Solar blind ultraviolet band electron fluorescence excitation high-sensitivity detector and application thereof

Abstract

The application discloses a high-sensitivity detector for day-blind ultraviolet band electronic fluorescence excitation, which comprises a vacuum chamber, a nano-tip combination, a micro-channel plate, an aluminized fluorescent screen, a fiber-optic light cone and a photosensitive element assembly. ‑ 6 mBar~9*10 ‑6 mBar, wherein the ultraviolet incident window, the nano-tip combination, the micro-channel plate, the aluminized fluorescent screen and the visible light output window are sequentially arranged; the nano-tip combination comprises a substrate and a nano-tip array, and the nano-tip array comprises a plurality of nano-tip structures arranged in an array; the tip of each nano-tip structure points to the micro-channel plate; the fiber-optic light cone is arranged between the aluminized fluorescent screen and the photosensitive element assembly, one end of the fiber-optic light cone is connected with the aluminized fluorescent screen, and the other end is connected with a photosensitive element mounting plate. The application can form multiplied electrons. The accelerated electrons excite the aluminized fluorescent screen to generate strong visible light, thereby realizing high-sensitivity detection of ultraviolet band conversion.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of ultraviolet detectors, and more particularly relates to a high-sensitivity solar-blind ultraviolet band electron fluorescence excitation detector and application thereof. BACKGROUND

[0002] Due to the characteristics of almost no interference from various electromagnetic waves, high bit resolution, low eavesdropping rate, etc., ultraviolet detection is widely used in military fields such as missile early warning and ultraviolet encrypted communication, and meets civilian and industrial needs such as fire monitoring, biochemical detection, and welding arc detection. Based on different needs and material properties and environments, corresponding detection structures and material systems have been developed. Currently, commonly used commercial ultraviolet detectors are mainly based on silicon-based photodiodes or vacuum photomultiplier tubes.

[0003] The former is limited by the characteristics of narrow-bandgap silicon-based materials, and the response band is not limited, which can easily introduce interference signals of other bands. The latter has fast response speed, but the device size is large. In addition, a series of new wide-bandgap semiconductor material type ultraviolet detectors have been developed, mainly including photoconductive type, metal-semiconductor-metal (MSM) type, Schottky junction type device, homojunction PN junction, and heterojunction type device. This detection mode based on only photoelectric signal generation has developed rapidly in recent years and has shown technical characteristics and cost advantages covering the ultraviolet spectral domain. However, there are still obvious defects, which are manifested in the following aspects: (1) the photoelectric sensitivity is more than one order of magnitude lower than that of photonic devices; (2) the dark current is large due to serious leakage current, and the signal-to-noise ratio is limited; (3) it has large thermal inertia and low speed due to slow photoelectric response; (4) the device has poor working stability, short service life, and limited manufacturing area. The above defects have become a difficult and bottleneck problem for the development of photosensitive imaging technology, and urgent new breakthroughs are needed. SUMMARY

[0004] In view of the above defects or improvement needs of the prior art, the present application provides a high-sensitivity solar-blind ultraviolet band electron fluorescence excitation detector and application thereof, which resonantly focuses ultraviolet weak signals through a nanotip array, compresses high-density surface "wandering state" electrons at the nanotip end, induces electron multiplication and acceleration through a microchannel plate type electron multiplier, and then emits a high-sensitivity detector that uses tip electrons to excite fluorescence to perform photoelectric conversion. Meanwhile, a surface array type detection method and a single-pixel detection method based on the architecture are proposed, which can be used for staring imaging and scanning imaging.

[0005] To achieve the above object, according to one aspect of the present application, there is provided a high-sensitivity detector excited by day-blind ultraviolet band electronic fluorescence, characterized in that it comprises a vacuum chamber, a nano-tip combination, a micro-channel plate, an aluminized fluorescent screen, a fiber-optic light cone and a photosensitive element assembly, the nano-tip combination, the micro-channel plate and the aluminized fluorescent screen are all located in the vacuum chamber, and the vacuum chamber is provided with an ultraviolet incidence window and a visible light output window on opposite two side plates respectively, wherein:

[0006] The air pressure in the vacuum chamber is 10 -6 mBar~9*10 - 6 mBar, the ultraviolet incidence window, the nano-tip combination, the micro-channel plate, the aluminized fluorescent screen and the visible light output window are arranged in sequence along the light path, the photosensitive element assembly is located outside the vacuum chamber and arranged corresponding to the position of the aluminized fluorescent screen, and the photosensitive element assembly comprises a photosensitive element mounting plate and a plurality of photosensitive elements distributed on the photosensitive element mounting plate.

[0007] The nano-tip combination comprises a substrate and a nano-tip array arranged on the substrate, the nano-tip array comprises a plurality of nano-tip structures arranged in an array, and the substrate and the nano-tip structures are both made of silicon nitride.

[0008] The tip of each nano-tip structure points to the micro-channel plate.

[0009] The fiber-optic light cone is arranged between the aluminized fluorescent screen and the photosensitive element assembly, sealedly mounted on the visible light output window, and one end of the fiber-optic light cone is connected with the aluminized fluorescent screen and the other end is connected with the photosensitive element assembly.

[0010] The nano-tip structure is in the shape of a circular cone or a right pyramid, and:

[0011] When the nano-tip structure is in the shape of a circular cone, the height of the circular cone is 550nm~670nm, the angle between the generatrix of the circular cone and the bottom surface of the circular cone is 70°~85°, the diameter of the bottom surface of the circular cone is 400nm~420nm, and the spacing between the bottom surfaces of any two adjacent circular cones in the same row and the same column is 480nm~500nm.

[0012] When the nano-tip structure is in the shape of a right pyramid, the height of the right pyramid is 550nm~670nm, the angle between the side surface of the right pyramid and the bottom surface of the right pyramid is 70°~85°, the side length of the bottom surface of the right pyramid is 400nm~420nm, and the spacing between the bottom surfaces of any two adjacent right pyramids in the same row and the same column is 480nm~500nm.

[0013] Preferably, the substrate adopts 100 crystal orientation and is n-type doped.

[0014] Preferably, the ultraviolet incident window is made of CaF2 material.

[0015] Preferably, the gap between the aluminized screen and the microchannel plate is 1.5mm-2.5mm.

[0016] Preferably, the gap between the nano-tip array and the microchannel plate is 4mm-5mm.

[0017] Preferably, the vacuum chamber is made of aluminum.

[0018] According to another aspect of the present application, the application of the above-mentioned high-sensitivity detector of the solar-blind ultraviolet band electron fluorescence excitation is also provided, characterized in that a voltage of 200V-1000V is applied between the substrate of the nano-tip combination and the microchannel plate, a voltage of 1600V-1800V is applied on the microchannel plate, and a voltage of 5900V-6200V is applied between the microchannel plate and the aluminized screen.

[0019] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0020] 1) The high-sensitivity detector of the solar-blind ultraviolet band electron fluorescence excitation of the present application places the nano-tip combination, the microchannel plate and the aluminized screen in a vacuum chamber with a vacuum degree of 10 -6 mBar~9x10 -6 mBar, and when the ultraviolet light irradiates the nano-tip combination after passing through the ultraviolet incident window, a large number of surface states filled with free electrons are generated at the tip of the nano-tip structure due to the tip effect, so that the free electrons have a very high surface distribution density at the tip of the nano-tip structure. At the same time, when the excited surface wave propagates to the tip of the nano-tip structure, the tip boundary guides the surface wave to converge to the nano-tip, and finally realizes nano-focusing of the incident light. Under the action of the voltage, a large number of electrons at the tip of the nano-tip structure can escape to the microchannels of the microchannel plate, and when the electrons bombard the microchannels of the microchannel plate, secondary electrons can be generated. Especially when the microchannel plate is applied with a voltage at both ends, an electric field is formed inside the microchannel, and the secondary electrons generated by the electron bombardment of the nano-tip array are accelerated by the electric field and bombard the inside of the microchannel to generate more secondary electrons. This process is repeated several times in the same microchannel, and finally the multiplied electrons are output at the outlet end. These accelerated electrons excite the aluminized screen to generate strong visible light, thereby realizing high-sensitivity detection of ultraviolet band conversion. The incident solar-blind ultraviolet signal is amplified by the nano-tip array of the device. Through the execution of tip electron controlled accumulation and emission and electron multiplication acceleration, the response (R) and detection rate (D * ) of the detector to the ultraviolet signal are greatly improved.

[0021] 2) Low cost and high stability ultraviolet detection. The present application has the characteristics of realizing the fluorescence excitation ultraviolet-to-visible spectrum conversion of incident light wave by the controlled excitation of 300 nm ultraviolet signal on the surface of nano-tip structure and the nanofocusing surface wave.

[0022] 3) Convenient to use. The main body of the present application is plugged in the optical path in the vacuum chamber, which is easy to match and couple with the conventional optical and photoelectric mechanical structure. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the distribution diagram of the nano-tip combination, microchannel plate, aluminized fluorescent screen, optical fiber light cone and photosensitive element assembly of the present application;

[0024] Figure 2 is the schematic diagram of converting ultraviolet light into visible light in the present application;

[0025] Figures 3a-3c is the schematic diagram of one photosensitive element corresponding to one nano-tip structure, corresponding to two nano-tip structures and corresponding to three nano-tip structures, respectively;

[0026] Figures 4a-4e is the schematic diagram of the nano-tip structure being a circular cone, a regular triangular pyramid to a regular hexagonal pyramid, respectively;

[0027] Figure 5 is the parameter schematic diagram of the nano-tip combination in the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0029] With reference to the drawings, a solar blind ultraviolet band electronic fluorescence excitation high sensitivity detector includes a vacuum chamber 6, a nano-tip combination 1, a microchannel plate 2, an aluminized fluorescent screen 3, an optical fiber light cone 4 and a photosensitive element assembly 5. The vacuum chamber 6 is made of aluminum. The nano-tip combination 1, the microchannel plate 2 and the aluminized fluorescent screen 3 are located in the vacuum chamber 6. The opposite two side plates of the vacuum chamber 6 are respectively provided with an ultraviolet incident window 7 and a visible light output window 8, wherein:

[0030] The air pressure of the nano-tip combination 1, the microchannel plate 2 and the aluminized fluorescent screen 3 in the vacuum chamber is 10 -6 mBar~9×10 -6The ultraviolet incident window 7, the nano-tip combination 1, the micro-channel plate 2, the aluminized screen 3 and the visible light output window 8 are arranged in sequence along the light path in a vacuum environment of mBar, the ultraviolet incident window 7 is made of CaF2 material, the photosensitive element assembly 5 is located outside the vacuum chamber 6 and arranged corresponding to the position of the aluminized screen 3, the photosensitive element assembly 5 comprises a photosensitive element 51 mounting plate and a plurality of photosensitive elements 51 distributed on the photosensitive element 51 mounting plate, and the photosensitive element 51 is preferably CMOS. The aluminized screen 3 is coated with an aluminum film on the fluorescent powder particles, so that each obtains the same potential to avoid the formation of clusters, islands and uneven layers.

[0031] The nano-tip combination 1 comprises a substrate 11 and a nano-tip array arranged on the substrate 11, the nano-tip array comprises a plurality of nano-tip structures 12 arranged in an array, preferably arranged in an array of 3484x3484 (3484 rows and 3484 columns), wherein the substrate 11 and the nano-tip structure 12 are both made of silicon nitride. The nano-tip array has high electron emission capacity even under weak ultraviolet signal incident excitation, which makes the nano-tip array an effective solution for ultraviolet dual-color detection.

[0032] The tip of each nano-tip structure 12 points to the micro-channel plate 2.

[0033] The fiber optic taper 4 is arranged between the aluminized screen 3 and the photosensitive element assembly 5 and is sealed and mounted on the visible light output window 8, and one end of the fiber optic taper 4 is connected with the aluminized screen 3 and the other end is connected with the photosensitive element assembly 5. The photosensitive elements 51 are distributed within the range surrounded by the fiber optic taper 4.

[0034] The nano-tip structure 12 is in the shape of a cone or a right pyramid, and:

[0035] When the nano-tip structure 12 is in the shape of a cone, the height of the cone is 550nm-670nm, the angle between the generatrix of the cone and the bottom surface of the cone is 70°-85°, the diameter of the bottom surface of the cone is 400nm-420nm, and the spacing between the bottom surfaces of any two adjacent cones in the same row and the same column is 480nm-500nm;

[0036] When the nano-tip structure 12 is in the shape of a right pyramid, the height of the right pyramid is 550nm-670nm, the angle between the side surface of the right pyramid and the bottom surface of the right pyramid is 70°-85°, the side length of the bottom surface of the right pyramid is 400nm-420nm, and the spacing between the bottom surfaces of any two adjacent right pyramids in the same row and the same column is 480nm-500nm.

[0037] The above parameters can promote the nano-tip plasmonic element to have a strong response to ultraviolet of 300nm wavelength.

[0038] Further, the gap between the aluminized screen 3 and the microchannel plate 2 is 1.5mm-2.5mm, and the gap between the nano-tip array and the microchannel plate 2 is 4mm-5mm. The gap range is mainly to ensure that the aluminized screen 4 and the microchannel plate 3, the nano-tip array and the microchannel plate 3 are relatively close, and the shape and size of the nano-tip structure are matched to maintain high electron energy propagation efficiency, but too close distance will produce sparking under high voltage, which is not conducive to the normal operation of the device.

[0039] According to another aspect of the present application, the application of the high-sensitivity detector is also provided. A voltage (cathode voltage) of V c =200V-1000V is applied between the substrate 11 of the nano-tip combination 1 and the microchannel plate 2, a voltage (plate voltage) of V MCP =1600V-1800V is applied to the microchannel plate 2, and a voltage (screen voltage) of V a =5900V-6200V is applied between the microchannel plate 2 and the aluminized screen 3. In a vacuum environment of 10 -6 mBar-9×10 -6 mBar, the cathode voltage V c is set to 200V-1000V during use, the ultraviolet detection rate will increase with the increase of the cathode voltage, the plate voltage V MCP is set to 1600V-1800V, the screen voltage V a is set to 5900V-6200V, which is matched with the shape and size of the nano-tip structure, and the gap between the aluminized screen 3 and the microchannel plate 2 and the gap between the nano-tip array and the microchannel plate 2, which is easy to break down and accelerate the movement of electrons, within a limited range, the plate voltage V MCP of the microchannel plate 2 and the screen voltage V a of the aluminized screen 3 are higher, and the final screen luminous intensity is larger, which is beneficial to the light-sensitive element to receive light.

[0040] Further, the high-sensitivity detector is used for detecting the ultraviolet signal of 300nm wavelength.

[0041] The preparation method of the high-sensitivity detector mainly includes three key links: (1) manufacturing a large-size nano-tip combination 1; (2) integrating the nano-tip combination 1, the microchannel plate 2, the coated screen and the light-sensitive element assembly 5.

[0042] (1) Manufacturing a large-size nano-tip combination 1 mainly includes the following steps:

[0043] (1) cleaning process: sequentially using acetone, alcohol and deionized water solvent to ultrasonic cleaning and drying the silicon nitride material substrate (thickness of 450-500 um, 100 crystal direction, single side polishing, n type doping).

[0044] (2) focused electron beam etching process: scanning and etching one side of the substrate along a circular ring path or an edge rectangular inner circular ring path to form nano-tip structure 12;

[0045] (3) by shifting on the surface of the silicon plate and repeating step (2), a nano-tip array composed of nano-tip structure 12 is obtained; then through etching, the silicon plate is shaped into substrate 11 and nano-tip array on substrate 11;

[0046] (4) cleaning treatment.

[0047] (B) integrated nano-tip combination 1, microchannel plate 2, coated fluorescent screen and photosensitive element assembly 5 mainly includes the following steps:

[0048] (1) through the tool fixture, the gap between the aluminized fluorescent screen 3 and the microchannel plate 2 is 1.5-2.5 mm, and the gap between the nano-tip combination 1 and the microchannel plate 2 is 4-5 mm.

[0049] (2) using conventional metal electrical connection lead manufacturing process, connecting electrical connection lead on nano-tip array, microchannel plate 2 and coated fluorescent screen.

[0050] (3) placing nano-tip combination, microchannel plate 2 and coated fluorescent screen in vacuum chamber 6, leading out the respective electrical connection leads from the vacuum chamber 6, using rotary vane pump to preliminarily pump the vacuum chamber 6, after reaching the rough vacuum environment (about 10 - 2 mBar), switching to molecular pump to further high-vacuumize the environment in the vacuum chamber 6, reaching the air pressure of 10 -6 mBar-9*10 - 6 mBar, and then completing the structure packaging in the vacuum chamber 6.

[0051] (4) arranging photosensitive element assembly 5 outside the vacuum chamber 6 corresponding to the position of the coated fluorescent screen, setting fiber optic taper 4 between the aluminized fluorescent screen 4 and the photosensitive element assembly 5 and sealingly mounting on the visible light output window 8.

[0052] The present application realizes the amplification of incident light signal and the conversion of night vision ultraviolet / near ultraviolet to visible spectrum by the electron controlled emission of nano-tip structure 12 and the electron multiplication of microchannel plate 2, and realizes the dual-color ultraviolet-electron-visible light conversion imaging, which can realize the high-sensitivity detection of ultraviolet weak signal. Compared with the conventional ultraviolet detection array, the photoelectric sensitivity is significantly improved and the spectral response range is expanded.

[0053] The present application realizes high-sensitivity detection of weak ultraviolet signals by emitting 300nm ultraviolet weak signals at the nanometer tip through the upright nanometer tip array resonance focusing, coupling electron multiplication fluorescent film pieces through a micro-channel plate 2 to induce electron multiplication speed and excite fluorescence to perform photoelectric conversion.

[0054] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high sensitivity detector for the solar blind ultraviolet band, characterized in that, The vacuum chamber, the nano-tip combination, the micro-channel plate, the aluminized screen, the fiber optic taper and the photosensitive element assembly are arranged in the vacuum chamber, and the vacuum chamber is provided with an ultraviolet incident window and a visible light output window on two opposite side plates respectively. The nano-aperture assembly, microchannel plate, and aluminized fluorescent screen are housed in a vacuum chamber at a pressure of 10. -6 mBar~9×10 -6 In a vacuum environment of mBar, the ultraviolet incident window, nano-tip assembly, microchannel plate, aluminum-plated fluorescent screen and visible light output window are arranged sequentially along the optical path. The photosensitive element assembly is located outside the vacuum room and is arranged corresponding to the position of the aluminum-plated fluorescent screen. The photosensitive element assembly includes a photosensitive element mounting plate and multiple photosensitive elements distributed on the photosensitive element mounting plate. The nano-tip combination comprises a substrate and a nano-tip array arranged on the substrate, and the nano-tip array comprises a plurality of nano-tip structures arranged in an array. The tip of each nano-tip structure points to the micro-channel plate. The fiber optic taper is arranged between the aluminized screen and the photosensitive element assembly, is sealed and mounted on the visible light output window, and one end of the fiber optic taper is connected with the aluminized screen and the other end is connected with the photosensitive element assembly. The nano-tip structure is in the shape of a cone or a right pyramid. When the nano-tip structure is in the shape of a cone, the height of the cone is 550nm-670nm, the angle between the generatrix of the cone and the bottom surface of the cone is 70°-85°, the diameter of the bottom surface of the cone is 400nm-420nm, and the spacing between the bottom surfaces of any two adjacent cones in the same row and the same column is 480nm-500nm. When the nano-tip structure is in the shape of a right pyramid, the height of the right pyramid is 550nm-670nm, the angle between the side surface of the right pyramid and the bottom surface of the right pyramid is 70°-85°, the side length of the bottom surface of the right pyramid is 400nm-420nm, and the spacing between the bottom surfaces of any two adjacent right pyramids in the same row and the same column is 480nm-500nm.

2. The high sensitivity detector of claim 1, wherein the high sensitivity detector is a solar blind ultraviolet band electron fluorescence excitation high sensitivity detector. The substrate is in the 100 crystal orientation and is n-doped.

3. The high sensitivity detector of claim 1, wherein the high sensitivity detector is a solar blind ultraviolet band electron fluorescence excitation high sensitivity detector. The ultraviolet incident window is made of CaF2 material.

4. The high sensitivity detector of claim 1, wherein the high sensitivity detector is a solar blind ultraviolet band electron fluorescence excitation high sensitivity detector. The gap between the aluminized screen and the micro-channel plate is 1.5mm-2.5mm.

5. The high sensitivity detector of claim 1, wherein the high sensitivity detector is a solar blind ultraviolet band electron fluorescence excitation high sensitivity detector. The gap between the nano-tip array and the micro-channel plate is 4mm-5mm.

6. The high sensitivity detector of claim 1, wherein the high sensitivity detector is a solar blind ultraviolet band electron fluorescence excitation high sensitivity detector. The vacuum chamber is made of aluminum.

7. The use of a high sensitivity solar blind ultraviolet band electron fluorescent excitation detector according to any one of claims 1 to 6, characterized in that, A voltage of 200V-1000V is applied between the substrate of the nano-tip combination and the micro-channel plate, a voltage of 1600V-1800V is applied on the micro-channel plate, and a voltage of 5900V-6200V is applied between the micro-channel plate and the aluminized screen.

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