阅读说明：本技术 硅掺杂碳化锗膜、光学薄膜及其制备方法和应用 (Silicon-doped germanium carbide film, optical film, and preparation method and application thereof ) 是由 伏开虎 金扬利 何坤 高帅 何依雪 李宝迎 刘永华 祖成奎 于 2020-07-22 设计创作，主要内容包括：本发明的主要目的在于提供一种硅掺杂碳化锗膜、光学薄膜及其制备方法和应用。所述硅掺杂碳化锗膜组成为Ge<Sub>a1</Sub>Si<Sub>b</Sub>C<Sub>a2</Sub>,0.01≤b≤0.2,a1>0,a2>0,0.8≤a1+a2≤0.99,a1+a2+b＝1；所述光学薄膜包括基片,其材质为透红外材料；第一硅掺杂碳化锗膜,镀制于所述基片的表面。所要解决的技术问题是提供一种用于红外玻璃的功能层,使其不仅能提高碳化锗膜的硬度和抗摩擦磨损能力,同时又能保持碳化锗膜较低的应力和良好的红外透过率,获得综合性能优异的锗、硅共掺杂的红外碳基防护膜,将其制作为红外镜头应用于红外热成像系统中,可以延长其使用寿命,从而更加适于实用。(The invention mainly aims to provide a silicon-doped germanium carbide film, an optical film, and preparation methods and applications thereof. The silicon-doped germanium carbide film consists of Ge a1 Si b C a2 ，0.01≤b≤0.2，a1>0，a2>0, 0.8 and a1+ a2 and 0.99, and a1+ a2+ b is 1; the optical film comprises a substrate made of an infrared transmitting material; and the first silicon-doped germanium carbide film is plated on the surface of the substrate. The technical problem to be solved is to provide a deviceIn infrared glass's functional layer, make it can not only improve the hardness and the anti friction wearing and tearing ability of carborundum membrane, can keep the lower stress of carborundum membrane and good infrared transmissivity simultaneously again, obtain the infrared carbon base protective film of germanium, silicon co-doping that the comprehensive properties is excellent, be applied to infrared thermal imaging system with its preparation as infrared camera lens, can prolong its life to be suitable for the practicality more.)

1. A silicon-doped germanium carbide film characterized by having a composition of Ge_a1Si_bC_a2Wherein b is more than or equal to 0.01 and less than or equal to 0.2, a1>0，a2>0，0.8≤a1+a2≤0.99，a1+a2+b＝1。

2. An optical film, comprising:

the substrate is made of an infrared transmitting material;

a first silicon-doped germanium carbide film plated on the surface of the substrate; the first silicon-doped germanium carbide film consists of Ge_a1Si_bC_a2Wherein b is more than or equal to 0.01 and less than or equal to 0.2, a1>0，a2>0，0.8≤a1+a2≤0.99，a1+a2+b＝1。

3. An optical film as recited in claim 2, wherein the infrared transmissive material is selected from the group consisting of chalcogenide glass, zinc sulfide, germanium, silicon, zinc selenide, calcium fluoride, magnesium fluoride, sapphire, aluminate glass, and gallate glass.

4. The optical film of claim 2, further comprising n silicon-doped germanium carbide films sequentially deposited on the first silicon-doped germanium carbide film, wherein n is greater than or equal to 1; the composition of each layer of silicon-doped germanium carbide film is Ge_a1Si_bC_a2，0.01≤b≤0.2，a1>0，a2>0, 0.8 and a1+ a2 and 0.99, and a1+ a2+ b is 1; the optical film comprises n +1 layers of silicon-doped germanium carbide films;

and Ge in the silicon-doped germanium carbide film of the odd layers: the atomic number ratio of C is 3.5-8.8; ge in the even-numbered silicon-doped germanium carbide film: the atomic number ratio of C is 0.03-0.9;

or, the Ge content in the even number of layers of the silicon-doped germanium carbide film is as follows: the atomic number ratio of C is 3.5-8.8; ge in the silicon-doped germanium carbide film of the odd layers: the atomic number ratio of C is 0.03-0.9.

5. The preparation method of the optical film is characterized in that three elements of silicon, germanium and carbon are deposited on the surface of a clean substrate, and a silicon-doped germanium carbide film is formed on the surface of the substrate; the substrate is made of an infrared transmitting material; composition of the silicon-doped germanium carbide filmIs Ge_a1Si_bC_a2Wherein b is more than or equal to 0.01 and less than or equal to 0.2, a1>0，a2>0，0.8≤a1+a2≤0.99，a1+a2+b＝1。

6. The method according to claim 5, wherein the deposition of the three elements of silicon, germanium and carbon on the surface of the clean substrate is achieved by: three reaction gases containing silicon, germanium and carbon are introduced into the deposition chamber for chemical vapor deposition.

7. The method according to claim 5, wherein the deposition of the three elements of silicon, germanium and carbon on the surface of the clean substrate is performed by magnetron sputtering or ion beam sputtering.

8. The method according to claim 7, wherein the target material used for sputtering is a pure target formed from one of silicon, germanium, or carbon; or the target material adopted by the sputtering is a mixed target material consisting of at least two of silicon, germanium and carbon elements; the mixed target material is an embedded mixed target material or a powder hot-pressing mixed target material.

9. The method according to claim 8, wherein when the target material is a pure target, reactive gases of two other elements are introduced into the vacuum chamber during sputtering; when the target material is a mixed target material consisting of two elements, reactive gas of the other element is introduced into the vacuum chamber during sputtering.

10. An optical composite film comprising the optical thin film of any one of claims 2 or 3, and an infrared diamond-like film deposited on the first silicon-doped germanium carbide film; alternatively, it comprises the optical film of claim 4, and an infrared diamond-like film deposited on the n +1 th silicon-doped germanium carbide film.

11. An infrared thermal imaging system, comprising an infrared lens and an infrared detector, wherein the infrared detector detects a radiation source through the infrared lens, and the infrared lens is the optical film according to any one of claims 2 to 4.

Technical Field

The invention belongs to the technical field of infrared protection antireflection films, and particularly relates to a low-stress high-hardness silicon-doped germanium carbide film, an optical film, and preparation methods and applications thereof.

Background

The infrared thermal imaging system is more and more widely applied to the military and civil fields, can observe the surrounding environment at night, in heavy fog and other conditions, plays a role in early warning and monitoring, can also measure the temperature of a human body without contact, and has important significance for epidemic prevention and control of infectious diseases and the like. The infrared lens is a key component of an infrared thermal imaging system, and the infrared antireflection protective film on the surface of the infrared lens plays a vital role in the service life and the imaging quality of the infrared lens.

The infrared protective film comprises an infrared diamond-like film, an infrared germanium carbide film and the like, and the infrared diamond-like film, the infrared germanium carbide film and the like can play a role in infrared anti-reflection and physical and chemical protection on the surface of an infrared optical substrate such as chalcogenide glass, zinc sulfide, germanium, silicon and the like. Compared with the infrared diamond-like film, the infrared germanium carbide film has greatly reduced stress, so that the infrared germanium carbide film has good associativity with substrate film bases such as chalcogenide glass, zinc sulfide and the like; meanwhile, the refractive index of the germanium carbide film can be changed between 2 and 4 by adjusting the relative content of Ge element, so that film layers with different refractive indexes can be obtained, and an antireflection film system is facilitated.

However, the infrared germanium carbide film also has obvious defects, and the reduction of the stress and the reduction of the film hardness are usually accompanied, so that the physical protection performance of the infrared germanium carbide film is greatly reduced, and the resistance of the infrared germanium carbide film to sand dust and other friction and abrasion damages is reduced, so that the service life of an infrared thermal imaging system is shortened, and the application range of the infrared thermal imaging system is greatly limited.

Disclosure of Invention

The invention mainly aims to provide a low-stress high-hardness silicon-doped germanium carbide film, an optical thin film, a preparation method and application thereof, and aims to solve the technical problem of providing a functional layer for infrared glass, so that the functional layer can improve the hardness and the friction and abrasion resistance of the germanium carbide film, can keep lower stress and good infrared transmittance of the germanium carbide film, obtain a germanium and silicon co-doped infrared carbon-based protective film with excellent comprehensive performance, and can prolong the service life of the infrared carbon-based protective film when being manufactured into an infrared lens applied to an infrared thermal imaging system, thereby being more suitable for practical use.

The purpose of the invention and the technical problem to be solved are realized by adopting the following technical scheme. According to the invention, the silicon-doped germanium carbide film consists of Ge_a1Si_bC_a2Wherein b is more than or equal to 0.01 and less than or equal to 0.2, a1>0，a2>0，0.8≤a1+a2≤0.99，a1+a2+b＝1。

The purpose of the invention and the technical problem to be solved are realized by adopting the following technical scheme. According to the present invention, an optical film is provided, which includes:

the substrate is made of an infrared transmitting material;

a first silicon-doped germanium carbide film plated on the surface of the substrate; the first silicon-doped germanium carbide film consists of Ge_a1Si_bC_a2Wherein b is more than or equal to 0.01 and less than or equal to 0.2, a1>0，a2>0，0.8≤a1+a2≤0.99，a1+a2+b＝1。

The object of the present invention and the technical problems solved thereby can be further achieved by the following technical measures.

Preferably, the optical film is formed of an infrared-transmitting material selected from one of chalcogenide glass, zinc sulfide, germanium, silicon, zinc selenide, calcium fluoride, magnesium fluoride, sapphire, aluminate glass, and gallate glass.

Preferably, the optical thin film further comprises n layers of silicon-doped germanium carbide films sequentially plated on the first silicon-doped germanium carbide film, wherein n is greater than or equal to 1; the composition of each layer of silicon-doped germanium carbide film is Ge_a1Si_bC_a2，0.01≤b≤0.2，a1>0，a2>0, 0.8 and a1+ a2 and 0.99, and a1+ a2+ b is 1; the optical film comprises n +1 layers of silicon-doped germanium carbide films, wherein the Ge content in the silicon-doped germanium carbide films of the odd layers is as follows: the atomic number ratio of C is 3.5-8.8; ge in the even-numbered silicon-doped germanium carbide film: the atomic number ratio of C is 0.03-0.9; or, the Ge content in the even number of layers of the silicon-doped germanium carbide film is as follows: the atomic number ratio of C is 3.5-8.8; ge in the silicon-doped germanium carbide film of the odd layers: the atomic number ratio of C is 0.03-0.9.

The purpose of the invention and the technical problem to be solved are realized by adopting the following technical scheme. According to the preparation method of the optical film, three elements of silicon, germanium and carbon are deposited on the surface of a clean substrate, and a silicon-doped germanium carbide film is formed on the surface of the substrate; the substrate is made of an infrared transmitting material; the silicon-doped germanium carbide film consists of Ge_a1Si_bC_a2Wherein b is more than or equal to 0.01 and less than or equal to 0.2, a1>0，a2>0，0.8≤a1+a2≤0.99，a1+a2+b＝1。

The object of the present invention and the technical problems solved thereby can be further achieved by the following technical measures.

Preferably, the foregoing preparation method, wherein the deposition of the three elements of silicon, germanium and carbon on the surface of the clean substrate is implemented by the following method: three reaction gases containing silicon, germanium and carbon are introduced into the deposition chamber for chemical vapor deposition.

Preferably, the deposition of the three elements of silicon, germanium and carbon on the surface of the clean substrate is realized by magnetron sputtering or ion beam sputtering.

Preferably, in the preparation method, the target material used in the sputtering is a pure target formed by one of silicon, germanium or carbon elements; or the target material adopted by the sputtering is a mixed target material consisting of at least two of silicon, germanium and carbon elements; the mixed target material is an embedded mixed target material or a powder hot-pressing mixed target material.

Preferably, in the preparation method, when the target material is a pure target, reactive gases of two other elements are introduced into the vacuum chamber during sputtering; when the target material is a mixed target material consisting of two elements, reactive gas of the other element is introduced into the vacuum chamber during sputtering.

The purpose of the invention and the technical problem to be solved are realized by adopting the following technical scheme. According to the optical composite film provided by the invention, the optical composite film comprises the optical film and an infrared diamond-like film deposited on the first silicon-doped germanium carbide film; or the optical film comprises the optical film and an infrared diamond-like film deposited on the n +1 th layer of silicon-doped germanium carbide film.

The purpose of the invention and the technical problem to be solved are realized by adopting the following technical scheme. According to the infrared thermal imaging system provided by the invention, the infrared detector detects a radiation source through the infrared lens, wherein the infrared lens is the optical film.

By the technical scheme, the low-stress and high-hardness silicon-doped germanium carbide film and the optical film, and the preparation method and the application thereof provided by the invention at least have the following advantages:

1. according to the low-stress and high-hardness silicon-doped germanium carbide film, silicon elements are introduced into the infrared germanium carbide film to form a germanium and silicon co-doped infrared carbon-based protective film; by introducing silicon element into the film, C-C, C-Ge and C-Si sp in the film are improved³The relative content of the bond obviously improves the nano hardness (hardness and hardness of the germanium carbide film)The hardness of the infrared diamond-like film is approximate) and the friction and abrasion resistance, so that the friction and abrasion resistance of the germanium carbide film is greatly improved; meanwhile, the lower stress and the good infrared transmittance of the germanium carbide film can be kept, and the germanium and silicon co-doped infrared carbon-based protective film with excellent comprehensive performance is formed;

2. the low-stress high-hardness silicon-doped germanium carbide film provided by the invention can independently play a role in anti-reflection protection and physical and chemical protection on the surface of an infrared substrate, and also can be used as a stress transition layer and an optical matching layer between an infrared diamond-like film and the infrared substrate to prepare an infrared material which has excellent comprehensive performance and sequentially comprises an infrared glass substrate, the silicon-doped germanium carbide film and the infrared diamond-like film;

3. the low-stress high-hardness silicon-doped germanium carbide film provided by the invention is applied to an infrared thermal imaging system, so that the environmental adaptability of the film can be enhanced, and the service life of the film can be prolonged;

4. the silicon-doped germanium carbide film has good economic value in the military and civil fields.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings.

Drawings

FIG. 1 is a graph of the infrared transmission performance of a silicon-doped germanium carbide film according to the present invention;

FIG. 2 is a comparison of hardness and residual stress for silicon-doped germanium carbide films in accordance with the present invention;

fig. 3 is a schematic view of an optical film according to the present invention.

Detailed Description

To further illustrate the technical means and effects of the present invention for achieving the predetermined objects, the following detailed description will be given of a low-stress and high-hardness silicon-doped germanium carbide film, an optical film, a method for manufacturing the same, and embodiments, structures, features and effects thereof according to the present invention with reference to the accompanying drawings and preferred embodiments.

The invention provides a silicon-doped germanium carbide film which comprises Ge_a1Si_bC_a2Wherein b is more than or equal to 0.01 and less than or equal to 0.2, a1>0，a2>0，0.8≤a1+a2≤0.99，a1+a2+b＝1。

When the film is prepared, the sputtering rate of the sputtering ions to silicon element, germanium element and carbon element is different. Generally, the sputtering rates of the three elements follow the law of Ge > Si > C under the same process conditions. In the silicon-doped germanium carbide film, the content of silicon element is mainly realized by determining the preparation process parameters through a large number of experiments.

The silicon-doped germanium carbide film is formed by co-doping silicon element in the germanium carbide film, and depositing silicon atoms, carbon atoms and germanium atoms on a substrate according to a certain atomic number percentage to form a co-doped film with the silicon element atom number percentage content of 1-20%; the co-doped film has lower residual stress and higher hardness, as shown in figure 2, the figure 2 has no abscissa and is only used for expressing the performance difference of two films; the ordinate on the left side represents the residual stress of the film layer, and the ordinate on the right side represents the nano-hardness of the film layer; and the co-doped film also has better infrared transmission performance, as shown in figure 1, the abscissa of figure 1 is wavelength, and the ordinate represents transmittance.

The doping proportion of the silicon element in the silicon-doped germanium carbide film can be adjusted according to the requirement of film system performance design, and the atomic number percentage of the silicon element can be 1% -2%, 2% -3%, 3% -4%, 4% -5%, 5% -6%, 6% -7%, 7% -8%, 8% -9%, 9% -10%, 10% -11%, 11% -12%, 12% -13%, 13% -14%, 14% -15%, 15% -16%, 16% -17%, 17% -18%, 18% -19% and 19% -20%. The properties of the film are closely related to the ratio of silicon, germanium and carbon, but the law of variation of the relationship with the single element is not obvious.

Preferably, in the silicon-doped germanium carbide film, in terms of atomic number percentage, Ge: si: the proportion of C is 3-88: 1-20: 10 to 95. In the silicon-doped germanium carbide film, the ratio of Ge: the proportion of C is 0.03-8.8. Under the condition that the content of the silicon element is determined, the content of the germanium element in the film layer can be adjusted within a wider range, the refractive index of the film layer is changed within a larger range by adjusting the relative content of the germanium element, and thus the antireflection film systems with different antireflection capabilities are obtained by combining and matching various refractive indexes.

In the silicon-doped germanium carbide film, the refractive index of carbon element is the lowest and is about 2 in medium-wave and long-wave infrared wave bands, the refractive index of germanium element is higher and is about 4, the refractive index of silicon element is about 3.5, and the refractive index of the silicon-doped germanium carbide film formed by germanium, silicon and carbon is between 2 and 4. With the higher content of the carbon element, the lower the refractive index of the silicon-doped germanium carbide film is, the closer the refractive index of the carbon element is; the higher the content of the germanium element and the silicon element is, the closer the refractive index of the silicon-doped germanium carbide film is to the refractive index of the germanium element and the silicon element. By adjusting the composition structure of each film layer, a silicon-doped germanium carbide film (H) with high refractive index and a silicon-doped germanium carbide film (L) with low refractive index can be alternately plated on the surface of the infrared substrate to form an antireflection film system, so that an optical film with a structure of' substrate/H/L/H/L & cndot & ltsubstrate/H/L/H/L & cndot & gtis obtained, and further, the antireflection effect is realized in medium-wave and long-wave infrared bands.

Preferably, in the silicon-doped germanium carbide film, in terms of atomic number percentage, Ge: si: the proportion of C is 44-70: 9-14: 19 to 47, as shown in examples 1 to 5. The film layer has good binding force with the substrate, small residual stress with the substrate, compression stress/tensile stress of less than or equal to 0.05Gpa, high nano-hardness of more than or equal to 14.5Gpa, and excellent friction and abrasion resistance.

Preferably, in the silicon-doped germanium carbide film, in terms of atomic number percentage, Ge: si: the proportion of C is 51-70: 11-14: 19 to 35 as shown in example 1 and examples 3 to 5. The film layer has better bonding force with the substrate, smaller residual stress with the substrate and higher nano-hardness.

Preferably, when the silicon-doped germanium carbide film is used for designing and preparing an infrared antireflection film system, in the silicon-doped germanium carbide film (H) with a high refractive index, the ratio of Ge: the proportion of C is 3-8.8; preferably, Ge: the ratio of C may be 3.5-8.8, 4-8.8, 4.5-8.8, 5-8.8, 5.5-8.8, 6-8.8, 6.5-8.8, 7-8.8, 7.5-8.8, 8-8.8.

Preferably, when the silicon-doped germanium carbide film is used for designing and preparing an infrared antireflection film system, in the silicon-doped germanium carbide film (L) with the low refractive index, the ratio of Ge: the proportion of C is 0.03-1; preferably, Ge: the ratio of C may be 0.03-0.9, 0.03-0.8, 0.03-0.7, 0.03-0.6, 0.03-0.5, 0.03-0.4, 0.03-0.3, 0.03-0.2, 0.03-0.1.

The present invention also provides an optical film, as shown in fig. 3, which includes: a substrate 1 of infrared transmitting material; a first silicon-doped germanium carbide film formed on the surface of the substrate 1 and composed of Ge_a1Si_bC_a2Wherein b is more than or equal to 0.01 and less than or equal to 0.2, a1>0，a2>0, 0.8 and a1+ a2 and 0.99, and a1+ a2+ b are 1. The infrared transmitting material is selected from one of chalcogenide glass, zinc sulfide, germanium, silicon, zinc selenide, calcium fluoride, magnesium fluoride, sapphire, aluminate glass and gallate glass.

The optical film is prepared according to the following method: the surface of the substrate is first cleaned and then placed in a vacuum chamber for pre-sputtering.

The surface cleaning method comprises the following specific steps: an organic solvent, for example, an alcohol solution or a mixed solution of alcohol and ether is dropped into the dust-free cloth, and the surface of the substrate is wiped with the dust-free cloth.

The pre-sputtering comprises the following specific steps: putting the substrate with clean surface into a magnetron sputtering or ion beam sputtering film plating machine, and vacuumizing the vacuum chamber to 3 x 10^-3And introducing argon gas below Pa, closing the baffle, and pre-sputtering for 3-20 min.

After the surface of the substrate is cleaned and pre-sputtered, impurities on the surface of the substrate are thoroughly removed, and the substrate can be used for depositing three elements of germanium, silicon and carbon on the surface of the substrate in proportion.

The invention also provides a preparation method of the optical film, which comprises the steps of depositing three elements of silicon, germanium and carbon on the surface of the clean substrate to form a silicon-doped germanium carbide film on the surface of the substrate; wherein the substrate is made of an infrared transmitting material; the silicon-doped germanium carbide film consists of Ge_a1Si_bC_a2Wherein b is more than or equal to 0.01 and less than or equal to 0.2, a1>0，a2>0，0.8≤a1+a2≤0.99，a1+a2+b＝1。

Preferably, the three elements of silicon, germanium and carbon can be deposited on the surface of the clean substrate by a chemical vapor deposition method, and the specific process operation is as follows:

by adopting a Plasma Enhanced Chemical Vapor Deposition (PECVD) mode or a hot filament plasma chemical vapor deposition (HFCVD) mode, selecting a hydrocarbon gas (such as methane), a Si-containing gas (such as silane) and a Ge-containing gas (such as germane) as reaction gases, and controlling the proportion of the three elements in the film after film formation by regulating the flow proportion of the three gases. Meanwhile, the quality of the film layer can be further optimized by adjusting parameters such as power, heating temperature and the like.

The chemical vapor deposition technology is a method for generating a film by performing a chemical reaction on the surface of a substrate by using one or more gas-phase compounds or simple substances containing film elements. The properties of the film can be precisely controlled by the deposition process of the gas phase doping.

Preferably, the three elements of silicon, germanium and carbon can also be deposited on the surface of the clean substrate by a physical vapor deposition method, which is realized by magnetron sputtering or ion beam sputtering, and the three elements are formed by gasifying the material source-solid or liquid surface into gaseous atoms, molecules or parts of gaseous atoms and molecules into ions by a physical method under the vacuum condition, and depositing a film with a certain special function on the surface of the substrate by a low-pressure gas (or plasma) process. The specific process operation is as follows:

adjusting the radio frequency power of sputtering to 50-5000W, opening a baffle plate, and plating three elements of silicon, germanium and carbon on the surface of the substrate according to the proportion; the target material adopted by the sputtering is a pure target formed by one of silicon, germanium or carbon elements; or the target material adopted by the sputtering is a mixed target material consisting of at least two of silicon, germanium and carbon elements. The mixed target material is an embedded mixed target material or a powder hot-pressing mixed target material.

Preferably, when the single element is used as the target material, namely the adopted target material is a pure target, reactive gas containing other two elements is required to be introduced into the vacuum chamber during sputtering; when the target material is a mixed target material consisting of two elements, reactive gas containing another element is required to be introduced into the vacuum chamber during sputtering; when the target is a mixed target consisting of three elements, only argon working gas needs to be introduced into the vacuum chamber during sputtering, and no reaction gas needs to be introduced.

In the deposition process of the silicon-doped germanium carbide film, the deposition rate of the film layer is stabilized, and then the thickness of the film layer is controlled by controlling the deposition time of the film layer so as to enable the thickness of the film layer to meet the thickness of a target film layer.

The invention also provides an optical film, which also comprises n layers of silicon-doped germanium carbide films sequentially plated on the first silicon-doped germanium carbide film, wherein n is more than or equal to 1; the composition of each layer of silicon-doped germanium carbide film is Ge_a1Si_bC_a2，0.01≤b≤0.2，a1>0，a2>0, 0.8 and a1+ a2 and 0.99, and a1+ a2+ b is 1; the optical film comprises n +1 layers of silicon-doped germanium carbide films, and the n +1 layers of silicon-doped germanium carbide films are collectively called as a functional layer 2; and Ge in the silicon-doped germanium carbide film of the odd layers: the atomic number ratio of C is 3.5-8.8; ge in the even-numbered silicon-doped germanium carbide film: the atomic number ratio of C is 0.03-0.9; or, the Ge content in the even number of layers of the silicon-doped germanium carbide film is as follows: the atomic number ratio of C is 3.5-8.8; ge in the silicon-doped germanium carbide film of the odd layers: the atomic number ratio of C is 0.03-0.9. As shown in figure 3, the optical film comprises a substrate 1 and a functional layer 2, wherein the functional layer 2 comprises 3 silicon-doped silicon germanium carbide films, namely a first silicon-doped silicon germanium carbide film 21, a second silicon germanium carbide film 22 and a third silicon germanium carbide filmA silicon germanium film 23. The optical film is an infrared antireflection coating system and is used for infrared antireflection. According to different requirements of anti-reflection performance of the film layer, the refractive index of each layer is controlled by adjusting the content of germanium element and silicon element and the content of carbon element in each layer, so that the distribution with the refractive index distribution of high-low-high-low … … in sequence is formed.

The antireflection film system consists of n +1 layers of silicon-doped germanium carbide films, and the silicon-doped germanium carbide films are sequentially plated according to the preparation method of the silicon-doped germanium carbide films when the antireflection film system is prepared; the composition of each layer of silicon-doped silicon carbide germanium film is adjusted by controlling the flow of reaction gas and sputtering process parameters; the thickness of each layer of silicon-doped silicon germanium carbide film is controlled by the deposition time; after preparing a layer of silicon-doped silicon carbide germanium film, adjusting the flow of reaction gas and sputtering process parameters, and starting to prepare the next silicon-doped silicon carbide germanium film with different silicon contents; and (5) circulating operation in turn.

The invention also provides an optical composite film which comprises the optical film and an infrared diamond-like film deposited on the functional layer. The functional layer is one or more layers of silicon-doped germanium carbide films. The preparation method of the infrared material comprises the following steps: the optical film with the surface plated with the silicon-doped germanium carbide film is prepared according to the method, and then the infrared diamond-like film is sputtered on the surface by magnetron sputtering or ion beam sputtering.

The silicon-doped germanium carbide film is used as a stress transition layer and an optical matching layer between the infrared diamond-like film and the infrared glass substrate, and through the comprehensive performance action of the infrared diamond-like film and the silicon-doped germanium carbide film, the stress between the functional layer and the infrared glass substrate is low, the surface of the functional layer has extremely high hardness, and the prepared infrared material has excellent comprehensive performance.

The invention further provides an infrared thermal imaging system which comprises an infrared lens and an infrared detector, wherein the infrared detector detects a radiation source through the infrared lens, and the infrared lens is the optical film.

The present invention will be further described with reference to the following examples, but the present invention is not limited thereto.