Double-function switchable terahertz absorber based on vanadium dioxide and embedded copper cylinder control and method
By designing a structure based on vanadium dioxide and embedded copper pillars, a dual-function switchable terahertz absorber was fabricated, which solved the problems of single function and complex switching of existing absorbers, and achieved efficient absorption switching and fast mode conversion over a wide frequency range.
Patent Information
- Application Number
- CN202511102469.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-07
- Publication Date
- 2025-11-14
AI Technical Summary
Existing terahertz absorbers are mostly single-function and have complex switching processes, making it difficult to meet the needs of practical applications, especially in terms of frequency and function switching, where there is a lack of simple and fast implementation methods.
The structure, based on vanadium dioxide and embedded copper pillars, includes a base plate, a via dielectric layer, a vanadium dioxide resonant layer, a blind via dielectric layer, and a metal ring. It is fabricated by connecting copper pillar arrays in series and combining atomic layer deposition and electron beam evaporation techniques to achieve the switching between the insulating and metallic states of vanadium dioxide, forming a dual-function switchable terahertz absorber.
It achieves efficient absorption switching over a wide frequency range, with an absorption rate of over 90%, and maintains excellent performance under different polarization angles and wide incident angles. The absorption mode can be switched quickly.
Smart Images
Figure CN120955370A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of terahertz wave technology, specifically relating to a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars, and also to a method for preparing the dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars. Background Technology
[0002] Terahertz (THz) waves generally refer to electromagnetic waves with frequencies between 0.1 THz and 10 THz, falling between infrared light and microwaves. In recent years, terahertz functional devices have demonstrated potential applications in numerous fields, such as military, communications, and medicine. Metamaterials are man-made materials with special properties that do not exist in nature. By adjusting the microstructure of metamaterials and their constituent substrates, terahertz absorbers that meet practical needs can be designed efficiently.
[0003] Early metamaterial absorbers were often single-function and non-switchable, which limited their practical applications. Recent switchable absorbers employ multi-layered stacked structures or use in-layer resonators to achieve single-frequency to multi-frequency switching. Furthermore, these switchable absorbers incorporate functional materials such as graphene and vanadium dioxide, requiring external force to alter their physical properties during function switching. To better meet practical needs, this switching process should be simpler and faster. Therefore, there is an urgent need to develop a terahertz broadband absorber with a simple structure, convenient fabrication, and rapid mode switching capability to meet the needs of practical terahertz applications. Summary of the Invention
[0004] The first objective of this invention is to propose a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control. This terahertz absorber can switch between broadband high absorption and dual-frequency absorption functions over a wide frequency range, and the terahertz absorber has a simple structure.
[0005] The second objective of this invention is to propose a method for preparing a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars.
[0006] The first technical solution adopted in this invention is a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars, comprising M×N dual-function switchable terahertz absorption units based on vanadium dioxide and embedded copper pillars, wherein the M×N dual-function switchable terahertz absorption units are distributed in an M×N two-dimensional pattern, where M and N are both positive integers. The dual-function switchable terahertz absorption unit based on vanadium dioxide and embedded copper pillars includes, from bottom to top, a base plate, a via dielectric layer, a vanadium dioxide resonant layer, a blind via dielectric layer, and a metal ring; it also includes a copper pillar array, which connects the base plate, the via dielectric layer, the vanadium dioxide resonant layer, and the blind via dielectric layer in series.
[0007] The invention is further characterized in that: The metal ring is located at the center of the upper surface of the blind via dielectric layer; the metal ring is made of copper and has a conductivity of 5.8 × 10⁻⁶. 7 S / m; The dimensions of the metal ring are as follows: outer radius r1 is 4.6µm-5.3µm, inner radius r2 is 0.5µm-1.5µm, and thickness t5 is 0.1µm-2µm.
[0008] The blind via dielectric layer is a square dielectric layer, and four blind vias are provided on the side surface of the blind via dielectric layer facing the copper pillar array; The copper pillar array consists of four copper pillars arranged in a 2×2 array. The arrangement of blind holes is the same as the arrangement of copper pillars in the copper pillar array; there is a one-to-one correspondence between blind holes and copper pillars. The bottom of each copper pillar is attached to the base plate, and the pillar body of each copper pillar passes through the interconnecting dielectric layer and the vanadium dioxide resonant layer from bottom to top. The top of each copper pillar is set in a blind hole.
[0009] The height h of the copper column is 5.06µm-8.06µm, and the cross-sectional radius r6 of the copper column is 4µm-5.6µm. The side length p1 of the blind via dielectric layer is 38µm-42µm, the depth g of the blind via is 3µm-4.6µm, the radius r3 of the blind via is 4µm-5.6µm, and the thickness t4 of the blind via dielectric layer is 5µm-6µm. The material of the blind via dielectric layer is silicon dioxide crystal with a relative permittivity of 3.75 and a loss tangent of 0.0004.
[0010] The vanadium dioxide resonant layer consists of four independent vanadium dioxide resonant plates, with a gap of 1µm between adjacent vanadium dioxide resonant plates; the vanadium dioxide resonant plates are square in shape. The arrangement of the four vanadium dioxide resonator plates is the same as that of the copper pillars in the copper pillar array; the vanadium dioxide resonator plates correspond one-to-one with the copper pillars, and each vanadium dioxide resonator plate has a first through hole in its center. Each copper pillar passes through the first through hole and is connected to a vanadium dioxide resonator plate. The side length a of the vanadium dioxide resonant plate is 18µm-20µm, and the thickness t3 of the vanadium dioxide resonant plate is 0.05µm-0.07µm; the radius r4 of the first through hole is 4µm-5.6µm.
[0011] The conductivity of the vanadium dioxide resonator plate is 20 S / m in the insulating phase and 200,000 S / m in the metallic phase.
[0012] The via dielectric layer is a square dielectric layer with four second through holes; The arrangement of the four second through holes is the same as the arrangement of the copper pillars in the copper pillar array; the second through holes correspond one-to-one with the copper pillars; one copper pillar passes through one second through hole, and the connecting hole dielectric layer is connected to the four copper pillars. The via dielectric layer is made of silicon dioxide crystal with a relative permittivity of 3.75 and a loss tangent of 0.0004. The side length p2 of the via dielectric layer is 38µm-42µm, and the dielectric layer thickness t2 is 2.8µm-3.2µm.
[0013] The base plate is made of copper with an electrical conductivity of 5.8 × 10⁻⁶. 7 S / m, the base plate is square in shape, the side length p3 of the base plate is 38µm-42µm, and the thickness t1 is 0.2µm-0.4µm.
[0014] The second technical solution adopted in this invention is, The fabrication method of a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars includes the following steps: Step A: Place the copper pillars arranged in a 2×2 array onto the base plate; then deposit a perforated dielectric layer along the sidewalls of the copper pillars; Step B: Attach a vanadium dioxide thin film; Step C: At room temperature, a blind via dielectric layer is prepared on a pre-prepared pure silicon mold using atomic deposition. The prepared blind via dielectric layer is then installed by attaching the copper pillars and blind vias one by one. Step D: Place the top copper ring.
[0015] The invention is further characterized in that: The process of depositing the interconnecting medium layer in step A is as follows: at room temperature (20℃~25℃), dilute sulfuric acid with a mass concentration of 27% is used to remove the oxide layer and plasma on the surface of the base plate with copper pillars. Then, in the order of "from inside to outside, from bottom to top", atomic layer deposition (ALD) is used to attach the interconnecting medium layer along the sidewall of the copper pillars. Step B is as follows: Under an ambient temperature of 150℃~300℃, an atomic layer deposition method is used to react and generate a vanadium dioxide layer that can completely cover the dielectric layer along the sidewall of the copper pillar on the surface of the interconnecting dielectric layer. Then, ultraviolet photolithography is used to create gaps on the vanadium dioxide layer, dividing the vanadium dioxide layer into an array composed of 2×2 square vanadium dioxide resonant plates. Step D specifically involves: depositing a metal ring on a high-purity silicon substrate using electron beam evaporation, and then ultrasonically cleaning it with acetone, ethanol, and deionized water for 10-15 minutes to remove surface contaminants; placing the metal ring according to the method of corresponding center of the circle and unit center; wherein the metal ring is a copper ring.
[0016] The beneficial effects of this invention are: (1) This invention is based on a dual-function switchable terahertz absorber controlled by vanadium dioxide and embedded copper pillars. By introducing a vanadium dioxide thin film layer between two dielectric layers, the resonant cavity formed by the absorber dielectric layer differs in the two states, thereby achieving switchability between two different functions. When vanadium dioxide is in the metallic state, under normal incidence, the absorption rate reaches over 90% in the frequency range of 4.15THz-8.05THz, with an absorption bandwidth of 3.90THz and a center frequency of 6.10THz. When vanadium dioxide is in the insulating state, under normal incidence, the absorption rate exceeds 99% at two frequency points: 4THz and 6.33THz. This terahertz absorber achieves dynamic switchability between two absorption modes over a wide frequency range.
[0017] (2) The present invention has a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control, which is polarization insensitive and maintains excellent absorption performance under different polarization angles and wide incident angles. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the structure of a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control provided in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the unit structure of a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control provided in Embodiment 1 of the present invention. Figure 3 This is a layered schematic diagram of the unit structure of a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars, provided in Embodiment 1 of the present invention. Figure 4 This is a top view of the top metal ring of the dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars, provided in Embodiment 1 of the present invention. Figure 5 This is a front view of the blind hole dielectric layer of a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars, provided in Embodiment 1 of the present invention. Figure 6 This is a top view of the vanadium dioxide resonant layer of the dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars, provided in Embodiment 1 of the present invention. Figure 7This is a top view of the perforated dielectric layer of a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars, provided in Embodiment 1 of the present invention. Figure 8 This is a schematic diagram of a copper pillar array layer structure with a base plate, based on a dual-function switchable terahertz absorber controlled by vanadium dioxide and embedded copper pillars, provided in Embodiment 1 of the present invention. Figure 9 This is a front view of the structure of the dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control provided in Embodiment 1 of the present invention; Figure 10 This is a fabrication roadmap for a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars, provided in Embodiment 1 of the present invention. Figure 11 The absorption spectrum of vanadium dioxide in the insulating and metallic states of the dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars in Embodiment 1 of the present invention. Figure 12 This is a schematic diagram of the incident angle variation in TE mode of a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control, provided in Embodiment 1 of the present invention. Figure 13 This is a schematic diagram of the incident angle variation in TM mode of a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars, provided in Embodiment 1 of the present invention. Figure 14 This is a schematic diagram of heat conduction in the switching state of the dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control provided in Embodiment 1 of the present invention. In the figure, 1. Single metal ring, 2. Blind hole dielectric layer, 3. Vanadium dioxide resonator plate, 4. Through hole dielectric layer, 5. Copper pillar, 6. Base plate; 2-1. Blind hole; 3-1. First through hole; 4-1. Second through hole. Detailed Implementation
[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0020] This invention provides a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control, such as... Figures 1-9 As shown, it includes M×N dual-function switchable terahertz absorption units controlled by vanadium dioxide and embedded copper pillars. The M×N dual-function switchable terahertz absorption units controlled by vanadium dioxide and embedded copper pillars are distributed in an M×N two-dimensional pattern, where M and N are both positive integers. The dual-function switchable terahertz absorption unit based on vanadium dioxide and embedded copper pillars includes, from bottom to top, a base plate 6, a via dielectric layer 4, a vanadium dioxide resonant layer, a blind via dielectric layer 2, and a metal ring 1; it also includes a copper pillar array, which connects the base plate 6, the via dielectric layer 4, the vanadium dioxide resonant layer, and the blind via dielectric layer 2 in series. The layers are bonded together.
[0021] Metal ring 1 is located at the center of the upper surface of the blind via dielectric layer 2; metal ring 1 is made of copper and has an electrical conductivity of 5.8 × 10⁻⁶. 7 S / m; The dimensions of metal ring 1 are as follows: outer circle radius r1 is 4.6µm-5.3µm, inner circle radius r2 is 0.5µm-1.5µm, and thickness t5 is 0.1µm-2µm.
[0022] The blind via dielectric layer 2 is a square dielectric layer, and four blind vias 2-1 are provided on the side surface of the blind via dielectric layer 2 facing the copper pillar array; The copper pillar array consists of four copper pillars arranged in a 2×2 array. The arrangement of blind holes 2-1 is the same as that of copper pillars 5 in the copper pillar array; blind holes 2-1 correspond one-to-one with copper pillars 5. The bottom of each copper pillar 5 is attached to the base plate 6 (by welding). The pillar body of each copper pillar 5 passes through the connecting hole dielectric layer 4 and the vanadium dioxide resonant layer from bottom to top. The top of each copper pillar 5 is set in the blind hole 2-1.
[0023] The height h of the copper pillar 5 is 5.06µm-8.06µm, and the cross-sectional radius r6 of the copper pillar 5 is 4µm-5.6µm. The side length p1 of the blind via dielectric layer 2 is 38µm-42µm, the depth g of the blind via 2-1 is 3µm-4.6µm, the radius r3 of the blind via 2-1 is 4µm-5.6µm, and the thickness t4 of the blind via dielectric layer 2 is 5µm-6µm. The material of the blind via dielectric layer 2 is silicon dioxide crystal with a relative permittivity of 3.75 and a loss tangent of 0.0004.
[0024] The vanadium dioxide resonant layer consists of four independent vanadium dioxide resonant plates 3, with a gap of 1µm between adjacent vanadium dioxide resonant plates 3; the vanadium dioxide resonant plates 3 are square in shape. The arrangement of the four vanadium dioxide resonant plates 3 is the same as the arrangement of the copper pillars 5 in the copper pillar array; the vanadium dioxide resonant plates 3 and the copper pillars 5 correspond one-to-one, and each vanadium dioxide resonant plate 3 has a first through hole 3-1 in the center, and each copper pillar 5 passes through the first through hole 3-1 and is sleeved with a vanadium dioxide resonant plate 3. The side length a of the vanadium dioxide resonant plate 3 is 18µm-20µm, and the thickness t3 of the vanadium dioxide resonant plate 3 is 0.05µm-0.07µm; the radius r4 of the first through hole 3-1 is 4µm-5.6µm.
[0025] The conductivity of the vanadium dioxide resonant plate is 20 S / m when it is in the insulating phase and 200,000 S / m when it is in the metallic phase.
[0026] The via dielectric layer 4 is a square dielectric layer with four second through holes 4-1; The arrangement of the four second through holes 4-1 is the same as the arrangement of the copper pillars 5 in the copper pillar array; the second through holes 4-1 correspond one-to-one with the copper pillars 5; one copper pillar 5 passes through one second through hole 4-1, and the connecting hole dielectric layer 4 is sleeved with the four copper pillars 5. The via dielectric layer 4 is made of silicon dioxide crystal with a relative permittivity of 3.75 and a loss tangent of 0.0004. The side length p2 of the via dielectric layer 4 is 38µm-42µm and the dielectric layer thickness t2 is 2.8µm-3.2µm.
[0027] The base plate 6 is made of copper with an electrical conductivity of 5.8 × 10⁻⁶. 7 S / m, the shape of the base plate 6 is square, the side length p3 of the base plate 6 is 38µm-42µm, and the thickness t1 is 0.2µm-0.4µm.
[0028] This invention also provides a method for fabricating a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars, such as... Figure 10 As shown, the specific steps include: Step A: Place the copper pillars arranged in a 2×2 array onto the base plate; then deposit a perforated dielectric layer along the sidewalls of the copper pillars; The process of depositing the interconnecting medium layer in step A is as follows: at room temperature of 20℃~25℃, dilute sulfuric acid with a mass concentration of 27% is used to remove the oxide layer and plasma on the surface of the base plate with copper pillars. Then, in the order of "from inside to outside, from bottom to top", atomic layer deposition (ALD) is used to attach the interconnecting medium layer along the sidewall of the copper pillars. Step B: Attach a vanadium dioxide thin film; Step B is as follows: Under an ambient temperature of 150℃~300℃, an atomic layer deposition method is used to react and generate a vanadium dioxide layer that can completely cover the dielectric layer along the sidewall of the copper pillar on the surface of the interconnecting dielectric layer. Then, ultraviolet photolithography is used to create gaps on the vanadium dioxide layer, dividing the vanadium dioxide layer into an array composed of 2×2 square vanadium dioxide resonant plates. Step C: At room temperature, a blind via dielectric layer is prepared on a pre-prepared pure silicon mold using atomic deposition. The prepared blind via dielectric layer is then installed by attaching the copper pillars and blind vias one by one. Step D: Place the top copper ring.
[0029] Step D specifically involves: depositing a metal ring on a high-purity silicon substrate using electron beam evaporation, and then ultrasonically cleaning it with acetone, ethanol, and deionized water for 10-15 minutes to remove surface contaminants; placing the metal ring according to the method of corresponding center of the circle and unit center; wherein the metal ring is a copper ring.
[0030] Example 1 like Figure 1-3 As shown, the dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars includes 3×3 dual-function switchable terahertz absorption units based on vanadium dioxide and embedded copper pillars. The number of dual-function switchable terahertz absorption units based on vanadium dioxide and embedded copper pillars does not affect the overall absorption performance. Each dual-function switchable terahertz absorption unit based on vanadium dioxide and embedded copper pillars includes a base plate 6, a perforated dielectric layer 4, a vanadium dioxide resonant layer, a blind via dielectric layer 2, and a metal ring 1 arranged sequentially from bottom to top; it also includes a copper pillar array, which connects the base plate 6, the perforated dielectric layer 4, the vanadium dioxide resonant layer, and the blind via dielectric layer 2 in series.
[0031] Metal ring 1 is located at the center of the upper surface of the blind via dielectric layer 2; a top view of metal ring 1 is shown below. Figure 4 As shown, the outer radius r1 is 4.9µm and the inner radius r2 is 0.9µm; The blind via dielectric layer 2 is a square dielectric layer, and four blind vias 2-1 are provided on the side surface of the blind via dielectric layer 2 facing the copper pillar array; the copper pillar array includes four copper pillars 5 arranged in a 2×2 array; the arrangement of the blind vias 2-1 is the same as the arrangement of the copper pillars 5 in the copper pillar array; the blind vias 2-1 correspond one-to-one with the copper pillars 5; the bottom end of each copper pillar 5 is attached to the base plate 6, and the pillar body of each copper pillar 5 passes through the interconnecting dielectric layer 4 and the vanadium dioxide resonant layer from bottom to top, and the top end of each copper pillar 5 is located in the blind via 2-1.
[0032] The front view of blind via dielectric layer 2 is shown below. Figure 5 As shown, the side length p1 of the blind via dielectric layer 2 is 40µm, the blind via depth g is 3µm, and the blind via radius r3 is 5µm. The material of the blind via dielectric layer 2 is silicon dioxide crystal with a relative permittivity of 3.75 and a loss tangent of 0.0004. A top view of the vanadium dioxide resonator layer is shown below. Figure 6As shown, the vanadium dioxide resonant layer consists of four independent vanadium dioxide resonant plates 3, with a gap of 1µm between adjacent vanadium dioxide resonant plates 3; the shape of the vanadium dioxide resonant plates 3 is square; the arrangement of the four vanadium dioxide resonant plates 3 is the same as the arrangement of the copper pillars 5 in the copper pillar array; the vanadium dioxide resonant plates 3 correspond one-to-one with the copper pillars 5, and each vanadium dioxide resonant plate 3 has a first through hole 3-1 in its center, and each copper pillar 5 passes through the first through hole 3-1 and is sleeved with a vanadium dioxide resonant plate 3; the side length a of the vanadium dioxide resonant plate 3 is 19µm, and the radius r4 of the first through hole 3-1 is 5µm; the thickness t3 of the vanadium dioxide resonant plate 3 is 0.05µm; the conductivity of the vanadium dioxide resonant plate 3 is 20S / m in the insulating phase and 200000S / m in the metallic phase. The via dielectric layer 4 is a square dielectric layer with four second through holes 4-1. The arrangement of the four second through holes 4-1 is the same as the arrangement of the copper pillars 5 in the copper pillar array. The second through holes 4-1 correspond one-to-one with the copper pillars 5. One copper pillar 5 passes through one second through hole 4-1, and the via dielectric layer 4 is connected to the four copper pillars 5. The material of the via dielectric layer 4 is silicon dioxide crystal, with a relative permittivity of 3.75 and a loss tangent of 0.0004. The top view of the via dielectric layer 4 is shown below. Figure 7 As shown, the side length p2 of the via dielectric layer 4 is 40µm, and the radius r5 of the second via 4-1 is 5µm. Figure 7 As shown, the bottom end of each copper pillar 5 is bonded to the base plate 6 by welding. The base plate 6 is made of copper and has an electrical conductivity of 5.8 × 10⁻⁶. 7 S / m, the base plate 6 is square in shape, and the side length p3 of the base plate is 40µm; the height h of the copper column 5 welded on top is 6.06µm, and the cross-sectional radius r6 of the copper column 5 is 5µm. The front view of the complete absorber is as follows. Figure 8 As shown, the thicknesses of each layer from bottom to top are t1=0.2µm, t2=3µm, t3=0.06µm, t4=5.5µm, and t5=0.1µm.
[0033] like Figure 11 As shown, the vanadium dioxide resonator plate has a conductivity of 20 S / m in the insulating phase (3) and operates in a dual-frequency absorption mode. Under normal incidence, the absorption rate exceeds 99% at both 4 THz and 6.33 THz. By heating the copper base to a temperature exceeding 68°C, vanadium dioxide undergoes a phase transition, resulting in a conductivity of 200,000 S / m in the metallic phase (3) of the vanadium dioxide resonator plate. It operates in a broadband absorption mode, achieving an absorption rate of over 90% in the 4.15-8.05 THz frequency range under normal incidence, with an absorption bandwidth of 3.90 THz and a center frequency of 6.10 THz.
[0034] The absorption spectra of vanadium dioxide in different states are as follows: Figure 10As shown, when vanadium dioxide is in an insulating state, it operates in a dual-frequency absorption mode. Under normal incidence, the absorption rate exceeds 99% at both 4 THz and 6.33 THz. This is due to the resonance between the copper ring and copper pillar in the top layer. By heating the copper base to a temperature exceeding 68°C, vanadium dioxide undergoes a phase transition. When the vanadium dioxide resonant layer is in the metallic phase, its conductivity is 200,000 S / m, and it operates in a broadband absorption mode. Under normal incidence, the absorption rate reaches over 90% in the frequency range of 4.15-8.05 THz. The addition of this vanadium dioxide resonant layer constitutes an FP resonant cavity, thereby expanding the absorption bandwidth of the absorber and improving the absorption efficiency.
[0035] A schematic diagram of the spectrum showing the change in incident angle in TE mode of the absorber is shown below. Figure 11 As shown, the spectral schematic of the incident angle variation in TM mode is as follows: Figure 12 and Figure 13 As shown in the diagram. Due to the centrosymmetry of the absorber, the spectral diagrams of the incident angle changes in the two modes are basically the same. Within the incident angle range of 0-45°, the broadband absorption performance is relatively stable. When the incident angle is greater than 60°, the absorption performance drops sharply. This is related to the gap width between the small squares in the vanadium dioxide resonant layer, which results in a small propagation path for incident waves at large incident angles, leading to low loss within the absorber and consequently low absorption efficiency. When switching the absorption mode of the absorber, the heat conduction path of the absorber during heating or cooling of the copper substrate is as follows... Figure 14 As shown, the copper base plate serves as the heating / cooling port, and its temperature is changed by directly contacting the temperature-sensitive end face of the heater (such as a CNC electric heater, a thermostat, etc.). Since the copper base plate is welded to the copper pillar, the temperature of the blind via dielectric layer and the interconnecting via dielectric layer, which are in direct contact with the copper pillar, can be altered by changing the temperature of the copper pillar. The temperature changes of the two dielectric layers are almost identical, achieving uniform heating / cooling of vanadium dioxide. Furthermore, the direct contact between the embedded copper pillar and the vanadium dioxide resonant layer enables rapid switching of the absorber's absorption mode.
[0036] A method for fabricating a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars, such as... Figure 10 As shown, the specific steps include: Step A: Place the copper pillars arranged in a 2×2 array onto the base plate; then deposit a perforated dielectric layer along the sidewalls of the copper pillars; The process of depositing the interconnecting medium layer in step A is as follows: at room temperature (20°C), dilute sulfuric acid with a mass concentration of 27% is used to remove the oxide layer and plasma on the surface of the base plate with copper pillars. Then, in the order of "from inside to outside, from bottom to top", atomic layer deposition (ALD) is used to attach the interconnecting medium layer along the sidewall of the copper pillars. Step B: Attach a vanadium dioxide thin film; Step B is as follows: Under an ambient temperature of 150℃, an atomic layer deposition method is used to react and generate a vanadium dioxide layer that can completely cover the dielectric layer along the sidewall of the copper pillar on the surface of the interconnecting dielectric layer. Then, ultraviolet photolithography is used to create gaps on the vanadium dioxide layer, dividing the vanadium dioxide layer into an array composed of 2×2 square vanadium dioxide resonant plates. Step C: At room temperature, a blind via dielectric layer is prepared on a pre-prepared pure silicon mold using atomic deposition. The prepared blind via dielectric layer is then installed by attaching the copper pillars and blind vias one by one. Step D: Place the top copper ring.
[0037] Step D specifically involves: depositing a metal ring on a high-purity silicon substrate using electron beam evaporation, followed by ultrasonic cleaning with acetone, ethanol, and deionized water for 10 minutes to remove surface contaminants; placing the metal ring according to the method of corresponding center of the circle and center of the unit; wherein the metal ring is a copper ring.
[0038] Example 2 The dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars comprises 3×3 dual-function switchable terahertz absorption units based on vanadium dioxide and embedded copper pillars. The number of dual-function switchable terahertz absorption units based on vanadium dioxide and embedded copper pillars does not affect the overall absorption performance. Each dual-function switchable terahertz absorption unit based on vanadium dioxide and embedded copper pillars includes, from bottom to top, a base plate 6, a perforated dielectric layer 4, a vanadium dioxide resonant layer, a blind via dielectric layer 2, and a metal ring 1; it also includes a copper pillar array, which connects the base plate 6, the perforated dielectric layer 4, the vanadium dioxide resonant layer, and the blind via dielectric layer 2 in series.
[0039] The outer radius of metal ring 1 is r1, which is 4.6µm, and the inner radius is r2, which is 0.5µm. The side length of blind via dielectric layer 2 is p1, which is 40µm; the depth of the blind via is g, which is 3.5µm; and the radius of the blind via is r3, which is 4.8µm. The side length of vanadium dioxide resonator plate 3 is a, which is 19µm; the gap between vanadium dioxide resonator plates 3 is 1µm; and the radius of the first through-hole 3-1 is r4, which is 4.8µm. The side length of interconnecting dielectric layer 4 is p2, which is 40µm; and the radius of the second through-hole 4-1 is r5, which is 4.8µm. The side length of metal base plate 6 is p3, which is 40µm; the height h of the copper pillar 5 welded above it is 6.55µm; and the cross-sectional radius r6 of the copper pillar 5 is 4.8µm. The thicknesses of each layer are t1 = 0.4µm, t2 = 3.2µm, t3 = 0.05µm, t4 = 6µm, and t5 = 2µm.
[0040] A method for fabricating a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars, such as... Figure 10 As shown, the specific steps include: Step A: Place the copper pillars arranged in a 2×2 array onto the base plate; then deposit a perforated dielectric layer along the sidewalls of the copper pillars; The process of depositing the interconnecting medium layer in step A is as follows: at room temperature of 25°C, dilute sulfuric acid with a mass concentration of 27% is used to remove the oxide layer and plasma on the surface of the base plate with copper pillars. Then, in the order of "from inside to outside, from bottom to top", atomic layer deposition (ALD) is used to attach the interconnecting medium layer along the side wall of the copper pillars. Step B: Attach a vanadium dioxide thin film; Step B is as follows: Under an ambient temperature of 300℃, an atomic layer deposition method is used to react and generate a vanadium dioxide layer that can completely cover the dielectric layer along the sidewall of the copper pillar on the surface of the interconnecting dielectric layer. Then, ultraviolet photolithography is used to create gaps on the vanadium dioxide layer, dividing the vanadium dioxide layer into an array composed of 2×2 square vanadium dioxide resonant plates. Step C: At room temperature, a blind via dielectric layer is prepared on a pre-prepared pure silicon mold using atomic deposition. The prepared blind via dielectric layer is then installed by attaching the copper pillars and blind vias one by one. Step D: Place the top copper ring.
[0041] Step D specifically involves: depositing a metal ring on a high-purity silicon substrate using electron beam evaporation, and then ultrasonically cleaning it for 15 minutes with acetone, ethanol, and deionized water to remove surface contaminants; placing the metal ring according to the method of corresponding center of the circle and center of the unit; wherein, the metal ring is a copper ring.
[0042] Example 3 The dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars comprises 3×3 dual-function switchable terahertz absorption units based on vanadium dioxide and embedded copper pillars. The number of dual-function switchable terahertz absorption units based on vanadium dioxide and embedded copper pillars does not affect the overall absorption performance. Each dual-function switchable terahertz absorption unit based on vanadium dioxide and embedded copper pillars includes, from bottom to top, a base plate 6, a perforated dielectric layer 4, a vanadium dioxide resonant layer, a blind via dielectric layer 2, and a metal ring 1; it also includes a copper pillar array, which connects the base plate 6, the perforated dielectric layer 4, the vanadium dioxide resonant layer, and the blind via dielectric layer 2 in series.
[0043] The outer radius of metal ring 1 is r1 = 5µm, and the inner radius is r2 = 1µm. The side length of blind via dielectric layer 2 is p1 = 42µm, the depth of the blind via is g = 4.6µm, and the radius of the blind via is r3 = 5µm. The side length of vanadium dioxide resonator plate 3 is a = 20µm, and the gap between vanadium dioxide resonator plates 3 is 1µm; the radius of the first through hole 3-1 is r4 = 5µm. The side length of the connecting via dielectric layer 4 is p2 = 42µm, and the radius of the second through hole 4-1 is r5 = 5µm. The side length of metal base plate 6 is p3 = 42µm, the height g of the metal column 5 welded above it is 7.7µm, and the cross-sectional radius r6 of the copper column 5 is 5µm. The thicknesses of each layer are t1 = 0.4µm, t2 = 2.8µm, t3 = 0.1µm, t4 = 5.5µm, and t5 = 0.2µm.
[0044] A method for fabricating a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars, such as... Figure 10 As shown, the specific steps include: Step A: Place the copper pillars arranged in a 2×2 array onto the base plate; then deposit a perforated dielectric layer along the sidewalls of the copper pillars; The process of depositing the interconnecting medium layer in step A is as follows: at room temperature of 25°C, dilute sulfuric acid with a mass concentration of 27% is used to remove the oxide layer and plasma on the surface of the base plate with copper pillars. Then, in the order of "from inside to outside, from bottom to top", atomic layer deposition (ALD) is used to attach the interconnecting medium layer along the side wall of the copper pillars. Step B: Attach a vanadium dioxide thin film; Step B is as follows: Under an ambient temperature of 280℃, an atomic layer deposition method is used to react and generate a vanadium dioxide layer that can completely cover the dielectric layer along the sidewall of the copper pillar on the surface of the interconnecting dielectric layer. Then, ultraviolet photolithography is used to create gaps on the vanadium dioxide layer, dividing the vanadium dioxide layer into an array composed of 2×2 square vanadium dioxide resonant plates. Step C: At room temperature, a blind via dielectric layer is prepared on a pre-prepared pure silicon mold using atomic deposition. The prepared blind via dielectric layer is then installed by attaching the copper pillars and blind vias one by one. Step D: Place the top copper ring.
[0045] Step D specifically involves: depositing a metal ring on a high-purity silicon substrate using electron beam evaporation, and then ultrasonically cleaning it for 12 minutes with acetone, ethanol, and deionized water to remove surface contaminants; placing the metal ring according to the method of corresponding center of the circle and center of the unit; wherein the metal ring is a copper ring.
[0046] Example 4 The dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars comprises 3×3 dual-function switchable terahertz absorption units based on vanadium dioxide and embedded copper pillars. The number of dual-function switchable terahertz absorption units based on vanadium dioxide and embedded copper pillars does not affect the overall absorption performance. Each dual-function switchable terahertz absorption unit based on vanadium dioxide and embedded copper pillars includes, from bottom to top, a base plate 6, a perforated dielectric layer 4, a vanadium dioxide resonant layer, a blind via dielectric layer 2, and a metal ring 1; it also includes a copper pillar array, which connects the base plate 6, the perforated dielectric layer 4, the vanadium dioxide resonant layer, and the blind via dielectric layer 2 in series.
[0047] The outer radius of metal ring 1 is r1 = 5.3µm, and the inner radius is r2 = 1.5µm. The side length of blind via dielectric layer 2 is p1 = 38µm, the depth of the blind via is g = 3.5µm, and the radius of the blind via is r3 = 5.6µm. The side length of vanadium dioxide resonator plate 3 is a = 18µm, and the gap between vanadium dioxide resonator plates 3 is 1µm; the radius of the first through hole 3-1 is r4 = 5.6µm. The side length of interconnecting dielectric layer 4 is p2 = 38µm, and the radius of the second through hole 4-1 is r5 = 5.6µm. The side length of metal base plate 6 is p3 = 38µm, the height h of the copper pillar 5 welded on top is 6.56µm, and the cross-sectional radius r6 of the copper pillar 5 is 5.6µm. The thicknesses of each layer are t1 = 0.3µm, t2 = 3µm, t3 = 0.06µm, t4 = 6µm, and t5 = 0.1µm.
[0048] Example 5 The dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars comprises 3×3 dual-function switchable terahertz absorption units based on vanadium dioxide and embedded copper pillars. The number of dual-function switchable terahertz absorption units based on vanadium dioxide and embedded copper pillars does not affect the overall absorption performance. Each dual-function switchable terahertz absorption unit based on vanadium dioxide and embedded copper pillars includes, from bottom to top, a base plate 6, a perforated dielectric layer 4, a vanadium dioxide resonant layer, a blind via dielectric layer 2, and a metal ring 1; it also includes a copper pillar array, which connects the base plate 6, the perforated dielectric layer 4, the vanadium dioxide resonant layer, and the blind via dielectric layer 2 in series.
[0049] The outer radius of metal ring 1 is r1, which is 4.9µm, and the inner radius is r2, which is 0.9µm. The side length of blind via dielectric layer 2 is p1, which is 40µm, the depth of the blind via is g, which is 3.1µm, and the radius of the blind via is r3, which is 5µm. The side length of vanadium dioxide resonator plate 3 is a, which is 19µm, the gap between vanadium dioxide resonator plates 3 is 1µm, and the radius of the first through hole 3-1 is r4, which is 5µm. The side length of connecting via dielectric layer 4 is p2, which is 40µm, and the radius of the second through hole 4-1 is r5, which is 5µm. The side length of metal base plate 6 is p3, which is 40µm, the height h of the copper pillar 5 welded on top is 6.16µm, and the cross-sectional radius r6 of the copper pillar 5 is 5µm. The thicknesses of each layer are t1 = 0.2µm, t2 = 3µm, t3 = 0.06µm, t4 = 5.6µm, and t5 = 0.1µm.
[0050] Example 6 The dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars comprises 3×3 dual-function switchable terahertz absorption units based on vanadium dioxide and embedded copper pillars. The number of dual-function switchable terahertz absorption units based on vanadium dioxide and embedded copper pillars does not affect the overall absorption performance. Each dual-function switchable terahertz absorption unit based on vanadium dioxide and embedded copper pillars includes, from bottom to top, a base plate 6, a perforated dielectric layer 4, a vanadium dioxide resonant layer, a blind via dielectric layer 2, and a metal ring 1; it also includes a copper pillar array, which connects the base plate 6, the perforated dielectric layer 4, the vanadium dioxide resonant layer, and the blind via dielectric layer 2 in series.
[0051] The outer radius of metal ring 1 is r1, which is 4.9µm, and the inner radius is r2, which is 1.5µm. The side length of blind via dielectric layer 2 is p1, which is 42µm, the depth of the blind via is g, which is 3.1µm, and the radius of the blind via is r3, which is 5µm. The side length of vanadium dioxide resonator plate 3 is a, which is 20µm. The gap between vanadium dioxide resonator plates 3 is 1µm, and the radius of the first through hole 3-1 is r4, which is 5µm. The side length of interconnecting dielectric layer 4 is p2, which is 42µm, and the radius of the second through hole 4-1 is r5, which is 5µm. The side length of metal base plate 6 is p3, which is 42µm. The height h of the copper pillar 5 welded above it is 6.18µm, and the cross-sectional radius r6 of the copper pillar 5 is 5µm. The thicknesses of each layer are t1 = 0.2µm, t2 = 3µm, t3 = 0.08µm, t4 = 5.5µm, and t5 = 0.1µm.
[0052] This invention relates to a dual-function switchable terahertz absorption unit based on vanadium dioxide and embedded copper pillars. The absorption mode of the absorber is reversibly switched by inducing a phase transition in vanadium dioxide. When vanadium dioxide is in the metallic state, optimized structural parameters enable the absorber to achieve excellent absorption performance in a wide frequency range of 4.15-8.05 THz. When vanadium dioxide is in the insulating state, the absorber achieves an absorption rate exceeding 99% at both 4 THz and 6.33 THz. This invention, based on a dual-function switchable terahertz absorber controlled by vanadium dioxide and embedded copper pillars, features a simple structure, good absorption performance, and has potential application value.
Claims
1. A dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control, characterized in that, It includes M×N dual-function switchable terahertz absorption units controlled by vanadium dioxide and embedded copper pillars. The M×N dual-function switchable terahertz absorption units controlled by vanadium dioxide and embedded copper pillars are distributed in an M×N two-dimensional pattern, where M and N are both positive integers. The dual-function switchable terahertz absorption unit based on vanadium dioxide and embedded copper pillars includes a base plate (6), a via dielectric layer (4), a vanadium dioxide resonant layer, a blind via dielectric layer (2), and a metal ring (1) arranged sequentially from bottom to top; it also includes a copper pillar array, which connects the base plate (6), the via dielectric layer (4), the vanadium dioxide resonant layer, and the blind via dielectric layer (2) in series.
2. The dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control according to claim 1, characterized in that, The metal ring (1) is located at the center of the upper surface of the blind hole dielectric layer (2); the metal ring (1) is made of copper with a conductivity of 5.8 × 10⁻⁶. 7 S / m; The dimensions of the metal ring (1) are: outer circle radius r1 is 4.6µm-5.3µm, inner circle radius r2 is 0.5µm-1.5µm, and thickness t5 is 0.1µm-2µm.
3. The dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control according to claim 1, characterized in that, The blind hole dielectric layer (2) is a square dielectric layer, and four blind holes (2-1) are provided on the side surface of the blind hole dielectric layer (2) facing the copper pillar array. The copper pillar array includes four copper pillars arranged in a 2×2 array (5). The arrangement of blind holes (2-1) is the same as that of copper pillars (5) in the copper pillar array; blind holes (2-1) correspond one-to-one with copper pillars (5); The bottom end of each copper pillar (5) is attached to the base plate (6). The pillar body of each copper pillar (5) passes through the connecting hole dielectric layer (4) and the vanadium dioxide resonant layer from bottom to top. The top end of each copper pillar (5) is set in the blind hole (2-1).
4. The dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control according to claim 3, characterized in that, The height h of the copper column (5) is 5.06µm-8.06µm, and the cross-sectional radius r6 of the copper column (5) is 4µm-5.6µm; The side length p1 of the blind hole dielectric layer (2) is 38µm-42µm, the depth g of the blind hole (2-1) is 3µm-4.6µm, the radius r3 of the blind hole (2-1) is 4µm-5.6µm, and the thickness t4 of the blind hole dielectric layer (2) is 5µm-6µm. The material of the blind via dielectric layer (2) is silicon dioxide crystal with a relative permittivity of 3.75 and a loss tangent of 0.0004.
5. The dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control according to claim 3, characterized in that, The vanadium dioxide resonant layer consists of four independent vanadium dioxide resonant plates (3), with a gap of 1µm between adjacent vanadium dioxide resonant plates (3); the shape of the vanadium dioxide resonant plates (3) is square. The arrangement of the four vanadium dioxide resonator plates (3) is the same as the arrangement of the copper pillars (5) in the copper pillar array; the vanadium dioxide resonator plates (3) and the copper pillars (5) correspond one-to-one, and each vanadium dioxide resonator plate (3) has a first through hole (3-1) in the center, and each copper pillar (5) passes through the first through hole (3-1) and is connected to a vanadium dioxide resonator plate (3). The side length a of the vanadium dioxide resonant plate (3) is 18µm-20µm, the thickness t3 of the vanadium dioxide resonant plate (3) is 0.05µm-0.07µm, and the radius r4 of the first through hole (3-1) is 4µm-5.6µm.
6. The dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control according to claim 5, characterized in that, The conductivity of the vanadium dioxide resonant plate (3) is 20 S / m in the insulating phase and 200000 S / m in the metallic phase.
7. The dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control according to claim 3, characterized in that, The perforated dielectric layer (4) is a square dielectric layer with four second through holes (4-1); The arrangement of the four second through holes (4-1) is the same as the arrangement of the copper pillars (5) in the copper pillar array; the second through holes (4-1) correspond one-to-one with the copper pillars (5); one copper pillar (5) passes through one second through hole (4-1), and the connecting hole dielectric layer (4) is sleeved with the four copper pillars (5); The material of the via dielectric layer (4) is silicon dioxide crystal, with a relative permittivity of 3.75 and a loss tangent of 0.0004; the side length p2 of the via dielectric layer (4) is 38µm-42µm, and the dielectric layer thickness t2 is 2.8µm-3.2µm.
8. The dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillar control according to claim 1, characterized in that, The base plate (6) is made of copper with an electrical conductivity of 5.8 × 10⁻⁶. 7 S / m, the shape of the base plate (6) is square, the side length p3 of the base plate (6) is 38µm-42µm, and the thickness t1 is 0.2µm-0.4µm.
9. The method for preparing a dual-function switchable terahertz absorber based on vanadium dioxide and embedded copper pillars according to any one of claims 1-8, characterized in that, Specifically, the following steps are included: Step A: Place the copper pillars arranged in a 2×2 array onto the base plate; then deposit a perforated dielectric layer along the sidewalls of the copper pillars; Step B: Attach a vanadium dioxide thin film; Step C: At room temperature, a blind via dielectric layer is prepared on a pre-prepared pure silicon mold using atomic deposition. The prepared blind via dielectric layer is then installed by attaching the copper pillars and blind vias one by one. Step D: Place the top copper ring.
10. The method for fabricating a dual-frequency / broadband switchable dynamically tunable metamaterial terahertz absorber according to claim 9, characterized in that... : The process for depositing the via dielectric layer in step A is as follows: at room temperature, use 27% dilute sulfuric acid to remove the oxide layer and plasma present on the surface of the base plate with copper pillars. Then, in the order of "from inside to outside, from bottom to top", atomic layer deposition is used to attach the via dielectric layer along the sidewall of the copper pillars. Step B is as follows: Under an ambient temperature of 150℃~300℃, an atomic layer deposition method is used to react and generate a vanadium dioxide layer that can completely cover the dielectric layer along the sidewall of the copper pillar on the surface of the interconnecting dielectric layer. Then, ultraviolet photolithography is used to create gaps on the vanadium dioxide layer, dividing the vanadium dioxide layer into an array composed of 2×2 square vanadium dioxide resonant plates. Step D specifically involves: depositing a metal ring on a high-purity silicon substrate using electron beam evaporation, and then ultrasonically cleaning it with acetone, ethanol, and deionized water for 10-15 minutes to remove surface contaminants; placing the metal ring according to the method of corresponding center of the circle and unit center; wherein the metal ring is a copper ring.