Method for detecting wide-spectrum ultraviolet light by using diamond solid-state quantum spin and ultraviolet electric detector

Abstract

The invention relates to a method for detecting wide-spectrum ultraviolet light by using diamond solid-state quantum spin and application of an ultraviolet detector, and relates to a method for detecting wide-spectrum ultraviolet light by using diamond solid-state quantum spin and application of the ultraviolet detector. The characteristic that a diamond NV color center charge state can be converted under the action of UV and the spectral intensity can be correspondingly changed is utilized. According to the method for detecting the wide-spectrum ultraviolet light through the diamond solid-state quantum spin, firstly, the diamond with the NV color center is prepared, laser is used for conducting irradiation excitation on the diamond with the NV color center, an optical sensor is used for collecting a fluorescence intensity signal at the position of a diamond epitaxial area, and when the diamond with the NV color center is irradiated by the ultraviolet light, the fluorescence intensity signal is detected. And a fluorescence intensity signal generates enhanced response at the wave band of 575-637 nm. According to the characteristic that a diamond NV color center charge state is sensitive to ultraviolet, the change of response of a photoelectric signal to 575nm and an optical signal within a phonon sideband range is monitored through an optical sensor when the diamond is loaded with UV under laser excitation, and the ultraviolet is detected.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor materials and quantum technology, and specifically relates to a method for detecting wide-spectrum ultraviolet light by using diamond solid-state quantum spin and an ultraviolet electrical detector. Background Art

[0002] Ultraviolet (UV) detection technology is a new detection technology developed after infrared and laser detection technology. Ultraviolet detection has important application value and development prospects in both civilian and military fields. For example, ultraviolet detection technology based on solar-blind ultraviolet photoelectric detectors is a key detection technology for both civilian and military use. Due to the absorption of solar ultraviolet rays by the ozone layer, photons with wavelengths less than 280nm in the space near the surface are very few and can be ignored. Therefore, solar-blind ultraviolet detectors that work in the solar-blind band and have no response to other bands can be used in the fields of fire monitoring, corona monitoring, petroleum industry and environmental pollution in the civilian field, and in the military field, they can be used in the fields of missile plume detection, missile guidance, space-based communications and machine vision.

[0003] The working mechanisms of current ultraviolet photodetectors are generally based on the photoelectric effect and the photothermal effect, and most of the materials with these effects used in devices are semiconductor materials. Diamond is a new type of semiconductor material with a high bandgap, high carrier mobility, and high thermal conductivity. By doping impurity atoms, such as nitrogen atoms or silicon atoms, into the diamond lattice, luminescence centers can be formed in the crystal. These luminescence centers have the characteristics of quantum light sources and can be used in quantum computing, quantum communication, and quantum detection. In the study, it was found that the charge state of the nitrogen vacancy (NV) center of diamond responds to ultraviolet light. Therefore, a method based on diamond solid-state quantum spin detection of wide-spectrum ultraviolet light with a different working mechanism from the past was proposed. Summary of the invention

[0004] The present invention utilizes the characteristics that the charge state of diamond NV color center will change under the action of UV and its spectral intensity will change accordingly, and proposes a method and ultraviolet electrical detector that converts ultraviolet detection into spectral detection in the visible light range and can achieve wide-spectrum ultraviolet detection.

[0005] The method of the present invention for detecting wide-spectrum ultraviolet light using diamond solid-state quantum spin is implemented by the following steps:

[0006] 1. Cleaning:

[0007] Cleaning the high temperature and high pressure diamond substrate to obtain a clean diamond substrate;

[0008] 2. Preparation of solid-state quantum spin in diamond NV color center:

[0009] a. Place the clean diamond substrate into the CVD growth chamber, evacuate the chamber and introduce hydrogen, adjust the pressure in the CVD growth chamber to 8-12 mbar, start the microwave generator and activate the plasma;

[0010] b. Increase the gas pressure in the CVD growth chamber and the power of the microwave generator to make the temperature of the clean diamond substrate reach 700-1000°C;

[0011] c. Introduce methane and control the methane flow rate to 4-32 sccm;

[0012] d. Introduce doping element gas, control the temperature of the diamond substrate to be stable at 700-1000°C, and carry out CVD epitaxial growth. After the growth, turn off the methane and doping element gas, gradually reduce the power of the microwave generator and the air pressure in the CVD growth chamber, close the hydrogen valve, and release the gas to atmospheric pressure, thereby obtaining diamond with NV color center;

[0013] 3. Ultraviolet light detection:

[0014] The diamond with NV color center is irradiated and excited by laser, and the fluorescence intensity signal at the diamond epitaxial area (point) is collected by optical sensor. When the diamond with NV color center is irradiated by ultraviolet light, the fluorescence intensity signal produces an enhanced response in the 575nm to 637nm band, thereby completing the method of using diamond solid-state quantum spin to detect wide-spectrum ultraviolet light;

[0015] The doping element gas in step d is nitrogen.

[0016] The present invention uses a method for detecting wide-spectrum ultraviolet light using diamond solid-state quantum spin. The ultraviolet electrical detector includes a diamond with an NV color center, an excitation light source and an optical sensor. Laser is used as the excitation light source to excite the diamond with the NV color center. Under the condition that the NV color center is excited, the fluorescence intensity signal of the diamond with the NV color center in the wavelength range of 575nm to 635nm is detected by the optical sensor. When the fluorescence intensity signal is enhanced relative to the laser irradiation of the diamond with the NV color center, it indicates that ultraviolet light is detected.

[0017] The present invention converts the hard-to-detect ultraviolet light into spectral detection within the visible light range, and utilizes the sensitivity of the diamond NV color center to ultraviolet response to achieve wide-spectrum ultraviolet detection, with simple process and novel form.

[0018] The method of the present invention for detecting wide-spectrum ultraviolet light using diamond solid-state quantum spin has the following beneficial effects:

[0019] 1. The present invention uses the characteristic that the charge state of diamond NV color center is sensitive to ultraviolet light. By using an optical sensor to monitor the changes in the response of the photoelectric signal to the optical signal within the range of 575nm and its phonon sidebands, the ultraviolet light is indirectly detected, which provides a new idea for ultraviolet detection technology and can realize the detection of wide-spectrum ultraviolet light.

[0020] 2. The present invention detects wide-spectrum ultraviolet light based on diamond solid-state quantum spin, has a simple process flow, and uses NV color center quantum light source, which can effectively promote application research based on diamond color centers. At the same time, it provides technical support for key technical engineering fields such as diamond color center-based quantum sensor devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The experimental optical path diagram of the method of using diamond solid-state quantum spin to detect wide-spectrum ultraviolet light in the embodiment;

[0022] Figure 2 The photoelectric signal comparison diagram of the high-concentration color center samples CH-2 and CH-3 in the embodiment;

[0023] Figure 3 This is a comparison diagram of the photoelectric signals of the low-concentration color center sample CH-1 in the embodiment;

[0024] Figure 4 Graph showing the test results of diamond ultraviolet transmittance of samples with different concentrations in the embodiment. DETAILED DESCRIPTION

[0025] Specific implementation method 1: This implementation method of using diamond solid-state quantum spin to detect broadband ultraviolet light is implemented according to the following steps:

[0026] 1. Cleaning:

[0027] Cleaning the high temperature and high pressure diamond substrate to obtain a clean diamond substrate;

[0028] 2. Preparation of solid-state quantum spin in diamond NV color center:

[0029] a. Place the clean diamond substrate into the CVD growth chamber, evacuate the chamber and introduce hydrogen, adjust the pressure in the CVD growth chamber to 8-12 mbar, start the microwave generator and activate the plasma;

[0030] b. Increase the gas pressure in the CVD growth chamber and the power of the microwave generator to make the temperature of the clean diamond substrate reach 700-1000°C;

[0031] c. Introduce methane and control the methane flow rate to 4-32 sccm;

[0032] d. Introduce doping element gas, control the temperature of the diamond substrate to be stable at 700-1000°C, and carry out CVD epitaxial growth. After the growth, turn off the methane and doping element gas, gradually reduce the power of the microwave generator and the air pressure in the CVD growth chamber, close the hydrogen valve, and release the gas to atmospheric pressure, thereby obtaining diamond with NV color center;

[0033] 3. Ultraviolet light detection:

[0034] The diamond with NV color center is irradiated and excited by laser, and the fluorescence intensity signal at the diamond epitaxial area (point) is collected by optical sensor. When the diamond with NV color center is irradiated by ultraviolet light, the fluorescence intensity signal produces an enhanced response in the 575nm to 637nm band, thereby completing the method of using diamond solid-state quantum spin to detect wide-spectrum ultraviolet light;

[0035] The doping element gas in step d is nitrogen.

[0036] The wavelength range of ultraviolet light that can be detected in step three of this embodiment is 225-380nm.

[0037] This implementation method uses the characteristics of diamond NV color center quantum light source to provide a new method for detecting ultraviolet light, promoting the development of ultraviolet detection technology. At the same time, it provides technical support for key technical engineering fields such as diamond color center-based quantum sensor devices, and plays an important demonstration and traction role.

[0038] Specific implementation method 2: The difference between this implementation method and specific implementation method 1 is that in step 1, the high temperature and high pressure diamond substrate is placed in acetone, deionized water, and anhydrous ethanol in sequence for ultrasonic cleaning.

[0039] Specific implementation method 3: This implementation method is different from specific implementation methods 1 or 2 in that in step a, a clean diamond substrate is placed in a CVD growth chamber, and the chamber pressure is evacuated to 3.0×10 -6 ~5.0×10 -6 mbar and then hydrogen was introduced.

[0040] Specific implementation method 4: The difference between this implementation method and any one of specific implementation methods 1 to 3 is that in step a, the gas pressure in the CVD growth chamber is adjusted to 10 mbar, the microwave generator is started, and the plasma is activated.

[0041] Specific implementation method five: This implementation method is different from specific implementation methods one to four in that the methane flow rate in step c is controlled to be 5 to 10 sccm.

[0042] Specific implementation example 6: This implementation example is different from specific implementation example 5 in that the flow rate of the doping element gas in step d is controlled to be 0.01 sccm to 0.1 sccm.

[0043] Specific embodiment 7: This embodiment is different from any one of specific embodiments 1 to 6 in that the CVD growth time in step d is 24 to 48 hours.

[0044] Specific embodiment eight: This embodiment differs from any one of specific embodiments one to seven in that the concentration of NV color centers in the diamond with NV color centers in step d is 400 ppb to 20 ppm.

[0045] Specific implementation method 9: The difference between this implementation method and any one of specific implementation methods 1 to 8 is that the laser light source in step 3 is 532nm excitation light, and the energy is controlled to be 0.05-5mW.

[0046] In this embodiment, the scanning time of the laser light source is 0.2 to 10 seconds.

[0047] Embodiment 1: The method of using diamond solid-state quantum spin to detect wide-spectrum ultraviolet light in this embodiment is implemented according to the following steps:

[0048] 1. Diamond cleaning:

[0049] The high temperature and high pressure diamond seed crystals were placed in acetone, deionized water and anhydrous ethanol in turn, and cleaned for 30 minutes respectively under the condition of ultrasonic power of 100W to obtain a clean diamond substrate;

[0050] 2. Growth of diamond containing NV color center:

[0051] a. Place the clean diamond substrate into the CVD growth chamber, close the chamber, and evacuate the chamber to a pressure of 5.0×10 -6 mbar, then hydrogen is introduced with a hydrogen flow rate of 200 sccm, the gas pressure in the CVD growth chamber is adjusted to 10 mbar, and the microwave generator is started to activate the plasma;

[0052] b. Increase the gas pressure in the CVD growth chamber and the power of the microwave generator to make the temperature of the clean diamond substrate reach 750°C;

[0053] c. Adjust the hydrogen flow rate to 192 sccm, introduce methane, and control the methane flow rate to 8 sccm;

[0054] d. Nitrogen was introduced, and the nitrogen flow rate was set to 0.01 sccm. At this time, the nitrogen concentration was about 1 ppm. The gas pressure and power were adjusted to control the temperature of the diamond substrate to be stable at 830°C. CVD epitaxial growth was carried out for 48 hours. After the growth, methane and nitrogen were turned off, and the gas pressure in the CVD growth chamber was gradually reduced to 10 mbar. The hydrogen valve was closed and the gas was released to atmospheric pressure to obtain diamond with NV color center. The NV concentration was about 400 ppb. The sample number was CH-2.

[0055] 3. Fluorescence spectroscopy characterization:

[0056] (1) Use a 10x microscope to focus on the upper surface of the diamond with NV color centers and determine the characterization area;

[0057] (2) Use a 50x microscope to observe, select the test point in the normal epitaxial area of ​​the diamond, and focus again;

[0058] (3) The UV light source uses a deuterium lamp from Ocean Optics DH-2000. The UV light is introduced from DH-2000 through an optical fiber. The optical fiber head is equipped with a convex lens to collimate the light. The angle is adjusted so that the UV light can fully irradiate the surface of the diamond sample.

[0059] (4) Using an excitation light source of 532 nm, an energy of 3 mW, a scanning time of 1 s, and an optical filter that can pass through an optical band of 550 to 700 nm, the photoelectric signal at a point in the normal epitaxial region of the diamond is measured using an optical sensor without UV loading;

[0060] (5) Turn on the UV light source and use the same test parameters as in step (4). Under the simultaneous loading of UV and laser, measure the photoelectric signal at the same point as in step (4). The experimental optical path is as follows: Figure 1 As shown;

[0061] (6) Turn off the ultraviolet light source, turn on the halogen lamp of DH-2000, use the test parameters consistent with step (4), and measure the photoelectric signal at the same point as step (4) under the simultaneous loading of the halogen lamp and the laser;

[0062] (7) Turn off the halogen lamp, turn off the laser, turn on the ultraviolet light source, the scanning time is 1 s, and measure the photoelectric signal at the same point as step (4) under only UV loading;

[0063] The test results of the photoelectric signal in this embodiment are as follows: Figure 2 shown.

[0064] This example focuses on the fluorescence intensity signal in the range of 575 to 635 nm. By comparison, it can be found that under UV and laser loading, NV 0The signal intensity of the ZPL (zero phonon line), 575nm, and the phonon sideband, 575-635nm range increases. Comparing the photoelectric signals of halogen lamp and laser loading, it can be found that the difference with the results of laser loading alone is very small, indicating that the light source of low intensity in the visible light range cannot produce the same effect as UV, indicating that the diamond color center is not sensitive to low intensity visible light. The photoelectric signal obtained by only UV loading can be obtained. The UV emitted from DH-2000 is not enough to excite the NV color center to generate a signal, indicating that the photoelectric signal obtained by simultaneous loading of UV and laser is not a simple superposition of the photoelectric signal results obtained when the two are loaded separately. In summary, the photoelectric signal of diamond in the 575-635nm band is monitored using an optical sensor. If the signal intensity in this range increases, it means that ultraviolet light is detected.

[0065] 4. Diamond UV transmittance test

[0066] The transmittance of diamond is tested at different wavelengths, and the incident light intensity and the outgoing light intensity are compared to obtain a graph showing the variation of transmittance with wavelength, such as Figure 4 As shown, the CH-2 sample responds to ultraviolet light in the 200-400nm band.

[0067] Embodiment 2: This embodiment is different from Embodiment 1 in that:

[0068] (1) During the growth of diamond containing NV color centers, the nitrogen flow rate was set to 0.001 sccm, the nitrogen concentration was about 0.1 ppm, and the NV concentration of the grown sample was about 30 ppb, named CH-1;

[0069] (2) In the UV detection, there are only two tests: laser loading alone and UV and laser loading at the same time, but there is no control test of halogen lamp and UV loading alone;

[0070] (3) Obtain the photoelectric signal comparison diagram as follows Figure 3 As shown, only the signal in the range of 575-635nm is concerned. By comparison, it can be found that the low-concentration NV diamond sample cannot achieve good UV detection in this spectral range. Figure 4 From the ultraviolet transmittance of diamonds with different NV concentrations, we can see that CH-1 has low ultraviolet absorption at 220-400nm, and the charge state of the NV color center changes little, which is reflected in the photoelectric signal as no obvious change in intensity.

[0071] Embodiment 3: This embodiment is different from Embodiment 1 in that:

[0072] During the growth of diamond containing NV color centers, the nitrogen flow rate was set to 0.1 sccm, the added nitrogen concentration was about 10 ppm, and the NV concentration of the grown sample was about 3.5 ppm. The sample was named CH-3.

[0073] The photoelectric signal comparison diagram obtained in this embodiment is Figure 2 The result is the same. Figure 4 It can be seen that the UV transmittance of CH-3 and CH-2 is different in the band after 220nm. Since the output power of the UV light source in the present invention is relatively small, the influence on the sample has not reached saturation. Therefore, the photoelectric signal comparison diagram of CH-3 and CH-2 ( Figure 2 ) have the same results.

Claims

1. A method for detecting broad-spectrum ultraviolet light using diamond solid-state quantum spin, characterized in that The method for detecting broad-spectrum ultraviolet light using diamond solid-state quantum spin is implemented by the following steps:

1. Cleaning: Cleaning the high temperature and high pressure diamond substrate to obtain a clean diamond substrate; 2. Preparation of solid-state quantum spin in diamond NV color center: a. Place the clean diamond substrate into the CVD growth chamber, evacuate the chamber and introduce hydrogen, adjust the pressure in the CVD growth chamber to 8-12 mbar, start the microwave generator and activate the plasma; b. Increase the gas pressure in the CVD growth chamber and the power of the microwave generator to make the temperature of the clean diamond substrate reach 700-1000°C; c. Introduce methane and control the methane flow rate to 4-32 sccm; d. Introduce doping element gas, control the temperature of the diamond substrate to be stable at 700-1000°C, and carry out CVD epitaxial growth. After the growth, turn off the methane and doping element gas, gradually reduce the power of the microwave generator and the air pressure in the CVD growth chamber, close the hydrogen valve, and release the gas to atmospheric pressure, thereby obtaining diamond with NV color centers in the epitaxial region; 3. Ultraviolet light detection: Diamonds with NV color centers are irradiated and excited by laser, and fluorescence intensity signals at the diamond epitaxial region are collected by optical sensors. When diamonds with NV color centers are irradiated with ultraviolet light, the fluorescence intensity signals produce an enhanced response in the 575nm to 637nm band, thereby completing a method for detecting wide-spectrum ultraviolet light using diamond solid-state quantum spins. The doping element gas in step d is nitrogen.

2. The method for detecting broad-spectrum ultraviolet light using diamond solid-state quantum spin according to claim 1, characterized in that In step 1, the high temperature and high pressure diamond substrate is placed in acetone, deionized water and anhydrous ethanol in turn for ultrasonic cleaning.

3. The method for detecting broad-spectrum ultraviolet light using diamond solid-state quantum spin according to claim 1, characterized in that In step a, a clean diamond substrate is placed in the CVD growth chamber and the chamber is evacuated to a pressure of 3.0×10 -6 ~5.0×10 -6 mbar and then hydrogen was introduced.

4. The method for detecting broad-spectrum ultraviolet light using diamond solid-state quantum spin according to claim 1, characterized in that In step a, the gas pressure in the CVD growth chamber is adjusted to 10 mbar, and the microwave generator is started to activate the plasma.

5. The method for detecting broad-spectrum ultraviolet light using diamond solid-state quantum spin according to claim 1, characterized in that In step c, the methane flow rate is controlled to be 5-10 sccm.

6. The method for detecting broad-spectrum ultraviolet light using diamond solid-state quantum spin according to claim 5, characterized in that In step d, the flow rate of the doping element gas is controlled to be 0.01 sccm to 0.1 sccm.

7. The method for detecting broad-spectrum ultraviolet light using diamond solid-state quantum spin according to claim 1, characterized in that The CVD growth time in step d is 24 to 48 hours.

8. The method for detecting broad-spectrum ultraviolet light using diamond solid-state quantum spin according to claim 1, characterized in that The concentration of NV color centers in the diamond with NV color centers in step d is 400 ppb to 20 ppm.

9. The method for detecting broad-spectrum ultraviolet light using diamond solid-state quantum spin according to claim 1, characterized in that In step three, the laser light source is 532nm excitation light, and the energy is controlled at 0.05-5mW.

10. Ultraviolet electric detector, characterized in that The ultraviolet electrical detector includes a diamond with an NV color center, an excitation light source and an optical sensor. Laser is used as the excitation light source to excite the diamond with the NV color center. Under the condition that the NV color center is excited, the fluorescence intensity signal of the diamond with the NV color center in the waveband range of 575nm to 635nm is detected by the optical sensor. When the fluorescence intensity signal is enhanced relative to the laser irradiation on the diamond with the NV color center, it indicates that ultraviolet light is detected.

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