Silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible invisibility and preparation method thereof

Abstract

The application discloses a silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealth and a preparation method thereof, and belongs to the technical field of functional thin film materials. The silicon-based photonic crystal is composed of a substrate, an infrared light band film layer and a visible light band film layer from bottom to top, the infrared light band film layer is composed of thin film layers of high and low refractive index materials with different thicknesses which are sputtered and deposited alternately, and the most surface visible light band film layer is composed of a thin film layer of low refractive index material. The total layer number of the silicon-based photonic crystal is 12-16. The application is suitable for electromagnetic wave detectors of different wavelengths; can realize selective low emissivity, achieve reasonable utilization of non-infrared atmospheric windows for radiation heat dissipation and laser compatible stealth effect with 10.6 mu m; can realize camouflage colors matched with different environments such as forests, oceans and deserts, achieve visible light stealth compatible with infrared / laser stealth; the preparation process does not need to replace target materials, realizes in-situ integrated preparation, realizes control of film layer thickness and uniformity through optimization of sputtering parameters, and has high film forming quality.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of functional thin film materials, and relates to a silicon-based photonic crystal capable of achieving effective heat dissipation and infrared / laser / visible light compatible stealth and a preparation method thereof. BACKGROUND

[0002] With the wide application of imaging detection technology, infrared / laser / visible light compatible stealth has become an important direction of military technology development. According to the Stefan-Boltzmann law, the total radiation exitance of an actual object is proportional to the surface temperature and the surface emissivity of the object. Therefore, there are mainly two measures to reduce the infrared radiation of a target: one is to reduce the emissivity of the target surface; and the other is to control the temperature of the target surface. According to the Kirchhoff infrared theory, the emissivity of an object is proportional to the absorption rate, so it is necessary to seek a material with high reflectivity and low absorption rate to achieve the infrared stealth effect at the atmospheric window of 3-5 μm and 8-14 μm. Traditional infrared low-emissivity coatings are based on the low-emissivity characteristics of natural materials such as metals or semiconductors, and cannot obtain lower emissivity and selective low-emissivity effect, and it is more difficult to achieve compatible stealth. Therefore, designing and preparing a new type of infrared stealth material capable of achieving effective heat dissipation and laser / visible light compatible stealth has become a current research hotspot.

[0003] From the current development status of infrared stealth materials, traditional infrared stealth coatings are difficult to meet the comprehensive requirements of selective low-emissivity and compatible stealth proposed by the increasingly improved infrared stealth technology. Therefore, it is necessary to explore infrared stealth metamaterials and superstructures. Photonic crystals are a kind of artificial structure crystals formed by arranging multiple dielectric materials with different dielectric constants in space in a certain period. Photonic crystals have great development space and good application prospect in infrared / laser / visible light compatible stealth by using photonic bandgap, photonic localization and surface plasmon interference characteristics. For example, patent 201510232577.X discloses a structure design of photonic crystals, which realizes a low emissivity of below 0.1 at 3-5 μm and 8-14 μm, and realizes a high emissivity of above 0.6 at 5-8 μm non-window band, achieving the effects of selective low-emissivity and effective heat dissipation. N Patent 202110068134.7 discloses a structure design and preparation method of one-dimensional hetero-photonic crystals, and the photonic crystals prepared on a quartz substrate by an electron beam deposition method have an average emissivity of 0.056 and 0.223 at 3-5 μm and 8-14 μm respectively, and an average emissivity of 0.553 at 5-8 μm. N N Patent 201311405840.6 discloses a [Ge / ZnSe] photonic crystal containing a defect layer.​N and [Ge / ZnS] N Photonic crystal structure, which realizes high reflectivity of greater than 0.95 at 3-5 μm and 8-14 μm and low reflectivity of less than 0.05 at 10.6 μm wavelength. Patent 201910956785.2 discloses a [Ge / ZnS] N Photonic crystal structure design and preparation method, the photonic crystal prepared by electron beam evaporation method realizes high reflectivity of greater than 0.8 at 3-5 μm and 8-14 μm, low reflectivity of less than 0.5 at 5-8 μm non-window waveband, low reflectivity of less than 0.2 at 10.6 μm wavelength, and color is formed by using a surface ZnS layer. The above patent attempts to realize selective low emissivity and compatible stealth by constructing a photonic crystal, but the stealth performance and compatibility need to be further improved. And most of the photonic crystals have more types of elements in the material itself and too many film layer periods, which causes the need to replace the evaporation or sputtering target in the preparation process, and the process is complex and time-consuming.

[0004] Si is a kind of semiconductor material with abundant reserves and mature purification technology, Si and its oxide SiO2 have stable chemical properties, high hardness, small thermal expansion coefficient and excellent moisture resistance under service conditions, which can meet the application needs. Through retrieval, at present, [Si / SiO2] N The structure design and preparation method of silicon-based photonic crystal have not been reported. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the deficiencies and defects mentioned in the above background art, and to provide a silicon-based photonic crystal that can realize infrared / laser / visible light compatible stealth, and also to provide a process simple, excellent performance of infrared / laser / visible light compatible stealth silicon-based photonic crystal in-situ integrated preparation process. Realize high reflectivity of infrared detection window (3-5 μm, 8-14 μm), low reflectivity of non-infrared detection window (5-8 μm), low reflectivity of CO2 laser detector wavelength (10.6 μm), and color for optical camouflage in visible light band.

[0006] According to the one-dimensional photonic crystal photonic bandgap theory, the larger the refractive index ratio of high and low refractive index materials, the wider the high reflection zone (R≥80%) formed in the infrared waveband. Theoretical calculation by using the transfer matrix method shows that when n H / n SWhen the value is greater than 1.92, the high reflection region formed by the photonic crystal can completely cover the atmospheric window band. Therefore, the film layer material of the photonic crystal in the infrared light band is usually combined with high refractive index materials such as Ge, Te, Si, etc. and low refractive index materials such as MgF2, CaF2, YbF3, SiO2, TiO2, ZnS, ZnSe, etc. In addition, with the increase of the number of layers of the photonic crystal film system, the same phase light beams reflected from all interfaces of the film system are accumulated, the constructive interference becomes more and more obvious, and the reflection effect increases. However, when the number of layers of the film system is too large, on the one hand, the film layer processing technology is difficult, and on the other hand, the increase of the material internal stress leads to the decrease of the film forming quality of the photonic crystal or the increase of the infrared loss due to dispersion, extinction, etc., which damages the infrared stealth capability. Therefore, the total number of layers of the high and low refractive index material thin film layers of the photonic crystal should be designed within a reasonable range.

[0007] In order to achieve the above-mentioned purposes, the technical scheme adopted by the present application is as follows:

[0008] A silicon-based photonic crystal structure capable of realizing infrared / laser / visible light compatible stealth is composed of a substrate, an infrared light band film layer and a visible light band film layer. The infrared light band film layer is composed of high and low refractive index material thin film layers of different thicknesses which are sputtered and deposited alternately. The visible light band film layer is composed of a low refractive index material thin film layer. The total number of layers of the high and low refractive index material thin film layers is 12-16, the thickness of each film layer of the infrared light band film layer is in the range of λ1 / (4n H ) to λ2 / (4n S ), and the thickness of the visible light band film layer is less than λ1 / (4n s ). Herein, λ1<λ2, λ1 and λ2 are 3-14 μm, n H and n S are the refractive indexes of the high and low refractive index material thin film layers, respectively.

[0009] As a preferred embodiment, the substrate material is selected from inorganic non-metallic base composite material, metal base composite material, flexible organic material, etc. Further, the substrate material is preferably single crystal silicon wafer, aluminum base composite material and polyimide.

[0010] As a preferred embodiment, the high refractive index material of the infrared light band film layer includes Ge, Te, Si, etc., the low refractive index material includes MgF2, CaF2, YbF3, SiO2, TiO2, ZnS, ZnSe, etc., and the material of the visible light band film layer at the outermost layer is low refractive index material such as MgF2, CaF2, YbF3, SiO2, TiO2, ZnS, ZnSe, etc. Further, the high refractive index material is preferably Si, and the low refractive index material is preferably SiO2. The refractive index of Si is about 3.40, the refractive index of SiO2 is about 1.45, and the refractive index ratio of the two is 2.34 (greater than 1.92), which can meet the requirement that the [Si / SiO2]N The photonic crystal high reflection band covers 3-5 μm and 8-14 μm atmospheric windows, and realizes good infrared stealth performance. Si and SiO2 have stable chemical properties under service conditions, high hardness, small thermal expansion coefficient, and good moisture resistance, and can meet the needs of practical applications. Si and SiO2 thin films are prepared by magnetron sputtering of a Si target, and silicon-based [Si / SiO2] N The photonic crystal is prepared in situ and integrally.

[0011] As preferred, the total number of thin film layers of the high and low refractive index materials is 12, and from the light incident direction to the substrate, the deposition thicknesses of the layers are as follows: the most surface visible light band film layer: SiO2 thickness of 0.07-0.11 μm (different thicknesses are selected according to different specific environmental requirements such as forests, oceans, and deserts); the infrared light band film layer: Si thickness of 0.85±0.01 μm, SiO2 thickness of 1.36±0.01 μm, Si thickness of 0.85±0.01 μm, SiO2 thickness of 0.77±0.01 μm, Si thickness of 0.27±0.01 μm, SiO2 thickness of 0.61±0.01 μm, Si thickness of 0.24±0.01 μm, SiO2 thickness of 0.61±0.01 μm, Si thickness of 0.65±0.01 μm, SiO2 thickness of 1.64±0.01 μm, Si thickness of 0.83±0.01 μm, and the total thickness is about 8.68 μm.

[0012] The silicon-based photonic crystal can meet the following requirements:

[0013] The average reflectivity of light in the 3-5 μm band is above 0.95;

[0014] The average reflectivity of light in the 8-14 μm band is above 0.90;

[0015] The reflectivity of light in the 10.6 μm band is below 0.02;

[0016] The average band range in which the reflectivity is less than 80% near 10.6 μm is less than 0.50 μm;

[0017] The average reflectivity of light in the 5-8 μm band is below 0.55, and effective heat dissipation is realized;

[0018] Different surface layer colors are realized to meet the requirements of different environmental visible light stealth.

[0019] The silicon-based photonic crystal that can realize infrared / laser / visible light compatible stealth can realize infrared / laser compatible stealth, and the principle is that the photonic crystal has different thin film layer thicknesses to produce a photonic band gap, so that it has a blocking effect on photons of specific wavelengths or bands, thereby achieving selective low emissivity and laser stealth compatibility.

[0020] The principle of realizing different colors of visible light of the infrared / laser / visible light compatible stealth silicon-based photonic crystal is that the thickness of the second layer of silicon is 0.85±0.01 μm from the incident direction, so that the silicon layer in the visible light band can be regarded as having a large enough optical thickness, and other film layers except the surface layer do not affect the reflection spectrum of the visible light band, and the surface layer also does not affect the reflection spectrum of the infrared band. At this time, the thickness change of the surface SiO2 layer brings about the equal inclination interference of the specific wave band of visible light, that is, the adjustment of the visible light reflection spectrum, and then the color of the surface SiO2 layer with different thicknesses can be judged according to the peak value method and the mixing rule of colored light, so as to select the application for different specific environments.

[0021] As a general technical concept, another object of the present application provides a preparation method of the above-mentioned infrared / laser / visible light compatible stealth silicon-based photonic crystal, comprising the following steps:

[0022] (1) Preparation of an infrared light band film layer

[0023] 1.1) Substrate cleaning: prepare the substrate material, and sequentially ultrasonically clean with acetone, deionized water and anhydrous ethanol for 5-15 min, and dry;

[0024] 1.2) Argon gas is introduced into the chamber, and a high refractive index Si thin film layer is prepared by using a Si target by a magnetron sputtering method;

[0025] 1.3) After the high refractive index layer reaches the designed thickness, the argon gas is kept while a certain partial pressure of oxygen is introduced, and a low refractive index SiO2 thin film layer is prepared by using the same Si target;

[0026] 1.4) After the low refractive index SiO2 thin film layer reaches the designed thickness, the oxygen flow is closed, and the high refractive index Si thin film layer is continuously prepared in the argon environment;

[0027] 1.5) Repeat steps 1.3)-1.4) for a total of 5-7 cycles, and by adjusting the working gas atmosphere and process parameters, an infrared light band film layer is prepared in situ and integrated.

[0028] (2) Preparation of a visible light band film layer

[0029] After the preparation of the infrared light band film layer in step (1) is completed, argon-oxygen mixed gas is introduced into the same chamber, and a low refractive index SiO2 thin film layer is prepared as the surface layer by using the same Si target.

[0030] The preparation method of the silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealthiness, preferably, in the step (1), the sputtering conditions of the magnetron sputtering high-refractive Si film layer include that the purity of the silicon target is higher than 4N, the substrate temperature is 550-650 DEG C, the sputtering power is 90-110 W, the working pressure is 0.1-0.3 Pa, and the deposition time is 25-120 min; the sputtering conditions of the magnetron sputtering low-refractive SiO2 film layer include that the purity of the silicon target is higher than 4N, the oxygen partial pressure is 10-20%, the substrate temperature is 550-650 DEG C, the sputtering power is 110-130 W, the working pressure is 0.1-0.3 Pa, and the deposition time is 190-530 min.

[0031] The preparation method of the silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealthiness, preferably, in the step (2), the sputtering conditions of the magnetron sputtering low-refractive SiO2 film layer include that the purity of the silicon target is higher than 4N, the oxygen partial pressure is 10-20%, the substrate temperature is 550-650 DEG C, the sputtering power is 110-130 W, the working pressure is 0.1-0.3 Pa, and the deposition time is 20-35 min (different deposition times are selected according to different specific environment requirements such as forest, ocean and desert).

[0032] The present application has the following beneficial effects: (1) a simple structure design of the silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealthiness is proposed for different wavelength electromagnetic wave detector technologies; (2) selective low emissivity is realized by adjusting the thickness of each film layer of the photonic crystal, so that the non-infrared atmospheric window is reasonably utilized for radiation heat dissipation and the compatible stealth effect with 10.6 mu m laser is achieved; (3) the equal inclination interference of different wavelengths of visible light is generated by using the variable thickness of the surface SiO2 layer, so that the camouflage color matched with different environments is realized, and the visible light stealth compatible with infrared / laser stealth is achieved; (4) the target material does not need to be replaced in the preparation process, the in-situ integrated preparation is realized, and the control of the film layer thickness and uniformity is realized by optimizing the magnetron sputtering parameters, so that the film quality is high. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The design schematic of the silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealthiness in the embodiment 1 of the present application is shown.

[0034] Figure 2 The reflectivity spectrum of the silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealthiness in the embodiment 1 of the present application in the 2-22 mu m wave band is shown.

[0035] Figure 3 The visible light wave band reflectivity spectrum of the silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealthiness in the embodiment 1 of the present application when the thickness of the surface SiO2 layer is 90 nm is shown.

[0036] Figure 4 Influence of the thickness of the SiO2 layer on the reflectivity spectrum of the infrared / laser / visible light compatible stealth silicon-based photonic crystal of Example 1 in the present application in the 2-22 μm wave band.

[0037] Figure 5 Reflectivity spectrum of the infrared / laser / visible light compatible stealth silicon-based photonic crystal of Example 2 in the present application in the 2-22 μm wave band.

[0038] Figure 6 Reflectivity spectrum of the visible light wave band of the infrared / laser / visible light compatible stealth silicon-based photonic crystal of Example 2 in the present application when the thickness of the SiO2 layer on the surface is 70 nm.

[0039] Figure 7 Reflectivity spectrum of the infrared / laser / visible light compatible stealth silicon-based photonic crystal of Example 3 in the present application in the 2-22 μm wave band.

[0040] Figure 8 Reflectivity spectrum of the visible light wave band of the infrared / laser / visible light compatible stealth silicon-based photonic crystal of Example 3 in the present application when the thickness of the SiO2 layer on the surface is 100 nm. DETAILED DESCRIPTION

[0041] In order to better understand the present application, the present application is further described below through examples, which are only used to explain the present application and will not constitute any limitation on the present application.

[0042] Example 1

[0043] The infrared / laser / visible light compatible stealth silicon-based photonic crystal of Example 1 is prepared by in-situ integrated coating with a Si target in a magnetron sputtering device as shown in Figure 1 The steps are as follows:

[0044] (1) Preparation of the infrared light wave band film layer

[0045] 1.1) Substrate cleaning: prepare a single crystal Si substrate, and sequentially clean with acetone, deionized water and anhydrous ethanol for 10 min by ultrasonic cleaning, and dry;

[0046] 1.2) Introduce argon into the chamber, and prepare a high refractive index Si thin film layer by using a Si target by a magnetron sputtering method;

[0047] 1.3) After the high refractive index layer reaches the designed thickness, keep the argon while introducing a certain partial pressure of oxygen, and prepare a low refractive index SiO2 thin film layer by using the same Si target;

[0048] 1.4) After the low-refractive SiO2 film layer reaches the designed thickness, the oxygen flow is closed, and the high-refractive Si film layer is prepared in an argon environment;

[0049] 1.5) The above steps 1.3)-1.4) are repeated for a total of 5 cycles, and the infrared light wave band film layer is prepared in situ by adjusting the working gas atmosphere and process parameters;

[0050] (2) Preparation of a visible light wave band film layer

[0051] After the preparation of the infrared light wave band film layer in the same chamber according to the above step (1), argon-oxygen mixed gas is introduced, and the outermost low-refractive SiO2 film layer is prepared by using the same Si target.

[0052] In the above preparation method, in the step (1), the sputtering process for preparing the Si film is as follows: the purity of the silicon target is higher than 4N, the substrate temperature is 600℃, the sputtering power is 100W, and the working gas pressure is 0.2Pa.

[0053] In the above preparation method, in the steps (1) and (2), the sputtering process for preparing the SiO2 film is as follows: the purity of the silicon target is higher than 4N, the oxygen partial pressure is 15%, the substrate temperature is 600℃, the sputtering power is 120W, and the working gas pressure is 0.2Pa.

[0054] When depositing thin films of the same material with different designed thicknesses, the sputtering conditions are the same during repeated sputtering, and only the deposition time needs to be adjusted. From the light incident direction to the substrate, the specific deposition time of each layer is 28min, 119min, 431min, 119min, 244min, 39min, 193min, 33min, 193min, 91min, 520min, and 116min, respectively. The specific deposition thickness of each layer is as follows: the outermost visible light wave band film layer: the thickness of SiO2 is 0.09μm (the thickness is selected according to the requirements of forest environment); the infrared light wave band film layer: the thickness of Si is 0.85±0.01μm, the thickness of SiO2 is 1.36±0.01μm, the thickness of Si is 0.85±0.01μm, the thickness of SiO2 is 0.77±0.01μm, the thickness of Si is 0.27±0.01μm, the thickness of SiO2 is 0.61±0.01μm, the thickness of Si is 0.24±0.01μm, the thickness of SiO2 is 0.61±0.01μm, the thickness of Si is 0.65±0.01μm, the thickness of SiO2 is 1.64±0.01μm, and the thickness of Si is 0.83±0.01μm, with a total thickness of about 8.68μm. A silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealth is obtained.

[0055] As Figure 2As shown, the silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealth can realize the average high reflectivity of 0.962 in the infrared atmospheric window 3-5 μm band and 0.930 in the 8-14 μm band, and the average low reflectivity of 0.515 in the infrared non-atmospheric window band 5-8 μm. Under the condition that the structure temperature is greater than the atmospheric temperature, effective heat dissipation can be realized. At the same time, the low reflectivity at 10.6 μm of the CO2 laser detector is 0.004, and the band range with reflectivity less than 80% is only 0.484 μm, indicating that the laser stealth and the 8-14 μm infrared stealth are well compatible.

[0056] As shown in Figure 3 , the thickness of the SiO2 film for forming color on the surface of Example 1 is 90 nm, and the reflectivity peak position is 532.916 nm, falling within the green visible light range 492-577 nm, so that the camouflage color matching the forest environment is obtained. Figure 4 As shown in , when the thickness of the SiO2 film for forming color on the surface is 90 nm, the infrared reflectivity spectrum of the entire silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealth in the mid-infrared band is almost unaffected, and the visible light stealth and the infrared / laser stealth have excellent compatibility.

[0057] Example 2

[0058] Example 2

[0059] (1) Preparation of infrared light band film layer

[0060] 1.1) Substrate cleaning: prepare an aluminum-based composite material substrate, and ultrasonically clean with acetone, deionized water and anhydrous ethanol in sequence for 5 min, and dry;

[0061] 1.2) Argon is introduced into the chamber, and a high refractive index Si film layer is prepared by using a Si target by a magnetron sputtering method;

[0062] 1.3) After the high refractive index layer reaches the designed thickness, the argon is kept while a certain partial pressure of oxygen is introduced, and a low refractive index SiO2 film layer is prepared by using the same Si target;

[0063] 1.4) After the low refractive index SiO2 film layer reaches the designed thickness, the oxygen flow is closed, and the high refractive index Si film layer is continuously prepared in the argon environment;

[0064] 1.5) Repeat steps 1.3)-1.4) for a total of 6 cycles, and by adjusting the working gas atmosphere and process parameters, an infrared light band film layer is prepared in situ and integrated;

[0065] (2) Preparation of visible light band film layer

[0066] After the preparation of the infrared light band film layer in step (1) above, the argon-oxygen mixed gas is introduced, and the low refractive index SiO2 film layer is prepared on the top layer by using the same Si target.

[0067] In the step (1) above, the sputtering process for preparing the Si film is as follows: the purity of the silicon target is higher than 4N, the substrate temperature is 550℃, the sputtering power is 90W, and the working pressure is 0.1Pa.

[0068] In the steps (1) and (2) above, the sputtering process for preparing the SiO2 film is as follows: the purity of the silicon target is higher than 4N, the oxygen partial pressure is 20%, the substrate temperature is 650℃, the sputtering power is 130W, and the working pressure is 0.3Pa.

[0069] When depositing the thin films of the same material with different designed thicknesses, the sputtering conditions are repeated, and only the deposition time needs to be adjusted. From the light incident direction to the substrate, the specific deposition time of each layer is 22min, 101min, 365min, 101min, 206min, 33min, 165min, 28min, 165min, 77min, 441min, 98min, 244min, and 80min, respectively. The specific deposition thickness of each layer is as follows: the top visible light band film layer: SiO20.07μm (the thickness is selected according to the requirements of the marine environment); the infrared light band film layer: Si thickness 0.72±0.01μm, SiO2 thickness 1.15±0.01μm, Si thickness 0.72±0.01μm, SiO2 thickness 0.65±0.01μm, Si thickness 0.24±0.01μm, SiO2 thickness 0.52±0.01μm, Si thickness 0.20±0.01μm, SiO2 thickness 0.52±0.01μm, Si thickness 0.55±0.01μm, SiO2 thickness 1.39±0.01μm, Si thickness 0.70±0.01μm, SiO2 thickness 0.77±0.01μm, Si thickness 0.57±0.01μm, and the total thickness is about 8.70μm. The silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealth is obtained.

[0070] As Figure 5As shown, the silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealth can realize an average high reflectivity of 0.962 in the infrared atmospheric window 3-5 μm band and 0.930 in the 8-14 μm band, an average low reflectivity of 0.516 in the infrared non-atmospheric window band 5-8 μm, and effective heat dissipation under the condition that the structure temperature is greater than the atmospheric temperature. At the same time, the low reflectivity at 10.6 μm of the CO2 laser detector is 0.009, and the band range with a reflectivity less than 80% is only 0.476 μm, indicating that the laser stealth and the 8-14 μm infrared stealth are well compatible.

[0071] As shown in Figure 6 the surface of the SiO2 film for forming color in Example 2 is 70 nm thick, and the reflectivity peak position is 443.922 nm, falling within the blue visible light range 435-450 nm, thus obtaining a camouflage color matching the marine environment. When the surface of the SiO2 film for forming color is 70 nm thick, it is greatly different from the second layer of silicon with a thickness of 0.72 μm, and the infrared reflectivity spectrum of the entire silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealth in the mid-infrared band is almost unaffected, and the visible light stealth and the infrared / laser stealth have excellent compatibility.

[0072] Example 3

[0073] The silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealth in Example 3 is obtained by in-situ integrated plating of a Si target in a magnetron sputtering device. The steps are as follows:

[0074] (1) Preparation of infrared light band film layer

[0075] 1.1) Substrate cleaning: prepare a polyimide substrate, and ultrasonically clean it with acetone, deionized water and anhydrous ethanol in sequence for 15 min, and dry it;

[0076] 1.2) Introduce argon into the chamber, and prepare a high refractive index Si film layer by using a Si target by a magnetron sputtering method;

[0077] 1.3) After the high refractive index layer reaches the designed thickness, keep the argon and introduce a certain partial pressure of oxygen, and prepare a low refractive index SiO2 film layer by using the same Si target;

[0078] 1.4) After the low refractive index SiO2 film layer reaches the designed thickness, close the oxygen flow, and continue to prepare a high refractive index Si film layer in an argon environment;

[0079] 1.5) Repeat steps 1.3)-1.4) for a total of 7 cycles, and in-situ integrally prepare the infrared light band film layer by adjusting the working gas atmosphere and process parameters;

[0080] (2) Preparation of visible light band film layer

[0081] After the preparation of the infrared light band film layer in step (1) above, the argon-oxygen mixed gas is introduced, and the low refractive index SiO2 film layer is prepared on the top layer using the same Si target.

[0082] In the above preparation method, in step (1), the sputtering process for preparing the Si film is as follows: the purity of the silicon target is better than 4N, the substrate temperature is 650℃, the sputtering power is 110W, and the working pressure is 0.3Pa.

[0083] In the above preparation method, in steps (1) and (2), the sputtering process for preparing the SiO2 film is as follows: the purity of the silicon target is better than 4N, the oxygen partial pressure is 10%, the substrate temperature is 550℃, the sputtering power is 110W, and the working pressure is 0.1Pa.

[0084] When depositing thin films of the same material with different designed thicknesses, the sputtering conditions are repeated, and only the deposition time needs to be adjusted. From the light incident direction to the substrate, the specific deposition time of each layer is 32min, 88min, 317min, 88min, 180min, 29min, 146min, 25min, 146min, 67min, 384min, 85min, 212min, 70min, 158min, and 94min, respectively. The specific deposition thickness of each layer is as follows: the top visible light band film layer: SiO2 thickness of 0.10μm (thickness selected according to the desert environment requirement); the infrared light band film layer: Si thickness of 0.63±0.01μm, SiO2 thickness of 1.00±0.01μm, Si thickness of 0.63±0.01μm, SiO2 thickness of 0.57±0.01μm, Si thickness of 0.21±0.01μm, SiO2 thickness of 0.46±0.01μm, Si thickness of 0.18±0.01μm, SiO2 thickness of 0.46±0.01μm, Si thickness of 0.48±0.01μm, SiO2 thickness of 1.21±0.01μm, Si thickness of 0.61±0.01μm, SiO2 thickness of 0.67±0.01μm, Si thickness of 0.50±0.01μm, SiO2 thickness of 0.50±0.01μm, Si thickness of 0.67±0.01μm, and the total thickness is about 8.78μm. A silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealth is obtained.

[0085] As Figure 7As shown, the silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealth can realize average high reflectivity of 0.961 in the infrared atmospheric window 3-5 μm band, 0.929 in the 8-14 μm band, average low reflectivity of 0.514 in the infrared non-atmospheric window band 5-8 μm, and effective heat dissipation under the condition that the structure temperature is greater than the atmospheric temperature. At the same time, it has low reflectivity of 0.013 at 10.6 μm of the CO2 laser detector, and the band range with reflectivity less than 80% is only 0.484 μm, indicating that the laser stealth and the 8-14 μm infrared stealth are well compatible.

[0086] As shown in Figure 8 the surface of the SiO2 film for forming color is 100 nm, and the reflectivity peak position is 592.046 nm, falling in the yellow visible light range 577-597 nm, so that the camouflage color matched with the desert environment is obtained. When the surface of the SiO2 film for forming color is 100 nm, it is very different from the second layer silicon thickness 0.63 μm, and the infrared reflectivity spectrum of the entire silicon-based photonic crystal capable of realizing infrared / laser / visible light compatible stealth in the mid-infrared band is almost not affected, and the visible light stealth and the infrared / laser stealth have excellent compatibility.

[0087] Comparative Example 1

[0088] Patent

CN 110703370B, a multi-band effective compatible heat dissipation functional infrared stealth material

[0089] The above is a detailed description of the present application combined with specific examples, and cannot be regarded as limiting the specific implementation of the present application to these descriptions. For those skilled in the art to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be regarded as falling within the scope of the present application.

Claims

1. A silicon-based photonic crystal capable of achieving infrared / laser / visible light compatible stealth, characterized in that: The silicon-based photonic crystal is composed of a substrate, an infrared band film layer and a visible light band film layer from bottom to top; the infrared band film layer is composed of high and low refractive index material thin film layers of different thicknesses deposited by alternating sputtering; the visible light band film layer is composed of a low refractive index material thin film layer; the total number of layers of the silicon-based photonic crystal is 12 to 16, and the thickness of each film layer of the infrared band film layer ranges from λ1 / (4n H )~λ2 / (4n S ), the film thickness in the visible light band is less than λ1 / (4n s ), where λ1<λ 2， λ1,λ2 are 3~14 μm, n H , n S are the refractive indices of the high and low refractive index material film layers respectively; According to different practical application requirements, the substrate material is selected from inorganic non-metallic composite materials, metal-based composite materials, and flexible organic materials; The high refractive index material of the infrared light band film layer is Si, and the low refractive index material is SiO2; The low refractive index material of the outermost visible light band film layer is SiO2.

2. The silicon-based photonic crystal capable of achieving infrared / laser / visible light compatible stealth according to claim 1, characterized in that: The substrate material includes single crystal silicon wafer, aluminum-based composite material, titanium-based composite material, polyvinyl alcohol or polyimide.

3. The silicon-based photonic crystal capable of achieving infrared / laser / visible light compatible stealth according to claim 1, characterized in that: The silicon-based photonic crystal has a total of 12 layers. From the light incident direction to the substrate, the deposition thickness of each layer is as follows: the outermost visible light band film layer: SiO2 thickness 0.07~0.11µm; infrared light band film layer: Si thickness 0.85±0.01µm, SiO2 thickness 1.36±0.01µm, Si thickness 0.85±0.01 µm, SiO2 thickness 0.77±0.01µm, Si thickness 0.27±0.01 µm, SiO2 thickness 0.61±0.01µm, Si thickness 0.24±0.01 µm, SiO2 thickness 0.61±0.01 µm, Si thickness 0.65±0.01 µm, SiO2 thickness 1.64±0.01 µm, Si thickness 0.83±0.01µm, and the total thickness is approximately 8.68 µm.

4. A silicon-based photonic crystal capable of achieving infrared / laser / visible light compatible stealth according to any one of claims 1 to 3, characterized in that: The silicon-based photonic crystal can meet the following requirements: The average reflectivity of light in the 3~5µm band is above 0.95; The average reflectivity of light in the 8~14µm band is above 0.90; The reflectivity of light in the 10.6µm band is below 0.02; The average wavelength range where the reflectivity is less than 80% near 10.6 μm is less than 0.50 μm; The average reflectivity of light in the 5~8µm band is below 0.55, achieving effective heat dissipation; Achieve different surface layer colors to meet visible light stealth requirements in different environments.

5. A method for preparing a silicon-based photonic crystal capable of achieving infrared / laser / visible light compatible stealth according to any one of claims 1 to 4, comprising the following steps: (1) Preparation of infrared light band film layer 1.1) Substrate cleaning: Prepare the substrate material and ultrasonically clean it with acetone, deionized water, and anhydrous ethanol in sequence, and then dry it; 1.2) Argon gas is introduced into the chamber, and a high refractive index Si thin film layer is prepared using a Si target by magnetron sputtering; 1.3) After the high refractive index layer reaches the designed thickness, retain the argon gas while introducing a certain partial pressure of oxygen to prepare a low refractive index SiO2 thin film layer using the same Si target; 1.4) After the low-refractive-index SiO2 thin film layer reaches the designed thickness, turn off the oxygen flow and continue to prepare the high-refractive-index Si thin film layer in an argon environment; 1.5) Repeat steps 1.3)-1.4) for a total of 5-7 cycles, adjusting the working gas atmosphere and process parameters to achieve an in-situ integrated infrared film. (2) Preparation of visible light band film After completing the infrared band film preparation in the same chamber following the above step (1), an argon-oxygen mixed gas is introduced and the outermost low-refractive-index SiO2 thin film layer is prepared using the same Si target.

6. The method for preparing a silicon-based photonic crystal capable of achieving infrared / laser / visible light compatible stealth according to claim 5, characterized in that: In the step (1), the sputtering conditions of the magnetron sputtering high refractive index Si thin film layer include: silicon target purity better than 4N, substrate temperature of 550-650°C, sputtering power of 90-110 W, working gas pressure of 0.1-0.3 Pa, and deposition time of 30-120 min; The sputtering conditions of the magnetron sputtering low refractive index SiO2 thin film layer include: silicon target purity better than 4N, oxygen partial pressure of 10~20%, substrate temperature of 550~650℃, sputtering power of 110~130 W, working gas pressure of 0.1~0.3 Pa, and deposition time of 190~530 min.

7. The method for preparing a silicon-based photonic crystal capable of achieving infrared / laser / visible light compatible stealth according to claim 5, characterized in that: In the step (2), the sputtering conditions of the magnetron sputtering low refractive index SiO2 thin film layer include: silicon target purity better than 4N, oxygen partial pressure of 10~20%, substrate temperature of 550~650℃, sputtering power of 110~130W, working gas pressure of 0.1~0.3 Pa, and deposition time of 20~35min.

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