A method for enhancing diamond NV-color center fluorescence by preparing one-dimensional photonic crystals and nanometer noble metals on a diamond surface

Abstract

The application discloses a method for enhancing diamond NV ‑ Color center fluorescence, belongs to the field of photoluminescence and quantum color center.The present application solves the problems of complex process and high preparation cost of existing diamond NV ‑ Color center fluorescence intensity.The present application prepares TiO2, SiO2 alternating dielectric film structure one-dimensional photonic crystal, and prepares nano Ag micro column on the other surface of the diamond, based on the light regulation effect of one-dimensional photonic crystal photonic band gap and the surface plasmon effect of nano metal, the light at zero phonon line (ZPL) 637nm wave band of diamond NV ‑ Color center is regulated, and the fluorescence intensity of diamond NV ‑ Color center is improved.The present application lays a foundation for the development and research of diamond NV ‑ Color center quantum platform.

Description

Technical Field

[0001] This invention belongs to the field of photoluminescence and quantum color centers, specifically relating to a method for enhancing diamond NV using a one-dimensional photonic crystal structure and the surface plasmon effect of nanometals. - The fluorescence intensity of the color center. Background Technology

[0002] Nitrogen-vacancy centers (NVs) in diamond are in a negatively charged state. - A color center (NV) is a nanoscale solid-state spin quantum system with a stable spin energy level structure, which can be used as a qubit. It exhibits ultralong spin coherence time and efficient optical transitions at room temperature, enabling convenient optical initialization and readout of quantum states. A single NV... - Color centers are stable and reliable single-photon sources, highly sensitive to external fields, making them excellent quantum sensing materials. However, diamond NV... - The spontaneous emission of a color-center zero-phonon line (ZPL) is less than 4%, and NV typically needs to be modulated. - To improve NV by using the light field near the color center - The fluorescence intensity of the color center.

[0003] Because single-crystal diamond has no grain boundaries and is of high quality, it typically has higher NV (noise, vibration, and gradation) compared to nanodiamonds and polycrystalline diamonds. - It has a higher ground state lifetime, therefore it contains NV - Color-centered single-crystal diamond is more suitable as a quantum material.

[0004] Currently, improving the NV of single-crystal diamond - The methods for color center fluorescence are mainly based on subtractive fabrication methods using existing micro- and nanofabrication technologies. For example, single-crystal diamond can be processed into two-dimensional photonic crystals in the form of air columns or diamond dielectric columns can be prepared through reactive ion etching or focused ion beam etching. - The color center ZPL is coupled to the fabricated optical microcavity with a large quality factor Q and a small mode volume V. Additive manufacturing methods, such as the bottom-up template-assisted fabrication of two-dimensional photonic crystals in the form of diamond nanopillars, also attempt to achieve the coupling of the microcavity with the NV. - Coupling of color centers ZPL. However, the above method is complex and costly to prepare. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of existing reinforced diamond NV - To address the challenges of complex and costly fabrication processes for enhancing color center fluorescence intensity, a method was invented to develop a one-dimensional photonic crystal with a periodically alternating TiO2 and SiO2 dielectric film structure on the diamond surface to improve diamond NV (noise, fluorescence, and intensity). -Methods for enhancing the fluorescence intensity of color centers in diamond NV - The fluorescence intensity of the color center was determined by depositing nano-Ag micropillars on the diamond surface using porous anodic aluminum oxide (AAO) as a template.

[0006] This invention provides a method for fabricating a one-dimensional photonic crystal on the surface of diamond using TiO2 and SiO2 as high- and low-refractive-index media materials, respectively. The method involves controlling the photonic bandgap in the diamond NV... - The color center is near ZPL637nm, which improves the diamond NV. - Color center fluorescence intensity.

[0007] To address the aforementioned technical problems, the present invention adopts the following technical solution:

[0008] The purpose of this invention is to provide a method for surface-processing one-dimensional photonic crystals to enhance diamond NV. - The method for color center fluorescence includes the following steps:

[0009] Step 1: Clean the diamond substrate and heat it in a mixed acid solution;

[0010] Step 2: By magnetron sputtering, five alternating TiO2 / SiO2 thin films are deposited on one surface of a diamond substrate, followed by an additional TiO2 film.

[0011] Step 3: Using porous anodic aluminum oxide (AAO) as a mask, deposit an Ag layer on the other surface of the diamond substrate by magnetron sputtering, and then remove the AAO mask; this completes the process.

[0012] The mixed acid solution is prepared by mixing concentrated HNO3 and concentrated H2SO4 in a volume ratio of 1:1.

[0013] Furthermore, the diamond substrate is selected from CVD single-crystal diamond.

[0014] To further specify, in step one, the diamond substrate is ultrasonically cleaned for 20 minutes each using anhydrous ethanol, acetone, and deionized water in sequence.

[0015] Further specifying, in step one, heating is carried out continuously at 250°C for 2 hours.

[0016] Further specifying, step two is performed as follows: depositing six cycles of alternating TiO2 / SiO2 thin films.

[0017] Further specifying the method, TiO2 is deposited first, followed by SiO, using magnetron sputtering equipment; the deposition process is alternating, and the specific steps are as follows:

[0018] Step 1: Using high-purity titanium metal as the target material, high-purity Ar and O2 are introduced into the cavity. The magnetron sputtering RF power is 100W, the Ar flow rate is 20sccm, and the O2 flow rate is 5sccm to prepare an amorphous TiO2 thin film.

[0019] Step 2: Using single-crystal silicon as the target material, the magnetron sputtering RF power is controlled at 100W, the Ar flow rate is 20sccm, and the O2 flow rate is 8sccm to prepare an amorphous SiO2 thin film.

[0020] Step 3: Repeat steps 1 and 2 a total of 4 times.

[0021] Further specifying, the silver layer thickness is 30nm.

[0022] To further define the process, the specific steps for depositing the silver layer are as follows:

[0023] Using a magnetron sputtering apparatus, high-purity metallic silver was used as the target material, and high-purity Ar was introduced. The radio frequency power was 40W, the Ar flow rate was 20sccm, and the deposition time was 40s to obtain silver with a thickness of 30nm.

[0024] Further, high-temperature tape was used to remove the AAO mask.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] Diamond NV - The fluorescence intensity of the color center increased by 60%, while NV 0 The fluorescence intensity of the color centers hardly changed, and even showed a decreasing trend.

[0027] By fabricating a one-dimensional photonic crystal on the lower surface of diamond and metal nanoparticles on the upper surface, diamond NV synthesis was achieved at a relatively low cost. - Enhanced fluorescence at color centers contributes to the enhancement of NV in single-crystal diamond. - The fluorescence intensity of color centers provides new ideas and methods.

[0028] This invention combines one-dimensional photonic crystals with surface plasmon-based metal nanoparticles for localized control of electromagnetic fields, providing new ideas and methods for optical field manipulation and improving photon collection efficiency.

[0029] This invention is for diamond NV - The development and research of the Color Center Quantum Platform laid the foundation.

[0030] To further understand the features and technical content of this invention, please refer to the following detailed description and accompanying drawings. However, the accompanying drawings are for reference and illustration only and are not intended to limit the invention. Attached Figure Description

[0031] Figure 1 This invention relates to a method for preparing one-dimensional photonic crystals and nano-Ag-reinforced diamond NV crystals via surface fabrication. - Schematic diagram of the structure of color center fluorescence;

[0032] Figure 2 A comparison of transmittance in the 550nm–700nm wavelength range before and after preparing a TiO2 / SiO2 one-dimensional photonic crystal on the diamond base of this invention.

[0033] Figure 3 This is a scanning electron microscope (SEM) image of the silver nanoparticles prepared on the diamond surface according to the present invention.

[0034] Figure 4 This is a scanning electron microscope (SEM) image of the one-dimensional photonic crystal prepared on the diamond base of this invention.

[0035] Figure 5 This invention relates to the preparation of one-dimensional photonic crystals and nano-Ag on diamond surfaces before and after NV formation. - Comparison of fluorescence intensity at color centers. Detailed Implementation

[0036] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, while not limiting the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0037] Example 1: In this example, one-dimensional photonic crystal-enhanced diamond NV is fabricated on the surface. - The method for color center fluorescence includes the following steps:

[0038] Step 1, Sample Cleaning: CVD single-crystal diamond with dimensions of 5mm*5mm*0.3mm produced by Hubei Carbon Six Technology Co., Ltd. was selected as the substrate. The single-crystal diamond substrate was ultrasonically cleaned in sequence with anhydrous ethanol, acetone, and deionized water.

[0039] Step 2, hydrophilicity treatment: The diamond substrate is placed in a mixed acid solution (concentrated HNO3 and concentrated H2SO4 in a 1:1 volume ratio) and heated to 250°C for 2 hours to significantly improve the hydrophilicity of the diamond surface.

[0040] Step 3: Fabrication of the one-dimensional photonic crystal: Using magnetron sputtering, five alternating TiO2 / SiO2 thin films are deposited on a diamond substrate, followed by an outer TiO2 film. The TiO2 / SiO2 alternating films are deposited alternately, with TiO2 deposited first, then SiO2. The thickness of each TiO2 and SiO2 dielectric film is designed using the quarter-wavelength center wavelength stacking method. Here, the center wavelength is designed at the diamond NV... - At the color center ZPL, approximately 637 nm, amorphous TiO2 films were prepared using magnetron sputtering with high-purity titanium as the target. High-purity Ar and O2 were introduced into the cavity. The magnetron sputtering RF power was 100 W, the Ar flow rate was 20 sccm, and the O2 flow rate was 5 sccm. Similarly, amorphous SiO2 films were prepared using single-crystal silicon as the target, with the magnetron sputtering RF power controlled at 100 W, the Ar flow rate at 20 sccm, and the O2 flow rate at 8 sccm.

[0041] Step 4, Preparation of nano-silver: A porous anodic aluminum oxide (AAO) template with a pore size of 30 nm, a spacing of 65 nm, and a size of Φ13 mm was attached to the surface of the diamond sample with adhesive tape. A 30 nm thick layer of silver was deposited on the surface of the sample by magnetron sputtering. After the deposition was completed, the AAO template was removed.

[0042] The samples prepared in Example 1 were subjected to visible light transmittance testing, scanning electron microscopy (SEM) characterization, and photoluminescence (PL) testing.

[0043] Figure 1 As shown in the schematic diagram, the lower surface of the diamond is a one-dimensional photonic crystal with an alternating TiO2 / SiO2 film structure prepared in this invention, and the upper surface is nano-silver prepared by the mask method.

[0044] The transmittance comparison diagram in the 550nm–700nm wavelength range before and after fabricating the TiO2 / SiO2 one-dimensional photonic crystal on the diamond base in this embodiment is shown below. Figure 2 As shown, Figure 2 In the diagram, the black curve represents the transmittance of the diamond sample in the 550nm–700nm wavelength range before treatment, while the red curve represents the transmittance after sequentially preparing a one-dimensional photonic crystal with alternating TiO2 / SiO2 films and nanosilver on the lower and upper surfaces of the sample. Figure 2 It can be seen that our method enables diamonds to be used in NV - The color center ZPL is located in the photonic band gap.

[0045] The scanning electron microscope (SEM) image of the silver nanoparticles prepared on the diamond surface in this embodiment is shown below. Figure 3 As shown, Figure 3This indicates that the nano-Ag we prepared is uniformly distributed on the surface of the diamond sample, without obvious clustering.

[0046] The longitudinal section SEM image of the one-dimensional photonic crystal with the TiO2 / SiO2 alternating film structure prepared in this embodiment is shown below. Figure 4 As shown, by Figure 4 It can be seen that the TiO2 and SiO2 alternating film structure prepared in this embodiment has distinct layers and uniform thickness, and is a relatively ideal one-dimensional photonic crystal.

[0047] This embodiment describes the preparation of a one-dimensional photonic crystal on a diamond surface before and after NV. - The fluorescence intensity comparison diagram of the color centers is shown below. Figure 5 As shown, Figure 5 This indicates that the preparation method of this embodiment enables the production of diamond NV. - The fluorescence of the color center was significantly improved, while NV... 0 The fluorescence of the color center remained almost unchanged.

[0048] Example 2: This example differs from Example 1 in that it involves depositing six cycles of alternating TiO2 / SiO2 thin films. All other steps and parameters are the same as in Example 1.

Claims

1. A method for surface-processing one-dimensional photonic crystal-enhanced diamond NV - The method of color center fluorescence is characterized by, Includes the following steps: Step 1: Clean the diamond substrate and heat it in a hot mixed acid solution; Step 2: By magnetron sputtering, five alternating TiO2 / SiO2 thin films are deposited on one surface of a diamond substrate in five cycles, followed by the deposition of another TiO2 film. The thickness of each TiO2 and SiO2 dielectric film is designed according to the quarter-center wavelength film stacking method. Here, the center wavelength is designed at the diamond NV-color center ZPL, i.e., 637nm. Step 3: Using porous anodic aluminum oxide (AAO) as a mask, deposit a silver layer on the other surface of the diamond substrate by magnetron sputtering, and then remove the AAO mask; this completes the process; the silver layer thickness is 30 nm. The mixed acid solution is prepared by mixing concentrated HNO3 and concentrated H2SO4 in a volume ratio of 1:

1.

2. The method according to claim 1, characterized in that, The diamond substrate is made of CVD single-crystal diamond.

3. The method according to claim 1, characterized in that, In step one, the diamond substrate is ultrasonically cleaned for 20 minutes each using anhydrous ethanol, acetone, and deionized water in sequence.

4. The method according to claim 1, characterized in that, In step one, heat at 250°C for 2 hours.

5. The method according to claim 1, characterized in that, In step two, six cycles of alternating TiO2 / SiO2 films are deposited.

6. The method according to claim 1, characterized in that, The steps for magnetron sputtering alternating TiO2 / SiO2 thin films are as follows: Step 1: Using high-purity titanium metal as the target material, high-purity Ar and O2 are introduced into the cavity. The magnetron sputtering RF power is 100W, the Ar flow rate is 20sccm, and the O2 flow rate is 5sccm to prepare an amorphous TiO2 thin film. Step 2: Using single-crystal silicon as the target material, the magnetron sputtering RF power is controlled at 100W, the Ar flow rate is 20sccm, and the O2 flow rate is 8sccm to prepare an amorphous SiO2 thin film. Step 3: Repeat steps 1 and 2 a total of 4 times.

7. The method according to claim 1, characterized in that, The steps for depositing a silver layer are as follows: Using a magnetron sputtering apparatus, high-purity metallic silver was used as the target material, and high-purity Ar was introduced into the cavity. The magnetron sputtering RF power was 40W, the Ar flow rate was 20sccm, and the deposition time was 40s to obtain a silver layer.

8. The method according to claim 1, characterized in that, High-temperature tape was used to remove the AAO mask.

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