CN107179571A - A kind of visible ultra-wideband absorber and preparation method thereof - Google Patents

Abstract

Infrared broad band absorber and preparation method thereof is arrived the invention discloses one kind is visible.The device is made up of sandwich construction, is metal back layer, polymer particles layers, metal intermediate layer, dielectric layer and metal outer successively upwards from substrate.Absorber operation wavelength can covering visible light wave band (0.4~0.8 μm), shortwave (1.1~3 μm), medium wave (3~6 μm) and long wave (6~14 μm) infrared band.Peak absorbance rate A may be up to 99%, and full width at half maximum (FWHM) is up to 2 μm.The absorber has that absorption efficiency is high, service band is wide, Wavelength tunable；It is insensitive to incident light polarization, angle；And technique it is simple, with low cost, can large area prepare and can be grown in the first-class series of advantages of flexible substrate.

Description

Visible infrared broadband absorber and preparation method thereof

technical field

The invention relates to the technical field of optical devices, and relates to a visible to infrared broadband absorber and a preparation method thereof.

Background technique

Broadband perfect absorbers have always been a hot topic in the field of science and technology, especially broadband absorption in the visible and infrared bands, because of their important application requirements in many fields such as solar energy harvesting, infrared detection, information sensing, and photothermal utilization. extensive attention. Traditional enhanced absorption methods usually use the absorption properties of the material itself combined with anti-reflection and anti-reflection means, or use a more complex structural system to achieve the purpose of broadband absorption. These methods have their own characteristics, but the general system is relatively thick or can only work in a specific band.

The emergence of plasmonic metamaterials provides a new idea for research in this field. There are many schemes to achieve total absorption based on plasmonic metamaterial systems, and the metal particle-dielectric layer-metal layer metamaterial system is one of the typical structures for realizing superabsorption. Compared with traditional methods, this system has deep subwavelength characteristics, and the overall thickness of the general system is only a few hundredths of the working wavelength. However, this structure generally has a narrow working band. In order to achieve broadband absorption, people have successively proposed to change the top layer from a single-sized metal particle to periodic or non-periodic metal particles of different sizes, or to stack dielectric-metal periodic layers on the basis of the original three-layer structure to form multiple layers. A complex structure of layer stacks. These methods can indeed broaden the working wavelength of the system, but the preparation of materials usually requires advanced modern micro-nano processing technologies such as electron beam lithography or ultraviolet lithography, and the preparation process is complicated, high in cost and low in efficiency.

The invention discloses a visible-infrared broadband absorber prepared by assembling a double-layer spherical shell structure on any substrate in a self-assembled manner of polystyrene spheres through simple gas-phase deposition or liquid-phase deposition to grow thin films. The advantages include: the structure has high absorption efficiency, and the peak absorption rate can be as high as 100%; the working band is wide, and the full width at half maximum can reach 2 μm; , the angle is not sensitive; and the process is simple, the cost is low, and it can be prepared in a large area and can be grown on a flexible substrate.

Contents of the invention

The invention discloses a visible infrared broadband absorber and a large-area, low-cost, simple and controllable preparation method for realizing a broadband perfect absorber.

The method of the present invention adopts gas phase deposition or liquid phase deposition to grow metal thin film layer on the substrate, utilizes polystyrene ball self-assembly mode to pave single-layer bead on this thin film layer, thereafter successively on polystyrene ball The metal inner spherical shell layer, the dielectric layer, and the metal outer spherical shell layer are deposited to form a double spherical shell structure.

The structure of the double spherical shell structure involved in the present invention is as follows: on the substrate 1, there are metal thin film layer 2, polymer particles 3, metal inner spherical shell layer 4, dielectric layer 5, metal outer spherical shell 6, in:

As shown in accompanying drawing 1, described metal thin film layer 2 is noble metal thin film layers such as platinum, gold, silver, copper, aluminum, and thickness is 100nm or more;

As shown in Figure 1, the polymer particles can be polystyrene, polymethyl methacrylate or polymer/silicon dioxide composite material, and the diameter of the particles can be adjusted within the range of 100 nanometers to 1 micron. The balls are approximately arranged in a hexagonal close-packed manner, with long-range order;

The polymer particles 3 are polystyrene balls with a spherical dielectric constant of 1.57-1.62 in the visible and near-infrared bands at room temperature. The ball diameter can range from 100-1000nm,

As shown in accompanying drawing 1, described metal inner spherical shell layer 4 is metal thin film layers such as platinum, gold, silver, copper, aluminum, and the range of thickness is 5-15nm;

As shown in accompanying drawing 1, described dielectric layer 5 can be the oxide or sulfide etc. of weak absorption to corresponding working band, as aluminum oxide, titanium oxide, zinc oxide, zinc sulfide etc., and the thickness of film layer is 5- 100nm;

As shown in Figure 1, the metal outer spherical shell 6 is a metal film layer such as platinum, gold, silver, copper, aluminum, etc., with a thickness of 5-15nm.

The absorber has a series of advantages such as high absorption efficiency, wide working band, adjustable wavelength, insensitive to polarization and angle of incident light, simple process, low cost, large-area preparation and growth on a flexible substrate.

Description of drawings

Figure 1: Schematic diagram of the infrared broadband absorber with metal double spherical shell structure. In the figure, 1 is a silicon substrate; 2 is a metal (gold) bottom layer with a thickness of 100nm; 3 is a polystyrene ball with a diameter of 450nm; 4 is a metal inner spherical shell with a thickness of 5nm; 5 is a dielectric layer (oxidized Aluminum) with a thickness of 50nm; 6 is the metal outer spherical shell with a thickness of 5nm.

Figure 2: Scanning electron microscope (SEM) image of a sample of a mid-wave infrared broadband absorber with a metal double spherical shell structure. In figure a, the diameter of polystyrene ball is 300nm; in picture b, the diameter of polystyrene ball is 450nm; in picture c, the diameter of polystyrene ball is 800nm; in picture d, the diameter of polystyrene ball is 4μm.

Figure 3: The sample absorption spectrum of the mid-wave infrared broadband absorber with a metal double spherical shell structure. Figure a is the result of FDTD simulation calculation; Figure b is the experimental result. The diameter of the polystyrene ball used in the experiment is 450nm, and the metal inner spherical shell The thickness of the outer spherical shell layer and the outer layer are both 5nm, and the thickness of the aluminum oxide dielectric layer is 50nm.

detailed description:

In order to make the content, technical solutions and advantages of the present invention clearer, the present invention will be further described below in conjunction with specific examples. These examples are only used to illustrate the present invention, and the present invention is not limited to the following examples. The specific embodiment of the present invention is described in detail below in conjunction with accompanying drawing:

Example 1

A 100nm gold (Au) thin film was deposited on a silicon substrate by thermal evaporation, and a monolayer of PS balls was formed on the film by self-assembly of polystyrene (PS) balls. The PS spheres we use are 10 wt% aqueous solutions of polystyrene spheres produced by Thermo Scientific. The diameter of PS pellets is 400 nm. Then a 5nm gold film is deposited by thermal evaporation, a 10nm zinc oxide film is deposited by metal organic chemical vapor phase, and a 5nm gold film is deposited on the outermost layer by thermal evaporation. The sample is tested, and the obtained absorption spectrum is greater than 90% at 1.5-2.4 μm, the peak absorption rate (98%), and the full width at half maximum is (0.5 μm).

Example 2

A 100nm gold thin film is electron beam evaporated on a glass substrate, and a monolayer of PS spheres is formed on the film by self-assembly of polystyrene (PS) spheres. The PS spheres used are 10 wt% aqueous solutions of polystyrene spheres produced by Thermo Scientific. The diameter of PS pellets is 400 nm. Then a 5nm gold film is evaporated by electron beam, a 30nm aluminum oxide film is deposited by atomic layer, and a 5nm gold film is sputtered on the outermost layer by an argon ion beam. The sample is tested, and the obtained absorption spectrum is greater than 90% at 1.5-2.9 μm, the peak absorption rate (95%), and the full width at half maximum is (0.7 μm).

Example 3

A 100nm gold film was sputtered by argon ion beams on a GaAs substrate, and a monolayer of PS balls was formed on the film by self-assembly of polystyrene (PS) balls. The PS spheres we use are 10 wt% aqueous solutions of polystyrene spheres produced by Thermo Scientific. The diameter of the PS ball is 500nm, which is etched to 300nm by oxygen ion, then a 5nm gold film is sputtered by an argon ion beam, a 100 nm zinc oxide film is magnetron sputtered, and a 5nm gold film is sputtered on the outermost layer by an argon ion beam gold film. The sample is tested, and the obtained absorption spectrum is greater than 85% at 2-3.8 μm, the peak absorption rate (98%), and the full width at half maximum is (0.9 μm).

Example 4

A 100nm gold thin film was deposited by thermal evaporation on a copper substrate, and a monolayer of PS spheres was formed on the film by self-assembly of polystyrene (PS) spheres. The PS spheres we use are 10 wt% aqueous solutions of polystyrene spheres produced by Thermo Scientific. The PS pellets have a diameter of 450 nm. Then a 5nm gold film is deposited by thermal evaporation, a 10nm aluminum oxide film is deposited by a metal-organic chemical vapor phase method, and a 5nm gold film is deposited on the outermost layer by thermal evaporation. The sample is tested, and the obtained absorption spectrum is greater than 90% at 2.2-4.4 μm, the peak absorption rate (95%), and the full width at half maximum is (1 μm).

Example 5

A 100nm gold film was evaporated by electron beam on a quartz substrate, and a monolayer of PS spheres was formed on the film by self-assembly of polystyrene (PS) spheres. The PS spheres we use are 10 wt% aqueous solutions of polystyrene spheres produced by Thermo Scientific. The PS pellets have a diameter of 450 nm. Then a 5nm gold film is evaporated by electron beam, a 30nm aluminum oxide film is deposited by atomic layer, and a 5nm gold film is sputtered on the outermost layer by an argon ion beam. The sample is tested, and the obtained absorption spectrum is greater than 90% at 2.4-4.5 μm, the peak absorption rate (99%), and the full width at half maximum is (1.8 μm).

Example 6

A 100nm gold film was sputtered by argon ion beams on a GaAs substrate, and a monolayer of PS balls was formed on the film by self-assembly of polystyrene (PS) balls. The PS spheres we use are 10 wt% aqueous solutions of polystyrene spheres produced by Thermo Scientific. The PS pellets have a diameter of 450 nm. Then a 5nm gold film is sputtered with an argon ion beam, a 50nm aluminum oxide film is magnetron sputtered, and a 5nm gold film is sputtered with an argon ion beam on the outermost layer. The samples were tested, and the obtained absorption spectrum results are shown in Figure 3. It can be seen from the figure that the absorption rate of the sample is greater than 90% at 2.9-6 μm, the peak absorption rate (99%), and the full width at half maximum is (2 μm).

Example 7

A 150nm aluminum film was evaporated by electron beam on a silicon substrate, and a monolayer of PS spheres was formed on the film by self-assembly of polystyrene (PS) spheres. The PS spheres we use are 10wt% aqueous solutions produced by Thermo Scientific. The diameter of PS pellets is about 200nm. Then a 9nm aluminum film is evaporated by an electron beam, a 20nm aluminum oxide film is sputtered by magnetron, and a 9nm aluminum film is evaporated by an electron beam on the outermost layer. It can realize a broad-band absorption spectrum greater than 90% in the ultraviolet band.

Example 8

A 200nm silver thin film was evaporated by electron beam on a glass substrate, and a monolayer of PS balls was formed on the film by self-assembly of polystyrene (PS) balls. The PS spheres we use are 10wt% aqueous solutions produced by Thermo Scientific. The diameter of PS pellets is about 1000nm. Then use electron beam to evaporate 8nm silver film, magnetron sputtering 30nm aluminum oxide film, and utilize electron beam to evaporate 8nm silver film on the outermost layer. It can realize a broad-band absorption spectrum greater than 90% in the visible light band.

Claims (2)

1. A visible infrared broadband absorber, its structure is: from the substrate (1) upwards are the metal bottom layer (2), the polymer particle layer (3), the metal inner spherical shell layer (4), the dielectric layer (5), metal outer spherical shell (6), its characteristics are as follows: The substrate (1) is selected from silicon, germanium, or silicon dioxide, or polytetrafluoroethylene with flexible properties; The polymer of the polymer particle layer (3) is polystyrene or polymethyl methacrylate, or a composite material of these two polymers and silicon dioxide, and the particle diameter is in the range of 200 nanometers to 1 micron; The metal bottom layer (2), the metal inner spherical shell layer (4) and the metal outer spherical shell layer (6) are made of platinum, gold, silver, copper, aluminum, and the thickness of the metal bottom layer is much greater than that of the light-absorbing metal The penetration depth of internal propagation; the thickness of the metal inner spherical shell (4) and the metal outer spherical shell (6) is 5-20 nanometers; The dielectric layer (5) is aluminum oxide, zinc oxide, titanium dioxide, silicon dioxide or zinc sulfide compound, with a thickness of 5-100 nanometers. 2. A kind of method for preparing a kind of visible infrared broadband absorber as claimed in claim 1 is characterized in that comprising the following main steps: 1) Structural design, using finite difference time domain method or finite element method to design the absorber, the absorber consists of metal bottom layer (2), polymer particle layer (3), metal inner ball from the substrate (1) upwards Shell layer (4), dielectric layer (5), metal outer spherical shell layer (6); in order to make the system non-transmissive, the thickness of the metal bottom layer is much greater than the penetration depth of the absorbed light propagating into the metal, for different working wavelengths, The geometric parameters of other layers need to be optimized accordingly; 2) According to the result of the structural design in step 1), one of methods such as magnetron sputtering, electron beam evaporation, and dual ion beam sputtering can be used to prepare the metal film; 3) According to the result of the structural design in step 1), the polymer particle layer can be prepared by a self-assembly method. Take the polystyrene ball produced by ThermoScientific Company as an example, prepare a cleaned and hydrophilically treated silicon chip, soak in sodium lauryl sulfate solution for twelve hours; get the concentration of 10wt% polystyrene ball aqueous solution and no Water and ethanol were evenly mixed at a ratio of 1:1 and sonicated for 15 minutes. The solution is dropped on the soaked, washed and dried silicon wafer, and dried to form a single-layer PS pellet film. The monolayer film can be transferred to other substrate surfaces; 4) According to the result of structural design in step 1), the dielectric layer (5) is prepared by atomic layer lamination method.