Near-field radiation filling type structure and method based on hyperbolic material

Abstract

The invention relates to a near-field radiation filling type structure and method based on a hyperbolic material, the near-field radiation filling type structure based on the hyperbolic material comprises an emitting electrode, a filling layer and a receiving electrode which are connected in sequence, and the emitting electrode is made of N-type doped silicon; the receiving electrode and the emitting electrode are arranged in parallel, and the material of the receiving electrode is N-type doped silicon; the emitting electrode and the receiving electrode are arranged in parallel, and the filling layer is arranged between the emitting electrode and the receiving electrode. According to the invention, the maximum excitation hyperbolic mode can be realized, so that the heat flow is greatly improved. The parallel wave vector is greatly improved due to excitation of the hyperbolic mode, and more photons reach the surface of the receiving pole medium through the tunneling effect in the maximum excitation hyperbolic mode.

Description

Technical Field

[0001] The invention relates to a near-field radiation heat transfer material, and in particular to a near-field radiation filling structure and method based on a hyperbolic material. Background Art

[0002] At present, energy issues have gradually become a barrier to the progress and development of human society. The main energy source for human beings is fossil energy, which is gradually lagging behind the development of the times due to its non-renewable nature and high pollution to the environment. Therefore, the technological breakthrough of sustainable clean, low-carbon, safe and efficient green energy is crucial. In recent years, with the rise of micro-nano processing technology, the near-field thermal radiation-based thermophotovoltaic system has attracted much attention due to its proven high energy density and high conversion efficiency, and has great advantages in the field of thermoelectric conversion such as waste heat recovery power generation.

[0003] The study of near-field thermal radiation began in the 1960s and 1970s. In 1967, Rytov first revolutionized the process from the wave point of view, based on the random Maxwell equations and the fluctuation dissipation theory, regarded the energy transfer process as the emission, propagation (including scattering) and absorption of electromagnetic waves, established fluctuation electrodynamics, and used it to analyze radiation heat transfer problems. This method is applicable to far-field radiation heat transfer problems and near-field radiation heat transfer problems, and has good versatility. In 1971, D. Polder et al. first theoretically derived the near-field thermal radiation formula between two parallel plates. Due to the limitations of the micro-nano processing technology at the time, the near-field thermal radiation phenomenon has not received widespread attention. In recent years, as the size of components has gradually entered the micro-nano scale, the near-field thermal radiation phenomenon between objects has even become the dominant factor in total heat transfer and has received widespread attention, becoming a research hotspot in the field of thermal radiation.

[0004] Regarding the theoretical research on near-field radiation heat transfer, the current focus is on the near-field thermal radiation between objects of different shapes and materials in a vacuum gap. The shapes include flat plates and flat plates, particles and spheres, etc., and the materials include isotropic materials, anisotropic materials, metamaterial surfaces, etc.

[0005] In 2011, Basu et al. studied the maximum near-field radiation heat transfer that can be achieved between two thin film plates of isotropic materials. The study showed that when the ratio of film thickness to vacuum gap D is equal to or less than 0.1, the maximum heat flux density is independent of D. With the rise of micro-nano processing technology, researchers have achieved breakthrough results in the field of near-field experiments, which has aroused great enthusiasm among near-field researchers. At present, near-field radiation heat transfer experiments can be divided into particle-plate, sphere-plate, plate-plate according to the shape of the system structure. Among them, the plate-plate experiment has attracted much attention because this structure is closest to the actual application scenario, such as near-field thermal photovoltaic system, chip heat dissipation, etc.

[0006] In 2018, Ghashami et al. developed a multifunctional near-field experimental device based on a nanopositioning platform and used multiple positioners to measure Near-field thermal radiation from a quartz plate to a vacuum gap of nearly 200 nm.

[0007] In 2019, DeSutter developed a near-field radiation heat transfer device based on a millimeter-scale doped silicon surface, which achieved significant thermal radiation enhancement using a precisely controlled vacuum gap (about 110 nm). The device separates the high-temperature emitter and the low-temperature receiver through a micro-pillar structure, which is manufactured in a micron-scale pit with a height of 4.5 to 45 times that of the nanoscale vacuum gap. Through this design, they succeeded in significantly reducing heat conduction without destroying the structural integrity of the device, and achieved a near-field radiation heat flux enhancement effect of about 28.5 times the blackbody radiation limit.

[0008] The experimental design of near-field radiation has made great progress in the past decade, but from the practical application level, the three experimental methods mentioned above have their own shortcomings. For example, the positioner control method requires an expensive high-precision control system and needs to consider the thermal deformation and surface roughness of the plate; the nanopillar method introduces unnecessary heat conduction and has high requirements for processing technology; the application scenarios of the micro-electromechanical system control method are very limited, etc. Therefore, the various experimental devices currently developed for near-field research have not yet left the laboratory, and some new solutions still need to be explored.

[0009] The above reasons are ultimately caused by the existence of vacuum gaps. Maintaining a vacuum gap at the micro-nano scale means high-precision control and processing methods. Therefore, the present invention abandons the traditional vacuum gap structure and proposes a filling structure model, which will provide a new idea for experimental design. Summary of the invention

[0010] The present invention provides a near-field radiation filling structure based on a hyperbolic material, aiming to solve at least one of the technical problems existing in the prior art.

[0011] The technical solution of the present invention relates to a near-field radiation filling structure based on a hyperbolic material, wherein the near-field radiation filling structure based on a hyperbolic material comprises an emitter, a filling layer and a receiving electrode connected in sequence, wherein:

[0012] The emitter is made of N-type doped silicon; the receiver is arranged in parallel with the emitter, and the receiver is made of N-type doped silicon;

[0013] The emitter and the receiver are arranged in parallel, and the filling layer is arranged between the emitter and the receiver.

[0014] Furthermore, the material of the emitter and the material of the receiver are made by doping nitrogen atoms in pure silicon wafers, wherein the doping concentration of nitrogen atoms is 1×10 20 / cm 3 ,

[0015] In the low frequency range When , the real parts of the dielectric functions of the emitter and the receiver are negative, showing heavy metal characteristics;

[0016] In the transition frequency , the emitter and the receiving electrode are neither non-metallic nor dielectric;

[0017] In the high frequency range When , the real part of the dielectric function of the emitter and the receiver is greater than 1, showing dielectric characteristics.

[0018] Furthermore, the temperature of the emitter is 400K, the temperature of the receiving electrode The temperature of the conductive layer is 300K, and the thickness of the emitter and the receiver is 10 times the thickness of the filling layer.

[0019] Furthermore, the thickness of the filling layer is 100 nm.

[0020] Furthermore, the filling layer is made of a hyperbolic material, the hyperbolic material is an anisotropic material, and the product of the real parts of the parallel direction and the vertical direction of the hyperbolic material is a negative number.

[0021] Furthermore, the hyperbolic material is a low-loss hyperbolic material, wherein:

[0022] The imaginary part of the dielectric function of a low-loss hyperbolic material is:

[0023] .

[0024] Furthermore, the hyperbolic material is hexagonal boron nitride hBN, and the optical axis of the hexagonal boron nitride hBN is perpendicular to the surfaces of the emitter and the receiver.

[0025] Furthermore, since the hexagonal boron nitride hBN is and the second frequency band Both are low-loss hyperbolic materials, and the hexagonal boron nitride hBN is set to work in the first frequency band and the second frequency band between, wherein the first frequency band for:

[0026] ,

[0027] The second frequency band for:

[0028] .

[0029] Another aspect of the technical solution of the present invention relates to a method for preparing a near-field radiation filling structure based on a hyperbolic material, which is used to prepare the near-field radiation filling structure based on a hyperbolic material. The method for preparing the near-field radiation filling structure based on a hyperbolic material comprises:

[0030] S100, using two high-purity single crystal silicon wafers respectively, and using HPM solution and DHF solution in turn to remove impurities on the surface of the high-purity single crystal silicon wafers;

[0031] S200, using a vapor diffusion method, placing the cleaned single crystal silicon wafer in a low-pressure chemical vapor deposition furnace, filling the vapor deposition furnace with ammonia and nitrogen, heating to 1000° C. to 1200° C., and maintaining for 5 hours to promote the diffusion of nitrogen atoms;

[0032] S300, slowly cool the vapor deposition furnace to room temperature and perform annealing in a nitrogen atmosphere to obtain two uniform doping concentrations of 1×10 20 / cm 3 Heavily doped silicon;

[0033] S400, placing the hexagonal boron nitride film between two heavily doped silicon wafers, relying on external mechanical preload and interatomic van der Waals forces to tightly connect the two, forming a near-field radiation filling structure based on hyperbolic materials.

[0034] Another aspect of the technical solution of the present invention relates to glass provided with the near-field radiation filling structure based on hyperbolic material.

[0035] The beneficial effects of the present invention are as follows:

[0036] The near-field radiation filling structure and method based on hyperbolic materials of the present invention can realize the maximum excitation hyperbolic mode, greatly improving the heat flow. The parallel wave vector is greatly improved due to the excitation of the hyperbolic mode. In the maximum excitation hyperbolic mode, more photons reach the surface of the receiving pole medium through the tunneling effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of a near-field radiation heat transfer model of a filling structure according to an embodiment of the present invention.

[0038] Figure 2 is a flow chart of studying the influence mechanism of near-field radiation heat transfer in a filling structure according to an embodiment of the present invention.

[0039] Figure 3 According to an embodiment of the present invention, the doping concentration is Schematic diagram of the dielectric function of doped silicon.

[0040] Figure 4 3 is a spectral heat flow comparison diagram of an isotropic material filling structure according to an embodiment of the present invention.

[0041] Figure 5 is a comparison diagram of spectral heat fluxes of different hyperbolic material filling structures according to an embodiment of the present invention.

[0042] Figure 6 1 and 10 . These are transmission coefficient cloud diagrams of different material fillings according to an embodiment of the present invention: (a) vacuum gap structure, (b) isotropic material filling structure, (c) hyperbolic material large imaginary part filling structure, and (d) hyperbolic material small imaginary part filling structure.

[0043] Figure 7 Schematic diagram of preparing a hexagonal boron nitride filled near-field thermophotovoltaic device according to an embodiment of the present invention.

[0044] Figure 8 2 is a diagram of the dielectric constant of hexagonal boron nitride according to an embodiment of the present invention, (a) a schematic diagram of the real part of the dielectric function in two directions changing with the angular frequency; (b) a schematic diagram of the imaginary part of the dielectric function in two directions changing with the angular frequency.

[0045] Fig. 9 Calculation results of the hexagonal boron nitride filling structure according to an embodiment of the present invention: (a) spectral heat flow; (b) total transmission coefficient cloud diagram.

[0046] Fig.10 4 is a flow chart of a method for preparing a near-field radiation filling structure based on a hyperbolic material according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The following will be combined with the embodiments and drawings to clearly and completely describe the concept, specific structure and technical effects of the present invention, so as to fully understand the purpose, scheme and effect of the present invention. It should be noted that the embodiments and features in the embodiments of this application can be combined with each other without conflict.

[0048] It should be noted that, unless otherwise specified, when a feature is referred to as being "fixed" or "connected" to another feature, it may be directly fixed or connected to the other feature, or it may be indirectly fixed or connected to the other feature. In addition, the descriptions of up, down, left, right, top, bottom, etc. used in the present invention are only relative to the relative positional relationship of the components of the present invention in the drawings.

[0049] In addition, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art. The terms used in this specification are only for describing specific embodiments, not for limiting the present invention. The term "and / or" used herein includes any combination of one or more related listed items.

[0050] It should be understood that, although the terms first, second, third, etc. may be used to describe various elements in the present disclosure, these elements should not be limited to these terms. These terms are only used to distinguish elements of the same type from each other. For example, without departing from the scope of the present disclosure, the first element may also be referred to as the second element, and similarly, the second element may also be referred to as the first element.

[0051] See also Figures 1 to 10 , the near-field radiation filling structure based on hyperbolic material of the technical solution of the present invention, the near-field radiation filling structure based on hyperbolic material comprises an emitter, a filling layer and a receiving electrode connected in sequence, wherein,

[0052] The emitter is made of N-type doped silicon; the receiver is arranged in parallel with the emitter, and the receiver is made of N-type doped silicon;

[0053] The emitter and the receiver are arranged in parallel, and the filling layer is arranged between the emitter and the receiver.

[0054] The beneficial effects of the present invention are as follows:

[0055] The near-field radiation filling structure and method based on hyperbolic materials of the present invention can realize the maximum excitation hyperbolic mode, greatly improving the heat flow. The parallel wave vector is greatly improved due to the excitation of the hyperbolic mode. In the maximum excitation hyperbolic mode, more photons reach the surface of the receiving pole medium through the tunneling effect.

[0056] Reference Figure 1 , showing the transmission paths of evanescent waves of the same wave vector (β) in different types of materials in a filled structure, Figure 1 middle It is expressed as the thickness of the emitter and the receiver; Indicates the thickness of the filling layer; represents the wave vector, subscript represents the direction of the wave vector; represents the plane wave vector; represents the vacuum wave vector.

[0057] Reference Figure 1 ,① indicates that when the filling layer is vacuum, , the evanescent wave decays exponentially from the emitter to the receiver; ② indicates that when the filling layer is a non-hyperbolic material, there is still , the evanescent wave decays exponentially from the emitter to the receiver; ③ indicates that when the filling layer is a hyperbolic material, the hyperbolic mode exists. , the evanescent wave is transformed into a propagation wave, which extends the propagation length and effectively improves the radiation intensity.

[0058] Reference Figure 2 First, the influence mechanism of the changes in the optical parameters of the filling material (such as refractive index and absorption coefficient) on the near-field radiation heat transfer in the filling structure is studied, and the changing trend of the near-field radiation heat flow is summarized. Then, by generating a transmission coefficient cloud map, the regulating effect of the optical properties of the material on the heat transfer performance is presented in an intuitive form and the internal energy transmission mechanism is explained. Finally, taking the actual material as an example, a comparative analysis is conducted with the vacuum gap model to illustrate the advantages and application potential of the filling structure.

[0059] Furthermore, the material of the emitter and the material of the receiver are made by doping nitrogen atoms in pure silicon wafers, wherein the doping concentration of nitrogen atoms is 1×10 20 / cm 3 ,

[0060] In the low frequency range When , the real parts of the dielectric functions of the emitter and the receiver are negative, showing heavy metal characteristics;

[0061] In the transition frequency , the emitter and the receiving electrode are neither non-metallic nor dielectric;

[0062] In the high frequency range When , the real part of the dielectric function of the emitter and the receiver is greater than 1, showing dielectric characteristics.

[0063] Specifically, refer to Figure 3 ,Optical parameter screening of model materials,Before studying the near-field radiation heat transfer mechanism of the filled structure, it is necessary to determine the optical parameters of each part of the material in the research model.,First, the filling material is regarded as a hypothetical material, and no specific thermal conductivity is specified, so the influence of heat conduction and multi-layer near-field thermal radiation is ignored, and it is regarded as composed of three semi-infinite parallel plates with uniform surfaces, and a simplified three-layer filled flat plate structure model can be used for calculation.

[0064] Secondly, when considering the emitter and receiver materials, N-type doped silicon is selected as the parallel plate material on both sides of the emitter and receiver because it can excite broadband surface plasmon resonance and has many good properties such as adjustable optical parameters and easy preparation. The classic Drude model is used to characterize the dielectric function of doped silicon, and its expression is:

[0065]

[0066] in, is the plasma frequency of doped silicon, which is ; is the scattering rate, which is ; The contribution of band gap absorption and lattice vibration is about 11.7.

[0067] Reference Figure 3 , and the doping concentration is The dielectric function of doped silicon can be seen in the low frequency band When the real part of its dielectric function is negative, it exhibits heavy metal characteristics. The range belongs to the transition section, which neither behaves as non-metal nor as dielectric. When , the real part of its dielectric function is greater than 1, showing dielectric properties.

[0068] Furthermore, the temperature of the emitter is 400K, the temperature of the receiving electrode The temperature of the conductive layer is 300K, and the thickness of the emitter and the receiver is 10 times the thickness of the filling layer.

[0069] Specifically, in order to ensure that the two side plates are block structures rather than thin films, the temperature of the emitter Fixed to , the temperature of the receiving electrode Fixed to , and its thickness is always set to 10 times the distance between the two plates.

[0070] Furthermore, the thickness of the filling layer is 100 nm.

[0071] Furthermore, the filling layer is made of a hyperbolic material, the hyperbolic material is an anisotropic material, and the product of the real parts of the parallel direction and the vertical direction of the hyperbolic material is a negative number.

[0072] Specifically, for the selection of filling layer materials, according to the dispersion relationship, they can be divided into isotropic materials (non-hyperbolic materials) and hyperbolic materials.

[0073] according to and According to the size relationship and sign of , materials can be divided into four types, as shown in Table 1. Among them, dielectric materials and metal materials can be called isotropic materials because the real and imaginary parts of the dielectric function in three directions are equal; while hyperbolic materials are a special case of anisotropic materials, and the sign of the real part of the dielectric function in the direction parallel to the plane is different from that in the direction perpendicular to the plane.

[0074] Table 1, Material classification table

[0075]

[0076] First, we study the law and influence of the optical parameters of non-hyperbolic materials, mainly isotropic materials, on near-field radiation heat transfer when they are used as filling materials. Since the refractive index and extinction coefficient of isotropic materials in three directions, or the real and imaginary parts of the dielectric constant, are equal ( , ), so the near-field thermal radiation is only affected by two parameters and Influence change.

[0077] In order to explore the effect of the real part of the dielectric function on the near-field radiation, the real value of the dielectric function of the isotropic material is selected as and At the same time, in order to explore the influence of the imaginary part of the dielectric function of isotropic materials on the near-field radiation, the imaginary part of the dielectric function Reduce to . There are four material combinations in total, combining them in pairs.

[0078] Reference Figure 4 The real and imaginary parts of the dielectric constant are introduced as variables to calculate the Fresnel reflection coefficient r. Taking the vacuum medium as the reference point, a spectral heat flow comparison diagram of the filled structure and the vacuum gap structure with four materials as the filling layer is drawn. The spectral heat flow diagram under the change of the dielectric function of the isotropic material is shown when the emitter temperature is 400K, the receiving electrode temperature is 300K, the middle plate thickness is 100nm.

[0079] Reference Figure 4 The black curve represents the spectral heat flux curve of the traditional near-field thermal radiation model when the middle layer is vacuum, that is, without filling. Under this structure, due to the surface plasmon polaritons excited at the interface between doped silicon and vacuum, Figure 4 , it can be clearly observed that there is a There is a clear peak in the spectral heat flux nearby, which is consistent with the calculation results of Basu et al.

[0080] The remaining four curves show two rules when high refractive index isotropic materials are used as filling materials:

[0081] (1) When the real part of the dielectric constant of the filling material is equal and the imaginary part is reduced, the spectral heat flow peak and the total heat increase slightly. This corresponds to or When unchanged, From 1 to 10 -3 When the loss is reduced, more wave vectors are allowed to pass through the intermediate medium to reach the receiver, thereby increasing the heat flow at each frequency.

[0082] (2) When the imaginary part of the dielectric constant of the filling material is equal and the real part increases, the spectral heat flux peak and the total heat increase, and the peak corresponding frequency point shifts to the left. This corresponds to or When unchanged, When the value changes from 4 to 9, the Fresnel reflection coefficient increases, which excites stronger surface plasmon polaritons at the interface between doped silicon and the filling material. This is still mainly contributed by the evanescent wave. At the same time, due to the change in refractive index, the resonance frequency point between the media also shifts, resulting in a shift in the peak point of the heat flow. This means that in practical applications, such as filled near-field thermal photovoltaic systems, the optical parameters of the intermediate filling material can be adjusted to match the photovoltaic cell with a suitable band gap, thereby improving the cell energy conversion efficiency.

[0083] At the same time, through Figure 4 It can be seen that the near-field radiation heat flow of the high-refractive-index, low-loss isotropic material as a filling structure is greatly improved compared to the traditional vacuum structure, with the peak value increased by 1-5 times. The heat flow in other frequency bands is also higher than that of the traditional vacuum structure, which significantly proves the excellent performance and advantages of the filling structure.

[0084] The following is the law of near-field radiation heat transfer of hyperbolic materials:

[0085] Hyperbolic materials are not only anisotropic materials, but also have a negative real product in two directions, which means that they can exhibit two different material properties in two different directions. The calculation of the Fresnel reflection coefficient is more complicated and is affected by four parameters: , , and In order to observe the law more conveniently and reduce the variables, the absolute values ​​of the real parts in the parallel and vertical directions are set equal, that is, ; The imaginary parts in both directions are also set equal Compared with isotropic materials, only one more real variable in the vertical direction is introduced, which greatly reduces the difficulty of data processing.

[0086] Reference Figure 5In order to compare with the isotropic material, the same dielectric function value as the isotropic material as the filling material is selected, and the real part of the dielectric function of the hyperbolic material is selected as and Similarly, in order to explore the effect of the imaginary part of the dielectric function on near-field heat transfer in hyperbolic materials, this chapter sets the imaginary part of the dielectric function to and . It is also composed of four materials and compared with the vacuum gap structure. Figure 5 , demonstrating the near-field radiation heat transfer law when the filling material is a hyperbolic material.

[0087] (1) Compared with isotropic high refractive index and dielectric materials, when hyperbolic materials are used as filling materials and the imaginary part is large, the spectral heat flux does not increase significantly, and the corresponding frequency points do not shift significantly; this corresponds to When the real part of the dielectric function of the hyperbolic material is or When the spectral heat flux is less than that of the isotropic material with high refractive index, it has no obvious improvement.

[0088] (2) When the imaginary part of the hyperbolic material is reduced by 3 orders of magnitude, the heat flux is greatly enhanced, and the peak value is 10 times higher than that before the imaginary part is reduced. 5 times, 10 under vacuum filling 6 times. This corresponds to the dielectric function of the hyperbolic material or , Reduce to The heat flow is greatly enhanced.

[0089] Therefore, a very important conclusion can be drawn from the above, that is, when the filling material is a low-loss hyperbolic material, the near-field radiation heat flux value can be greatly enhanced, and the lower the loss, the greater the enhancement effect.

[0090] Reference Figure 6 , respectively, show the total transmission coefficient cloud diagrams for different structural conditions. Through the cloud diagrams, we can observe the contribution of the photon energy of the propagating wave and the evanescent wave in different frequency bands and different wave vector domains: Figure 6 (a) shows that in the vacuum gap model, since there is only a single doped silicon surface SPPs excitation in the structure, its evanescent wave contributes only in the wavelet vector domain and is concentrated in frequency point; similarly, Figure 6 (b) in the figure shows that when isotropic materials are used as filling materials, higher SPPs excitation is only caused by the change in the optical parameters of the filling layer, and there is no coupling excitation of other modes. Figure 6(c) shows that when the filling layer is a hyperbolic material and the imaginary part is large, the surface SPPs excitation of the doped silicon and the coupling of the hyperbolic modes (HMs) of the hyperbolic material produce a completely different result from the previous one. From the dispersion relation, we can see that the parallel wave vector is allowed in the hyperbolic mode. Breaking through the vacuum wave vector The upper limit of its parallel wave vector becomes . The original evanescent wave is converted into a propagating wave that does not decay with distance, so that the photon energy has a higher contribution in the large wave vector domain. Figure 6 (d) in the figure indicates that when the imaginary part of the hyperbolic material is small, the loss of photon energy through the medium is greatly reduced, and more energy passes through the large wave vector region, which greatly improves the near-field radiation heat flow.

[0091] It can be concluded that the near-field radiation heat flux increase brought about by the low-loss hyperbolic material as the filling layer of the filling structure is huge, which means that under the filling material that meets the rules, the heat flux of near-field thermal radiation may be equivalent to the heat flux of thermal conduction. This once again shows that the filling structure has excellent heat flux adjustability, and at the same time greatly simplifies the difficulty of near-field radiation heat transfer experiments and large-scale applications.

[0092] Furthermore, the hyperbolic material is a low-loss hyperbolic material, wherein the imaginary part of the dielectric function of the low-loss hyperbolic material is:

[0093] .

[0094] In a specific embodiment, the real part of the dielectric function of the low-loss hyperbolic material is:

[0095] or .

[0096] Furthermore, the hyperbolic material is hexagonal boron nitride hBN, and the optical axis of the hexagonal boron nitride hBN is perpendicular to the surfaces of the emitter and the receiver.

[0097] Specifically, the following is the near-field radiation heat transfer calculation based on the hexagonal boron nitride filled structure:

[0098] Reference Figure 7 When the filling material is a hyperbolic material, that is, the product of the real parts in the parallel direction and the vertical direction is negative, and the imaginary parts in both directions are small enough, the hyperbolic mode can be maximally excited, greatly improving the heat flow. Hexagonal boron nitride has the characteristics of being easy to prepare and stable.

[0099] Furthermore, since the hexagonal boron nitride hBN is and the second frequency band Both are low-loss hyperbolic materials, and the hexagonal boron nitride hBN is set to work in the first frequency band and the second frequency band between, wherein the first frequency band for:

[0100] ,

[0101] The second frequency band for:

[0102] .

[0103] Reference Figure 8 , hexagonal boron nitride are respectively and In these two frequency bands, it behaves as a low-loss hyperbolic material. Figure 3-Figure 6 (a) shows the change curve of the real part of the dielectric constant of hexagonal boron nitride, refer to Figure 8 , represents the change curve of the imaginary part of the dielectric constant of hexagonal boron nitride, while the gray area represents the hyperbolic segment, and the red area indicates that the imaginary parts in both directions are less than 0.01. In the remaining non-hyperbolic segments, it behaves as a non-hyperbolic material with a higher refractive index and lower loss. When used as a filling layer, it can also stimulate the SPPs effect to enhance the near-field radiation heat flow.

[0104] Reference Fig. 9 , hexagonal boron nitride is used as the filling material in the filled structure to perform near-field thermal radiation calculations, and its total transmission coefficient cloud map is derived.

[0105] Fig. 9 (a) shows that when hexagonal boron nitride is used as the filling material, its spectral heat flux in the entire frequency band is significantly improved compared to vacuum, especially in the hyperbolic section, the first peak point is increased by about 100 times, and the second peak point is increased by about 1000 times, proving the accuracy of the law. Fig. 9 The horizontal axis in (b) represents the parallel wave vector normalized to the first Brillouin zone. It can be seen from the total transmission coefficient cloud diagram that the parallel wave vector is greatly improved due to the excitation of the hyperbolic mode, which means that in this mode, more photons reach the surface of the receiving electrode medium through the tunneling effect.

[0106] Therefore, the present invention analyzes the filling materials with different optical properties, reveals the internal heat transfer mechanism of the filling structure, and points out that at a spacing of 100nm, low-loss hyperbolic materials can significantly extend the propagation length of the wave to the cutoff upper limit, and the heat flux intensity is increased by 5-6 orders of magnitude compared with the vacuum gap structure. And hexagonal boron nitride is substituted into the filling structure model as the filling material, and it is calculated that the near-field radiation heat flux of the model is 4000 times higher than the near-field radiation heat flux of the vacuum gap structure model under the same conditions.

[0107] Another aspect of the technical solution of the present invention relates to a method for preparing a near-field radiation filling structure based on a hyperbolic material, which is used to prepare the near-field radiation filling structure based on a hyperbolic material, referring to Fig.10 , the preparation method of the near-field radiation filling structure based on hyperbolic material comprises:

[0108] S100, using two high-purity single crystal silicon wafers respectively, and using HPM solution and DHF solution in turn to remove impurities on the surface of the high-purity single crystal silicon wafers;

[0109] S200, using a vapor diffusion method, placing the cleaned single crystal silicon wafer in a low-pressure chemical vapor deposition furnace, filling the vapor deposition furnace with ammonia and nitrogen, heating to 1000° C. to 1200° C., and maintaining for 5 hours to promote the diffusion of nitrogen atoms;

[0110] S300, slowly cool the vapor deposition furnace to room temperature and perform annealing in a nitrogen atmosphere to obtain two uniform doping concentrations of 1×10 20 / cm 3 Heavily doped silicon;

[0111] S400, placing the hexagonal boron nitride film between two heavily doped silicon wafers, relying on external mechanical preload and interatomic van der Waals forces to tightly connect the two, forming a near-field radiation filling structure based on hyperbolic materials.

[0112] Specifically, in step S100, the thickness of the high-purity single crystal silicon wafer is 1 micron; the component ratio of the HPM solution is HCl:H2O2:H2O=1:1:5, and the temperature of the HPM solution is 70-90°C; the component ratio of the DHF solution is HF:H2O=1:95, and the temperature of the DHF solution is 25-30°C.

[0113] Another aspect of the technical solution of the present invention relates to glass provided with the near-field radiation filling structure based on hyperbolic material.

[0114] The above is only a preferred embodiment of the present invention. The present invention is not limited to the above implementation. As long as the technical effect of the present invention is achieved by the same means, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the scope of protection of the present disclosure. All should belong to the protection scope of the present invention. Within the protection scope of the present invention, its technical scheme and / or implementation method can have various modifications and changes.

Claims

1. A near-field radiation filling structure based on hyperbolic materials, characterized in that: The near-field radiation filling structure based on hyperbolic materials comprises an emitter, a filling layer and a receiving electrode connected in sequence, wherein: The emitter is made of N-type doped silicon; the receiver is arranged in parallel with the emitter, and the receiver is made of N-type doped silicon; The emitter and the receiver are arranged in parallel, and the filling layer is arranged between the emitter and the receiver.

2. The near-field radiation filling structure based on hyperbolic material according to claim 1, characterized in that: The material of the emitter and the material of the receiver are made of pure silicon doped with nitrogen atoms, wherein the doping concentration of the nitrogen atoms is 1×10 20 / cm 3 , In the low frequency range When , the real parts of the dielectric functions of the emitter and the receiver are negative, showing heavy metal characteristics; In the transition frequency , the emitter and the receiving electrode are neither non-metallic nor dielectric; In the high frequency range When , the real part of the dielectric function of the emitter and the receiver is greater than 1, showing dielectric characteristics.

3. The near-field radiation filling structure based on hyperbolic material according to claim 1, characterized in that: The temperature of the emitter is 400K, the temperature of the receiving electrode The temperature of the conductive layer is 300K, and the thickness of the emitter and the receiver is 10 times the thickness of the filling layer.

4. The near-field radiation filling structure based on hyperbolic material according to claim 3, characterized in that: The thickness of the filling layer is 100 nm.

5. The near-field radiation filling structure based on hyperbolic material according to claim 1, characterized in that: The filling layer is made of a hyperbolic material, which is an anisotropic material, and the product of the real parts of the parallel direction and the vertical direction of the hyperbolic material is a negative number.

6. The near-field radiation filling structure based on hyperbolic material according to claim 5, characterized in that: The hyperbolic material is a low-loss hyperbolic material, wherein: The imaginary part of the dielectric function of a low-loss hyperbolic material is: 。 7. The near-field radiation filling structure based on hyperbolic material according to claim 1, characterized in that: The hyperbolic material is hexagonal boron nitride, and the optical axis of the hexagonal boron nitride is perpendicular to the surfaces of the emitter and the receiver.

8. The near-field radiation filling structure based on hyperbolic material according to claim 7, characterized in that: Since the hexagonal boron nitride is in the first frequency band and the second frequency band Both are low-loss hyperbolic materials, and the hexagonal boron nitride is set to work in the first frequency band and the second frequency band between, wherein the first frequency band for: ， The second frequency band for: 。 9. A method for preparing a near-field radiation filling structure based on a hyperbolic material, used for preparing a near-field radiation filling structure based on a hyperbolic material as claimed in any one of claims 1 to 8, characterized in that: The preparation method of the near-field radiation filling structure based on hyperbolic material comprises: S100, using two high-purity single crystal silicon wafers respectively, and using HPM solution and DHF solution in turn to remove impurities on the surface of the high-purity single crystal silicon wafers; S200, using a vapor diffusion method, placing the cleaned single crystal silicon wafer in a low-pressure chemical vapor deposition furnace, filling the vapor deposition furnace with ammonia and nitrogen, heating to 1000° C. to 1200° C., and maintaining for 5 hours to promote the diffusion of nitrogen atoms; S300, slowly cool the vapor deposition furnace to room temperature and perform annealing in a nitrogen atmosphere to obtain two uniform doping concentrations of 1×10 20 / cm 3 Heavily doped silicon; S400, placing the hexagonal boron nitride film between two heavily doped silicon wafers, relying on external mechanical preload and interatomic van der Waals forces to tightly connect the two, forming a near-field radiation filling structure based on hyperbolic materials.

10. A glass, characterized in that: A near-field radiation filling structure based on a hyperbolic material as claimed in any one of claims 1 to 8 is provided.

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