High-detectivity infrared detector and application thereof

Abstract

The application discloses a kind of high detection rate infrared detector, including vacuum chamber, nano-tip combination, microchannel plate, aluminized screen, fiber optic light cone and photosensitive element assembly, the nano-tip combination, microchannel plate and aluminized screen in vacuum environment, infrared incident window, nano-tip combination, microchannel plate, aluminized screen and visible light output window are sequentially arranged along optical path;Nano-tip combination includes silicon substrate and nano-tip array, and the nano-tip array includes nano-tip structure, and the material of silicon substrate and nano-tip structure is silicon wafer;The tip of each nano-tip structure is directed to microchannel plate;Fiber optic light cone is arranged between aluminized screen and photosensitive element assembly, one end of fiber optic light cone is connected with aluminized screen and the other end is connected with photosensitive element assembly.The application can output multiplied electron, and these accelerated electrons stimulate aluminized screen to generate strong visible light, so as to realize high sensitive detection and high detection rate of infrared band conversion.

Description

Technical Field

[0001] This invention belongs to the field of infrared detectors, and more specifically, relates to a high-detectability infrared detector and its applications. Background Technology

[0002] Compared to ultraviolet and visible light detection, infrared detection has the following advantages: ① Infrared detection has better weather performance than visible light, and can be used both day and night, making it suitable for nighttime reconnaissance needs; ② Infrared detection can use the difference in infrared radiation characteristics between the target and the background to identify targets and reveal camouflage; ③ The infrared spectrum can penetrate clouds and smoke, and detect objects that visible light cannot detect; ④ It has good concealment and is not easy to be detected or interfered with.

[0003] Therefore, infrared optical detection has unparalleled advantages over visible light remote sensing in military, meteorological, hydrological, geological, environmental monitoring, agricultural, and forestry fields. Meanwhile, to meet the demands of third-generation infrared detectors for multi-band detection, dual-color night vision infrared / near-infrared technology simultaneously acquires target information in two bands, suppressing complex backgrounds and effectively eliminating interference sources. This improves detection accuracy and enhances target recognition capabilities under artificial and complex background interference. High responsivity, extended operating bands, high resolution, and integration are becoming the development directions for infrared detection technology.

[0004] Currently, the mainstream dual-color detection material, mercury cadmium telluride (HgCdTe), faces significant challenges in both preparation and device fabrication. The weak chemical bonds between Hg and Te lead to unstable HgCdTe material properties, resulting in poor uniformity and low yield in focal plane array devices. Summary of the Invention

[0005] To address the above-mentioned deficiencies or improvement needs of existing technologies, this invention provides a high detectivity infrared detector and its application. It achieves controlled electron emission through a nano-tip structure and electron multiplication through a microchannel plate, and utilizes fluorescence excitation to amplify the incident light signal and convert the infrared to visible light spectrum. Compared with conventional infrared detection arrays, it significantly improves photoelectric sensitivity and expands the spectral response range.

[0006] To achieve the above objectives, according to one aspect of the present invention, a high detectivity infrared detector is provided, characterized in that it comprises a vacuum chamber, a nano-tip assembly, a microchannel plate, an aluminized fluorescent screen, a fiber optic cone, and a photosensitive element assembly, wherein the nano-tip assembly, the microchannel plate, and the aluminized fluorescent screen are all located within the vacuum chamber, and an infrared incident window and a visible light output window are respectively provided on two opposite side plates of the vacuum chamber, wherein:

[0007] 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 - 6In a vacuum environment of mBar, the infrared 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 component is located outside the vacuum room and is arranged corresponding to the position of the aluminum-plated fluorescent screen. The photosensitive element component includes a photosensitive element mounting plate and multiple photosensitive elements arrayed on the photosensitive element mounting plate.

[0008] The nano-tip assembly includes a silicon substrate and a nano-tip array disposed on the silicon substrate. The nano-tip array includes multiple nano-tip structures distributed in an array, and the tip of each nano-tip structure points to a microchannel plate. The silicon substrate and the nano-tip structures are both made of silicon wafers.

[0009] The fiber optic cone is disposed between the aluminum-plated fluorescent screen and the photosensitive element component and is sealed on the visible light output window. One end of the fiber optic cone is connected to the aluminum-plated fluorescent screen and the other end is connected to the photosensitive element mounting plate.

[0010] The nano-tip structure is conical or pyramidal in shape, and:

[0011] When the nano-tip structure is cone-shaped, the height of the cone is 1.1 μm to 1.4 μm, the angle between the generatrix of the cone and the base of the cone is 45° to 55°, the diameter D of the base of the cone is 1.7 μm to 2.2 μm, and the distance B1 between the bases of any two adjacent cones in the same row and column is 0.8 μm to 0.9 μm.

[0012] When the shape of the nano-tip structure is a regular pyramid, the height of the regular pyramid is 1.1μm to 1.4μm, the angle between the side face and the base of the regular pyramid is 45° to 55°, the side length L of the base of the regular pyramid is 1.7μm to 2.2μm, and the distance B2 between the bases of any two adjacent regular pyramids in the same row and column is 0.8μm to 0.9μm.

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

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

[0015] Preferably, the gap between the aluminum-plated fluorescent 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 invention, an application of the aforementioned high detectivity infrared detector is also provided, characterized in that a voltage of 200V-1000V is applied between the silicon substrate and the microchannel plate of the nano-tip assembly, a voltage of 1400V-1800V is applied on the microchannel plate, and a voltage of 5600V-5700V is applied between the microchannel plate and the aluminum-coated fluorescent screen.

[0019] Preferably, the high detectivity infrared detector is used for detecting infrared signals at wavelengths of 980nm and 2.2μm.

[0020] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0021] The high detectivity infrared detector of this invention places a nano-tip assembly, a microchannel plate, and an aluminum-coated fluorescent screen in a vacuum chamber with a vacuum level of 10⁻⁶ mBar to 9 × 10⁻⁶ mBar. Due to the high degree of vacuum, when infrared light passes through the infrared incident window and irradiates the nano-tip assembly, 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, resulting in a high surface distribution density of free electrons at the tip. Simultaneously, when the excited surface wave propagates to the tip of the nano-tip structure, the tip boundary guides the surface wave towards the tip, ultimately achieving nano-focusing of the incident light. Under the action of voltage, a large number of electrons at the tip of the nano-tip structure can escape into the microchannels of the microchannel plate. When these electrons bombard the microchannels, secondary electrons are generated. Especially when voltage is applied to both ends of the microchannel plate, an electric field is formed inside the microchannel. The secondary electrons generated by the electron bombardment of the nano-tip array are accelerated by the electric field, bombarding the microchannel again and generating even more secondary electrons. This process is repeated multiple times in the same microchannel, ultimately resulting in a multiplied number of electrons output at the exit end. These accelerated electron-excited aluminum-coated fluorescent screens produce strong visible light, thereby achieving high-sensitivity detection and high detectability in the infrared band. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention;

[0023] Figure 2 This is a schematic diagram illustrating how the present invention converts infrared light into visible light;

[0024] Figures 3a-3e These are schematic diagrams showing the nano-point structure as a cone, a regular triangular pyramid, and a regular hexagonal pyramid, respectively;

[0025] Figure 4 This is a schematic diagram of the parameters of the nano-tip combination in this invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Referring to the accompanying drawings, a high detectivity infrared detector includes a vacuum chamber 7, a nano-tip assembly 2, a microchannel plate 3, an aluminum-coated fluorescent screen 4, a fiber optic cone 5, and a photosensitive element 6. The vacuum chamber 7 is made of aluminum. The nano-tip assembly 2, the microchannel plate 3, and the aluminum-coated fluorescent screen 4 are all located within the vacuum chamber 7. An infrared entrance window 1 and a visible light output window 8 are respectively provided on two opposite side plates of the vacuum chamber 7.

[0028] The pressure inside the vacuum chamber 7 of the nano-contact assembly 2, microchannel plate 3, and aluminized fluorescent screen 4 is 10. -6 mBar~9×10 -6 In a vacuum environment of mBar, the infrared incident window 1, nano-tip assembly 2, microchannel plate 3, aluminum-coated phosphor screen 4, and visible light output window 8 are arranged sequentially along the optical path. The infrared incident window 1 is made of CaF2 material. The photosensitive element assembly 6 is located outside the vacuum chamber 7 and is arranged corresponding to the position of the aluminum-coated phosphor screen 4. The photosensitive element assembly 6 includes a photosensitive element mounting plate and multiple photosensitive elements 61 arrayed on the photosensitive element mounting plate. The photosensitive elements 61 are preferably CMOS. The aluminum-coated phosphor screen 4 is formed by coating a layer of aluminum film on phosphor particles to ensure that each particle has the same potential, thereby avoiding the formation of clusters, islands, and non-uniform layers.

[0029] The nano-tip assembly 2 includes a silicon substrate 21 and a nano-tip array disposed on the silicon substrate 21. The nano-tip array includes multiple nano-tip structures arranged in an array, preferably in a 3484×3484 array (3484 rows and 3484 columns). Both the silicon substrate 21 and the nano-tip structures 22 are made of silicon wafers. The nano-tip array retains high electron emission capability even under weak infrared signal incident excitation, making it an effective solution for infrared dual-color detection.

[0030] The tip of each of the nano-tip structures 22 points toward the microchannel plate 3.

[0031] The fiber optic cone 5 is disposed between the aluminized fluorescent screen 4 and the photosensitive element 6 and is sealed and installed on the visible light output window 8. One end of the fiber optic cone 5 is connected to the aluminized fluorescent screen 4 and the other end is connected to the photosensitive element 6. Photosensitive elements 61 are distributed within the area enclosed by the fiber optic cone 5.

[0032] The nano-tip structure 22 is conical or regular pyramidal in shape, and:

[0033] Reference Figure 4 When the nano-tip structure 22 is conical in shape, the height of the cone is 1.1 μm to 1.4 μm, the angle between the generatrix of the cone and the base of the cone is 45° to 55°, the diameter D of the base of the cone is 1.7 μm to 2.2 μm, and the distance B1 between the bases of any two adjacent cones in the same row and column is 0.8 μm to 0.9 μm (the distance between the bases of two cones refers to the minimum distance between a point on the edge of the base of one cone and a point on the edge of the base of another cone). Setting the above parameters can enable the nano-tip plasmonic unit to have a strong response to short-wave infrared, such as short-wave infrared signals of wavelengths of 980 nm and 2.2 μm. In addition, the design of these parameters is also related to the matching degree of the size period.

[0034] When the nano-tip structure 22 is in the shape of a regular pyramid, the height of the regular pyramid is 1.1μm to 1.4μm, the angle between the side face and the base of the regular pyramid is 45° to 55°, the side length L of the base of the regular pyramid is 1.7μm to 2.2μm, and the distance B2 between the bases of any two adjacent regular pyramids in the same row and column is 0.8μm to 0.9μm.

[0035] Generally speaking, the ratio of the period (B1, the distance between the bases of two cones if it is a conical shape, and B2, the distance between the bases of two regular pyramids if it is a regular pyramidal shape) to the nano-tip size (B1 / D, or B2 / L, the diameter D of the base of a cone if it is a conical shape, and the side length L of the base of a regular pyramidal shape), also known as the filling factor, should be controlled between 0.2 and 0.8 to ensure a better response to infrared signals.

[0036] Furthermore, the gap between the aluminized phosphor screen 4 and the microchannel plate 3 is 1.5mm-2.5mm, and the gap between the nano-tip array and the microchannel plate 3 is 4mm-5mm. This gap range is mainly to ensure that the aluminized phosphor screen 4 and the microchannel plate 3, and the nano-tip array and the microchannel plate 3 are relatively close, which, in conjunction with the shape and size of the nano-tip structure, can maintain a high electron energy propagation efficiency. However, if the distance is too close, arcing will occur under high voltage, which is not conducive to the normal operation of the device.

[0037] According to another aspect of the invention, an application of the aforementioned high detectivity infrared detector is also provided, wherein a Vt is applied between the silicon substrate 21 of the nano-tip assembly 2 and the microchannel plate 3. c A voltage of 200V-1000V (cathode voltage) is applied to microchannel plate 3. MCPA voltage of 1400V-1800V (plate voltage) is applied between the microchannel plate 3 and the aluminum-coated fluorescent screen 4. a == 5600V-5700V (plate voltage). In 10 -6 mBar~9×10 -6 In a vacuum environment of mBar, the cathode voltage V needs to be set when used in a vacuum environment. c With a voltage range of 200V-1000V, the infrared detectivity will increase with the increase of the cathode voltage. The plate voltage V of microchannel plate 3 is set accordingly. MCP Set the plate voltage V to 1400V-1800V. a With a voltage of 5600V-5700V, and in combination with the shape and size of the nano-tip structure, as well as the gap between the aluminum-plated fluorescent screen 4 and the microchannel plate 3, and the gap between the nano-tip array and the microchannel plate 3, it is easy to break down and generate electrons and accelerate their movement. Within the above-mentioned limited range, the higher the plate pressure of the microchannel plate 3 and the plate pressure of the fluorescent screen, the greater the final luminous intensity of the fluorescent screen, which is beneficial for the photosensitive element to receive light.

[0038] Furthermore, the high detectivity infrared detector is used for detecting infrared signals at wavelengths of 980nm and 2.2μm.

[0039] The method for fabricating a high detectivity infrared detector according to the present invention mainly includes three key steps: (i) fabricating a large-size nano-tip assembly 2; (ii) integrating the nano-tip assembly 2, microchannel plate 3, coated fluorescent screen and photosensitive element 6.

[0040] (I) The main steps in fabricating a large-sized nano-tip assembly 2 are as follows:

[0041] (1) Cleaning process: The silicon wafer material (thickness 450μm, 100 crystal orientation, single-sided polishing, n-type doping) was ultrasonically cleaned and dried in sequence with acetone, alcohol and deionized water solvent.

[0042] (2) Focused electron beam etching process: The focused electron beam is scanned and etched along a circular path or an inner circular path of the edge rectangle to form a nano-tip structure 22.

[0043] (3) By shifting on the surface of the silicon substrate and repeating step (2), a nano-tip array composed of nano-tip structures 22 is obtained. Then, after etching, the silicon substrate is shaped into a silicon substrate 21 and a nano-tip array on the silicon substrate 21.

[0044] (4) Cleaning treatment;

[0045] (II) The integration of nano-array, microchannel plate 3, coated fluorescent screen and photosensitive component 6 mainly includes the following steps:

[0046] (1) The gap between the aluminum-plated fluorescent screen 4 and the microchannel plate 3 is reduced to 1.5mm-2.5mm and the gap between the nano-tip assembly 2 and the microchannel plate 3 is reduced to 4mm-5mm by using tooling fixtures.

[0047] (2) Using conventional metal electrical connection lead fabrication process, electrical connection leads are connected on the nano-aperture, microchannel plate 3, and coated fluorescent screen.

[0048] (3) Place the nano-tip assembly, microchannel plate 3, and coated fluorescent screen in vacuum chamber 7, and lead out their respective electrical connection leads from vacuum chamber 7. Use a rotary vane pump to initially evacuate vacuum chamber 7. After reaching a rough vacuum environment (approximately 10 minutes) - 2 (mBar), switching to a molecular pump to further increase the vacuum level in vacuum chamber 6, reaching a pressure of 10 mBar. -6 mBar~9×10 -6 mBar, and then the structure is encapsulated in vacuum chamber 7.

[0049] (4) The photosensitive element 6 is arranged outside the vacuum chamber 7 at a position corresponding to the coated fluorescent screen. The fiber optic cone 5 is placed between the aluminum-coated fluorescent screen 4 and the photosensitive element 6 and is sealed on the visible light output window 8.

[0050] This invention utilizes controlled electron emission from a nano-structure and electron multiplication of a microchannel plate 3, along with excitation by an aluminum-coated fluorescent screen 4, to amplify the incident light signal and perform a night-vision infrared / near-infrared to visible light spectral conversion. This enables dual-color infrared-electron-visible light conversion for imaging, achieving highly sensitive detection of weak infrared signals. Compared to conventional infrared detection arrays, this significantly improves photoelectric sensitivity and expands the spectral response range.

[0051] By resonating with a vertical nano-tip array, weak infrared signals with incident wavelengths of 980 nm and 2.2 μm can be emitted at the tip of the nano-scale nano-tip array. The electron multiplication fluorescence film coupled by the microchannel plate 3 induces electron multiplication acceleration and excites fluorescence to perform photoelectric conversion, thus achieving highly sensitive detection of weak infrared signals.

[0052] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high detectivity infrared detector, characterized by, The infrared detector comprises a vacuum chamber, a nano-tip combination, a micro-channel plate, an aluminized screen, a fiber optic light cone and a light-sensitive element assembly, the nano-tip combination, the micro-channel plate and the aluminized screen are located in the vacuum chamber, and an infrared entrance window and a visible light output window are respectively arranged on opposite two side plates of the vacuum chamber. 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 infrared 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 component is located outside the vacuum room and is arranged corresponding to the position of the aluminum-plated fluorescent screen. The photosensitive element component includes a photosensitive element mounting plate and multiple photosensitive elements arrayed on the photosensitive element mounting plate. The nano-tip combination comprises a silicon substrate and a nano-tip array arranged on the silicon substrate, the nano-tip array comprises a plurality of nano-tip structures arranged in an array, and a tip end of each nano-tip structure points to the micro-channel plate. The fiber optic light cone is arranged between the aluminized screen and the light-sensitive element assembly and is sealingly mounted on the visible light output window, one end of the fiber optic light cone is connected with the aluminized screen, and the other end is connected with the light-sensitive element mounting plate. The nano-tip structure is in the shape of a cone or a right pyramid, and when the nano-tip structure is in the shape of a cone, the height of the cone is 1.1-1.4 μm, the angle between the generatrix of the cone and the bottom surface of the cone is 45-55°, the diameter D of the bottom surface of the cone is 1.7-2.2 μm, and the spacing B1 of the bottom surfaces of any two adjacent cones in the same row and the same column is 0.8-0.9 μm; when the nano-tip structure is in the shape of a right pyramid, the height of the right pyramid is 1.1-1.4 μm, the angle between the side surface of the right pyramid and the bottom surface of the right pyramid is 45-55°, the side length L of the bottom surface of the right pyramid is 1.7-2.2 μm, and the spacing B2 of the bottom surfaces of any two adjacent right pyramids in the same row and the same column is 0.8-0.9 μm.

2. The high detectivity infrared detector of claim 1, wherein, The silicon substrate is in a 100 crystal orientation and is n-doped.

3. The high detectivity infrared detector of claim 1, wherein, The infrared entrance window is made of CaF2.

4. The high detectivity infrared detector of claim 1, wherein, The gap between the aluminized screen and the micro-channel plate is 1.5-2.5 mm.

5. The high detectivity infrared detector of claim 1, wherein, The gap between the nano-tip array and the micro-channel plate is 4-5 mm.

6. The high detectivity infrared detector of claim 1, wherein, The vacuum chamber is made of aluminum.

7. Use of a high-detectivity infrared detector according to any one of claims 1 to 6, characterized in that, A voltage of 200-1000 V is applied between the silicon substrate of the nano-tip combination and the micro-channel plate, a voltage of 1400-1800 V is applied on the micro-channel plate, and a voltage of 5600-5700 V is applied between the micro-channel plate and the aluminized screen.

8. The use of a high-detectivity infrared detector according to claim 7, characterized in that, The high-detection-rate infrared detector is used for detecting infrared signals of two wavelengths of 980 nm and 2.2 μm.

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