Diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence and outdoor ultraviolet signal detection system thereof

Abstract

The invention discloses a diamond ultraviolet flame detector capable of detecting hydroxyl free radical luminescence and an outdoor ultraviolet signal detection system thereof, and aims to solve the problem of low detection efficiency of an OH * group ultraviolet luminescence signal. The plane symmetry type diamond ultraviolet flame detector comprises a diamond layer, a TiO2 film layer, a first contact electrode and a second contact electrode, the diamond layer is intrinsic diamond, nitrogen-doped diamond or boron-doped diamond, the TiO2 film layer is deposited on the diamond layer, and the first contact electrode and the second contact electrode are deposited on the two sides of the upper surface of the TiO2 film layer respectively. The invention also relates to a Schottky junction type diamond ultraviolet flame detector. The diamond ultraviolet flame detector capable of detecting hydroxyl free radical luminescence can generate hyperspectral selective response light current to weak OH * ultraviolet luminescence, and is insensitive to visible light and infrared light with extremely high luminous intensity in flame and sunlight background.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor electronic devices, and in particular relates to a diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence and an outdoor ultraviolet signal detection system thereof. Background Art

[0002] The study of hydrocarbon fuel combustion is of great significance in a wide range of fields, including energy, environment, chemistry, materials, aerospace, safety engineering, and renewable energy. The luminescence of hydrocarbon fuel flame combustion includes broadband radiation from carbon particles and free radical chemical light with unique spectral characteristics. Common free radical luminescence includes OH*, with a luminescence center at 309 nm, CH* at 430 nm, and C2* at 516 nm. OH* is one of the most important intermediate products in hydrocarbon fuel combustion; its presence indicates the ongoing combustion process. For aircraft design, unstable engine exhaust flames also generate significant amounts of OH*. Due to the absence of background noise, ultraviolet luminescence spectroscopy can provide more extensive and richer operating condition information than infrared spectroscopy. Therefore, detecting OH* free radical ultraviolet luminescence is crucial for accurately monitoring the combustion of hydrocarbon fuels, facilitating combustion condition analysis and inverse optimization design for aircraft engines.

[0003] Current UV detection equipment is often based on bulky photomultiplier tubes or CMOS UV cameras. The former requires complex filtering and modulation systems, is expensive, and is prone to breakage. The latter requires narrowband filters with very limited transmittance. Due to the low quantum efficiency of the UV emission band of OH* radicals, they also require an enhanced conversion device to convert the UV band into the visible band, where the camera is more sensitive, further increasing the complexity and cost of the equipment. The UV emission signal of OH* radicals is very weak and easily drowned out by the strong visible and infrared background light in flames. Therefore, wide-bandgap semiconductors with spectral selectivity for OH* radical UV emission are required for detection. Diamond has an effective response band in the solar-blind UV region and is immune to long-wavelength noise signals, eliminating the need for bulky filtering equipment. Its excellent combination of high carrier mobility, thermal conductivity, mechanical strength, chemical inertness, and radiation resistance make it a top choice for solar-blind UV detection. However, diamond is only sensitive to solar-blind UV signals between 200 and 280 nm, with a low response to OH* emission at 309 nm. TiO2, on the other hand, has an optical band gap of 3 eV and an optical absorption edge at 375 nm, resulting in a high response to ultraviolet light around 300 nm. However, it lacks the excellent properties of diamond semiconductors. Combining diamond and TiO2 into a type II heterojunction can leverage the built-in electric field of the heterojunction to accelerate the separation of photogenerated carriers, increasing detection efficiency while simultaneously combining the excellent properties of both semiconductors. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of low detection efficiency of ultraviolet luminescence signals of OH* groups and the lack of corresponding semiconductor detection devices, and to provide a diamond ultraviolet flame detector that can detect hydroxyl radical luminescence and its outdoor ultraviolet signal detection system.

[0005] The diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence is divided into a self-powered Schottky junction type and a planar symmetrical type requiring an external power supply according to the electrode structure.

[0006] The Schottky junction diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence comprises a heavily boron-doped diamond layer, a first contact electrode, an epitaxial diamond layer, a terminal, a TiO2 film and a second contact electrode. The boron doping concentration in the heavily boron-doped diamond layer is greater than 10 17 cm -3 A contact electrode No. 1 is deposited on the lower surface of the heavily boron-doped diamond layer. The contact electrode No. 1 forms an ohmic contact with the heavily boron-doped diamond layer. An epitaxial diamond layer is epitaxially grown on the upper surface of the heavily boron-doped diamond layer. The boron doping concentration in the epitaxial diamond layer is less than 10 16 cm -3 The epitaxial diamond layer has a terminal, a TiO2 film is deposited on the upper surface of the epitaxial diamond layer, a second contact electrode is deposited on the TiO2 film, and the TiO2 film forms a Schottky contact with the second contact electrode.

[0007] The present invention provides a planar symmetrical diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence, comprising a diamond layer, a TiO2 film layer, a first contact electrode, and a second contact electrode. The diamond layer is intrinsic diamond, nitrogen-doped diamond, or boron-doped diamond. A TiO2 film layer with a thickness of 10 to 1000 nm is deposited on the diamond layer. The first contact electrode and the second contact electrode are respectively deposited on both sides of the upper surface of the TiO2 film layer. The first contact electrode and the second contact electrode simultaneously form Schottky contacts or ohmic contacts on the upper surface of the TiO2 film layer.

[0008] The outdoor ultraviolet signal detection system constructed based on the diamond ultraviolet flame detector that can detect the luminescence of hydroxyl free radicals in the present invention includes an ultraviolet optical system, a Schottky junction diamond ultraviolet flame detector and a signal acquisition module. The ultraviolet light signal collected by the ultraviolet optical system is focused on the Schottky junction diamond ultraviolet flame detector. The first contact electrode in the Schottky junction diamond ultraviolet flame detector is grounded, and the current signal of the second contact electrode (signal output end) is collected by the signal acquisition module.

[0009] The outdoor ultraviolet signal detection system constructed based on the diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence includes an ultraviolet optical system, a plane-symmetrical diamond ultraviolet flame detector, a signal acquisition module, and a direct current power supply. The ultraviolet light signal collected by the ultraviolet optical system is focused on the plane-symmetrical diamond ultraviolet flame detector. The positive electrode of the direct current power supply is connected to the first contact electrode of the plane-symmetrical diamond ultraviolet flame detector (positive and negative poles are not distinguished). The current signal of the second contact electrode is collected by the signal acquisition module. The signal acquisition module is connected to the negative pole of the direct current power supply and is grounded.

[0010] The present invention provides two types of diamond ultraviolet flame detectors, Schottky junction type and planar symmetric type, capable of detecting hydroxyl radical luminescence, and their outdoor ultraviolet signal detection systems. The diamond ultraviolet flame detector comprises a diamond layer, a TiO2 thin film, a low-resistance ohmic contact electrode, and a Schottky contact electrode. The diamond layer can be an intrinsic diamond layer or boron-doped diamond, and its semiconductor physical properties enable efficient detection of solar-blind ultraviolet light. The TiO2 thin film exhibits good spectral selectivity for OH* luminescence at 309 nm, with both the bottom and top of the conduction band lower than those of oxygen-terminated diamond, allowing it to form a type II heterojunction with diamond. The Schottky contact is fabricated on the surface of the TiO2 thin film, and its built-in electric field, combined with the heterojunction electric field, accelerates the separation of photogenerated carriers. The ohmic contact has extremely low contact resistance and potential barrier, resulting in a low load voltage divider within the circuit loop. The signal acquisition module embedded in the signal output module can be implemented using a single-chip microcomputer, etc., and provides digital-to-analog conversion and wireless transmission of photocurrent signals.

[0011] The ohmic contact electrode metal described in the present invention needs to meet the following conditions: the electrode material is not limited to one or more transition metals such as Ti / Cr / W / Pt. As long as it can produce low-resistance contact with the diamond or TiO2 surface after a simple surface high-temperature metallization treatment, it can be prepared using the structure provided by the present invention.

[0012] The diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence and its outdoor ultraviolet signal detection system according to the present invention can generate a highly spectrally selective response photocurrent to the weak OH* ultraviolet luminescence when detecting hydrocarbon fuel flame luminescence, while being insensitive to the extremely high intensity visible and infrared light in the flame and background sunlight. The outdoor ultraviolet signal detection system can respond promptly to rapid changes in the flame ultraviolet signal, can achieve anti-interference collection and real-time wireless transmission of the OH* ultraviolet signal, and has excellent stability and robustness. Compared with existing detection technologies, it has the advantages of no need for filters, no need for auxiliary heat dissipation, and small-volume payload assembly, and can provide solutions for different types of application scenarios such as aircraft tail flame detection and forest fire flame sensing in different environments such as on the ground and in space. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the structure of a Schottky junction diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence according to the present invention; wherein 1-1 is a heavily boron-doped diamond layer, 1-2 is a first contact electrode, 1-3 is an epitaxial diamond layer, 1-4 is an (oxygen) terminal, 1-5 is a TiO2 film, and 1-6 is a second contact electrode;

[0014] Figure 2 This is a schematic diagram of the structure of a planar symmetrical diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence according to the present invention; wherein 2-1 is a diamond layer, 2-2 is a TiO2 film layer, 2-3 is a first contact electrode, and 2-4 is a second contact electrode;

[0015] Figure 3 This is an IV curve diagram of the measured photoelectric response test of the diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence in Example 2;

[0016] Figure 4 This is a graph showing the relationship between the responsivity and incident light wavelength of the diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence in Example 2;

[0017] Figure 5 is the measured pulse time response of the diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence in the embodiment;

[0018] Figure 6 Schematic diagram of the structure of an outdoor ultraviolet signal detection system based on a Schottky junction diamond ultraviolet flame detector in an embodiment;

[0019] Figure 7 Schematic diagram of the structure of an outdoor ultraviolet signal detection system based on a plane-symmetrical diamond ultraviolet flame detector in an embodiment;

[0020] Figure 8 This is a test diagram of flame pulse real-time electrical signals collected during the day by an outdoor ultraviolet signal detection system based on a diamond ultraviolet flame detector in an embodiment;

[0021] Figure 9 3 is a graph showing real-time electrical signal data of flame pulses collected at night by an outdoor ultraviolet signal detection system based on a diamond ultraviolet flame detector in an embodiment. DETAILED DESCRIPTION

[0022] Specific embodiment 1: The self-powered Schottky junction diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence in this embodiment comprises a heavily boron-doped diamond layer 1-1, a first contact electrode 1-2, an epitaxial diamond layer 1-3, a terminal 1-4, a TiO2 film 1-5 and a second contact electrode 1-6, wherein the boron doping concentration in the heavily boron-doped diamond layer 1-1 is greater than 1017 cm -3 A contact electrode 1-2 is deposited on the lower surface of the heavily boron-doped diamond layer 1-1. The contact electrode 1-2 forms an ohmic contact with the heavily boron-doped diamond layer 1-1. An epitaxial diamond layer 1-3 is epitaxially grown on the upper surface of the heavily boron-doped diamond layer 1-1. The boron doping concentration in the epitaxial diamond layer 1-3 is less than 10 16 cm -3 The epitaxial diamond layer 1-3 has a terminal 1-4, a TiO2 film 1-5 is deposited on the upper surface of the epitaxial diamond layer 1-3, and a second contact electrode 1-6 is deposited on the TiO2 film 1-5. The TiO2 film 1-5 forms a Schottky contact with the second contact electrode 1-6.

[0023] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that the boron doping concentration in the epitaxial diamond layer 1-3 is 10 12 ~10 15 cm -3 .

[0024] Specific embodiment three: This embodiment differs from specific embodiment one or two in that a TiO2 film 1-5 is deposited on the upper surface of the epitaxial diamond layer 1-3 with surface terminations by using a magnetron sputtering process, an electron beam deposition process or a hydrothermal method.

[0025] Specific embodiment 4: This embodiment differs from any one of specific embodiments 1 to 3 in that the terminals 1 - 4 on the epitaxial diamond layer 1 - 3 are oxygen terminals, nitrogen terminals or fluorine terminals.

[0026] In this embodiment, the surface termination can be prepared by placing the diamond substrate in a hydrogen / nitrogen / fluorine / oxygen plasma environment for surface treatment.

[0027] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the thickness of the epitaxial diamond layer 1 - 3 is 0.05-20 μm.

[0028] Specific embodiment six: In this embodiment, a planar symmetrical diamond ultraviolet flame detector that can detect the luminescence of hydroxyl radicals includes a diamond layer 2-1, a TiO2 film layer 2-2, a first contact electrode 2-3 and a second contact electrode 2-4. The diamond layer 2-1 is intrinsic diamond, nitrogen-doped diamond or boron-doped diamond. A TiO2 film layer 2-2 with a thickness of 10 to 1000 nm is deposited on the diamond layer 2-1. The first contact electrode 2-3 and the second contact electrode 2-4 are respectively deposited on both sides of the upper surface of the TiO2 film layer 2-2. The first contact electrode 2-3 and the second contact electrode 2-4 simultaneously form Schottky contacts or ohmic contacts on the upper surface of the TiO2 film layer 2-2.

[0029] This embodiment provides two diamond flame detector structures with spectral selectivity for OH* luminescence and their associated outdoor UV signal detection systems. Depending on the contact electrodes, they can be divided into planar symmetric and Schottky junction types. The Schottky junction's built-in electric field can spontaneously separate and collect photogenerated carriers, enabling self-powered detection without the need for an external power source. Through band-engineered optical coatings, a TiO2 optical film is deposited on the diamond surface to broaden the diamond's response band. This provides excellent spectral selectivity for 309 nm OH* luminescence and is insensitive to the extremely high-intensity visible and infrared light in flames. Due to differences in band structures, diamond and TiO2 can form a type II heterojunction with a high built-in electric field, effectively separating photogenerated carriers and achieving ultra-high response speed. The resulting outdoor UV signal detection system can rapidly and effectively collect and transmit OH* signals from aircraft tail flames in sunlight, with excellent stability and robustness.

[0030] Specific embodiment seven: This embodiment is different from specific embodiment six in that the thickness of the TiO2 film layer 2-2 is 20-100 nm.

[0031] Specific embodiment eight: This embodiment differs from specific embodiment six or seven in that the first contact electrode 2 - 3 and the second contact electrode 2 - 4 are made of a laminated metal electrode formed of one or more of Ti, Au, Ag and Pt.

[0032] In this embodiment, a low-resistance ohmic contact or a barrier Schottky contact is formed between the first contact electrode and the second contact electrode and the TiO 2 film.

[0033] Specific embodiment 9: This embodiment is different from any one of specific embodiments 6 to 8 in that the thickness of the first contact electrode 2 - 3 and the second contact electrode 2 - 4 is 10-1000 nm.

[0034] Specific embodiment ten: In this embodiment, the outdoor ultraviolet signal detection system constructed based on the diamond ultraviolet flame detector that can detect the luminescence of hydroxyl radicals includes an ultraviolet optical system 3-1, a Schottky junction diamond ultraviolet flame detector 3-2 and a signal acquisition module 3-3. The ultraviolet light signal collected by the ultraviolet optical system 3-1 is focused on the Schottky junction diamond ultraviolet flame detector 3-2, the No. 1 contact electrode 1-2 in the Schottky junction diamond ultraviolet flame detector 3-2 is grounded, and the current signal (signal output end) of the No. 2 contact electrode 1-6 is collected by the signal acquisition module 3-3.

[0035] The signal acquisition module 3 - 3 of the present invention further includes a signal transmission module 3 - 4 , which can transmit the current signal acquired by the signal acquisition module 3 - 3 to the client 3 - 5 via Bluetooth or WiFi.

[0036] Specific embodiment eleven: In this embodiment, the outdoor ultraviolet signal detection system constructed based on the diamond ultraviolet flame detector that can detect the luminescence of hydroxyl radicals includes an ultraviolet optical system 3-1, a plane-symmetrical diamond ultraviolet flame detector 4-2, a signal acquisition module 3-3 and a DC power supply 3-6; the ultraviolet light signal collected by the ultraviolet optical system 3-1 is focused on the plane-symmetrical diamond ultraviolet flame detector 4-2, the positive pole of the DC power supply 3-6 is connected to the first contact electrode 2-3 of the plane-symmetrical diamond ultraviolet flame detector 4-2 (without distinguishing between positive and negative poles), and the current signal of the second contact electrode 2-4 is collected by the signal acquisition module 3-3, and the signal acquisition module 3-3 is connected to the negative pole of the DC power supply 3-6 and grounded.

[0037] Example 1: The preparation method of the self-powered Schottky junction diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence in this embodiment is implemented by the following steps:

[0038] 1. The boron content is 10 20 cm -3 The heavily boron-doped diamond single crystal is placed in aqua regia and boiled to remove surface impurities such as metal and graphite, and then ultrasonically cleaned with deionized water, alcohol, and acetone in sequence, and dried to obtain a pretreated heavily boron-doped diamond layer 2-1;

[0039] 2. Placing the pre-treated heavily boron-doped diamond layer 1-1 in a magnetron sputtering device, and depositing a Ti / Pt composite electrode on the lower surface of the heavily boron-doped diamond layer 1-1 as the first contact electrode 1-2;

[0040] 3. Place the heavily boron-doped diamond layer with the first contact electrode in a microwave plasma-assisted chemical vapor deposition (MPCVD) device, and epitaxially grow a shallow boron-doped diamond layer 1-3 on the upper surface of the heavily boron-doped diamond layer 1-1. The boron doping concentration of the epitaxial diamond layer 1-3 is less than 10 16 cm -3 The thickness of the epitaxial diamond layer is 3 μm. The high temperature of the epitaxial growth causes the first contact electrode 1-2 to undergo a metallization reaction with the heavily boron-doped diamond layer 1-1, forming a low-resistance ohmic contact.

[0041] Fourth, the heavily boron-doped diamond layer 1-1 with the epitaxial diamond layer was placed in a plasma cleaning machine, and an oxygen plasma was generated using a power of 80 W to clean the sample for 5 minutes for oxygen termination treatment;

[0042] 5. Depositing a TiO2 film 1-5 with a thickness of 18 nm on the surface of the heavily boron-doped diamond layer 1-1 with oxygen terminations using a magnetron sputtering method to obtain a heavily boron-doped diamond with a TiO2 film layer deposited thereon;

[0043] 6. Then, a 10 nm Pt layer is deposited on the surface of the heavily boron-doped diamond TiO2 film 1-5 by magnetron sputtering as the second contact electrode 1-6. The second contact electrode 1-6 forms a Schottky contact with the TiO2 film 2-5, thereby obtaining a Schottky junction diamond ultraviolet flame detector.

[0044] 6. Encapsulate the Schottky junction diamond UV flame detector 3-2 on a PCB and use gold wire to bond the two ends of the printed circuit board reserved on the PCB to the two electrodes of the detector. For a Schottky junction detector with self-powered detection, the bonding pin of contact electrode 1-6 is grounded, and the bonding pin of contact electrode 1-2 serves as the signal output terminal connected to the signal acquisition module 3-3. The signal acquisition module 3-3 has an embedded signal output module 3-4, which can transmit the collected signal to the user terminal 3-5 via Bluetooth or WiFi. The PCB encapsulating the diamond flame detector is assembled with the UV optical system 3-1 made of a highly UV-transmitting material such as quartz or sapphire, and the optical paths are aligned to form an outdoor UV signal detection system based on a self-powered Schottky junction diamond UV flame detector.

[0045] The Schottky junction diamond ultraviolet flame detector of the present invention, which can detect the luminescence of hydroxyl radicals, and its outdoor ultraviolet signal detection system can spontaneously achieve carrier separation and current output with the help of the photovoltaic effect of the Schottky built-in electric field. It has an excellent self-powered detection effect, that is, it can realize photoelectric sensing of flame signals without the need for an external power supply. It is suitable for the establishment of ultra-low power consumption sensor networks in long-term monitoring scenarios such as forest fires.

[0046] Example 2: The preparation method of the planar symmetrical diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence in this embodiment is implemented by the following steps:

[0047] 1. The boron content is 10 18 cm -3 The lightly boron-doped diamond is placed in aqua regia and boiled to remove surface impurities such as metal and graphite, and then ultrasonically cleaned with deionized water, alcohol, and acetone in sequence, and dried to obtain a pretreated diamond layer 2-1;

[0048] Second, the pretreated diamond layer was placed in a mixed oxidizing strong acid solution of 98% H2SO4 and 68% HNO3 at a volume ratio of 3:1 and boiled at 350°C for 2 hours to obtain a diamond layer with oxygen terminations.

[0049] 3. Using magnetron sputtering, a TiO2 film layer 2-2 with a thickness of 18 nm is deposited on the surface of the diamond layer with oxygen terminations to obtain a diamond with a TiO2 film layer deposited thereon;

[0050] Fourth, a first contact electrode 2-3 and a second contact electrode 2-4 are deposited on the left and right sides of the diamond surface deposited with the TiO2 film, respectively. The first contact electrode 2-3 and the second contact electrode 2-4 are symmetrical Ti / Pt composite electrodes, with a Ti layer thickness of 30 nm and a Pt layer thickness of 70 nm. The first contact electrode 2-3 and the second contact electrode 2-4 form Schottky contacts with the TiO2 film 2-2, thereby obtaining a planar symmetrical diamond ultraviolet flame detector;

[0051] 5. Encapsulate the plane-symmetrical diamond ultraviolet flame detector 4-2 on a PCB board, and use gold wire to bond the two ends of the printed circuit reserved on the PCB board to the first contact electrode 2-3 and the second contact electrode 2-4 of the diamond ultraviolet flame detector. For the plane-symmetrical diamond flame detector, the two electrodes do not distinguish between positive and negative poles; one side of the pin on the PCB board is connected to the signal acquisition module 3-3 as the signal output end, and the signal acquisition module 3-3 is connected to the negative pole of the DC power supply 3-6 and grounded, and the other side is connected to the positive pole of the DC power supply 3-6 as the electrical input end and inputs a 50 V bias voltage; the signal acquisition module 3-3 has an embedded signal output module 3-4, and can send the collected signal to the user end 3-5 via Bluetooth or WiFi; assemble the PCB board 3-2 encapsulating the diamond flame detector with the ultraviolet optical system 3-1 made of high ultraviolet transmittance materials such as quartz or sapphire, and align the optical path to form an outdoor ultraviolet signal detection system based on the plane-symmetrical diamond ultraviolet flame detector.

[0052] The plane symmetrical diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence and its outdoor ultraviolet signal detection system have been tested. The IV characteristics and pulse time response under different monochromatic light irradiation are shown in the attached figure. Figures 3-5 As shown. Starting from 200 nm, as the wavelength of the incident light increases, the relative magnitude of the photocurrent continues to increase and reaches a peak at 309 nm, at which point the light-to-dark current ratio is approximately one order of magnitude. As the incident wavelength continues to increase, the photocurrent intensity rapidly decays to a level close to the dark current level, indicating that the diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence of the present invention has a high spectral selectivity for the ultraviolet luminescence of hydroxyl radicals at 309 nm, and is insensitive to visible light and infrared light. The response curve of the diamond ultraviolet flame detector of the present invention as a function of incident wavelength is shown in the attached figure. Figure 4 As shown in the figure, compared with the absorption cutoff edge of diamond at 225 nm, the detector of the present invention has a significant response peak at 300 nm, indicating that under the action of the TiO2 film, the response band of diamond has been substantially broadened. The transient response of the device was tested using a pulsed laser, and the t rise is 9.6 ns, t decayThe ultra-fast response speed of 9.4 ns ensures the accurate detection of the rapidly changing aircraft tail flame.

[0053] After outdoor field tests, the current signals collected by the planar symmetrical diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence and its outdoor ultraviolet signal detection system during two aircraft tester ignition tests at daytime and nighttime are shown in the attached figure. Figure 8 With attached Figure 9 As shown in the figure, a net photocurrent signal amplitude of 7.3 pA was collected during the daytime test, while a net photocurrent signal amplitude of approximately 18 pA was collected at night. Both pulse signals collected showed no photocurrent signal tailing caused by the persistent photoconductivity effect, and the dark current noise signals collected twice differed by only 0.6 pA, indicating that the diamond flame detector of the present invention has excellent day-blind characteristics. In addition to the uniformly increased fluorescence background within the flame spectrum less than 320 nm, only the 309 nm characteristic peak of hydroxyl radicals appears. Furthermore, the diamond ultraviolet flame detector of the present invention is insensitive to visible and infrared light, indicating that the diamond ultraviolet flame detector of the present invention can rapidly respond to transient changes in the ultraviolet signal of hydroxyl radicals in the aircraft tail flame.

Claims

1. A Schottky junction diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence, characterized in that The Schottky junction diamond ultraviolet flame detector comprises a heavily boron-doped diamond layer (1-1), a first contact electrode (1-2), an epitaxial diamond layer (1-3), a terminal (1-4), a TiO2 film (1-5) and a second contact electrode (1-6), wherein the boron doping concentration in the heavily boron-doped diamond layer (1-1) is greater than 10 17 cm -3 A contact electrode (1-2) is deposited on the lower surface of the heavily boron-doped diamond layer (1-1), the contact electrode (1-2) forms an ohmic contact with the heavily boron-doped diamond layer (1-1), and an epitaxial diamond layer (1-3) is epitaxially grown on the upper surface of the heavily boron-doped diamond layer (1-1), wherein the boron doping concentration in the epitaxial diamond layer (1-3) is less than 10 16 cm -3 The epitaxial diamond layer (1-3) has a terminal (1-4), a TiO2 film (1-5) is deposited on the upper surface of the epitaxial diamond layer (1-3), a second contact electrode (1-6) is deposited on the TiO2 film (1-5), and the TiO2 film (1-5) forms a Schottky contact with the second contact electrode (1-6).

2. The Schottky junction diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence according to claim 1, characterized in that The boron doping concentration in the epitaxial diamond layer (1-3) is 10 12 ~10 15 cm -3 .

3. The Schottky junction diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence according to claim 1, characterized in that A TiO2 film (1-5) is deposited on the upper surface of an epitaxial diamond layer (1-3) with surface terminations by using a magnetron sputtering process, an electron beam deposition process or a hydrothermal method.

4. The Schottky junction diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence according to claim 1, characterized in that The terminations (1-4) on the epitaxial diamond layer (1-3) are oxygen terminations, nitrogen terminations or fluorine terminations.

5. The Schottky junction diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence according to claim 1, characterized in that The thickness of the epitaxial diamond layer (1-3) is 0.05~20 μm.

6. A planar symmetrical diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence, characterized in that A planar symmetrical diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence comprises a diamond layer (2-1), a TiO2 film layer (2-2), a first contact electrode (2-3) and a second contact electrode (2-4). The diamond layer (2-1) is intrinsic diamond, nitrogen-doped diamond or boron-doped diamond. A TiO2 film layer (2-2) with a thickness of 10 to 1000 nm is deposited on the diamond layer (2-1). The first contact electrode (2-3) and the second contact electrode (2-4) are respectively deposited on both sides of the upper surface of the TiO2 film layer (2-2). The first contact electrode (2-3) and the second contact electrode (2-4) simultaneously form Schottky contacts or ohmic contacts on the upper surface of the TiO2 film layer (2-2).

7. The planar symmetrical diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence according to claim 6, characterized in that The thickness of the TiO2 film layer (2-2) is 20~100 nm.

8. The planar symmetrical diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence according to claim 6, characterized in that The first contact electrode (2-3) and the second contact electrode (2-4) are made of a laminated metal electrode formed of one or more of Ti, Au, Ag and Pt.

9. Application of the Schottky junction diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence according to claim 1, characterized in that The outdoor ultraviolet signal detection system comprises an ultraviolet optical system (3-1), a Schottky junction diamond ultraviolet flame detector (3-2) and a signal acquisition module (3-3). The ultraviolet light signal collected by the ultraviolet optical system (3-1) is focused on the Schottky junction diamond ultraviolet flame detector (3-2). The first contact electrode (1-2) in the Schottky junction diamond ultraviolet flame detector (3-2) is grounded, and the current signal of the second contact electrode (1-6) is collected by the signal acquisition module (3-3).

10. Application of the planar symmetrical diamond ultraviolet flame detector capable of detecting hydroxyl radical luminescence according to claim 6, characterized in that The outdoor ultraviolet signal detection system comprises an ultraviolet optical system (3-1), a plane-symmetrical diamond ultraviolet flame detector (4-2), a signal acquisition module (3-3) and a direct current power supply (3-6); the ultraviolet light signal collected by the ultraviolet optical system (3-1) is focused on the plane-symmetrical diamond ultraviolet flame detector (4-2); the positive electrode of the direct current power supply (3-6) is connected to the first contact electrode (2-3) of the plane-symmetrical diamond ultraviolet flame detector (4-2); the current signal of the second contact electrode (2-4) is collected by the signal acquisition module (3-3); and the signal acquisition module (3-3) is connected to the negative electrode of the direct current power supply (3-6) and is grounded.

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