High-response low-noise quaternary alkali cathode film layer structure, preparation method and quaternary alkali cathode window of high-response low-noise quaternary alkali cathode film layer structure
By setting a multi-layer film layer structure on the tetra-alkali cathode, the problem of high dark noise in low illumination environments is solved, and the device's response ability and imaging quality are improved.
Patent Information
- Application Number
- CN202510527803.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-25
- Publication Date
- 2025-07-29
AI Technical Summary
The existing photocathode devices have poor imaging effects in low illumination environments, mainly due to the high dark noise, which affects the device's response ability and imaging quality.
The quaternary alkali cathode is provided with an interface passivation layer, a conductive sealing layer, an interface transition layer, a photoelectric absorption layer, an electron transport layer, a structural transition layer, an electron escape layer and an escape protection layer. Through the combination of these layers, structural defects can be reduced, the probability of photogenerated electrons escape is increased, and dark noise is reduced.
It realizes improving the device's response capability in low illumination environments, while reducing dark noise and improving imaging effects.
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Figure CN120388873A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of night vision technology, and in particular to a quaternary alkali cathode film layer structure with high response and low noise, a preparation method thereof, and a quaternary alkali cathode window. Background Art
[0002] In the field of low-light technology, devices such as image intensifiers, photomultiplier tubes, and back-illuminated electron-bombarded active pixel imagers are the main core devices for photoelectric conversion and photoelectric amplification. Compared with visible light semiconductor sensors, they have excellent low-light limit performance and can achieve clear imaging under illuminance conditions below 10 -3 lx, and can be used to assist various activities in dark environments, such as various night vision activities, underwater imaging, medical devices, high-energy physics research and other fields.
[0003] As a photoelectric conversion component, the photocathode is the core component of an image intensifier or a photomultiplier tube. Its response level and dark background noise are important indicators determining the cathode performance.
[0004] High response means that the ability of the optical signal to excite the cathode to convert into an electron signal is strong, and usually the sensitivity (μA / lm) is used as an index. The higher the sensitivity value, the weaker the optical signal that can be detected, that is, the signal target with lower illuminance can be detected. However, the weakest detectable signal is not completely determined by the response ability, but also depends on the background noise of the photocathode, also called the dark noise situation.
[0005] Dark noise refers to the situation of the output electrons of the cathode when a working voltage is applied to the cathode without an optical signal input. It is usually expressed by the dark current (μA). For any vacuum optoelectronic device, the higher the dark current, the higher the output of the cathode without input noise of the device. The higher this noise output, the worse the imaging effect of the device in a low-illuminance environment, and the more serious the dark current noise output in the obtained image.
[0006] Therefore, in order to improve the performance of the device, in addition to improving the response ability of the cathode, it is also necessary to reduce the dark noise of the cathode.
[0007] The information disclosed in the background art section according to the characteristics of the optoelectronic material is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art. Summary of the Invention
[0008] The present application provides a quaternary alkali cathode film layer structure with high response and low noise, a preparation method thereof, and a quaternary alkali cathode window for the above technical problems.
[0009] The present application provides a high-response and low-noise quaternary alkali cathode film layer structure, including the following layers disposed on the quaternary alkali cathode: an interface passivation layer; a conductive sealing layer disposed in a region near the periphery on the outer side surface of the interface passivation layer; an interface transition layer disposed in the central region of the outer side surface of the interface passivation layer; a photoabsorption layer disposed on the outer side surface of the interface transition layer; an electron transport layer disposed on the outer side surface of the photoabsorption layer; a structural transition layer disposed on the outer side surface of the electron transport layer; an electron emission layer disposed on the outer side surface of the structural transition layer; and an emission protection layer disposed on the outer side surface of the electron emission layer.
[0010] Preferably, the thickness of the interface passivation layer is 5 - 10 nm.
[0011] Preferably, the thickness of the conductive sealing layer is 300 - 600 mnm; the thickness of the interface transition layer is 5 - 8 nm; the thickness of the photoabsorption layer is 100 - 120 nm.
[0012] Preferably, the thickness of the electron transport layer is 20 - 30 nm; the thickness of the structural transition layer is 10 - 15 nm; the thickness of the electron emission layer is 10 - 15 nm; the thickness of the emission protection layer is 5 - 10 nm.
[0013] Preferably, the lead content of the quaternary alkali cathode is 0.1%.
[0014] Preferably, the thickness of the interface passivation layer is 10 nm; the thickness of the conductive sealing layer is 500 nm; the thickness of the interface transition layer is 5 nm; the thickness of the photoabsorption layer is 100 nm; the thickness of the electron transport layer is 25 nm; the thickness of the structural transition layer is 12 nm; the thickness of the electron emission layer is 15 nm; the thickness of the emission protection layer is 10 nm.
[0015] On the other hand, the present application also provides a method for preparing the high-response and low-noise quaternary alkali cathode film layer structure as described above, including the following steps:
[0016] 1) Using the cleaned cathode window as a substrate, depositing HfO2 to obtain the interface passivation layer. After plasma cleaning, depositing a silver metal layer as the conductive sealing layer, and then performing ultrasonic cleaning, plasma cleaning, and drying to obtain a coated device;
[0017] 2) Using the photocurrent method, sequentially depositing on the deposition surface of the coated device in the direction from the substrate outwards: the interface transition layer, the photoabsorption layer, the electron transport layer, the structural transition layer, the electron emission layer, and the emission protection layer to obtain the high-response and low-noise quaternary alkali cathode film layer structure.
[0018] Preferably, the deposition rate of HfO2 for the interface passivation layer is 1 nm / min; the deposition rate of the silver metal layer is 10 nm / min.
[0019] Preferably, during plating, the plating temperature of the interface transition layer is 150 °C, the plating temperature of the optoelectronic absorption layer is 165 °C, the plating temperature of the electron transport layer is 200 °C, the plating temperature of the structural transition layer is 230 °C, the plating temperature of the electron escape layer is 175 °C, and the plating temperature of the escape protection layer is 175 °C.
[0020] On the other hand, the present application also provides a quaternary base cathode, on which the high-response low-noise quaternary base cathode film layer structure as described above is provided.
[0021] The beneficial effects that can be produced by the present application include:
[0022] 1) The high-response low-noise quaternary base cathode film layer structure provided by the present application can reduce the structural defects between the film layers, improve the cathode response while reducing the dark noise caused by the defects, achieve the effect of reducing the dark current, and improve the imaging effect of the obtained device.
[0023] 2) For the quaternary base cathode provided by the present application, when the film structure with the above structure is provided on the quaternary base cathode, weak signal light can be absorbed by the optoelectronic absorption layer and excited to generate photoelectrons after passing through the highly transparent interface passivation layer and the transition layer from the input window. These electrons reach the electron escape layer through the electron transport layer and the structural transition layer under the action of the electric field, and finally escape to the vacuum output surface. The interface passivation layer, the interface transition layer, and the structural transition layer are used to transition between the key functional layers, reduce the structural stress, reduce the number of structural defects, reduce the dark background noise caused by the structural defects, and increase the escape probability of the photoelectrons. Description of the Drawings
[0024] Figure 1 Schematic diagram of the quaternary base cathode film layer structure prepared in at least one embodiment provided by the present application;
[0025] Figure 2 Schematic diagram of the test result of the surface roughness of the cathode plated with the interface passivation layer provided by the present application.
[0026] Figure 3 Graph of the cathode window transmittance curve before and after plating the interface passivation layer provided by the present application.
[0027] Figure 4 Physical photo of the quaternary base cathode provided by the present application.
[0028] Figure 5 Schematic diagram of the spectral response curve of the quaternary base cathode provided by the present application. Detailed Embodiments
[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Components of the embodiments of the present invention usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.
[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.
[0031] Technical means not detailed in this application and not used to solve the technical problems of this application are set according to common general knowledge in the art, and multiple ways of setting common general knowledge can be realized.
[0032] See Figures 1 to 5 , the high-response and low-noise quaternary cathode film layer structure provided by this application includes: an interface passivation layer provided on the top or bottom surface of the substrate; a conductive sealing layer provided in a region near the periphery on the outer side surface of the interface passivation layer; an interface transition layer provided in the central region of the outer side surface of the interface passivation layer; a photoabsorption layer provided on the outer side surface of the interface transition layer; an electron transport layer provided on the outer side surface of the photoabsorption layer; a structural transition layer provided on the outer side surface of the electron transport layer; an electron emission layer provided on the outer side surface of the structural transition layer; an emission protection layer provided on the outer side surface of the electron emission layer;
[0033] The film layer structure adopting the above structure can reduce the structural defects between the film layers, improve the cathode response while reducing the dark noise caused by the defects, achieve the effect of reducing the dark current, and improve the imaging effect of the obtained device.
[0034] In a specific embodiment, the thickness of the interface passivation layer is 5 - 10 nm.
[0035] In a specific embodiment, the thickness of the conductive sealing layer is 300 - 600 mnm.
[0036] In a specific embodiment, the thickness of the interface transition layer is 5 - 8 nm.
[0037] In a specific embodiment, the thickness of the photoabsorption layer is 100 - 120 nm.
[0038] In a specific embodiment, the thickness of the electron transport layer is 20 - 30 nm.
[0039] In a specific embodiment, the thickness of the structural transition layer is 10 - 15 nm.
[0040] In a specific embodiment, the thickness of the electron emission layer is 10 - 15 nm.
[0041] In a specific embodiment, the thickness of the emission protection layer is 5 - 10 nm.
[0042] Setting the thickness dimension in this way can ensure that the noise reduction effect of the obtained device is better.
[0043] In a specific embodiment, the substrate is a cathode window with a lead content of 0.1%.
[0044] In a specific embodiment, the thickness of the interface passivation layer is 10 nm; the thickness of the conductive sealing layer is 500 nm; the thickness of the interface transition layer is 5 nm; the thickness of the optoelectronic absorption layer is 100 nm; the thickness of the electron transport layer is 25 nm; the thickness of the structural transition layer is 12 nm; the thickness of the electron emission layer is 15 nm; the thickness of the emission protection layer is 10 nm. This device has the best effect of reducing dark current.
[0045] On the other hand, the present application also provides a preparation method for the above structure, including the following steps:
[0046] 1) Using the cleaned cathode window as the substrate, depositing HfO2 to obtain the interface passivation layer. After plasma cleaning, depositing a silver metal layer as the conductive sealing layer, and then performing ultrasonic cleaning, plasma cleaning, and drying to obtain a coated device;
[0047] 2) Using the photocurrent method, sequentially deposit on the coated surface of the coated device in the direction from the substrate outwards: the interface transition layer, the optoelectronic absorption layer, the electron transport layer, the structural transition layer, the electron emission layer, and the emission protection layer to obtain a high-response and low-noise quaternary alkali cathode film layer structure.
[0048] In a specific embodiment, the deposition rate of HfO2 for the interface passivation layer is 1 nm / min; the deposition rate of the silver metal layer is 10 nm / min.
[0049] In a specific embodiment, the cleaning operation of the cathode window is: the cathode window is ultrasonically cleaned in alcohol at a power of 120 W for 5 minutes and then dried, and then plasma cleaned at 1000 W and 9 MHz for 20 min.
[0050] In a specific embodiment, the plasma cleaning conditions after depositing the interface passivation layer are plasma cleaning at 1000 W and 9 MHz for 20 min.
[0051] In a specific embodiment, the plasma cleaning conditions after depositing the conductive sealing layer are: plasma cleaning at 1000 W and 9 MHz for 30 min. Cleaning under these conditions can ensure that the central region of the interface passivation layer meets the deposition requirements of the interface transition layer.
[0052] In a specific embodiment, the conditions for drying the plated device are baking at 200 - 250 °C for 24 hours.
[0053] In a specific embodiment, the temperatures during plating are as follows: the temperature of the interface transition layer is 150 °C, the temperature of the photo - electric absorption layer is 165 °C, the temperature of the electron transport layer is 200 °C, the temperature of the structure transition layer is 230 °C, the temperature of the electron emission layer is 175 °C, and the temperature of the emission protection layer is 175 °C.
[0054] In a specific embodiment, during plating, the plating temperature of the interface transition layer is 150 °C, the plating temperature of the photo - electric absorption layer is 165 °C, the plating temperature of the electron transport layer is 200 °C, the plating temperature of the structure transition layer is 230 °C, the plating temperature of the electron emission layer is 175 °C, and the plating temperature of the emission protection layer is 175 °C.
[0055] On the other hand, the present application also provides a quaternary alkali cathode, on which a film layer structure is provided as described above. The cathode with this structure can reduce the dark background noise caused by structural defects and increase the escape probability of photo - generated electrons.
[0056] Example
[0057] In the following examples, the materials and instruments used are obtained from commercial channels without special instructions; the detection methods used are existing methods without special instructions.
[0058] Example 1 Preparation of a high - response and low - noise quaternary alkali cathode film layer structure
[0059] (1) Place the cathode window with a lead content of 0.1% into alcohol with an ethanol volume concentration of 95%, ultrasonically clean it at a power of 1200W for 5 minutes, then dry it in a circulating oven at a temperature of 80 °C for 8h. After drying, put it into a plasma cleaner and perform plasma cleaning with parameters of 1000W and 9MHz for 20 minutes.
[0060] (2) Install the treated cathode window into a coating fixture, and then install the fixture into a vacuum coating machine. Deposit HfO2 (hafnium oxide) at a rate of 1nm / min for 10nm as the interface passivation layer.
[0061] (3) Plasma - clean the cathode window plated with the HfO2 layer again, with the cleaning parameters the same as those in (1).
[0062] (4) After depositing the interface passivation layer and completing plasma cleaning, send the cathode window into the vacuum coating machine and deposit a silver metal layer as the conductive sealing layer at a rate of 10nm / min for 500nm.
[0063] (5) Ultrasonically clean the plated cathode window at a power of 1200 W for 5 minutes, and dry it with a nitrogen gun.
[0064] (6) Place the dried cathode window into a plasma cleaner and perform plasma cleaning at parameters of 1000 W and 9 MHz for 30 minutes.
[0065] (7) Clamp the cleaned cathode window and send it into the vacuum coating chamber, evacuate the chamber, set the baking temperature to 200 °C - 250 °C, and bake for 24 hours.
[0066] (8) Sequentially deposit an interface transition layer, a photoabsorption layer, an electron transport layer, a structure transition layer, an electron escape layer, and an escape protection layer using the photocurrent method; the temperatures during deposition are 150 °C for the interface transition layer, 165 °C for the photoabsorption layer, 200 °C for the electron transport layer, the deposition rate is 8 nm / min, 230 °C for the structure transition layer, the deposition rate is 3 nm / min, 175 °C for the electron escape layer, the deposition rate is 1 nm / min, and 175 °C for the escape protection layer, the deposition rate is 1 nm / min; the thicknesses of each film layer are 5 nm for the interface transition layer, 100 nm for the photoabsorption layer, 25 nm for the electron transport layer, 12 nm for the structure transition layer, 15 nm for the electron escape layer, and 10 nm for the escape protection layer. The other parameters not detailed are in the existing literature.
[0067] Comparative Example 1
[0068] The difference from Example 1 is that the interface passivation layer is not provided.
[0069] Detect the surface roughness of the device with the interface passivation layer deposited. The obtained results are as Figure 2 shown. It can be seen from the figure that depositing the interface passivation layer can increase the surface roughness of the device, which is beneficial to reducing the defect ratio after subsequent layer stacking and reducing the imaging noise.
[0070] Manufacture cathode windows from the devices obtained in Example 1 and Comparative Example 1 respectively according to the existing method, and measure the transmittance. The obtained results are as Figure 3 shown. It can be seen from the figure that in the wavelength band of the incident light from 380 to 980 nm, after setting the interface passivation layer, the transmittance of the device is stable at 98%. While for the device without the interface passivation layer, the transmittance in the 380 - 580 nm wavelength band decreases but the difference from the device with the passivation layer is relatively small, indicating that the passivation layer will not significantly affect the transmittance of the substrate. Without the passivation layer, direct contact between the substrate layer and the cathode film layer leads to an increase in defects and a relatively large background noise, i.e., a large EBI, and the difference between the two can reach an order of magnitude.
[0071] The EBI test results of the devices obtained in Comparative Example 1 and Example 1 are shown in the following table. The test was carried out using an equivalent background illuminance tester:
[0072] Table
[0073] Experimental group EBI / ulx Control group EBI / ulx 0.07 0.37
[0074] The device obtained in Example 1 was made into a cathode window. The physical object obtained is as Figure 4 shown. As can be seen from the figure, the cathode window is sealed within the cathode ring; the central region of the cathode window can transmit imaging photons; a blackening film is provided at the peripheral region of the cathode window to suppress stray light.
[0075] The device obtained in Example 1 was made into a cathode window. The spectral response curve of the quaternary alkali cathode obtained is as Figure 5 shown. As can be seen from the figure, it can respond within the wavelength range of 380 - 1010 nm, and has a relatively high responsivity, and the response wavelength range is wider than that of a common ternary alkali cathode.
[0076] Example 2
[0077] The difference from Example 1 is that: the thickness of the interface passivation layer is 5 nm; the thickness of the conductive sealing layer is 300 mnm; the thickness of the interface transition layer is 5 nm; the thickness of the photoabsorption layer is 100 nm; the thickness of the electron transport layer is 20 nm; the thickness of the structure transition layer is 10 nm; the thickness of the electron emission layer is 10 nm; the thickness of the emission protection layer is 5 nm.
[0078] Example 3
[0079] The difference from Example 1 is that: the thickness of the interface passivation layer is 10 nm; the thickness of the conductive sealing layer is 600 mnm; the thickness of the interface transition layer is 8 nm; the thickness of the photoabsorption layer is 120 nm; the thickness of the electron transport layer is 30 nm; the thickness of the structure transition layer is 15 nm; the thickness of the electron emission layer is 15 nm; the thickness of the emission protection layer is 10 nm.
[0080] Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent substitution on some of the technical features. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A high-response and low-noise quaternary alkali cathode film layer structure, characterized in that, Including: an interface passivation layer disposed on a quaternary alkali cathode; a conductive sealing layer disposed in a region near the periphery on the outer side surface of the interface passivation layer; an interface transition layer disposed in the central region of the outer side surface of the interface passivation layer; a photoabsorption layer disposed on the outer side surface of the interface transition layer; an electron transport layer disposed on the outer side surface of the photoabsorption layer; a structural transition layer disposed on the outer side surface of the electron transport layer; an electron escape layer disposed on the outer side surface of the structural transition layer; and an escape protection layer disposed on the outer side surface of the electron escape layer.
2. The high-response and low-noise quaternary alkali cathode film layer structure according to claim 1, wherein The thickness of the interface passivation layer is 5 - 10 nm.
3. The high-response and low-noise quaternary alkali cathode film layer structure according to claim 1, characterized in that, The thickness of the conductive sealing layer is 300 - 600 mnm; the thickness of the interface transition layer is 5 - 8 nm; the thickness of the photoabsorption layer is 100 - 120 nm.
4. The high-response and low-noise quaternary alkaline cathode film layer structure according to claim 1, characterized in that The thickness of the electron transport layer is 20 - 30 nm; the thickness of the structural transition layer is 10 - 15 nm; the thickness of the electron escape layer is 10 - 15 nm; the thickness of the escape protection layer is 5 - 10 nm.
5. The high-response and low-noise quaternary basic cathode film layer structure according to claim 1, wherein The lead content of the quaternary alkali cathode is 0.1%.
6. The high-response and low-noise quaternary alkali cathode film layer structure according to claim 1, wherein, The thickness of the interface passivation layer is 10 nm; the thickness of the conductive sealing layer is 500 nm; the thickness of the interface transition layer is 5 nm; the thickness of the photoabsorption layer is 100 nm; the thickness of the electron transport layer is 25 nm; the thickness of the structural transition layer is 12 nm; the thickness of the electron escape layer is 15 nm; the thickness of the escape protection layer is 10 nm.
7. A method for preparing a high-response and low-noise quaternary base cathode film layer structure as described in any one of claims 1 to 6, characterized in that, Including the following steps: 1) Using the cleaned cathode window as a substrate, depositing HfO2 to obtain the interface passivation layer. After plasma cleaning, depositing a silver metal layer as the conductive sealing layer, and then performing ultrasonic cleaning, plasma cleaning, and drying to obtain a coated device; 2) Using the photocurrent method, sequentially depositing on the coated surface of the coated device in the direction from the substrate outwards: the interface transition layer, the photoabsorption layer, the electron transport layer, the structural transition layer, the electron escape layer, and the escape protection layer to obtain a high-response low-noise quaternary alkali cathode film structure.
8. The method according to claim 7, characterized in that, The deposition rate of HfO2 for the interface passivation layer is 1 nm / min; the deposition rate of the silver metal layer is 10 nm / min.
9. The method according to claim 7, wherein During deposition, the deposition temperature of the interface transition layer is 150 °C, the deposition temperature of the photoabsorption layer is 165 °C, the deposition temperature of the electron transport layer is 200 °C, the deposition temperature of the structural transition layer is 230 °C, the deposition temperature of the electron escape layer is 175 °C, and the deposition temperature of the escape protection layer is 175 °C.
10. A quaternary base cathode, characterized in that, A high-response low-noise quaternary alkali cathode film structure as described in any one of claims 1 - 6 is disposed on the quaternary alkali cathode.