Method for positioning and preparing diamond color center

Abstract

The invention relates to the technical field of diamond color center quantum light sources, in particular to a method for preparing a diamond color center in a positioning mode, and the method comprises the following steps that a single-face polished sapphire sheet serves as a substrate, and a microwave plasma chemical vapor deposition method is adopted for preparing a single crystal diamond with a (001) surface; preparing a metal layer on the surface of the monocrystal diamond by adopting a physical vapor deposition method, and dehumidifying and self-assembling to form balls; etching the surface of the monocrystal diamond (001) at a high temperature in a hydrogen atmosphere to form a conical pit structure with a different surface; and selectively growing a diamond color center in the cone pit by adopting a chemical vapor deposition method. Aiming at the problems that the existing ion implantation technology for positioning and preparing the diamond color center is difficult to realize nanoscale accurate control and high in cost, a foundation is laid for the integration and low-cost preparation of the high-purity and high-brightness diamond single photon source.

Description

Technical Field

[0001] The invention relates to the technical field of diamond color center quantum light source, and in particular to a method for positioning and preparing diamond color centers. Background Art

[0002] Diamond has always been considered an ideal material in many application fields. In particular, the color centers within its lattice have been found to have excellent optical properties in recent years, and have outstanding potential in quantum communications, quantum sensing, single-photon sources, etc.

[0003] Among them, diamond nitrogen vacancy color center is one of the earliest studied and most widely used diamond color centers. This color center is formed by replacing a carbon atom with a nitrogen atom and combining with the adjacent vacancy. Because the electron spin properties in its negative charge state are easy to initialize, manipulate and read, nitrogen vacancies are widely used in quantum sensing. Another diamond color center that has been studied more is the silicon vacancy color center, which is composed of two vacancies and a silicon atom located between the vacancies. Its outstanding advantage is that it has only weak phonon sidebands at room temperature, and the luminescence peak near the zero phonon line can account for more than 70% of the total, and its fluorescence lifetime is only 1ns~4ns, which makes it widely used in single-photon sources. The actual application process of diamond color center is usually coupled with nanostructures to achieve greater fluorescence output or higher contrast, such as diamond nanopillars, photonic crystal cavities, microrings, metal plasmons, etc. The most prominent problem is to couple the color center with the nanostructure in the nanoscale space, so researchers study this topic.

[0004] The existing preparation of diamond color centers mainly involves annealing diamond doped with color center atoms so that the color center atoms combine with vacancy defects in the diamond lattice to form color centers. The spatial positioning of diamond color centers is achieved by controlling the positions of color center atoms or vacancy defects respectively. At present, energy flows such as ion beams and electron beams are usually used to achieve this. On the one hand, the high cost and low efficiency make it difficult to be widely used. On the other hand, it is difficult to ensure the spatial accuracy of the energy flow injection in the diamond lattice. Summary of the invention

[0005] In view of the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a method for positioning and preparing diamond color centers. Through the method of self-assembly growth of diamond color centers, based on single crystal diamond with a (001) surface, with metal nickel as a catalyst, high-temperature hydrogen etching is used to prepare differential surface cone pit structures, and the diamond color centers are controlled to selectively grow into the nano-cone pit structure, so as to prepare diamond color centers in a low-cost and controllable positioning manner, laying the foundation for the preparation of high-quality diamond single-photon sources, high-precision quantum sensing and high-level integration, and solving the problems raised in the above-mentioned background technology.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for positioning and preparing a diamond color center comprises the following steps: The single crystal polished sapphire is pretreated, and the pretreated single crystal polished sapphire is used as a substrate, and a single crystal diamond with a (001) crystal plane is grown on the surface of the single crystal polished sapphire by a microwave plasma chemical vapor deposition method.

[0007] A metal film is deposited on the surface of the single crystal diamond with the (001) crystal plane by a physical vapor deposition method, and the single crystal diamond with the metal film deposited is annealed in a vacuum to obtain dehumidified self-assembled metal nanospheres on the surface of the single crystal diamond.

[0008] The surface of a single crystal diamond is etched at high temperature in a hydrogen atmosphere to form a conical pit with a side wall of (111) surface. At the same time, the metal nanospheres in the conical pit are corroded and removed. Since the energy of each crystal direction in the diamond crystal is different, the energy of the (111) surface is the highest compared to the (001) surface. Therefore, the (111) surface is the least susceptible to etching, so a conical pit with a side wall of (111) surface is prepared.

[0009] A chemical vapor deposition method is used to grow diamond color centers in the cone pit whose sidewall is a (111) surface, thereby achieving the localized growth of the diamond color centers.

[0010] The present invention realizes the preparation of dispersed metal nanospheres on the diamond surface by means of metal film self-assembly, and prepares a nano-cone pit structure with diamond (111) sidewalls on the single crystal diamond (001) surface by means of metal-assisted hydrogen etching, thereby realizing the construction of a differentiated surface structure on the diamond surface. By preparing nano-cone pits on the diamond surface, the selective adsorption of diamond color centers in the differentiated structure with (111) sidewalls is controlled, and the positioning preparation of diamond color centers on the single crystal diamond surface is realized by the selective adsorption of color centers in nano-cone pits on the diamond surface, so that the position of the prepared diamond color center is controllable, which facilitates the adjustment of the relative position and mutual coupling relationship between the diamond color center and the optical nanostructure, and promotes the application of diamond color centers in the fields of quantum communication, quantum sensing and single photon source.

[0011] In a preferred embodiment of the present invention, the microwave plasma chemical vapor deposition parameters are: the vacuum chamber pressure is 2×10 -4 Pa, the deposition gases are methane and hydrogen, the deposition temperature is 900℃~1000℃, and the microwave power is 1200W~5000W.

[0012] In a preferred embodiment of the present invention, the deposition time of the microwave plasma chemical vapor deposition method is 1 hour to 4 hours.

[0013] In a preferred embodiment of the present invention, the physical vapor deposition time is 60s to 180s.

[0014] In a preferred embodiment of the present invention, when growing diamond color centers by chemical vapor deposition, the deposition gas is methane, hydrogen and a doping gas source containing color center elements, the deposition temperature is 900°C to 1000°C, the pressure is 4000Pa, and the deposition time is 10 min to 30 min.

[0015] In a preferred embodiment of the present invention, the thickness of the metal film is 20 nm to 80 nm, and the metal is nickel, gold, silver or copper.

[0016] In a preferred embodiment of the present invention, when the metal film is a nickel film, the annealing temperature is 600° C. to 900° C., and the annealing time is 1 h to 3 h.

[0017] In a preferred embodiment of the present invention, the metal-assisted etching temperature is 800° C. to 900° C., and the etching time is 3 h to 4 h.

[0018] In a preferred embodiment of the present invention, the surface area of ​​the single crystal diamond (001) is 4 μm 2 ~16μm 2 .

[0019] In a preferred embodiment of the present invention, the pretreatment method of single crystal polished sapphire is: the single crystal polished sapphire is cleaned to remove impurities, then placed in a diamond suspension for ultrasonic crystal planting, and then cleaned to obtain the pretreated single crystal polished diamond.

[0020] In a preferred embodiment of the present invention, the mass concentration of the diamond suspension is 2kg / L to 3kg / L, the diamond particle size is 49nm to 51nm, and the number density is 1×10 10 Particles / g~3×10 10 Particles / g.

[0021] In a preferred embodiment of the present invention, the ultrasonic temperature is 25° C. to 40° C., the ultrasonic frequency is 600 Hz to 800 Hz, and the ultrasonic time is 30 min to 60 min.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. The method for positioning and preparing diamond color centers of the present invention comprises the following steps: using a pretreated single crystal polished sapphire as a substrate, growing a single crystal diamond having a (001) crystal plane on the surface of the single crystal polished sapphire by microwave plasma chemical vapor deposition, then depositing a metal film on the surface of the single crystal diamond having a (001) crystal plane by physical vapor deposition, vacuum annealing the single crystal diamond deposited with the metal film, obtaining dewetting self-assembled metal nanospheres on the surface of the single crystal diamond, then etching the single crystal diamond having a (001) surface by metal-assisted etching to form a cone pit having a side wall having a (111) surface, and simultaneously removing the metal nanospheres in the cone pit by etching, and finally growing a diamond color center in the cone pit having a side wall having a (111) surface by chemical vapor deposition, thereby achieving the positioning growth of the diamond color center. The present invention realizes the preparation of dispersed metal nanospheres on the diamond surface by means of metal film self-assembly, and prepares a nano-cone pit structure with diamond (111) sidewalls on the single crystal diamond (001) surface by means of metal-assisted hydrogen etching, thereby realizing the construction of a differentiated surface structure on the diamond surface. By preparing nano-cone pits on the diamond surface, the selective adsorption of diamond color centers in the differentiated structure with (111) sidewalls is controlled, and the positioning preparation of diamond color centers on the single crystal diamond surface is realized by the selective adsorption of color centers in nano-cone pits on the diamond surface, so that the position of the prepared diamond color center is controllable, which facilitates the adjustment of the relative position and mutual coupling relationship between the diamond color center and the optical nanostructure, and promotes the application of diamond color centers in the fields of quantum communication, quantum sensing and single photon source.

[0023] 2. The present invention adopts a method for self-assembly growth of diamond color centers, based on single crystal diamond with a (001) surface, and uses metal-assisted high-temperature hydrogen etching to prepare differential surface cone pit structures, and controls the selective growth of diamond color centers into the nano-cone pit structure, so as to prepare diamond color centers in a low-cost and controllable positioning manner, laying a foundation for the preparation of high-quality diamond single-photon sources, high-precision quantum sensing and high-level integration.

[0024] 3. The present invention breaks through the limitation that the preparation of diamond color centers can only be done through expensive electron beam or ion technology, and realizes the preparation of diamond color centers in a low-cost manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Flow chart for positioning and preparing diamond color centers for the present invention.

[0026] Figure 2 Schematic diagram of single crystal diamond grown on a single-sided polished sapphire sheet of the present invention, (a) is a main view, and (b) is a top view.

[0027] Figure 3(a) and (b) are SEM images of typical single crystal diamond with a diamond (001) surface grown on a single-side polished sapphire wafer of the present invention at different magnifications.

[0028] Figure 4 Schematic diagram of the deposition of nickel metal film on the surface of single crystal diamond according to the present invention, (a) is the main view, and (b) is the top view.

[0029] Figure 5 Schematic diagram of the high-temperature annealing and dehumidification self-assembly of nickel metal film on the diamond surface into spheres according to the present invention, (a) is the main view, and (b) is the top view.

[0030] Figure 6 This is a SEM picture of a 50 nm nickel metal film deposited on the diamond surface of the present invention and self-assembled into metal nanospheres after high temperature annealing and dehumidification.

[0031] Figure 7 Schematic diagram of nano-cone pits prepared by metal-assisted etching of diamond in a hydrogen atmosphere of the present invention, (a) is a top view, and (b) is an AA enlarged view of (a).

[0032] Figure 8 (a) and (b) are SEM images of different positions on the diamond surface after the nano-cone pit structure is prepared by metal-assisted etching of diamond in a hydrogen atmosphere of the present invention.

[0033] Fig. 9 Schematic diagram of the nanocone pits after the metal nanospheres are removed by strong acid corrosion cleaning in the present invention, (a) is a top view, and (b) is an AA enlarged view of (a).

[0034] Fig.10 (a) and (b) are SEM images of the diamond surface at different magnifications after the metal nanospheres are removed by strong acid corrosion cleaning according to the present invention.

[0035] Fig.11 Schematic diagram of the positioned growth of diamond color centers in nano-cone pits of the present invention, (a) is a top view, and (b) is an AA enlarged view of (a).

[0036] Fig.12 The SEM image (a) and EDS image (b) of the surface of the diamond single crystal particle after the diamond color center grows on the surface of the diamond single crystal particle of the present invention.

[0037] Fig.13 The SEM image (a) and EDS image (b) of the diamond (001) surface after the diamond color center is positioned and grown in the nano-cone pit of the present invention.

[0038] Among them, 101 is a single-sided polished sapphire sheet, 102 is a single crystal diamond, 103 is a diamond (001) surface, 104 is a nickel metal film, 105 is a metal nanosphere, 106 is a nanocone pit, 107 is a diamond (111) surface, 108 is a diamond film, and 109 is a diamond color center. DETAILED DESCRIPTION

[0039] The following is a detailed description of the technical solutions in the embodiments of the present invention in combination with the preferred embodiments and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be noted that all professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0041] The present invention provides a method for positioning and preparing diamond color centers, the preparation process is as follows: Figure 1 As shown, firstly, a single-side polished sapphire wafer is pretreated, and the pretreatment operation includes cleaning and crystal planting. Then, a chemical vapor deposition device is used to grow a single crystal diamond on the pretreated sapphire wafer, and then a physical vapor deposition device is used to deposit a metal film on the surface of the prepared single crystal diamond. Then, the deposited metal film is self-assembled into metal nanospheres by high-temperature dehumidification in a vacuum annealing furnace, and the diamond is etched by metal assistance in a hydrogen atmosphere in the vacuum annealing furnace to form nano-cone pits, and then a strong acid corrosion cleaning is used to remove the metal nanospheres in the nano-cone pits and on the surface of the single crystal diamond, and finally, a chemical vapor deposition device is used to control the selective growth of diamond color centers in the nano-cone pits.

[0042] Example 1 A method for positioning and preparing a diamond color center comprises the following steps: (1) A single-side polished sapphire wafer 101 was selected as a deposition substrate and ultrasonically cleaned with a 99.5% acetone solution for 10 min, a 99.7% anhydrous ethanol solution for 10 min, and a deionized water solution for 10 min. The acetone and ethanol cleanings were used to remove organic matter and other impurities on the surface of the single-side polished sapphire wafer 101. Organic matter includes organic matter in the air that may exist during the experiment and grease on contact. Deionized water is used to remove residual acetone and ethanol. The cleaning sequence cannot be adjusted to avoid affecting the cleanliness of the single-side polished sapphire wafer 101.

[0043] (2) The single-side polished sapphire sheet 101 cleaned in step (1) is placed in a diamond suspension for ultrasonic crystal planting, and then ultrasonically cleaned with a 99.5% acetone solution for 2 minutes, an anhydrous 99.7% ethanol solution for 2 minutes, and a deionized water solution for 10 minutes to remove the residual diamond suspension on the surface of the single-side polished sapphire sheet 101.

[0044] The diameter of the diamond particles in the diamond suspension is 50nm, and the ultrasonic grinding is carried out for 30min at an ultrasonic frequency of 700Hz. The ultrasonic grinding is ultrasonic crystal planting. The growth density of the single crystal diamond 102 is controlled by controlling the concentration, oscillation intensity and oscillation time of the diamond suspension. The mass concentration of the diamond suspension is 2.5kg / L, and the number density is 2×10 10 particles / g, and dilute it 1000 times with deionized water to obtain a diamond suspension.

[0045] The ultrasonic crystal planting is to convert the sound energy of the high-power ultrasonic frequency source into mechanical vibration, so that the diamond particles in the diamond suspension produce scratches on the single-sided polished sapphire sheet 101 to achieve the purpose of crystal planting.

[0046] (3) placing the single-sided polished sapphire sheet 101 cleaned in step (2) into a deposition chamber of a microwave plasma chemical vapor deposition device, growing a single crystal diamond 102 on the single-sided polished sapphire sheet 101, and forming a diamond substrate after the growth of the single crystal diamond 102. Figure 2 shown.

[0047] The vacuum chamber pressure of microwave plasma chemical vapor deposition equipment is 2×10 -4 Pa, heated to 900°C, microwave power of 1200W, 100sccm hydrogen, deposition pressure stabilized at 4000Pa, methane concentration of 1%, growth time of 2h, the size of single crystal diamond 102 can be controlled by adjusting the growth time of single crystal diamond 102.

[0048] The above growth parameters of the single crystal diamond 102 can realize the preparation of single crystal diamond with high purity, and most of the prepared single crystal diamonds 102 have a diamond (001) surface 103 on the surface, which is the basis for controlling the positioning of the diamond color center in the present invention. The typical single crystal diamond with a diamond (001) surface 103 prepared by this parameter is as follows: Figure 3 As shown, the square surface is the diamond (001) surface 103 .

[0049] (4) placing the sample prepared in step (3) into a physical vapor deposition device, and depositing a nickel metal film 104 on the surface of the single crystal diamond 102 having a diamond (001) surface (103), such as Figure 4 shown.

[0050] The thickness of the nickel metal film 104 prepared by physical vapor deposition is controllable, and the preparation of the nickel metal film 104 with nanometer-level thickness can be achieved, and the thickness is uniform and the surface roughness is low.

[0051] The vacuum chamber pressure of the physical vapor deposition equipment is 2×10 -4 Pa, at room temperature, the magnetron sputtering power is 40W, 25sccm argon gas is introduced, a nickel metal target with a purity of 99.99% is used, the deposition pressure is stabilized at 1Pa, and the deposition time is 120s. The thickness of the nickel metal film 104 can be controlled by adjusting the deposition time.

[0052] (5) placing the sample on which the nickel metal film 104 is deposited in step (4) into a vacuum annealing furnace, and performing vacuum annealing on the nickel metal film 104 to dehumidify and self-assemble into metal nanospheres 105, such as Figure 5 shown.

[0053] The vacuum chamber pressure of the vacuum annealing furnace is 2×10 -4 The annealing temperature is about 700° C. and the annealing time is 1 h. This parameter is only for the nickel metal film 104. Other metals need to change the parameters accordingly according to the properties of the metal materials.

[0054] The size and spacing of the metal nanospheres are controlled by the thickness of the nickel metal film 104, the annealing temperature and the annealing time. The metal nanospheres 105 formed after the nickel metal film 104 is dehumidified after being deposited for 120 seconds are as follows: Figure 6 shown.

[0055] The size and spacing of the metal nanospheres 105 are key parameters that determine the subsequent steps. By controlling the size and spacing of the metal nanospheres 105 , the size and spacing of the nanocone pits 106 in the subsequent steps can be controlled.

[0056] (6) The sample annealed in step (5) is placed in a vacuum annealing furnace, hydrogen is introduced as a reaction gas, and nickel-assisted hydrogen etching is performed on the diamond (001) surface 103 to prepare nano-cone pits 106 on the diamond (001) surface 103, as shown in FIG. Figure 7 and Figure 8 shown.

[0057] The nano-cone pits 106 prepared by the process of nickel-assisted hydrogen etching of the diamond (001) surface 103 have a regular structure and their side walls are all diamond (111) surfaces 107. The triangular surface is the diamond (111) surface 107. The above process can realize the preparation of nano-cone pits 106 with side walls as diamond (111) surfaces 107 on the diamond (001) surface 103, realize the preparation of differentiated nanoscale surfaces, and provide conditions for the selective growth of diamond color centers 109 on differentiated surfaces.

[0058] The hydrogen flow rate of the above reaction device is 25 sccm, the vacuum pressure is controlled to 5000 Pa, the temperature is 800° C., and the etching time is 3 h.

[0059] The preparation process of the nano-cone pit 106 is a process in which hydrogen atoms corrode the diamond (001) surface 103 near the metal under metal catalysis. Due to the relatively low reaction rate of the diamond (111) surface 107, the nano-cone pit 106 with a side wall having a diamond (111) surface 107 is prepared by etching the diamond (001) surface 103. Figure 8 As shown, it can be observed that metal particles are embedded in nano-cone pits 106 on the diamond (001) surface 103 .

[0060] (7) Use dilute hydrochloric acid to remove the metal nanospheres 105 from the surface of the sample by corrosion cleaning, see Fig. 9 and Fig.10 .

[0061] The above-mentioned dilute hydrochloric acid concentration of 20%-40% has the best effect. Compared with other acids and concentrations, it can ensure better removal of metallic nickel without affecting the diamond surface.

[0062] The diamond surface prepared by cleaning and removing the metal nanospheres is as follows Fig.10 As shown, it can be seen that nano-cone pits 106 with a quadrangular pyramid pit structure are distributed on the diamond (001) surface 103, and the side walls thereof are the diamond (111) surface 107.

[0063] (8) The sample after the removal of the metal nickel in step (7) is placed in a chemical vapor deposition device, and silane, methane, and hydrogen are used as gas sources to grow diamond color centers 109. The diamond color centers 109 grow on the diamond film 108 on the surface of the diamond (111), so that the diamond color centers 109 are positioned in the nano-cone pits 106. Fig.11 shown.

[0064] The vacuum chamber pressure of the above reaction device is 2×10 -4Pa, heated to 900℃, microwave power 1200W, 100sccm hydrogen, deposition pressure stabilized at 4000Pa, methane concentration 1%, silane concentration 0.5%, growth time 30min; the number of diamond color centers 109 can be controlled by adjusting the growth time.

[0065] The key to realizing the positioning and preparation of diamond color centers in nano-cone pits in the present invention is to etch and prepare nano-cone pits 106 with diamond (111) surfaces 107 on the side walls on the diamond (001) surface 103. Under the above parameters, silicon atoms in the diamond silicon color centers are more likely to be adsorbed on the diamond (111) surface 107 and grow into the diamond crystal. Silicon vacancy color centers are gradually formed around them during the growth process after preparation. Fig.12 As shown, by comparing the distribution of silicon elements on different surfaces of diamond, the darker the color, the greater the probability of silicon elements being distributed there. It can be found that the color on the square diamond (001) surface 103 is lighter than the color on the triangular diamond (111) surface 107. This proves that when silicon vacancy color centers are grown under this parameter, they are more likely to grow on the diamond (111) surface 107. This is the reason why the nano-cone pit 106 with a side wall having a diamond (111) surface 107 is prepared on the diamond (001) surface 103 in the present invention, thereby achieving the positioning of the color center in the nano-cone pit structure.

[0066] The diamond color center of the present invention is positioned and grown in the nano-cone pit, which can be proved by detecting the element distribution after the diamond color center 109 is grown on the diamond (001) surface 103 having the nano-cone pit 106 through SEM. Fig.13 As shown, the darker color of the silicon element detection distribution near the cone pit structure indicates that the diamond color center 109 has achieved the localized growth in the nano-cone pit 106 .

[0067] Example 2 The preparation method is the same as that of Example 1, except that the microwave plasma chemical vapor deposition parameters are: deposition temperature is 950° C., microwave power is 2000 W, and growth time is 4 h.

[0068] The physical vapor deposition time was 60 s.

[0069] The annealing temperature is 600°C and the annealing time is 3h.

[0070] When growing diamond color centers by chemical vapor deposition: the deposition temperature is 950°C and the deposition time is 20 minutes.

[0071] The metal assisted etching temperature is 850℃, 4h.

[0072] The mass concentration of diamond suspension is 2kg / L, the diamond particle size is 49nm, and the number density is 1×10 10 Particles / g.

[0073] The ultrasonic frequency was 600 Hz and the ultrasonic time was 60 min.

[0074] Example 3 The preparation method is the same as that of Example 1, except that the microwave plasma chemical vapor deposition parameters are: deposition temperature is 1000° C., microwave power is 5000 W, and growth time is 1 h.

[0075] The physical vapor deposition time was 180 s.

[0076] The annealing temperature is 900°C and the annealing time is 2h.

[0077] When growing diamond color centers by chemical vapor deposition: the deposition temperature is 1000°C and the deposition time is 10 minutes.

[0078] The metal assisted etching temperature is 900°C for 3.5h.

[0079] The mass concentration of diamond suspension is 3kg / L, the diamond particle size is 51nm, and the number density is 3×10 10 Particles / g.

[0080] The ultrasonic frequency was 800 Hz and the ultrasonic time was 40 min.

[0081] The undisclosed steps in Examples 2 and 3 of the present invention are the same as those in Example 1. The methods of Examples 2 and 3 can also be used to prepare nano-cone pits on the diamond surface, and to control the selective adsorption of diamond color centers in the differentiated structure of the side wall having a diamond (111) surface 107. Through the selective adsorption of the color centers in the nano-cone pits 106 on the diamond surface, the positioning preparation of diamond color centers 109 on the surface of the single crystal diamond 102 is achieved.

[0082] In summary, the method for positioning and preparing diamond color centers of the present invention uses a pretreated single crystal polished sapphire as a substrate, and adopts a microwave plasma chemical vapor deposition method to grow a single crystal diamond with a (001) crystal plane on the surface of the single crystal polished sapphire. Then, a metal film is deposited on the surface of the single crystal diamond with the (001) crystal plane by a physical vapor deposition method. The single crystal diamond deposited with the metal film is vacuum annealed to obtain dewetting self-assembled metal nanospheres on the surface of the single crystal diamond. Then, the single crystal diamond with a (001) surface is etched by metal assistance to form a cone pit with a side wall of a (111) surface, and the metal nanospheres in the cone pit are removed by etching at the same time. Finally, a diamond color center is grown in the cone pit with a side wall of a (111) surface by a chemical vapor deposition method, thereby realizing the positioning growth of the diamond color center. The present invention realizes the preparation of dispersed metal nanospheres on the diamond surface by metal film self-assembly, and prepares a nano-cone pit structure with diamond (111) sidewalls on the single crystal diamond (001) surface by metal-assisted hydrogen etching, thereby realizing the construction of a differentiated surface structure on the diamond surface. By preparing nano-cone pits on the diamond surface, the selective adsorption of diamond color centers in the differentiated structure with (111) sidewalls is controlled, and the positioning preparation of diamond color centers on the single crystal diamond surface is realized by the selective adsorption of color centers in nano-cone pits on the diamond surface, so that the position of the prepared diamond color center is controllable, which facilitates the adjustment of the relative position and mutual coupling relationship between the diamond color center and the optical nanostructure, and promotes the application of diamond color centers in quantum communication, quantum sensing, single photon source and other fields. This method can also be extended to the positioning preparation of other color centers in single crystal diamond.

[0083] It should be noted that when the present invention relates to a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundant description, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, once those skilled in the art know the basic creative concept, they can make other changes and modifications to these embodiments. Therefore, the attached protection scope is intended to be interpreted as including the preferred embodiment and all changes and modifications that fall within the scope of the present invention.

[0084] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the protection scope of the present invention and its equivalent technology, the present invention is also intended to include these changes and variations.

Claims

1. A method for positioning and preparing diamond color centers, characterized in that: The following steps are involved: Pre-treatment of single crystal polished sapphire; Taking the pre-treated single crystal polished sapphire as a substrate, a single crystal diamond having a (001) crystal plane is grown on the surface of the single crystal polished sapphire by microwave plasma chemical vapor deposition; Depositing a metal film on the surface of the single crystal diamond having a (001) crystal plane by a physical vapor deposition method; The single crystal diamond deposited with the metal film is annealed in vacuum to obtain dewetting self-assembled metal nanospheres on the surface of the single crystal diamond; In a hydrogen atmosphere, metal-assisted etching is performed on the surface of the single-crystal diamond to form a cone pit with a (111) surface on the sidewall, and the metal nanospheres in the cone pit are removed by etching at the same time; A chemical vapor deposition method is used to grow diamond color centers in the cone pit whose sidewall is a (111) surface, thereby achieving the localized growth of the diamond color centers.

2. The method for positioning and preparing diamond color centers according to claim 1, characterized in that: The deposition gases of microwave plasma chemical vapor deposition method are methane and hydrogen, the deposition temperature is 900℃~1000℃, and the microwave power is 1200W~5000W.

3. The method for positioning and preparing diamond color centers according to claim 1, characterized in that: The deposition time of microwave plasma chemical vapor deposition method is 1h~4h.

4. The method for positioning and preparing diamond color centers according to claim 1, characterized in that: The thickness of the metal film is 20nm~80nm.

5. The method for positioning and preparing diamond color centers according to claim 1, characterized in that: The metal film is a nickel metal film.

6. The method for positioning and preparing diamond color centers according to claim 5, characterized in that: When the metal film is a nickel film, the annealing temperature is 600°C~900°C, and the annealing time is 1h~3h.

7. The method for positioning and preparing diamond color centers according to claim 1, characterized in that: When growing diamond color centers by chemical vapor deposition, the deposition gases are methane, hydrogen and a doping gas source containing color center elements, the deposition temperature is 900°C~1000°C, and the deposition time is 10min~30min.

8. The method for positioning and preparing diamond color centers according to claim 1, characterized in that: The metal assisted etching temperature is 800℃~900℃, and the etching time is 3h~4h.

9. The method for positioning and preparing diamond color centers according to claim 1, characterized in that: The surface area of ​​the single crystal diamond (001) is 4 μm 2 ~16μm 2 .

10. The method for positioning and preparing diamond color centers according to claim 1, characterized in that: The pretreatment method of single crystal polished sapphire is: cleaning the single crystal polished sapphire to remove impurities, then putting it into a diamond suspension for ultrasonic crystal planting, and then cleaning it to obtain the pretreated single crystal polished diamond.

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