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

Abstract

The application discloses a method for detecting wide-spectrum ultraviolet light by using diamond solid-state quantum spin and application of an ultraviolet electric detector, and utilizes the characteristics that the electric charge state of a diamond NV color center will be changed under the action of UV, and the spectral intensity will be changed accordingly. In the method for detecting wide-spectrum ultraviolet light by using diamond solid-state quantum spin, first, a diamond with an NV color center is prepared, a laser is used to irradiate and excite the diamond with the NV color center, and a fluorescence intensity signal at an epitaxial area of the diamond is collected through an optical sensor; when the diamond with the NV color center is irradiated by ultraviolet light, the fluorescence intensity signal produces an enhanced response in a 575nm-637nm wave band. According to the characteristics that the electric charge state of the diamond NV color center is sensitive to ultraviolet, the change of a photoelectric signal in response to an optical signal in a 575nm and phonon sideband range is monitored to detect ultraviolet.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of semiconductor materials and quantum technology, and particularly relates to a method for detecting wide-spectrum ultraviolet light by using diamond solid-state quantum spin and an ultraviolet electric detector. BACKGROUND

[0002] Ultraviolet (UV) detection technology is a new type of detection technology developed after infrared and laser detection technologies, and ultraviolet detection has important application value and development prospect in civil and military fields. For example, ultraviolet detection technology based on solar blind ultraviolet photodetectors is a key detection technology for both civil and military use. Due to the absorption of the ozone layer to the solar ultraviolet light, there are very few photons with a wavelength less than 280 nm in the space near the ground surface, which can be ignored. Therefore, the solar blind ultraviolet detector working in the solar blind band and having no response to other bands can be applied to fire monitoring, corona monitoring, petroleum industry and environmental pollution in civil fields, and can be applied to missile plume detection, missile guidance, space-based communication and machine vision in military fields.

[0003] At present, the working mechanism of ultraviolet photodetectors is generally based on photoelectric effect and photothermal effect, and the materials applied to the devices having these effects are mostly semiconductor materials. Diamond is a new type of semiconductor material with high band gap, high carrier mobility and high thermal conductivity. When impurity atoms such as nitrogen atoms or silicon atoms are doped in the diamond lattice, luminescent centers can be formed in the crystal. These luminescent centers have the characteristics of quantum light sources and can be applied to the fields of quantum computing, quantum communication and quantum detection. In the research, it is found that the charge state of the nitrogen vacancy (NV) center of diamond will respond to ultraviolet light, and therefore a method for detecting wide-spectrum ultraviolet based on diamond solid-state quantum spin different from the previous working mechanism is proposed. SUMMARY

[0004] The application utilizes the characteristics that the charge state of the diamond NV color center will change under the action of UV, and the spectral intensity will also change accordingly, and proposes a method for converting ultraviolet detection into spectral detection in the visible light range and an ultraviolet electric detector capable of realizing wide-spectrum ultraviolet detection.

[0005] The method for detecting wide-spectrum ultraviolet light by using diamond solid-state quantum spin is realized according to the following steps:

[0006] I. Cleaning

[0007] The high-temperature and high-pressure diamond substrate is cleaned to obtain a clean diamond substrate.

[0008] II. Preparation of diamond NV color center solid-state quantum spin

[0009] a, the clean diamond substrate is put into the CVD growth cabin, hydrogen is introduced after vacuumizing, the air pressure in the CVD growth cabin is adjusted to 8-12 mbar, the microwave generator is started, and the plasma is activated;

[0010] b, the air pressure in the CVD growth cabin and the power of the microwave generator are increased, so that the temperature of the clean diamond substrate reaches 700-1000 DEG C;

[0011] c, methane is introduced, and the methane flow is controlled to be 4-32 sccm;

[0012] d, the doped element gas is introduced, the temperature of the diamond substrate is stably controlled at 700-1000 DEG C, CVD epitaxial growth is carried out, after growth, the introduction of methane and doped element gas is stopped, the power of the microwave generator and the air pressure in the CVD growth cabin are gradually reduced, the hydrogen valve is closed, and the air is released to atmospheric pressure, so that the diamond with NV color center is obtained;

[0013] III. Ultraviolet light detection:

[0014] The diamond with NV color center is irradiated and excited by using a laser, the fluorescence intensity signal at the epitaxial region (point) of the diamond is collected by an 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-637nm wave band, so that the method for detecting wide-spectrum ultraviolet light by using diamond solid-state quantum spin is completed;

[0015] In step d, the doped element gas is nitrogen.

[0016] The application of the method for detecting wide-spectrum ultraviolet light by using diamond solid-state quantum spin is that an ultraviolet electric detector is designed, which comprises a diamond with NV color center, an excitation light source and an optical sensor, the laser is used as the excitation light source, the diamond with NV color center is excited by using the laser, under the condition that the NV color center is excited, the fluorescence intensity signal of the diamond with NV color center in the 575nm-635nm wave band range is detected by the optical sensor, and when the fluorescence intensity signal is enhanced relative to the laser irradiation of the diamond with NV color center, it is indicated that the ultraviolet light is detected.

[0017] The present application converts the difficult-to-detect ultraviolet light into the spectrum detection in the visible light range, and the sensitivity of the diamond NV color center to the ultraviolet response can realize the detection of wide-spectrum ultraviolet, the process is simple, and the form is novel.

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

[0019] 1. The application utilizes the characteristics of diamond NV color center charge state sensitive to ultraviolet, monitors the optical sensor under laser excitation with UV and without UV, and indirectly detects ultraviolet by the changes of photoelectric signal response to optical signal in the range of 575nm and its phonon sideband, providing a new idea for ultraviolet detection technology, and realizing wide-spectrum ultraviolet detection.

[0020] 2. The application utilizes diamond solid-state quantum spin to detect wide-spectrum ultraviolet, and the process flow is simple, and the NV color center quantum light source can effectively promote the application research based on diamond color center. At the same time, it provides technical support for key technology engineering fields such as diamond color center-based quantum sensor devices. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The experimental optical path diagram of the method for detecting wide-spectrum ultraviolet light by utilizing diamond solid-state quantum spin in the embodiment;

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

[0023] Figure 3 The photoelectric signal comparison diagram of low-concentration color center sample CH-1 in the embodiment;

[0024] Figure 4 The diamond ultraviolet transmittance test result diagram of different concentration samples in the embodiment. DETAILED DESCRIPTION

[0025] Specific implementation one: the method for detecting wide-spectrum ultraviolet light by utilizing diamond solid-state quantum spin in the embodiment is implemented according to the following steps:

[0026] I. Cleaning:

[0027] The high-temperature and high-pressure diamond substrate is cleaned to obtain a clean diamond substrate;

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

[0029] a. Put the clean diamond substrate into the CVD growth cabin, introduce hydrogen after vacuumizing, adjust the gas pressure in the CVD growth cabin to 8-12 mbar, start the microwave generator, and activate the plasma;

[0030] b. Increase the gas pressure in the CVD growth cabin and the power of the microwave generator, so that the temperature of the clean diamond substrate reaches 700-1000℃;

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

[0032] d. introducing a doping element gas, controlling the temperature of the diamond substrate to be stable at 700-1000℃, performing CVD epitaxial growth, after growth, closing the methane and doping element gas, gradually reducing the power of the microwave generator and the air pressure in the CVD growth cabin, closing the hydrogen valve, and releasing to atmospheric pressure, thereby obtaining a diamond with NV color centers;

[0033] III. Ultraviolet light detection:

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

[0035] In step d, the doping element gas is nitrogen.

[0036] The wavelength range of the ultraviolet light that can be detected by the third step of the embodiment is 225-380nm.

[0037] The embodiment provides a new method for detecting ultraviolet light by utilizing the characteristics of diamond NV color center quantum light source, and promotes the development of ultraviolet detection technology. At the same time, it provides technical support for key technologies such as diamond quantum sensor devices based on color centers in engineering fields, and has important demonstration and leading roles.

[0038] Specific implementation method two: the difference between this embodiment and the first embodiment is that the high-temperature and high-pressure diamond substrate is sequentially placed in acetone, deionized water, and anhydrous ethanol for ultrasonic cleaning in step one.

[0039] Specific implementation method three: the difference between this embodiment and the first or second embodiment is that in step a, the clean diamond substrate is placed in the CVD growth cabin, and hydrogen is introduced after the air pressure in the cabin reaches 3.0x10 -6 ~ 5.0x10 -6 mbar.

[0040] Specific implementation method four: the difference between this embodiment and one of the first to third embodiments is that in step a, the air pressure in the CVD growth cabin is adjusted to 10mbar, and the microwave generator is started to activate the plasma.

[0041] Specific implementation method five: the difference between this embodiment and one of the first to fourth embodiments is that in step c, the flow rate of methane is controlled to be 5-10sccm.

[0042] Specific implementation method six: the difference between this embodiment and the fifth embodiment is that in step d, the flow rate of the doping element gas is controlled to be 0.01sccm-0.1sccm.

[0043] Specific embodiment seven: the difference between this embodiment and one of the specific embodiments one to six is that the CVD growth time in step d is 24-48 hours.

[0044] Specific embodiment eight: the difference between this embodiment and one of the specific embodiments one to seven is that the concentration of NV color centers in the diamond with NV color centers in step d is 400 ppb-20 ppm.

[0045] Specific embodiment nine: the difference between this embodiment and one of the specific embodiments one to eight is that the laser light source in step three is a 532 nm excitation light, and the control energy is 0.05-5 mW.

[0046] The scanning time of the laser light source in this embodiment is 0.2-10 s.

[0047] Example one: the method for detecting wide spectrum ultraviolet light by diamond solid state quantum spin is implemented according to the following steps:

[0048] I. Diamond cleaning:

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

[0050] II. Growth of diamond containing NV color centers:

[0051] a. Place the clean diamond substrate into the CVD growth cabin, close the cabin, and vacuumize the CVD growth cabin to an air pressure of 5.0 x 10 -6 mbar, then introduce hydrogen gas, the hydrogen flow rate is 200 sccm, adjust the air pressure in the CVD growth cabin to 10 mbar, start the microwave generator, and activate the plasma;

[0052] b. Increase the air pressure in the CVD growth cabin and the power of the microwave generator, so that the temperature of the clean diamond substrate reaches 750℃;

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

[0054] d. Introduce nitrogen gas, set the nitrogen flow rate to be 0.01 sccm, at this time the nitrogen concentration is about 1 ppm, adjust the air pressure and power, control the temperature of the diamond substrate to be stable at 830℃, and perform CVD epitaxial growth for 48 hours. After growth, close the methane and nitrogen, gradually reduce the air pressure in the CVD growth cabin to 10 mbar, close the hydrogen valve, and release to atmospheric pressure, thereby obtaining a diamond with NV color centers, the NV concentration is about 400 ppb, and the sample number is CH-2.

[0055] III. Fluorescence spectrum characterization:

[0056] (1) Using 10 times microscope to focus on the diamond surface with NV color center, determine the characterization area;

[0057] (2) Replace 50 times microscope to observe, select diamond normal epitaxial area test point, and focus again;

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

[0059] (4) Using 532nm excitation light as excitation light source, the energy is 3mW, the scanning time is 1s, the filter can pass the optical waveband of 550-700nm, and the photoelectric signal of the diamond normal epitaxial area point is measured by optical sensor without loading UV;

[0060] (5) Turn on the UV light source, use the same test parameters as step (4), measure the photoelectric signal of the same point as step (4) under the loading of UV and laser at the same time, and the experimental light path is shown in Figure 1 ;

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

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

[0063] The test results of photoelectric signal in this example are shown in Figure 2 .

[0064] This example focuses on the fluorescence intensity signal in the range of 575-635nm, and through comparison, it can be found that under the loading of UV and laser, the NV 0The signal intensity in the ZPL (zero phonon line) of CH-2, 575 nm, and the phonon sideband, 575-635 nm, increased. Comparing the photoelectric signal of halogen lamp and laser loading, it can be found that there is little difference between the results of single laser loading, indicating that low-intensity visible light source cannot produce the same effect as UV, indicating that diamond color centers are not sensitive to low-intensity visible light. The photoelectric signal obtained by only UV loading can be obtained from the UV emitted by DH-2000, which is not enough to excite the NV color center to produce 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 by single loading. In summary, the photoelectric signal of diamond in the 575-635 nm band is monitored by using an optical sensor, and if the signal intensity in this range increases, it indicates that ultraviolet light is detected.

[0065] IV. Ultraviolet transmittance test of diamond

[0066] The transmittance of diamond at different wavelengths was tested, and the transmittance as a function of wavelength was obtained by comparing the incident light intensity and the exit light intensity, as shown in Figure 4 , the CH-2 sample responds to 200-400 nm ultraviolet light.

[0067] Example Two: The difference between this example and Example One is:

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

[0069] (2) In the ultraviolet light detection, only the laser alone loading and the UV and laser simultaneous loading tests were performed, and there was no halogen lamp, UV alone loading control test;

[0070] (3) The comparison chart of the photoelectric signal is shown in Figure 3 , only the signal in the range of 575-635 nm is concerned, and by comparison, it can be found that the low-concentration NV diamond sample cannot achieve good ultraviolet detection in this spectral range. Combined with the ultraviolet transmittance of different NV concentration diamonds in Figure 4 , CH-1 has low ultraviolet absorption rate in 220-400 nm, and the NV color center charge state changes little, which is reflected in the photoelectric signal that the intensity does not change significantly.

[0071] Example Three: The difference between this example and Example One is:

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

[0073] The photoelectric signal contrast diagram obtained by the embodiment is the same as Figure 2 The result is the same. It can be known from Figure 4 that the ultraviolet transmittances of CH-3 and CH-2 are different in the waveband after 220 nm. Since the output power of the ultraviolet light source in the embodiment is small, the influence on the sample does not reach saturation, and therefore the results of CH-3 and CH-2 on the photoelectric signal contrast diagram Figure 2 ) are consistent.

Claims

1. A method for probing broad spectrum ultraviolet light using diamond solid state quantum spins, characterized in that The method for detecting wide-spectrum ultraviolet light by using diamond solid-state quantum spin is realized according to the following steps: I. Cleaning: The high-temperature and high-pressure diamond substrate is cleaned to obtain a clean diamond substrate; II. Preparation of diamond NV color center solid-state quantum spin: a. The clean diamond substrate is placed in a CVD growth chamber, vacuum is drawn, and then hydrogen is introduced. The gas pressure in the CVD growth chamber is adjusted to 8-12 mbar. The microwave generator is started to activate the plasma; b. The gas pressure in the CVD growth chamber and the power of the microwave generator are increased, so that the temperature of the clean diamond substrate reaches 700-1000 DEG C; c. Methane is introduced, and the methane flow is controlled to be 4-32 sccm; d. Doping element gas is introduced, and the temperature of the diamond substrate is controlled to be stable at 700-1000 DEG C. CVD epitaxial growth is carried out. After growth, the introduction of methane and doping element gas is stopped. The power of the microwave generator and the gas pressure in the CVD growth chamber are gradually reduced. The hydrogen valve is closed, and the gas is released to atmospheric pressure, so that the diamond with an epitaxial region with NV color centers is obtained; III. Ultraviolet light detection: The diamond with NV color centers is irradiated and excited by using a laser. The fluorescence intensity signal of the diamond epitaxial region is collected by an optical sensor. When the diamond with NV color centers is irradiated by ultraviolet light, the fluorescence intensity signal produces an enhanced response in the 575-637 nm waveband, thereby completing the method for detecting wide-spectrum ultraviolet light by using diamond solid-state quantum spin. In step d, the doping element gas is nitrogen. 2.The method of claim 1, wherein In step I, the high-temperature and high-pressure diamond substrate is sequentially placed in acetone, deionized water, and anhydrous ethanol for ultrasonic cleaning. 3.The method of claim 1, wherein The clean diamond substrate is put into the CVD growth chamber in step a, vacuum is drawn to make the pressure in the chamber reach 3.0 x 10 -6 ~5.0 x 10 -6 mbar, and then hydrogen is introduced. 4.The method of claim 1, wherein 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 of probing broad spectrum ultraviolet light with diamond solid state quantum spins according to claim 1, wherein In step c, the methane flow is controlled to be 5-10 sccm.

6. The method of probing broad spectrum ultraviolet light with diamond solid state quantum spins according to claim 5, wherein In step d, the flow of the doping element gas is controlled to be 0.01-0.1 sccm.

7. The method of probing broad spectrum ultraviolet light with diamond solid state quantum spins of claim 1, wherein In step d, the CVD growth time is 24-48 hours. 8.The method of claim 1, wherein In step d, the concentration of NV color centers in the diamond with NV color centers is 400 ppb-20 ppm. 9.The method of claim 1, wherein In step III, the laser light source is a 532 nm excitation light, and the energy is controlled to be 0.05-5 mW.

10. An ultraviolet electric detector using the method of detecting wide spectrum ultraviolet light by using diamond solid state quantum spin as claimed in claim 1, characterized in that The ultraviolet electric detector includes a diamond with NV color centers, an excitation light source, and an optical sensor. The laser is used as the excitation light source. The diamond with NV color centers is excited by using the laser. Under the excitation condition of the NV color centers, the fluorescence intensity signal of the diamond with NV color centers in the 575-635 nm waveband range is detected by the optical sensor. The fluorescence intensity signal is enhanced relative to the laser irradiation of the diamond with NV color centers, which indicates that the ultraviolet light is detected.

Images