperature. Annealing is to make the surface graphite react with oxygen to remove the graphite.

[0010] Further, in step (1), control the flow rate of CH 4 to be 10 - 50 / sccm, the flow rate of H 2 to be 100 - 800 / sccm, and the flow rate of N 2The flow rate is 0.1 - 5 / sccm, the substrate temperature during growth is 800 - 1000 °C, and the growth time is more than 12 h.

[0011] Further, in step (2), the electron irradiation dose is 1E17 / cm 2 .

[0012] Further, in step (2), the temperature of the vacuum annealing is 600 - 1400 °C, and the time is 4 h.

[0013] Further, in step (2), the temperature of the vacuum annealing is 1000 °C.

[0014] Further, in step (3), annealing is carried out in an air environment, the annealing temperature is 450 - 550 °C, and the annealing time is 0.5 - 1 h.

[0015] Further, in step (3), the method of polishing and cutting is as follows: polish the side of the single crystal diamond with NV color centers until the surface is flat, then perform laser cutting on the flat surface, adopt a double-sided cutting mode to obtain a diamond thin sheet with a micron size. The diamond thin sheet is first roughly polished to remove the surface graphite and grind the surface inclination angle caused by cutting, and then finely polished;

[0016] The diamond thin sheet after fine polishing is laser cut again in a single-sided cutting mode, and annealing treatment is carried out after cutting.

[0017] A micron-sized diamond particle with NV color centers is prepared by the said preparation method.

[0018] An application of a micron-sized diamond particle with NV color centers in a magnetic detection probe.

[0019] The beneficial effects of the present invention:

[0020] The present invention uses a diamond seed crystal, and by adjusting the ratio of N 2 / CH 4 , the nitrogen concentration of the nitrogen-doped single crystal diamond can be controlled, so that the NV concentration is higher. Moreover, during the diamond growth process, the coherence time of the NV color centers can be improved by the isotope purification method. Specifically, the C atom in CH 4 is C12, and by introducing CH 4 , the content of C13 in the C atoms of the grown diamond is made as small as possible to achieve isotope purification, reduce the C13 content in the diamond, thereby improving the coherence time and further improving the magnetic detection sensitivity. In addition, the size of the single crystal particle probe can be adjusted, from several hundred microns to dozens of microns, and microstructures can also be made, while powder materials cannot make microstructures. Description of the Drawings

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0022] Figure 1 Photoluminescence spectra of single-crystal diamond with NV centers at different annealing temperatures;

[0023] Figure 2 For different N 2 Flow rates, photoluminescence spectra of single-crystal diamond with NV centers;

[0024] Figure 3 Photoluminescence spectrum of micron-sized diamond particles with NV centers;

[0025] Figure 4 For the physical object of micron-sized diamond particles with NV centers Figure 1 ;

[0026] Figure 5 For the physical object of micron-sized diamond particles with NV centers Figure 2 . Detailed implementation manners

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0028] A method for preparing micron-sized diamond particles with NV centers, comprising the following steps:

[0029] (1) Select diamond seeds with a size of 3mm * 3mm * 1mm, ultrasonically clean them in acetone, alcohol, and deionized water for 15 minutes respectively. After cleaning, place the diamond seeds in a microwave chemical vapor deposition chamber, control the flow rate of CH 4 to be 15 / sccm, the flow rate of H 2 to be 300 / sccm, and the flow rate of N 2 to be 0.75 / sccm. The ratio of N 2 / CH 4 is 5%. Perform the growth of nitrogen-doped single-crystal diamond. The substrate temperature during growth is 800 °C, and the growth time is 12 h. The nitrogen content of the obtained nitrogen-doped single-crystal diamond is about 5 ppm;

[0030] (2) Electron irradiate the nitrogen-doped single-crystal diamond prepared in step (1), with an electron irradiation dose of 1E17 / cm 2 , and then perform vacuum annealing treatment on the irradiated single-crystal diamond sample in a tube furnace. Argon is introduced into the corundum tube for protection, and the vacuum environment is maintained by a mechanical pump to reduce the oxygen content as much as possible. The vacuum degree is about -0.1 Mpa. After annealing treatment, single-crystal diamond with NV color centers is obtained;

[0031] (3) Polish the side of the single-crystal diamond with NV color centers until the surface is flat. Cut the upper surface of the single-crystal diamond with a laser cutter in a double-sided cutting mode, select a cutting depth of 6 mm to obtain a diamond thin slice with a size of about 3 mm * 3 mm * 150 um. Roughly polish the cutting surface of the obtained diamond thin slice to remove the surface graphite, and grind the surface tilt angle caused by cutting. Then, perform fine polishing on the diamond thin slice. The rotation speed of the fine polishing disc is 190 revolutions per minute, and the fine polishing time is 48 h. The thickness of the obtained thin slice is about 120 um. Perform laser cutting on the thin slice in a single-sided cutting mode, select a cutting depth of 0.01 mm, and obtain single-crystal diamond NV color center particles with a size of 80 um * 80 um * 120 um. Anneal the cut sample in a tube furnace in an air environment, keep it at 500 °C for 30 min, and obtain micron-sized diamond particles with NV color centers.

[0032] The above cutting dimensions can be adjusted according to needs.

[0033] In step (2), the vacuum annealing temperature is as shown in the following table:

[0034] Vacuum annealing temperature (°C) Example 1 600 Example 2 800 Example 3 1000 Example 4 1200 Example 5 1400

[0035] Test the photoluminescence (pl) spectrum of the single-crystal diamond with NV color centers prepared in step (2). As Figure 1 shown, when the vacuum annealing temperature is 1000 °C, the signal is stronger, indicating a higher concentration of NV color centers.

[0036] Comparative Example 1

[0037] This comparative example is basically the same as Example 3, except that: the flow rate of N 2 is 15 / sccm, and the ratio of N 2 / CH 4 is 100%.

[0038] Test the photoluminescence (pl) spectra of the single-crystal diamonds with NV color centers prepared in Example 3 and Comparative Example 1. As Figure 2 shown, changing the ratio of nitrogen introduced during diamond growth can change the final NV color center concentration of the diamond, N2 / CH 4 When the proportion of / CH is relatively large, it is not conducive to increasing the concentration of NV color centers.

[0039] It is verified that the particles contain NV color centers by detecting the photoluminescence (pl) excited by the 532nm laser of the particles. The photoluminescence spectrum of the micron-sized diamond particles with NV color centers prepared in step (3) of Test Example 3 is as Figure 3 shown. There are NV color centers in the diamond particles. It can be seen that the cutting and annealing treatments in step (3) do not damage the diamond NV color centers.

[0040] The physical objects of the micron-sized diamond particles with NV color centers are as Figure 3 and 4 shown. The diamond particles can be used to prepare magnetic detection probes.

[0041] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing micron-sized diamond particles with NV color centers, characterized in that: The following steps are involved: (1) placing the cleaned diamond seed crystal in a microwave chemical vapor deposition chamber, introducing CH4, H2 and N2 to grow nitrogen-doped single crystal diamond; (2) Electron irradiation and vacuum annealing are performed on nitrogen-doped single crystal diamond in sequence to obtain single crystal diamond with NV color centers; (3) The single crystal diamond with NV color center is polished, cut and annealed to obtain micron-sized diamond particles with NV color center.

2. The method for preparing micron-sized diamond particles with NV color centers according to claim 1, characterized in that: In step (1), the flow rates of CH4, H2, and N2 are controlled to be 10-50 / sccm, 100-800 / sccm, and 0.1-5 / sccm, the substrate temperature is 800-1000°C during growth, and the growth time is more than 12 hours.

3. The method for preparing micron-sized diamond particles with NV color centers according to claim 1, characterized in that: In step (2), the electron irradiation dose is 1E17 / cm 2 .

4. The method for preparing micron-sized diamond particles with NV color centers according to claim 1, characterized in that: In step (2), the vacuum annealing temperature is 600-1400° C. and the time is 4 hours.

5. The method for preparing micron-sized diamond particles with NV color centers according to claim 4, characterized in that: In step (2), the temperature of vacuum annealing is 1000°C.

6. The method for preparing micron-sized diamond particles with NV color centers according to claim 1, characterized in that: In step (3), annealing is performed in an air environment at a temperature of 450-550° C. for a time of 0.5-1 h.

7. The method for preparing micron-sized diamond particles with NV color centers according to claim 1, characterized in that: In step (3), the polishing and cutting method is as follows: polishing the side of the single crystal diamond with NV color center until the surface is flat, and then laser cutting is performed on the flat surface in a double-sided cutting mode to obtain a micron-sized diamond slice. The diamond slice is first roughly polished to remove surface graphite and to flatten the surface inclination angle caused by cutting, and then fine polishing is performed; the finely polished diamond slice is laser cut again in a single-sided cutting mode, and annealing is performed after cutting.

8. A micron-sized diamond particle with NV color centers, prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the micron-sized diamond particles with NV color centers as claimed in claim 8 in a magnetic detection probe.

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