Preparation method of SiV color center nano-diamond with controllable silicon vacancy color center content

Abstract

The invention discloses a preparation method of SiV color center nano-diamond with controllable silicon vacancy color center content, and aims to solve the problems that the SiV color center nano-diamond prepared by the existing method contains more lattice defects and metal impurities, the silicon vacancy color center content of the SiV color center nano-diamond is uncontrollable, the shape is irregular and the like. Comprising the following steps: 1, cleaning a substrate and a cavity wall; 2, doping the silicon wafer; 3, modulation of growth parameters; 4, growing and collecting the SiV color center nano diamond; and 5, testing and characterizing the SiV color center nano-diamond. The SiV color center nano-diamond prepared through the method is CVD silicon vacancy color center nano-diamond, the SiV color center nano-diamond prepared through the method is free of lattice defects caused by metal impurities and ion irradiation, and the quality of crystals is high. The invention belongs to the technical field of quantum nano material preparation.

Description

Technical Field

[0001] The invention belongs to the technical field of nano-quantum material preparation, and in particular relates to a method for preparing SiV color center nano-diamond with controllable silicon vacancy color center content. Background Art

[0002] Nanodiamonds containing color centers (such as NV, SiV, GeV) have great potential in bioimaging and sensing applications due to their stable fluorescence. In particular, nanoprobes containing color centers have great development significance in the fields of bioimaging and quantum precision measurement.

[0003] At present, the preparation of nanodiamonds containing color centers (such as NV, SiV, GeV) is mainly carried out in two steps: first, a certain size of nanodiamonds is produced according to a certain synthesis method, and then a nanodiamond containing a specific color center is produced by specific ion implantation or irradiation. The production of nanodiamonds of specific sizes mainly includes detonation method and grinding method. The detonation method is to directly convert the carbon-containing substances in carbon-based explosives into nanodiamonds in a specific atmosphere through the high temperature (over 3000°C) and high pressure (over 20GPa) environment generated by the explosion of explosives; the grinding method, as the name implies, refers to the input of mechanical energy in a complex equipment system, the use of high-energy ball milling media in the tank The high-speed rotation, so that the diamond raw materials undergo mechanical crushing, mixing and metallurgical reactions, thereby preparing nanoparticles or diamond materials with nanostructures. The principle of this method to produce nanodiamonds is to convert mechanical energy into microscopic changes in diamond materials, and gradually reduce the particle size through strong collision, shear and impact forces, and finally form nanodiamonds of a certain size. After these two methods produce nanodiamonds of a certain size, diamond vacancy color centers such as NV, SiV, GeV, etc. are produced through corresponding ion implantation or ion irradiation or electron irradiation of the nanodiamond sample. However, the nanodiamonds prepared by the detonation method and the grinding method have irregular shapes and poor uniformity, and the nanodiamonds containing color centers produced by irradiation annealing often have some lattice defects and impurities, which can only be used for mechanical lubrication and filling materials, and are not suitable for high-precision quantum sensing and biological cell imaging applications. Summary of the invention

[0004] The present invention aims to solve the problems that SiV color center nanodiamond prepared by the existing method contains more lattice defects and metal impurities, and the silicon content of SiV color center nanodiamond is uncontrollable and the shape is irregular, and further proposes a preparation method of SiV color center nanodiamond with controllable silicon vacancy color center content.

[0005] The technical solution adopted by the present invention to solve the above problems is:

[0006] The method for preparing SiV color center nanodiamond with controllable silicon vacancy color center content described in the present invention comprises the following steps:

[0007] Step 1: Cleaning the substrate and cavity wall of the MPCVD (microwave plasma chemical vapor deposition) equipment;

[0008] Step 2: doping of silicon wafers: placing six intrinsic single-polished silicon wafers on a metal molybdenum substrate with blind holes reserved;

[0009] Step 3: Modulation of growth parameters: introducing hydrogen, methane and argon into the cavity, and adjusting the microwave power of the MPCVD equipment and the gas pressure in the cavity;

[0010] Step 4: Growth and collection of SiV color center nanodiamonds;

[0011] Step 5: Testing and characterization of SiV color center nanodiamond.

[0012] Furthermore, in step one, anhydrous ethanol and deionized water are used to ultrasonically clean the porous metal molybdenum substrate used for growing diamonds and the molybdenum columns used for regulating the plasma shape and distribution of the MPCVD equipment for 20 minutes, and the cavity of the MPCVD equipment with a microwave frequency of 2.45 GHz is wiped with a dust-free cloth dipped in anhydrous ethanol and deionized water.

[0013] Furthermore, the size of the metal molybdenum is Φ52mm×3mm, and the size of the molybdenum column is Φ8mm×4mm.

[0014] Furthermore, in step 2, the size of each crystal face is Φ5 mm×0.5 mm.

[0015] Furthermore, in step three, the microwave power of the MPCVD equipment is 2.3 kW, the gas pressure in the cavity is 11.5 kPa, the temperature of the metal molybdenum substrate is 680°C, the volume fractions of hydrogen, methane and argon introduced into the cavity are 75%, 20% and 5% respectively, and the total gas flow rate is 200 sccm.

[0016] Furthermore, in step four, under the process parameters of step three, when the temperature of the metal molybdenum substrate in the MPCVD chamber reaches 680°C, the growth is carried out for 16 hours, and then a small shovel is used to collect the nanodiamonds that fall on the molybdenum substrate after the gas phase nucleation growth.

[0017] Furthermore, in step five, the morphology, size, crystal quality and crystal plane of the SiV color center nanodiamond were characterized by scanning electron microscopy (SEM), Raman spectrometer, transmission electron microscopy (TEM), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy.

[0018] The beneficial effects of the present invention are:

[0019] 1. The SiV color center nanodiamond obtained by the preparation method of the present invention is a CVD silicon vacancy color center nanodiamond. The SiV color center nanodiamond prepared by this method is free of metal impurities and lattice defects caused by ion irradiation, and the crystal quality is high.

[0020] 2. The present invention uses a method for preparing SiV color center nanodiamonds by solid-state doping of solid silicon wafers. By controlling the size or number of silicon wafers and the distance between the silicon wafers and the metal molybdenum substrate, the content of SiV color centers in the nanodiamonds can be controlled.

[0021] 3. The present invention utilizes MPCVD equipment to prepare SiV color center nanodiamonds in an atmosphere of H2, CH4, and Ar. The size of the SiV color center nanodiamonds can be controlled by changing the proportion of Ar. In addition, compared with the grinding method and the detonation method, the SiV color center nanodiamonds prepared by this method have regular shapes and greater practical value.

[0022] 4. The present invention lays a foundation for the preparation of color-center nanodiamonds (such as NV, SiV, GeV) with low defects, no metal impurities and regular shapes.

[0023] 5. The present invention utilizes MPCVD equipment and designs the structure of the nucleation substrate in the cavity to regulate the distribution of groups in the plasma, thereby creating a gas phase nucleation space for nanodiamonds, thus breaking through the limitations of the traditional CVD method in the production of nanodiamonds and the morphology of thin films. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 (a) is a real shot of SiV color center nanodiamond prepared in MPCVD plasma environment;

[0025] Figure 1 (b) is the Raman spectra of SiV color center nanodiamonds prepared under different argon gas volume fractions (0%-50%);

[0026] Figure 1 (c) Photoluminescence spectra of SiV color center nanodiamonds prepared under different argon gas volume fractions (0%-50%);

[0027] Figure 2 (a) is a scanning electron microscope morphology of SiV color center nanodiamond prepared when the argon gas volume fraction is 10%;

[0028] Figure 2 (b) is a transmission electron microscope image of the small-sized nanodiamond in Figure (a);

[0029] Figure 2(c) is the XRD pattern of the SiV color center nanodiamond prepared by this method when the volume fraction of argon gas is 10%. DETAILED DESCRIPTION

[0030] Specific implementation method: The preparation method of SiV color center nanodiamond with controllable silicon vacancy color center content described in this implementation method is implemented by the following steps:

[0031] Step 1: Cleaning the substrate and cavity wall: Use anhydrous ethanol and deionized water to ultrasonically clean the porous metal molybdenum substrate (size Φ59mm×3mm) used to grow diamonds in the MPCVD equipment and the molybdenum pillars (Φ8mm×4mm) used to control the plasma shape and distribution for 20 minutes, and wipe the cavity of the MPCVD equipment with a microwave frequency of 2.45GHz with a dust-free cloth dipped in anhydrous ethanol and deionized water in turn.

[0032] Step 2: Silicon wafer doping: Place 6 intrinsic single-polished silicon wafers with a (100) crystal plane and a size of Φ3mm×0.5mm on a metal molybdenum substrate with blind holes reserved.

[0033] Step 3: Modulation of growth parameters: Adjust the microwave power of the MPCVD equipment to 2.3kW, the gas pressure in the cavity to 11.5kPa, the temperature of the metal molybdenum substrate to 680℃, the volume fractions of hydrogen, methane and argon introduced into the cavity to 75%, 20% and 5% respectively, and the total gas flow rate to 200sccm.

[0034] Step 4: Growth and collection of SiV color center nanodiamonds: Under the process parameters of step 3, when the temperature of the metal molybdenum substrate in the MPCVD chamber reaches 680°C, grow for 16 hours, and then use a small shovel to collect the nanodiamonds that fall on the molybdenum substrate after gas phase nucleation growth.

[0035] Step 5: Testing and characterization of SiV color center nanodiamond: The morphology, size, crystal quality and crystal plane of SiV color center nanodiamond were characterized by scanning electron microscopy (SEM), Raman spectrometer, transmission electron microscopy (TEM), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy.

[0036] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

[0037] like Figure 1 (a) shows a real shot of preparing SiV color center nanodiamond in an MPCVD environment. The molybdenum pillar with a size of Φ8mm×4mm in the center of the metal molybdenum substrate can regulate the plasma shape, thereby promoting the gas phase nucleation and growth of SiV color center nanodiamond. The size of the six blind holes on the molybdenum substrate is Φ3mm×1.5mm, and the distance between the center of the blind hole and the center of the molybdenum substrate is 8mm. In each blind hole, a (100) crystal plane intrinsic single-polished silicon wafer with a size of Φ3mm×0.5mm is placed, with the unpolished side facing up;

[0038] like Figure 1 (b) shows the Raman spectra of SiV color center nanodiamonds prepared at different Ar ratios, 1332 cm -1 The peak at is the characteristic peak of nanodiamond;

[0039] like Figure 1 As shown in (c), the curve is the photoluminescence spectrum (PL) of SiV color center nanodiamond prepared under different Ar ratios. From the curve in the figure, it can be seen that the fluorescence intensity of the SiV color center of the SiV color center nanodiamond is related to the volume fraction of Ar.

[0040] like Figure 2 (a) shows the scanning electron microscope morphology of the SiV color center nanodiamond prepared when the argon gas volume fraction is 10%. It can be seen from the figure that the SiV color center nanodiamond is spherical and its size ranges from Φ200nm to Φ20nm. This is mainly because the size of the SiV color center nanodiamond is unevenly distributed along the radial direction of the metal molybdenum substrate;

[0041] like Figure 2 (b) Figure 2 (b) Figure 2 (a) Transmission electron microscopy image of the selected small-sized SiV color center nanodiamond, indicating that the prepared SiV color center nanodiamond is a single crystal;

[0042] like Figure 2(c) shows the X-ray diffraction peak of the SiV color center nanodiamond prepared when the argon gas volume fraction is 10%, indicating that the crystal plane of the prepared SiV color center nanodiamond is almost the (111) crystal plane.

[0043] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing SiV color center nanodiamond with controllable silicon vacancy color center content, characterized in that: The method comprises the following steps: Step 1: Clean the MPCVD equipment substrate and chamber wall; Step 2: Silicon wafer doping: six intrinsic single-polished silicon wafers are placed on a metal molybdenum substrate with blind holes reserved; Step 3: Modulation of growth parameters: introducing hydrogen, methane and argon into the cavity, and adjusting the microwave power of the MPCVD equipment and the gas pressure in the cavity; Step 4: Growth and collection of SiV color center nanodiamonds; Step 5: Testing and characterization of SiV color center nanodiamond.

2. The method for preparing SiV color center nanodiamond with controllable silicon vacancy color center content according to claim 1, characterized in that: In step one, anhydrous ethanol and deionized water are used to ultrasonically clean the porous metal molybdenum substrate used to grow diamonds and the molybdenum columns used to control the plasma shape and distribution of the MPCVD equipment for 20 minutes, and the cavity of the MPCVD equipment with a microwave frequency of 2.45 GHz is wiped with a dust-free cloth dipped in anhydrous ethanol and deionized water.

3. The method for preparing SiV color center nanodiamond with controllable silicon vacancy color center content according to claim 2, characterized in that: The size of the metal molybdenum is Φ52mm×3mm, and the size of the molybdenum column is Φ8mm×4mm.

4. The method for preparing SiV color center nanodiamond with controllable silicon vacancy color center content according to claim 1, characterized in that: In step 2, the size of each crystal face is Φ5mm×0.5mm.

5. The method for preparing SiV color center nanodiamond with controllable silicon vacancy color center content according to claim 1, characterized in that: In step three, the microwave power of the MPCVD equipment is 2.3kW, the gas pressure in the cavity is 11.5kPa, the temperature of the metal molybdenum substrate is 680°C, the volume fractions of hydrogen, methane, and argon introduced into the cavity are 75%, 20%, and 5%, respectively, and the total gas flow rate is 200sccm.

6. The method for preparing SiV color center nanodiamond with controllable silicon vacancy color center content according to claim 1, characterized in that: In step 4, under the process parameters of step 3, when the temperature of the metal molybdenum substrate in the MPCVD chamber reaches 680°C, the growth is carried out for 16 hours, and then the nanodiamonds falling on the molybdenum substrate after gas phase nucleation growth are collected with a small shovel.

7. The method for preparing SiV color center nanodiamond with controllable silicon vacancy color center content according to claim 1, characterized in that: In step five, the morphology, size, crystal quality and crystal plane of the SiV color center nanodiamond are characterized by scanning electron microscope, spectrometer, transmission electron microscope, X-ray diffractometer and X-ray photoelectron spectroscopy.

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