Quantum electric field sensing structure and device based on diamond nitrogen vacancy color center and preparation method

Abstract

The invention provides a quantum electric field sensing structure and device and a preparation method. The quantum electric field sensing structure comprises a nitrogen vacancy color center diamond body; a first electrode and a second electrode are arranged on the upper surface and the lower surface of the nitrogen vacancy color center diamond body respectively, an open hole is formed in the first electrode, and the open hole penetrates through the upper surface of the nitrogen vacancy color center diamond body and is used for applying laser to the nitrogen vacancy color center diamond body and collecting fluorescence radiated by the nitrogen vacancy color center diamond body; each side wall of the nitrogen vacancy color center diamond body is covered with a light reflecting layer. According to the method, a first electrode and a second electrode are prepared on the upper surface and the lower surface of a nitrogen vacancy color center diamond to apply an electric field; the first electrode is provided with an opening, and a light reflecting layer is deposited on each side surface of the nitrogen vacancy color center diamond, so that fluorescent light radiated from the side surfaces is reflected and is only emitted from the opening in the upper surface, subsequent fluorescent light collection is facilitated, necessary conditions are provided for quantum measurement of an electric field, and the precision and sensitivity of electric field measurement are greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of electric field sensing technology, and in particular to a quantum electric field sensing structure and device based on diamond nitrogen vacancy color centers and a preparation method thereof. Background Art

[0002] Electric field measurement has important applications in many fields such as geophysical exploration, electrical engineering, meteorology, and aerospace. In the field of geophysical exploration, electric field sensors accurately capture electric field changes in conductive media, helping to discover coal fields, oil and gas resources, underground water veins, and metal and non-metallic mineral deposits. In the field of electrical engineering, whether it is monitoring the power frequency electric field strength under the transmission line or on the surface of the insulator, or accurately measuring the DC electric field environment in the valve hall of the converter station, or even the study of high voltage tests and corona discharge phenomena, it is inseparable from the accurate data support of electric field sensors. In meteorological science, electric field measurement technology achieves effective early warning of lightning activities by continuously monitoring the dynamics of the atmospheric electric field, providing a scientific basis for preventing lightning disasters and protecting people's lives and property. In the field of aerospace, with the rapid development of satellite, missile and other aircraft technologies, it has become particularly important to accurately grasp the atmospheric electric field environment at the landing point. This has prompted more stringent standards for the performance of space electric field sensors to ensure that aircraft can perform tasks safely and accurately in complex electromagnetic environments.

[0003] In recent years, quantum sensing technology has been widely studied, using quantum effects to measure physical quantities such as magnetic fields, electric fields, and temperature. It has obvious advantages over traditional sensors in terms of sensitivity, environmental adaptability, and range, and can greatly improve the accuracy and sensitivity of electric field measurements. Summary of the invention

[0004] In view of this, the present invention proposes a quantum electric field sensing structure, device and preparation method based on diamond nitrogen vacancy color center, aiming to solve the problem of insufficient sensitivity of traditional sensors in measuring electric field. In one aspect, the present invention proposes a quantum electric field sensing structure based on diamond nitrogen vacancy color center, comprising: a nitrogen vacancy color center diamond body; wherein, The upper and lower surfaces of the nitrogen vacancy color center diamond body are respectively provided with a first electrode and a second electrode, and the first electrode is provided with an opening for applying laser to the nitrogen vacancy color center diamond body and collecting fluorescence radiated by the nitrogen vacancy color center diamond body; Each side wall of the nitrogen vacancy color center diamond body is covered with a light reflecting layer.

[0005] Furthermore, in the above-mentioned quantum electric field sensing structure based on diamond nitrogen vacancy color centers, the light reflecting layer is a silicon dioxide coating.

[0006] Furthermore, in the above quantum electric field sensing structure based on diamond nitrogen vacancy color centers, both the first electrode and the second electrode are copper electrodes.

[0007] Furthermore, in the above-mentioned quantum electric field sensing structure based on diamond nitrogen vacancy color center, the nitrogen vacancy color center diamond body is a rectangular parallelepiped structure.

[0008] Furthermore, in the above-mentioned quantum electric field sensing structure based on diamond nitrogen vacancy color center, the opening is a circular hole with a diameter of 0.5-3 mm and a hole depth of 1-3 μm.

[0009] Furthermore, in the above-mentioned quantum electric field sensing structure based on diamond nitrogen vacancy color centers, the thickness of the light reflection layer is 80-120 nm.

[0010] The quantum electric field sensing structure based on diamond nitrogen vacancy color center in the present invention adopts micro-nano process to prepare the first electrode and the second electrode on the upper and lower surfaces of the nitrogen vacancy color center diamond so as to apply the electric field; and an opening is arranged on the first electrode, and a light reflection layer is deposited on each side of the nitrogen vacancy color center diamond, so that the fluorescence radiated from the side is reflected and emitted only from the opening on the upper surface, which is convenient for the subsequent collection of fluorescence, provides the necessary conditions for the quantum measurement of the electric field, and is conducive to greatly improving the accuracy and sensitivity of the electric field measurement.

[0011] On the other hand, the present invention also proposes a quantum electric field measuring device, comprising: a power supply, a laser, a dichroic mirror, a reflector, an objective lens, a microwave transmitting device and a quantum electric field sensing structure as described in any one of the above items; wherein, The power supply is connected to the quantum electric field sensing structure to apply voltage to the quantum electric field sensing structure to generate an electric field; The microwave emitting device is arranged on one side of the quantum electric field sensing structure, and is used to radiate microwaves of a preset frequency to the quantum electric field sensing structure; The dichroic mirror, the reflector and the objective lens are arranged in sequence from the output end of the laser to the upper surface of the nitrogen vacancy color center diamond body in the quantum electric field sensing structure, and the output end of the objective lens is close to the upper surface of the quantum electric field sensing structure; A photoelectric detector is also provided on one side of the dichroic mirror to detect the optical power of the fluorescence radiated by the nitrogen vacancy color center diamond body.

[0012] Furthermore, the above-mentioned quantum electric field measurement device further includes: a filter; wherein, The incident end of the filter is arranged close to the dichroic mirror, and the output end of the filter is arranged close to the photodetector.

[0013] In another aspect, the present invention further provides a method for preparing a quantum electric field sensing structure based on diamond nitrogen vacancy color centers, comprising the following steps: After depositing a light reflecting layer on the surface of the nitrogen vacancy color center diamond body, removing the light reflecting layer formed on the upper surface and the lower surface of the nitrogen vacancy color center diamond body; sputtering a metal film layer on the upper and lower surfaces of the nitrogen vacancy color center diamond body to form a first electrode and a second electrode; The upper surface of the nitrogen vacancy color center diamond body is sequentially subjected to photolithography and ion beam etching to form an opening on the first electrode.

[0014] Furthermore, in the above preparation method, after forming the opening on the first electrode, the method further comprises: A gold wire is led out from the first electrode.

[0015] The preparation method of the quantum electric field sensing structure provided by the present invention adopts diamond nitrogen vacancy color centers with fixed crystal orientation as electric field sensing units, manufactures electrodes and reflective layers on the surface thereof by micro-nano technology, and cooperates with external optical structures and microwave structures to realize quantum sensing of electric fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings: Figure 1 A schematic diagram of the structure of a quantum electric field sensing structure provided by an embodiment of the present invention; Figure 2 A perspective view of a quantum electric field sensing structure provided by an embodiment of the present invention; Figure 3 A schematic diagram of the structure of a quantum electric field measurement device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0018] See also Figure 1 and Figure 2 The quantum electric field sensing structure of the embodiment of the present invention includes: a nitrogen vacancy color center diamond body 1; wherein, the upper and lower surfaces of the nitrogen vacancy color center diamond body 1 are respectively provided with a first electrode 11 and a second electrode 12, and the first electrode 11 is provided with an opening for applying laser to the nitrogen vacancy color center diamond body 1 and collecting the fluorescence radiated by the nitrogen vacancy color center diamond body 1; each side wall of the nitrogen vacancy color center diamond body 1 is covered with a light reflection layer 13.

[0019] Specifically, the nitrogen vacancy color center diamond body 1 can be a cube, prism, cylinder, truncated cone or other structures, such as a rectangular parallelepiped structure, and its length, width and thickness can be 1-4mm*1-4mm*0.1-0.8mm, such as 3mm*3mm*0.5mm.

[0020] The electric field coupling component constant in the nitrogen vacancy color center diamond Hamiltonian is relatively small, that is, it is relatively insensitive to the electric field. In order to improve the signal-to-noise ratio of the measurement signal, it is necessary to collect the fluorescence radiated by the nitrogen vacancy color center diamond as much as possible. Since the radiated fluorescence is not directional, a silicon dioxide coating is plated around the diamond to reflect the fluorescence originally radiated from the side and emit only from the opening of the copper layer on the upper surface, which is convenient for the subsequent fluorescence collection.

[0021] In this embodiment, each side surface of the nitrogen vacancy color center diamond body 1 is provided with a light reflection layer 13. The light reflection layer 13 is a silicon dioxide coating. The thickness of the light reflection layer 13 is 80-120 nm, preferably 100 nm.

[0022] Applying an electric field requires a potential difference, i.e., voltage. Plating electrodes on the surface of nitrogen vacancy color center diamond can reduce the magnitude of the applied voltage and reduce safety hazards when the same intensity electric field is applied to the diamond. The first electrode 11 and the second electrode 12 are both copper electrodes. More specifically, in this embodiment, the dimensions (length, width, thickness) of the first electrode 11 and the second electrode 12 are 3 mm*3 mm*2 μm.

[0023] The opening 111 formed on the first electrode 11 is a circular hole with a diameter of 0.5-3 mm and a hole depth of 1-3 μm. Preferably, the diameter of the opening is 2 mm and the hole depth is 2 μm. In this embodiment, the opening 111 can be located at the center of the first electrode 11. It should be noted that the opening 111 only penetrates the upper and lower surfaces of the first electrode 11, and does not penetrate the upper surface of the nitrogen vacancy color center diamond body 1. The setting of the opening 111 facilitates the external laser to emit laser to the nitrogen vacancy color center diamond body 1, and also facilitates the collection of fluorescence radiated by the nitrogen vacancy color center diamond body.

[0024] It can be obviously concluded from the above that the quantum electric field sensing structure provided in this embodiment uses a micro-nano process to prepare the first electrode 11 and the second electrode 12 on the upper and lower surfaces of the nitrogen vacancy color center diamond to apply an electric field; and an opening is set on the first electrode 11, and a light reflection layer 13 is deposited on each side of the nitrogen vacancy color center diamond, so that the fluorescence radiated from the side is reflected and emitted only from the opening on the upper surface, which is convenient for the subsequent collection of fluorescence, provides the necessary conditions for the quantum measurement of the electric field, and is conducive to greatly improving the accuracy and sensitivity of the electric field measurement.

[0025] See also Figure 3 The present invention also provides a quantum electric field measuring device, comprising: a power supply 2, a laser 3, a dichroic mirror 4, a reflector 5, an objective lens 6, a microwave emitting device 7 and a quantum electric field sensing structure; wherein the power supply 2 is connected to the quantum electric field sensing structure to apply a voltage to the quantum electric field sensing structure to generate an electric field; the microwave emitting device 7 is arranged on one side of the quantum electric field sensing structure to radiate microwaves of a preset frequency to the quantum electric field sensing structure; the dichroic mirror 4, the reflector 5 and the objective lens 6 are arranged in sequence from the output end of the laser 3 to the upper surface of the nitrogen vacancy color center diamond body 1 in the quantum electric field sensing structure, and the output end of the objective lens 6 is close to the upper surface of the quantum electric field sensing structure; a photodetector 9 is also arranged on one side of the dichroic mirror 4 to detect the optical power of the fluorescence radiated by the nitrogen vacancy color center diamond body 1.

[0026] Specifically, the power supply 2 is connected to the first electrode 11 and the second electrode 12 in the quantum electric field sensing structure to generate an electric field in the nitrogen vacancy color center diamond body 1, and microwaves of a preset frequency are emitted to the nitrogen vacancy color center diamond body 1 by a microwave generating device. Laser light of a certain wavelength is generated by a laser 3. The laser light passes through the dichroic mirror 4, the reflector 5 and the objective lens 6 in sequence, passes through the opening of the first electrode 11 on the upper surface of the nitrogen vacancy color center diamond body 1 and irradiates the nitrogen vacancy color center diamond body 1. The nitrogen vacancy color center diamond body 1 radiates red fluorescence of a preset wavelength band under the action of the electric field, microwaves and laser light, and after being reflected by the light reflecting layer 13, it is emitted through the opening on the upper surface of the nitrogen vacancy color center diamond body 1, collected by the objective lens 6, and reflected again by the reflector 5 and the dichroic mirror 4, and then emitted into the photodetector.

[0027] In this embodiment, it may further include: a filter 8; wherein the incident end of the filter is arranged close to the dichroic mirror 4, and the output end of the filter is arranged close to the photodetector.

[0028] Specifically, the filter is disposed between the dichroic mirror 4 and the photodetector 9 to filter light of a preset wavelength.

[0029] The working process of the embodiment of the present invention is as follows: A voltage is applied to the first electrode 11 and the second electrode 12 to generate an electric field, and microwaves with a frequency of about 2.87 GHz are radiated to the electrode through an external microwave antenna. The laser 3 generates a 532 nm green laser, which passes through the dichroic mirror 4, the reflector 5, and the objective lens 6 in sequence, and irradiates the nitrogen vacancy color center diamond body 1 through the opening on the first electrode 11. Under the influence of the electric field, microwaves and lasers, the nitrogen vacancy color center diamond body 1 radiates red fluorescence in the 637 nm-800 nm band, which is emitted from the opening of the first electrode 11, collected by the objective lens 6, reflected by the reflector 5 and the dichroic mirror 4, and filtered by the filter with a wavelength below 637 nm, and then irradiated into the photodetector. The photodetector obtains the optical power of the fluorescence radiated by the nitrogen vacancy color center diamond body 1, and the fluorescence intensity can be calculated according to the optical power of the fluorescence, and the magnitude of the measured electric field can be solved according to the fluorescence intensity and the microwave frequency.

[0030] The embodiment of the present invention adopts micro-nano technology to prepare the first electrode 11, the second electrode 12 and the light reflecting layer 13 on the surface of the nitrogen vacancy color center diamond, cooperates with the external optical path structure and the microwave structure, and utilizes the energy level structure of the nitrogen vacancy color center to realize quantum measurement of the electric field, which greatly improves the measurement accuracy and sensitivity compared with the traditional non-quantum measurement method.

[0031] The present invention also provides a method for preparing a quantum electric field sensing structure, which is characterized by comprising the following steps: Step S1, after depositing the light reflection layer 13 on the surface of the nitrogen vacancy color center diamond body 1, remove the light reflection layer 13 formed on the upper surface and the lower surface of the nitrogen vacancy color center diamond body 1.

[0032] Specifically, before depositing the light reflecting layer 13 on the surface of the nitrogen vacancy color center diamond body 1, the nitrogen vacancy color center diamond body 1 is first cleaned, specifically, first ultrasonically cleaned with acetone for 30 minutes, then ultrasonically cleaned with isopropanol for 15 minutes, then ultrasonically cleaned with deionized water for 15 minutes, and finally rinsed with deionized water 5 times, and then the diamond was blown dry with a nitrogen gun.

[0033] In this embodiment, the light reflection layer 13 is deposited by atomic layer deposition, and a layer of silicon dioxide is deposited. During the deposition, 50 sccm of silane (SiH4) is first used, then 1500 sccm of nitrous oxide (N2O) is used, and then 80 sccm of ammonia (NH3) is used. The temperature range is set to 250-350 degrees, and the RF power is 250W.

[0034] After deposition, a cleaning machine is used to remove the silicon dioxide from both sides (upper and lower surfaces) of the diamond.

[0035] Step S2 , sputtering a metal film layer on the upper and lower surfaces of the nitrogen vacancy color center diamond body 1 to form a first electrode 11 and a second electrode 12 .

[0036] Specifically, the metal film layer can be a copper film layer. Before sputtering copper, a layer of chromium is first sputtered as an adhesion layer to make the sputtered gold layer more solid.

[0037] In the specific implementation, in the sputtering process, the nitrogen vacancy color center diamond body 1 is used as the substrate, the starting temperature is room temperature, the continuous deposition accumulation temperature can reach 200°C (can be heated to 200°C), the target size used is 8 inches, and the deposited materials are copper (Cu) and chromium (Cr). When sputtering the copper layer, the new target sputters at a rate of 4.6nm / s at a radio frequency of 1kW.

[0038] It should be noted that this embodiment does not limit the order of sputtering the copper film on the upper and lower surfaces of the nitrogen vacancy color center diamond body 1. The order of sputtering the copper film on the upper surface first and then the lower surface can also be the order of sputtering the copper film on the lower surface first and then the upper surface.

[0039] Step S3 , performing photolithography and ion beam etching in sequence on the upper surface of the nitrogen vacancy color center diamond body 1 to form an opening on the first electrode 11 .

[0040] Specifically, the lithography step may include: applying photoresist on the upper surface of the nitrogen vacancy color center diamond body 1, heating the nitrogen vacancy color center diamond body 1 to a preset temperature for reversal, maintaining the preset time, and then developing after continuous exposure. During the development process, pay attention to maintaining uniform coverage of the developer and stirring appropriately to ensure consistent development effects. Preferably, the coating thickness of the photoresist is 1-3μm, preferably 1μm. The set light intensity is 9-10 mW / cm², preferably 9.5mW / cm²; the preset temperature is 100-120°C, preferably 110°C. The preset duration of the reversal process is 1-5 minutes, preferably 1-2 minutes. The continuous exposure time is 30-50s, preferably 45s.

[0041] In the specific implementation, the photoresist used is AZ5214, with a coating thickness of 1μm to ensure uniform coating. A ma6 lithography machine is used for contact lithography, with a set light intensity of 9.5mW / cm² and an exposure time of 4.5 seconds. The sample is heated to 110℃ for inversion, kept for 1-2 minutes, and then continuously exposed for 45 seconds. 3038 developer is used for development in the developing basket for 30 seconds.

[0042] In this embodiment, ion beam etching is used to etch the upper surface of the nitrogen vacancy color center diamond body 1. The argon ion physical dry etching process is used to etch the processed upper surface copper electrode according to the photolithography development area to form a circular through hole of the copper electrode. A mechanical pump and a molecular pump are used to create a vacuum environment, the argon gas flow rate is 5 sccm, and the argon ion radiation energy is 3 keV.

[0043] In this embodiment, after forming the opening on the first electrode 11 , the method further includes: leading out a gold wire on the first electrode 11 .

[0044] In a specific implementation, before the gold wire is led out on the first electrode 11, the processed nitrogen vacancy color center diamond body 1 is cleaned twice to remove surface impurities. The method of the secondary cleaning can be the same as that of the primary cleaning.

[0045] A wire bonder is used to perform hot-compression bonding to lead out gold wires from the copper-plated layer on the upper surface of the diamond, facilitating the subsequent application of voltage to generate an electric field.

[0046] The related parts of the method embodiment and the above-mentioned device embodiment can be referred to each other and will not be described in detail here.

[0047] In summary, the quantum electric field sensing structure of the present invention adopts diamond nitrogen vacancy color centers with fixed crystal orientation as electric field sensing units, manufactures electrodes and reflective layers on their surfaces through micro-nano technology, and cooperates with external optical structures and microwave structures to achieve quantum sensing of electric fields.

[0048] 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 claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A quantum electric field sensing structure based on diamond nitrogen vacancy color centers, characterized in that: include: The nitrogen vacancy color center diamond body; wherein, The upper and lower surfaces of the nitrogen vacancy color center diamond body are respectively provided with a first electrode and a second electrode, and the first electrode is provided with an opening for applying laser to the nitrogen vacancy color center diamond body and collecting fluorescence radiated by the nitrogen vacancy color center diamond body; Each side wall of the nitrogen vacancy color center diamond body is covered with a light reflecting layer.

2. The quantum electric field sensing structure based on diamond nitrogen vacancy color center according to claim 1, characterized in that: The light reflecting layer is a silicon dioxide coating.

3. The quantum electric field sensing structure based on diamond nitrogen vacancy color center according to claim 1, characterized in that: The first electrode and the second electrode are both copper electrodes.

4. The quantum electric field sensing structure based on diamond nitrogen vacancy color center according to claim 1, characterized in that: The nitrogen vacancy color center diamond body is a rectangular parallelepiped structure.

5. The quantum electric field sensing structure based on diamond nitrogen vacancy color center according to claim 1, characterized in that: The opening is a circular hole with a diameter of 0.5-3 mm and a hole depth of 1-3 μm.

6. The quantum electric field sensing structure based on diamond nitrogen vacancy color center according to claim 1, characterized in that: The thickness of the light reflecting layer is 80-120 nm.

7. A quantum electric field measuring device, characterized in that: include: A power supply, a laser, a dichroic mirror, a reflector, an objective lens, a microwave emitting device and a quantum electric field sensing structure based on diamond nitrogen vacancy color center as claimed in any one of claims 1 to 6; wherein, The power supply is connected to the quantum electric field sensing structure to apply voltage to the quantum electric field sensing structure to generate an electric field; The microwave emitting device is arranged on one side of the quantum electric field sensing structure, and is used to radiate microwaves of a preset frequency to the quantum electric field sensing structure; The dichroic mirror, the reflector and the objective lens are arranged in sequence from the output end of the laser to the upper surface of the nitrogen vacancy color center diamond body in the quantum electric field sensing structure, and the output end of the objective lens is close to the upper surface of the quantum electric field sensing structure; A photoelectric detector is also provided on one side of the dichroic mirror to detect the optical power of the fluorescence radiated by the nitrogen vacancy color center diamond body.

8. The quantum electric field measurement device according to claim 7, characterized in that: Also includes: Filter; wherein, The incident end of the filter is arranged close to the dichroic mirror, and the output end of the filter is arranged close to the photodetector.

9. A method for preparing a quantum electric field sensing structure based on diamond nitrogen vacancy color centers according to any one of claims 1 to 6, characterized in that: The following steps are involved: After depositing a light reflecting layer on the surface of the nitrogen vacancy color center diamond body, removing the light reflecting layer formed on the upper surface and the lower surface of the nitrogen vacancy color center diamond body; sputtering a metal film layer on the upper and lower surfaces of the nitrogen vacancy color center diamond body to form a first electrode and a second electrode; The upper surface of the nitrogen vacancy color center diamond body is sequentially subjected to photolithography and ion beam etching to form an opening on the first electrode.

10. The method for preparing a quantum electric field sensing structure according to claim 9, characterized in that: After forming the opening on the first electrode, the method further comprises: A gold wire is led out from the first electrode.

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