Double-layer gold nano-pore structure supported by nano-needle tip and preparation method and application of double-layer gold nano-pore structure

Abstract

The invention belongs to the field of micro-nano structures, and relates to a double-layer gold nanopore structure supported by a nano needle tip as well as a preparation method and application of the double-layer gold nanopore structure. According to the preparation method, the double-layer gold nanopore structure supported by the nano needle tip is obtained through an electron beam thermal evaporation system, a polystyrene microsphere self-assembly technology and reactive ion etching (RIE), the preparation process is simple, the cost is low, the repeatability is good, the structural stability is good, and the tolerance is high. Compared with a single-layer gold nanopore structure, the single-layer gold nanopore structure not only has more modes, but also presents complex multi-mode response dependent on pumping wavelength.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of micro-nano structures, and relates to a double-layer gold nano-hole structure supported by a nano-needle tip and a preparation method and application thereof. BACKGROUND

[0002] A metasurface is a novel material system composed of sub-wavelength artificial structure units (usually referred to as "meta-atoms") arranged periodically or non-periodically on a two-dimensional plane. By precisely controlling the geometric shape, size, arrangement mode and used material of the meta-atoms, the metasurface can flexibly manipulate multiple degrees of freedom of an electromagnetic wave front, phase, amplitude and polarization under an extremely thin thickness, break through the limitations of traditional optical devices in volume and function, and be widely applied to the fields of frontier photonics such as planar lenses, holographic imaging, polarization control devices and stealth devices.

[0003] Although a large number of studies have proved the great potential of metasurfaces in static light field manipulation, once the traditional metasurface is nano-processed, its structure and optical response are fixed, and it is difficult to adapt to external stimuli or environmental changes. This "static control" characteristic seriously restricts the further expansion of the metasurface in practical applications such as adaptive optics, programmable optical devices, dynamic imaging and sensing. In order to solve the above problems, in recent years, researchers have proposed and continuously developed the concept of "reconfigurable metasurface", that is, by introducing adjustable materials or external excitation means, the dynamic real-time control of the optical performance of the metasurface is realized.

[0004] According to the different external excitation modes, the reconfigurable metasurface can be divided into electrically controlled, thermally controlled, force-controlled, phase change material driven and optically controlled types. Among them, the all-optically driven reconfigurable metasurface has attracted widespread attention due to its advantages such as no need for electrode wiring, ultrafast response speed, non-contact control and high spatial resolution. This type of metasurface can realize rapid control of optical response on a picosecond or even femtosecond time scale by exciting carrier concentration changes, local refractive index modulation or inducing material structural phase transition through pump light. Therefore, the all-optically driven reconfigurable metasurface has important potential in the development of high-integration, low-energy and intelligent photonic devices, and building such a platform with stable structure, fast response and precise controllability has become one of the hotspots and challenges in current optical device research. However, although many breakthroughs have been made in device design and material response, the technology still faces key challenges: on the experimental level, the inherent vibration mode induced by external field excitation in the traditional structure lacks controllable switching capability; on the theoretical level, the spatiotemporal reconstruction mechanism under multi-mode coupling has not been fully established. These problems significantly restrict the practical expansion of the all-optically driven reconfigurable metasurface in multi-functional dynamic response applications. SUMMARY

[0005] In view of the problem of insufficient controllability of inherent vibration mode switching of a traditional metasurface under an external field excitation, the application provides a nano-needle-tip-supported double-layer gold nano-hole structure and a preparation method thereof. The method maintains a high light force conversion efficiency and oscillation quality, and realizes multi-mode controllable switching in a femtosecond to picosecond time scale by inducing a spatial gradient distribution of a photothermal stress field in the metasurface through pump wavelength control. Meanwhile, the application provides a preparation method which is simple in process, large in operation space, short in cycle and low in cost. The obtained nano-needle-tip-supported double-layer gold nano-hole structure has the characteristics of large-area controllable preparation, high uniformity, long-range order and strong repeatability.

[0006] In order to achieve the above-mentioned purpose, the application adopts the following scheme: The preparation method of the nano-needle-tip-supported double-layer gold nano-hole structure comprises the following steps: S1: self-assembling polystyrene microspheres in a periodic arrangement on the upper surface of a silicon wafer; S2: reducing the volume of the microspheres by using reactive ion etching and O2; S3: depositing an Au film on the upper surface of the silicon wafer; S4: removing the microspheres to obtain an Au film with uniformly arranged nano-holes on the silicon wafer; S5: etching the silicon layer exposed by the nano-holes on the upper surface of the silicon wafer by using reactive ion etching and SF6, and controlling the etching time to obtain an Au film with uniformly arranged nano-holes supported by a silicon nano-table, as a first Au film; S6: depositing a SiO2 film on the upper surface of the product obtained in step S5, and then depositing an Au film on the SiO2 film as a second Au film, the thicknesses of the two Au films being the same; S7: etching the silicon nano-table and the SiO2 layer sandwiched between the two Au films by using reactive ion etching and SF6, and obtaining a double-layer Au film with uniformly arranged nano-holes supported by nano-needle-tips made of silicon material after the etching is completed; the nano-holes on the two Au films correspond to each other, and the support points of the nano-needle-tips supporting the Au film are located between the adjacent four nano-holes on the lower surface of the first Au film.

[0007] Preferably, in S1, the diameter of the polystyrene microspheres is 500 nm.

[0008] Preferably, S2 specifically comprises: placing the sample horizontally in the reaction ion etching instrument bin, setting the etching gas as O2, the flow rate as 50 sccm, the working pressure as 20 Pa, the power as 125 W, and the etching time as 40 s.

[0009] Preferably, the deposition of the Au film in S3 specifically comprises: using an electron beam thermal evaporation system for Au deposition, the pressure being 5*10 -4Pa, voltage 6 KV, deposition rate 0.4 Å / s, and deposition thickness 30 nm.

[0010] Preferably, in S4, the microspheres are removed, specifically by using a polyimide tape to physically peel off the polystyrene microspheres.

[0011] Preferably, in S5, the SF6 etching specifically includes: horizontally placing the silicon wafer in a reaction ion etching instrument chamber, setting the etching gas as SF6, the flow rate 65 sccm, the working pressure 20 Pa, the power 125 W, and the etching time 45 s.

[0012] Preferably, in S6, the deposition of a layer of SiO2 film specifically includes: using an electron beam thermal evaporation system to deposit SiO2, the pressure 5*10 -4 Pa, voltage 6 KV, SiO2 deposition rate 0.8 Å / s, and deposition thickness 60 nm; and the deposition of a layer of Au film specifically includes: using an electron beam thermal evaporation system to deposit Au, the deposition rate 0.4 Å / s, and the deposition thickness 30 nm.

[0013] Preferably, in S7, the simultaneous etching of the silicon nanotable and the SiO2 layer sandwiched between the two layers of Au film by using SF6 specifically includes: horizontally placing the product obtained in S6 in a reaction ion etching instrument chamber, setting the etching gas as SF6, the flow rate 65 sccm, the working pressure 20 Pa, the power 125 W, and the etching time 60 s.

[0014] The application further provides a nano-needle tip supported double-layer gold nanopore structure prepared by the preparation method.

[0015] The application further provides an application of the nano-needle tip supported double-layer gold nanopore structure, which is applied to a super surface and includes the following steps. changing the wavelength of pump light irradiating the super surface; changing the resonance mode of the super surface in the time scale range of femtoseconds to picoseconds; under 340 nm pump excitation, generating a global thermal stress distribution to excite 2.4 GHz, 3.0 GHz and 4.6 GHz vibration modes; under 690 nm excitation, selectively exciting 4.2 GHz, 5.0 GHz and 7.6 GHz modes through LSPR effect; and under 850 nm excitation, generating 4.0 GHz, 5.0 GHz and 7.4 GHz resonance modes by using a nanopore gap mode.

[0016] Compared with the single-layer Au nanopore structure supported by the nanoneedle tip, the application not only supports more vibration modes, but also can induce a spatially gradient-distributed photothermal stress field in the super surface by in-situ regulating the pump light wavelength, so as to realize the multi-mode controllable switching in the femtosecond to picosecond time scale. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Process diagram for preparing the double-layer Au nanopore structure supported by the nanoneedle tip.

[0018] Figure 2 Three-dimensional diagram of the double-layer Au nanopore structure supported by the nanoneedle tip.

[0019] Figure 3 Cross-sectional diagram of the double-layer Au nanopore structure supported by the nanoneedle tip.

[0020] Figure 4 SEM diagram of the double-layer Au nanopore structure supported by the nanoneedle tip.

[0021] Figure 5 Reflection spectrum of the double-layer Au nanopore structure supported by the nanoneedle tip (black curve) and finite element simulation (COMSOL, red curve).

[0022] Figure 6 Simulated near-field electric field intensity distribution of the double-layer Au nanopore structure supported by the nanoneedle tip.

[0023] Figure 7 Transient absorption spectrum diagram of the double-layer Au nanopore structure supported by the nanoneedle tip under 340 nm pump light.

[0024] Figure 8 Figure 7 Spectrum diagram (black curve) obtained by fast Fourier transform (FFT) and simulation result (red curve).

[0025] Figure 9 Transient absorption spectrum diagram of the double-layer Au nanopore structure supported by the nanoneedle tip under 690 nm pump light.

[0026] Figure 10 Figure 9 Spectrum diagram (black curve) obtained by fast Fourier transform (FFT) and simulation result (red curve).

[0027] Figure 11 Transient absorption spectrum diagram of the double-layer Au nanopore structure supported by the nanoneedle tip under 850 nm pump light.

[0028] Figure 12 Figure 11 ​​​The frequency spectrum (black curve) obtained by fast Fourier transform (FFT) and the simulation result (red curve). DETAILED DESCRIPTION

[0029] In order to further understand the present application, the preparation method of the nano-tip supported double-layer Au nanopore structure provided by the present application is described in detail below in combination with examples, and the protection scope of the present application is not limited by the following examples.

[0030] As Figure 1 A nano-tip supported double-layer gold nanopore structure and a preparation method thereof, comprising the following steps: S1. Using a culture dish with good hydrophilicity, polystyrene microspheres with periodic arrangement in a large area are obtained on the surface of a cleaned silicon wafer by self-assembly technology; S2. Using reactive ion etching, the volume of the microspheres is reduced by using O2; S3. Using an electron beam evaporation system, a layer of Au film is deposited; S4. Removing the polystyrene microspheres, a large area of uniformly arranged Au nanopores is obtained on the silicon wafer; S5. Using reactive ion etching, the exposed Si layer is etched by using SF6, and the etching time is controlled to obtain a single-layer Au nanopore supported by a silicon nanotable; S6. Using an electron beam evaporation system, a layer of SiO2 film is deposited, and then a layer of Au film is deposited; in order to induce a spatial gradient distribution of photothermal stress field inside the super surface, thereby realizing the controllable switching of multi-mode in the femtosecond to picosecond time scale, it is required that the Au film obtained in this step has the same thickness as the Au film obtained in the above step.

[0031] S7. Using reactive ion etching, SF6 is used to etch the silicon nanotable and the SiO2 layer at the same time, and after etching, a nano-tip supported double-layer gold nanopore structure is obtained. The product structure obtained is shown in Figure 2 and Figure 3 .

[0032] Preferably, in step S1, the diameter of the polystyrene microspheres is 500 nm.

[0033] Preferably, in step S2, the etching treatment specifically includes the following steps: placing the sample horizontally in the reactive ion etching instrument bin, setting the etching gas as O2, the flow rate as 50 sccm, the working pressure as 20 Pa, the power as 125 W, and the etching time as 40 s.

[0034] Preferably, in step S3, the film plating treatment specifically includes the following steps: using an electron beam thermal evaporation system for Au deposition, the pressure is 5×10 -4Pa, voltage 6 KV, deposition rate 0.4 Å / s, and the deposition thickness is 30 nm.

[0035] Preferably, in step S5, the etching treatment specifically includes the following steps: the sample is horizontally placed in the reaction ion etching instrument bin, the etching gas is set as SF6, the flow rate is 65 sccm, the working pressure is 20 Pa, the power is 125 W, and the etching time is 45 s.

[0036] Preferably, in step S6, the film coating treatment specifically includes the following steps: the SiO2 and Au are deposited by using the electron beam thermal evaporation system, the pressure is 5×10 -4 Pa, voltage 6 KV, SiO2 deposition rate 0.8 Å / s, and the deposition thickness is 60 nm; Au deposition rate 0.4 Å / s, and the deposition thickness is 30 nm.

[0037] Preferably, in step S7, the etching treatment specifically includes the following steps: the sample is horizontally placed in the reaction ion etching instrument bin, the etching gas is set as SF6, the flow rate is 65 sccm, the working pressure is 20 Pa, the power is 125 W, and the etching time is 60 s. Embodiment

[0038] Firstly, 500 nm polystyrene microspheres are transferred to the surface of a cleaned silicon wafer by self-assembly technology, and it is ensured that the polystyrene microspheres are uniformly arranged in a large area. Then, the volume of the polystyrene microspheres is reduced by introducing O2 through the reaction ion etching, the flow rate is 50 sccm, the working pressure is 20 Pa, the power is 125 W, and the etching time is 40 s. Then, a 30 nm Au film is deposited by using the electron beam thermal evaporation system, the pressure is 5×10 -4 Pa, voltage 6 KV, deposition rate 0.4 Å / s, and then the polystyrene microspheres are physically removed. Then, the exposed Si substrate is etched by introducing SF6 gas through the reaction ion etching, the flow rate is 65 sccm, the working pressure is 20 Pa, the power is 125 W, and the etching time is 45 s. Then, a 60 nm SiO2 and a 30 nm Au film are deposited by using the electron beam thermal evaporation system again, the SiO2 deposition rate is 0.8 Å / s, and the Au deposition rate is 0.4 Å / s. Finally, the Si platform and the SiO2 layer are etched by introducing SF6 gas through the reaction ion etching, the flow rate is 65 sccm, the working pressure is 20 Pa, the power is 125 W, and the etching time is 60 s, as shown in FIG. 2. Figure 4

[0039] Then, the reflectance spectrum of the double-layer Au nanopore structure supported by the nanoneedle tip is obtained by using a spectrometer, and three absorption valleys are presented at 500 nm, 690 nm and 840 nm.​Figure 5 (Black curve). Based on the finite element method (FEM) numerical simulation (using COMSOL Multiphysics software), the experimental and simulation results are as follows ( Figure 5 The red curve (the curve) almost perfectly matches the pattern. To further elucidate the physical mechanisms of these patterns, we... Figure 6 The diagram shows the near-field distribution of electric field intensity at various wavelengths. The 840 nm resonant absorption corresponds to the gap mode of the interlayer groove, the 690 nm absorption valley originates from the dipole localized surface plasmon resonance (LSPR) mode of the nanopores in the upper and lower gold layers, and the resonance at 500 nm is a characteristic of interband transitions in gold.

[0040] Subsequently, using pump-probe technology, the pump light was tuned to 340 nm, and we obtained the transient absorption spectrum of the bilayer Au nanopore structure supported by nanoneedle tips, such as... Figure 7 As shown. Fast Fourier Transform (FFT) analysis revealed three resonance peaks at 2.4 GHz, 3.0 GHz, and 4.6 GHz, as... Figure 8 As shown (black curve). Finally, the nanomechanical oscillation performance of the double-layer Au nanopore structure supported by nanoneedle tips was simulated using the COMSOL Multiphysics solid mechanics module. The simulation results of nanomechanical oscillation are as follows (…). Figure 8 The frequency (shown by the solid red line) closely matches the resonance frequency of the Fourier analysis spectrum. Example

[0041] The difference from Example 1 is that, when using the pump-probe technique for testing, the pump light was tuned to 690 nm, and a transient absorption spectrum was obtained, as shown below. Figure 9 As shown. FFT analysis revealed three resonance peaks at 4.2 GHz, 5.0 GHz, and 7.6 GHz, as... Figure 10 As shown (black curve). Simulation calculations were performed on its nanomechanical oscillation performance, and the simulation results of the nanomechanical oscillation are as follows (…). Figure 10 The resonant frequency (shown by the solid red line) remains highly consistent with the Fourier analysis spectrum. Example

[0042] The difference from Example 1 is that, when using the pump-probe technique for testing, the pump light was tuned to 850 nm, and a transient absorption spectrum was obtained, as shown below. Figure 11 As shown. FFT analysis revealed three resonance peaks at 4.0 GHz, 5.0 GHz, and 7.4 GHz, as... Figure 12 As shown (black curve). Simulation calculations were performed on its nanomechanical oscillation performance, and the simulation results of the nanomechanical oscillation are as follows (…). Figure 12The resonance frequencies of the Fourier analysis spectrum still remain highly consistent with the red solid line.

[0043] On the prepared nanoneedle-supported double-layer Au nanopore structure, it is proved by experiments and theoretical simulation that it can change its vibration and optical properties on a very fast time scale (from femtoseconds to picoseconds) according to the wavelength of light. Different colors of laser pump light will produce different thermal stress distributions in the structure, thereby exciting different vibration modes. Specifically, under the excitation of 340 nm pump, a global thermal stress distribution is generated, mainly exciting 2.4 GHz, 3.0 GHz and 4.6 GHz vibration modes; under the excitation of 690 nm, 4.2 GHz, 5.0 GHz and 7.6 GHz modes are selectively excited through the LSPR effect; under the excitation of 850 nm, 4.0 GHz, 5.0 GHz and 7.4 GHz resonance modes are generated by using the nanopore gap mode.

[0044] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for preparing a bilayer gold nanoporous structure supported by nanoneedle tips, characterized in that, Includes the following steps: S1 self-assembles into periodically arranged polystyrene microspheres on the upper surface of a silicon wafer; S2 uses reactive ion etching and utilizes O2 to reduce the volume of the microspheres; S3 deposits an Au film on the upper surface of the silicon wafer; S4 removes the microspheres, resulting in an Au film with uniformly arranged nanopores on a silicon wafer; S5 uses reactive ion etching to etch the silicon layer exposed by the nanopores on the upper surface of the silicon wafer using SF6. By controlling the etching time, an Au film with uniformly arranged nanopores supported by silicon nanostages is obtained, which serves as the first Au film. S6 deposits a SiO2 film on the upper surface of the product obtained in step S5, and then deposits an Au film on the SiO2 film as a second Au film. The two Au films have the same thickness. S7 uses reactive ion etching, which uses SF6 to simultaneously etch silicon nanostages and the SiO2 layer sandwiched between two Au films. After etching, a double-layer Au film with uniformly arranged nanopores is obtained, supported by silicon nanoneedles. The nanopores on the two Au films are positioned one-to-one, and the support points for the nanoneedles to support the Au films are located between four adjacent nanopores on the lower surface of the first Au film.

2. The method for preparing the nanoneedle-tip-supported bilayer gold nanoporous structure as described in claim 1, characterized in that, In S1, the polystyrene microspheres have a diameter of 500 nm.

3. The method for preparing the nanoneedle-tip-supported bilayer gold nanoporous structure as described in claim 1, characterized in that, S2 specifically includes: placing the sample horizontally in the reactive ion etching chamber, setting the etching gas to O2, flow rate to 50 sccm, working pressure to 20 Pa, power to 125 W, and etching time to 40 s.

4. The method for preparing the bilayer gold nanoporous structure supported by nanoneedle tips as described in claim 1, characterized in that, The deposition of an Au film as described in S3 specifically includes: Au deposition using an electron beam thermal evaporation system at a pressure of 5 × 10⁻⁶. -4 Pa, voltage 6 kV, deposition rate 0.4 Å / s, deposition thickness 30 nm.

5. The method for preparing the bilayer gold nanoporous structure supported by nanoneedle tips as described in claim 1, characterized in that, In S4, the removal of microspheres specifically involves physically peeling off the polystyrene microspheres using polyimide tape.

6. The method for preparing the bilayer gold nanoporous structure supported by nanoneedle tips as described in claim 1, characterized in that, The SF6 etching described in S5 specifically includes: placing the silicon wafer horizontally in the reactive ion etching chamber, setting the etching gas to SF6, a flow rate of 65 sccm, a working pressure of 20 Pa, a power of 125 W, and an etching time of 45 s.

7. The method for preparing the nanoneedle-tip-supported bilayer gold nanoporous structure as described in claim 1, characterized in that, In S6, The deposition of a SiO2 film specifically includes: SiO2 deposition using an electron beam thermal evaporation system at a pressure of 5 × 10⁻⁶. -4 Pa, voltage 6 kV, SiO2 deposition rate 0.8 Å / s, deposition thickness 60 nm; The deposition of an Au film specifically includes: Au deposition using an electron beam thermal evaporation system; a deposition rate of 0.4 Å / s and a deposition thickness of 30 nm.

8. The method for preparing the bilayer gold nanoporous structure supported by nanoneedle tips as described in claim 1, characterized in that, In S7, the simultaneous etching of silicon nanostages and SiO2 layer sandwiched between two Au films using SF6 specifically includes: placing the product obtained in S6 horizontally in the reactive ion etching chamber, setting the etching gas to SF6, flow rate to 65 sccm, working pressure to 20 Pa, power to 125 W, and etching time to 60 s.

9. A double-layer gold nanoporous structure supported by nanoneedle tips, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 8.

10. The application of the nanoneedle-tip-supported bilayer gold nanoporous structure as described in claim 9, characterized in that, When applied to metasurfaces, the following steps are included: Change the wavelength of the pump light irradiating the metasurface; Changing the resonance mode of metasurfaces within the femtosecond to picosecond timescale range; Under 340 nm pump excitation, a global thermal stress distribution is generated, exciting vibrational modes of 2.4 GHz, 3.0 GHz, and 4.6 GHz; under 690 nm excitation, modes of 4.2 GHz, 5.0 GHz, and 7.6 GHz are selectively excited via the LSPR effect; and under 850 nm excitation, resonant modes of 4.0 GHz, 5.0 GHz, and 7.4 GHz are generated using the nanopore gap mode.

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