A recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate and a preparation method thereof

Abstract

The present application relates to a kind of recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate and its preparation method.The high-sensitivity silicon-based surface-enhanced Raman scattering substrate includes: single crystal silicon wafer, and the array structure of several three-dimensional " umbrella " silicon-based nanocolumn unit structures formed on its surface;The three-dimensional " umbrella " silicon-based nanocolumn unit structure is composed of a " umbrella shaft " thick silicon column and several " umbrella rib " thin silicon columns which rely on the " umbrella shaft " thick silicon column circumferentially, and the surface of the three-dimensional " umbrella " silicon-based nanocolumn unit structure is uniformly modified with a large number of metal particles.The high-sensitivity silicon-based surface-enhanced Raman scattering substrate prepared according to the present application has a large adsorption surface area, can not only adsorb more metal particles and molecules to be measured simultaneously, but also provide sufficient three-dimensional " hot spots ", so as to realize the SERS performance of high sensitivity and high reproducibility, and the substrate can withstand strong wiping reuse detection, and has recyclable use.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of Raman scattering technology, in particular to a recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate and a preparation method thereof. BACKGROUND

[0002] Surface-enhanced Raman spectroscopy (SERS) is a powerful spectroscopic technique that can provide molecular fingerprint information with high specificity and sensitivity. The principle of SERS technology is derived from the amplification effect of molecular Raman signals on the surface or interface structure, which enables the detection and identification of trace amounts of molecules. There are two generally accepted SERS enhancement mechanisms: electromagnetic enhancement (electromagnetic field enhancement) and chemical enhancement (mainly charge transfer enhancement). Current results show that in most cases, the effect of the former is higher than that of the latter. Physical enhancement is mainly due to the local enhancement effect of the localized surface plasmon resonance mode between noble metal (gold or silver, etc.) substrates on the optical field, resulting in so-called SERS "hot spots", thereby enhancing the Raman effect of molecules. Therefore, one of the most important strategies to improve SERS sensitivity is to create enough hot spots on a large-scale substrate.

[0003] Traditional SERS substrates mainly use chemically synthesized nanoparticles or clusters of particles. Although these substrates have high sensitivity, they have poor repeatability. In recent years, with the development of micro-nano processing technology, various one-dimensional, two-dimensional and even three-dimensional SERS substrates such as periodic arrays of holes, discs and cylinders have been developed. Although these substrates enrich hot spots, improve sensitivity and repeatability, micro-nano processing technology is difficult to obtain large-area SERS substrates, and the process cost is high. In order to obtain low cost, many research works develop a method of photocatalytic degradation of biomolecules to reuse SERS substrates, but this method is extremely dependent on the degradation ability of biomolecules to light, and the time required for complete degradation of the molecules is usually on the order of hours. Therefore, so far, it is still difficult to obtain a SERS substrate with low cost, strong stability, high sensitivity and high repeatability. SUMMARY

[0004] The purpose of the present application is to provide a recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate and a preparation method thereof, thereby solving the problem that the prior art cannot prepare a SERS substrate with low cost, strong stability, high sensitivity and high repeatability.

[0005] In order to solve the above problems, the technical scheme adopted by the present application is as follows:

[0006] According to a first aspect of the present application, there is provided a recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate, comprising: a single-crystal silicon wafer, and an array structure formed on the surface of the single-crystal silicon wafer and composed of a plurality of three-dimensional "umbrella"-shaped silicon-based nanocolumn unit structures; wherein the three-dimensional "umbrella"-shaped silicon-based nanocolumn unit structure is composed of a "shaft" thick silicon column and a plurality of "rib" thin silicon columns arranged circumferentially around the "shaft" thick silicon column, and the surface of the three-dimensional "umbrella"-shaped silicon-based nanocolumn unit structure is uniformly modified with a large number of metal particles.

[0007] Preferably, the diameter of the "shaft" thick silicon column is 300-500 nm, the diameter of the "rib" thin silicon column is 30-60 nm, and the height of the "shaft" thick silicon column and the "rib" thin silicon column is 0.8-2 μm.

[0008] According to a preferred embodiment of the present application, the metal particles modified on the surface of the three-dimensional "umbrella"-shaped silicon-based nanocolumn unit structure can be gold particles or silver particles.

[0009] Preferably, the metal particles are gold particles with a diameter of 10-40 nm.

[0010] According to a second aspect of the present application, there is provided a method for preparing a recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate, comprising the following steps: S1: performing surface cleaning pretreatment on a single-crystal silicon wafer; S2: uniformly mixing two sizes of PS balls by ultrasonic mixing, and self-assembling a monolayer PS ball structure on the cleaned single-crystal silicon wafer; S3: etching the monolayer PS ball structure by a reactive ion beam etching method using oxygen to reduce the size of the PS balls; S4: evaporating an Au film on the etched monolayer PS ball structure, then completely immersing the sample in a HF / H2O2 mixed solution to etch and form silicon nanocolumns, and then sequentially immersing the sample in a KI / I2 solution and a tetrahydrofuran solution to remove the residual Au layer and PS ball mask layer, thereby forming a plurality of three-dimensional "umbrella"-shaped silicon-based nanocolumn unit structures; and S5: immersing the structure obtained in step S4 in a methoxypolyethylene glycol mercaptan solution (mPEG-SH), removing nitrogen and drying, dropping a gold particle aqueous solution, and naturally drying to uniformly modify the gold particles on the surface of the three-dimensional "umbrella"-shaped silicon-based nanocolumn unit structure, thereby obtaining a recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate.

[0011] Preferably, the step S1 comprises: firstly, cleaning the silicon wafer with acetone, methanol and deionized water for 3-5 minutes; then, immersing the silicon wafer in a concentrated H2SO4 / H2O2 solution to form a silicon dioxide layer on the surface of the silicon wafer, the volume ratio of the solution being 4:1, and the time being 10 minutes; and then, immersing the silicon wafer in a low-concentration HF solution and then washing it with deionized water to remove the surface oxide layer and obtain a hydrophobic surface, the concentration of the HF solution being 5%, the immersion time being 30 seconds, and the deionized water cleaning time being 3-5 minutes.

[0012] It should be understood that the step S1 needs to obtain a clean single-crystal silicon surface, and the step determines whether the self-assembly structure of the PS ball monolayer is successful. Incomplete cleaning is likely to cause the PS balls to stack and make it difficult to form a monolayer mask structure.

[0013] Preferably, in the step S2, the diameter of the large PS balls is 500-750 nm, the diameter of the small PS balls is 120-300 nm, and the large PS balls and the small PS balls are mixed in a volume ratio of 1: (2-3) at the same mass fraction, and the ultrasonic time is 30-90 seconds.

[0014] It should be understood that the purpose of the step S2 is to mix the two sizes of PS balls uniformly and make them disperse well during self-assembly. Otherwise, it is difficult to form a mask structure in which the small PS balls uniformly surround the large PS balls, and then it is difficult to form an "umbrella" structure.

[0015] Preferably, in the step S3, the diameter of the large PS balls after etching is 300-500 nm, and the diameter of the small PS balls is 30-60 nm.

[0016] It should be understood that the purpose of the step S3 of etching the monolayer PS ball structure by using a reactive ion beam etching method is to prepare for the subsequent formation of the tilted thin silicon pillar structure. Specifically, the etching mainly makes the diameter of the thin silicon pillar covered by the small balls smaller, so as to prepare for the subsequent formation of the tilted thin pillar, and finally obtain the umbrella structure. If no etching is performed, the silicon is basically shielded by the PS balls, and it is also difficult to etch the silicon nanometer pillar by using a subsequent wet etching method.

[0017] Preferably, the thickness of the gold film is 10-20 nm; the mass fractions of HF and H2O2 in the HF / H2O2 mixed solution are 40% and 30% respectively, and the volume ratio is 4:1; the composition of the KI / I2 solution is KI 10 g, I2 2.5 g, and H2O 100 mL; and the immersion time in the KI / I2 solution and the tetrahydrofuran solution is 2-2.5 hours.

[0018] Preferably, in the step S5, the mass fraction of the methoxy polyethylene glycol mercapto solution is 0.04%, the immersion time is 2-48 hours, the volume of the gold particle aqueous solution is determined according to the size of the substrate, and the diameter of the gold particles is 10-40 nm.

[0019] It should be understood that step S5 bridges the gold particles by introducing mPEG-SH, so that the mPEG-SH not only avoids the clustering of the gold particles, but also firmly adsorbs the gold particles on the surface of the silicon column, so that the gold particles are not easy to fall off.

[0020] According to a third aspect of the present application, a recycling method of a recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate is provided, wherein the recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate is placed in a plasma cleaning machine, and the molecules to be detected on the surface of the substrate are desorbed by plasma impact, so as to obtain a clean and reusable high-sensitivity silicon-based surface-enhanced Raman scattering substrate.

[0021] It should be understood that, as an example but not limitation, the above method can use oxygen plasma, or inert gas plasma such as Ar and N2, which all use the principle of physical bombardment to desorb the molecules.

[0022] According to the preparation method of the recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate provided by the present application, the key invention point is that a monolayer self-assembly structure of mixed PS balls of two sizes is obtained by using a self-assembly method, which is used as a mask to prepare a three-dimensional "umbrella"-shaped silicon-based nanocolumn structure based on reactive ion beam etching and metal chemical auxiliary etching method, and then gold particles are bridged by mPEG-SH, so that a recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate is first prepared.

[0023] The substrate structure prepared by the method of the present application is in the shape of "umbrella", which is completely different from the traditional two-dimensional and three-dimensional SERS substrates. The "umbrella"-shaped silicon-based structure is beneficial to adsorb a large number of metal particles and molecules to be detected in three-dimensional space, and on the other hand, the high-refractive silicon-based nanocolumn can support waveguide modes, while the metal particles can provide localized surface plasmon resonance modes. These optical modes interact with each other, and can form enough rich "hot spots" in three-dimensional space, so as to realize high-sensitivity SERS performance. The substrate designed in the present application is mainly based on silicon-based material, and the structure is stable, so that the recycling function can be realized.

[0024] In summary, compared with the prior art, the present application has at least the following advantages:

[0025] 1) The three-dimensional "umbrella"-shaped silicon-based nanocolumn surface-enhanced Raman scattering substrate designed in the present application has a large adsorption surface, which can not only simultaneously adsorb more metal particles and molecules to be detected, but also can provide enough rich three-dimensional "hot spots", so as to realize super-high sensitivity detection.

[0026] 2) The application uses mPEG-SH molecular bridging metal particles and silicon-based nanocolumns, and utilizes chemical bond interaction to make the metal particles not easy to be detached, so that the structure has good stability, and the cluster effect of metal particles in the traditional manufacturing process can be avoided, the metal particles can be uniformly modified on the silicon nanocolumns, and high reproducible SERS signals can be obtained;

[0027] 3) The high-sensitivity silicon-based surface-enhanced Raman scattering substrate prepared by the method of the application mainly relies on a self-assembly top-down processing method, does not need complex and expensive photolithography or electron beam writing technology, has low cost, can obtain a SERS substrate of centimeter size at one time, is suitable for large-scale industrial production, and the substrate structure can be accurately controlled through etching conditions, so that controllable SERS effect can be obtained;

[0028] 4) The high-sensitivity silicon-based surface-enhanced Raman scattering substrate prepared by the method of the application is mainly based on silicon-based materials, has excellent thermal stability, hardness and chemical inertness, can withstand multiple strong wiping detections, realizes recycling of the substrate, and the silicon-based substrate has good biocompatibility and CMOS compatibility, and has high practical application value. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a flow chart of a preparation method of a high-sensitivity silicon-based surface-enhanced Raman scattering substrate according to the application;

[0030] Figure 2 is a scanning electron microscope characterization photo of the high-sensitivity silicon-based surface-enhanced Raman scattering substrate prepared by the application;

[0031] Figure 3 is a high-sensitivity SERS spectrum of the high-sensitivity silicon-based surface-enhanced Raman scattering substrate prepared by the application;

[0032] Figure 4 is a reproducible SERS spectrum of the high-sensitivity silicon-based surface-enhanced Raman scattering substrate prepared by the application, wherein (a) is the specific characteristic spectrum of R6G of 10 random points on the silicon-based SERS substrate, and (b) is the RSD calculated from the Raman spectra of R6G of 30 random points on the silicon-based SERS substrate;

[0033] Figure 5 is a SERS spectrum of the high-sensitivity silicon-based surface-enhanced Raman scattering substrate prepared by the application after recycling by oxygen plasma cleaning. DETAILED DESCRIPTION

[0034] The application will be further described below in combination with specific embodiments. It should be understood that the following embodiments are only used to illustrate the application but not to limit the scope of the application.

[0035] The application provides a recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate and a preparation method thereof.

[0036] Embodiment 1

[0037] (1) The single crystal silicon is subjected to surface cleaning pretreatment.

[0038] Firstly, 4-inch n-type 0.01Ω·cm low-resistance silicon is selected, a silicon wafer with a size of 2cm*2cm is cut by using a diamond cutter, and the cut silicon wafer is sequentially immersed in anhydrous acetone, anhydrous methanol and deionized water, and is ultrasonically cleaned for 5 minutes, so that impurities and organic matters such as oil on the surface of the silicon wafer are fully removed, and the silicon wafer taken out from the deionized water is dried by blowing nitrogen. Then, the silicon wafer is soaked in a concentrated H2SO4 / H2O2 solution (volume ratio 4:1) for 10 minutes to form a silicon dioxide oxide layer on the surface of the silicon wafer; finally, the silicon wafer is soaked in a low-concentration HF solution (5%) for 30 seconds, and then is washed with deionized water for 5 minutes to remove the surface oxide layer and obtain a hydrophobic surface.

[0039] (2) Polystyrene (PS) balls with diameters of 650 nm and 220 nm are mixed in a volume ratio of 1:(2-3) according to the same mass fraction, and are ultrasonically mixed for 30 seconds, and then the mixed PS balls are self-assembled on the surface of the chemically cleaned silicon wafer to obtain a large-area single-layer PS ball structure.

[0040] (3) The single-layer PS ball self-assembly structure is etched by using oxygen through a reactive ion beam etching method, and the size of the PS ball is reduced; the cavity gas pressure of the reactive ion beam is 70 mTorr, the reaction power is 50 W, and the oxygen volume flow rate is 20 sccm. After the oxygen etching, the diameter of the large PS ball is 300-500 nm, and the diameter of the small PS ball is 30-60 nm.

[0041] (4) A 10-20 nm gold Au film is evaporated on the etched single-layer PS ball structure by using an electron beam evaporation film, and then the sample is completely immersed in an HF (40wt%) / H2O2 (30wt%) mixed solution (volume ratio 4:1), and under the catalytic action of Au, the Au-covered Si surface is etched, and the Si surface covered by the PS without Au deposition is protected from etching, so that a silicon nanocolumn is formed. The large PS ball corresponds to the etched coarse silicon column, and the small PS ball corresponds to the fine silicon column. Due to the effect of the water surface tension, the fine silicon column cannot support its own gravity and falls on the coarse silicon column. The sample is sequentially immersed in a KI / I2 solution (KI 10 g, I2 2.5 g, H2O 100 mL) and a tetrahydrofuran (THF) solution for 2 hours to remove the residual Au layer and the PS ball mask layer, respectively, so that a three-dimensional “umbrella”-shaped silicon-based nanocolumn SERS structure is obtained.

[0042] (5) The above sample is immersed in a methoxy polyethylene glycol thiol solution (mPEG-SH, mass fraction 0.04%) for 24 hours, the sample is taken out and dried by blowing nitrogen, and 50 μL of an aqueous gold particle (diameter 20 nm) solution is dropped on the surface. Through the bridging action of the mPEG-SH molecules, the -OCH3 on one side is bonded to the hydroxyl on the surface of the silicon nanocolumn, and the thiol on the other side is closely connected to the AuNPs, so that the gold particles can be uniformly modified on the surface of the silicon nanocolumn, and finally a gold-modified three-dimensional "umbrella"-shaped silicon-based nanocolumn SERS substrate is obtained.

[0043] The flow chart of the preparation method of such a recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate provided by the application is shown in Figure 1 .

[0044] The scanning electron microscope characterization photo of such a recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate provided by the application is shown in Figure 2 . As can be seen from the figure, the fine silicon columns are poured on the middle thick silicon columns to form a three-dimensional "umbrella"-shaped structure, and the gold particles are uniformly loaded on the three-dimensional "umbrella"-shaped silicon-based nanocolumn.

[0045] Example 2

[0046] In this embodiment, the three-dimensional "umbrella"-shaped silicon-based nanocolumn SERS substrate prepared in Example 1 is first washed on the surface using oxygen plasma for 2 minutes to improve the hydrophilicity of the substrate surface, and then 10 μL of 10 -5 M, 10 -6 M, 10 -7 M, 10 -8 M, 10 -10 M, 10 -12 M and 10 -14 M of rhodamine 6G (R6G) ethanol solution is dropped, and the sample is naturally dried at room temperature. Using a laser confocal micro-Raman spectrometer, a 633 nm laser is used as a light source, and a grating is 1800 line / mm, and the three-dimensional "umbrella"-shaped silicon-based nanocolumn substrate carrying different concentrations of R6G molecules is respectively subjected to SERS characterization test.

[0047] Figure 3 is the Raman spectrum of the three-dimensional "umbrella"-shaped silicon-based nanocolumn SERS substrate for different concentrations of R6G molecules. From high concentration to low concentration, the characteristic signal of the R6G molecules gradually weakens, and the characteristic signal of the R6G molecules can still be detected at 10 -14 M, indicating that the three-dimensional "umbrella"-shaped silicon-based nanocolumn SERS substrate prepared in Example 1 has super-high sensitivity.

[0048] Example 3

[0049] The three-dimensional "umbrella" silicon-based nanometer column SERS substrate prepared in Example 1 was selected in this example, and the surface was cleaned for 2 min using oxygen plasma cleaning to improve the hydrophilicity of the substrate surface. 10 μL of 10 -6 M R6G ethanol solution was dropped, and the substrate was naturally dried at room temperature. A laser confocal micro-Raman spectrometer was used, 633 nm laser was used as the light source, and the grating was 1800 line / mm. Thirty position points on the three-dimensional "umbrella" silicon-based nanometer column substrate were randomly selected for SERS characterization test, 30 SERS spectra were obtained, and the relative standard deviation RSD of R6G at 613 cm -1 , 774 cm -1 , 1184 cm -1 , 1310 cm -1 , 1362 cm -1 , 1507 cm -1 and 1649 cm -1 characteristic peaks were calculated.

[0050] Figure 4 (a) in the figure is the R6G specific characteristic spectrum of 10 random points on the three-dimensional "umbrella" silicon-based nanometer column SERS substrate, Figure 4 (b) in the figure is the RSD value calculated from the Raman spectrum of R6G on the three-dimensional "umbrella" silicon-based nanometer column SERS substrate. It can be seen that the R6G characteristic spectrum detected by the substrate shows relatively high uniformity and stability. The RSD of R6G at 613 cm -1 , 774 cm -1 , 1184 cm -1 , 1310 cm -1 , 1362 cm -1 , 1507 cm -1 and 1649 cm -1 characteristic peaks is in the range of 10.81% to 12.15%, and the average value is about 11%. The results show that the three-dimensional "umbrella" silicon-based nanometer column SERS substrate prepared in Example 1 has good uniformity and reproducibility.

[0051] Example 4

[0052] The three-dimensional "umbrella" silicon-based nanometer column SERS substrate prepared in Example 1 was selected in this example, and the surface was cleaned for 2 min using oxygen plasma cleaning to improve the hydrophilicity of the substrate surface. 10 μL of 10 -5M R6G ethanol solution, natural air-drying at room temperature. The three-dimensional "umbrella" shaped silicon-based nanometer column SERS substrate bearing R6G molecules was characterized and tested by using a laser confocal micro-Raman spectrometer, using 633nm laser as light source, and grating being 1800 line / mm. The three-dimensional "umbrella" shaped silicon-based nanometer column SERS substrate bearing R6G molecules was cleaned in oxygen plasma, and the substrate was taken out for SERS spectrum test at 2min, 6min and 9min of cleaning, respectively. At least 15 random point positions covering the whole SERS substrate range were selected for each process, and all the test conditions remained unchanged.

[0053] Figure 5 is the SERS spectrum of the three-dimensional "umbrella" shaped silicon-based nanometer column SERS substrate recycled by oxygen plasma cleaning, and it can be seen that with the increase of oxygen plasma cleaning time, the characteristic spectrum intensity of R6G molecules gradually weakens, and after 9min of cleaning, the characteristic peak of R6G molecules disappears completely, indicating that the R6G molecules on the SERS substrate are cleaned. Subsequently, 10μL of 10 -5 M R6G ethanol solution, R6G molecules can be tested again, and its intensity is equivalent to that before cleaning, which shows that the three-dimensional "umbrella" shaped silicon-based nanometer column SERS substrate prepared in the embodiment 1 can realize the wiping reuse function, and has recyclability.

[0054] The above is only the preferred embodiment of the present application, and is not intended to limit the scope of the present application. The above embodiment of the present application can be variously changed. Any simple, equivalent changes and modifications made according to the content of the claims and description of the present application fall within the scope of the claims of the present application. The present application is not described in detail, and is conventional technical content.

Claims

1. A recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate, characterized in that, The application relates to a single crystal silicon wafer and an array structure formed on the surface of the single crystal silicon wafer and composed of a plurality of three-dimensional "umbrella" shaped silicon-based nanometer column unit structures; wherein the three-dimensional "umbrella" shaped silicon-based nanometer column unit structure is composed of a middle "umbrella shaft" thick silicon column and a plurality of "umbrella rib" thin silicon columns which are arranged around the "umbrella shaft" thick silicon column; and the surface of the three-dimensional "umbrella" shaped silicon-based nanometer column unit structure is uniformly decorated with a large number of metal particles. The diameter of the "umbrella shaft" thick silicon column is 300-500 nm, the diameter of the "umbrella rib" thin silicon column is 30-60 nm, and the size of the "umbrella shaft" thick silicon column and the "umbrella rib" thin silicon column in the direction perpendicular to the surface of the single crystal silicon wafer is 0.8-2 mu m.

2. The high sensitivity silicon based surface enhanced Raman scattering substrate according to claim 1, wherein, The metal particles are gold particles with a diameter of 10-40 nm.

3. The high sensitivity silicon based surface enhanced Raman scattering substrate according to claim 1, wherein, The application further relates to a preparation method of the single crystal silicon wafer and the array structure.

4. The method for preparing the recyclable high-sensitivity silicon-based surface-enhanced Raman scattering substrate according to any one of claims 1 to 3, characterized in that, S1: performing surface cleaning pretreatment on a single crystal silicon wafer; S2: uniformly mixing two sizes of PS balls by ultrasonic mixing, and self-assembling the PS balls into a single-layer PS ball structure on the cleaned single crystal silicon wafer; S3: etching the single-layer PS ball structure by using oxygen through a reactive ion beam etching method, and reducing the size of the PS balls; S4: evaporating an Au film on the single-layer PS ball structure after the etching operation, then completely immersing the sample in a HF / H2O2 mixed solution, etching to form silicon nanometer columns, and then sequentially immersing the sample in a KI / I2 solution and a tetrahydrofuran solution to remove the residual Au layer and the PS ball mask layer respectively, so as to form a plurality of three-dimensional "umbrella" shaped silicon-based nanometer column unit structures; S5: immersing the structure obtained in step S4 in a methoxy polyethylene glycol mercapto solution, taking out and blowing dry with nitrogen, dropping gold particle aqueous solution, and naturally airing dry, so that the gold particles are uniformly decorated on the surface of the three-dimensional "umbrella" shaped silicon-based nanometer column unit structure, and finally a recyclable high-sensitivity silicon-based surface enhanced Raman scattering substrate is obtained. The step S1 comprises the following steps: firstly, sequentially cleaning the single crystal silicon wafer with acetone, methanol and deionized water by ultrasonic cleaning for 3-5 min; then immersing the single crystal silicon wafer in a concentrated H2SO4 / H2O2 solution to form a silicon dioxide oxidation layer on the surface of the single crystal silicon wafer, wherein the volume ratio of concentrated H2SO4 to H2O2 in the concentrated H2SO4 / H2O2 solution is 4:1, and the immersion time is 10 min; immersing the single crystal silicon wafer in a low-concentration HF solution, then washing with deionized water to remove the surface oxidation layer and obtain a hydrophobic surface, wherein the concentration of the HF solution is 5%, the immersion time is 30 s, and the deionized water cleaning time is 3-5 min.

5. The preparation method according to claim 4, characterized in that, In the step S2, the diameter of the large PS balls is 500-750 nm, the diameter of the small PS balls is 120-300 nm, the large PS balls and the small PS balls are mixed in a volume ratio of 1:(2-3) with the same mass fraction, and the ultrasonic time is 30-90 s.

6. The preparation method according to claim 4, characterized in that, In the step S3, the diameter of the large PS balls after etching is 300-500 nm, and the diameter of the small PS balls after etching is 30-60 nm.

7. The preparation method according to claim 6, characterized in that, ​ 8. The preparation method according to claim 4, characterized in that, The thickness of the gold film is 10-20 nm in the step S4; the mass fraction of HF and H2O2 in the HF / H2O2 mixed solution is 40% and 30% respectively, and the volume ratio is 4:1; the composition of the KI / I2 solution is KI 10 g, I2 2.5 g, and H2O 100 mL; the soaking time in the KI / I2 solution and the tetrahydrofuran solution is 2-2.5 h.

9. The preparation method according to claim 4, characterized in that, The mass fraction of the methoxypolyethylene glycol mercapto solution is 0.04% in the step S5, the soaking time is 2-48 h, and the volume of the gold particle aqueous solution is determined by the size of the substrate, and the diameter of the gold particle is 10-40 nm.

10. A method for recycling the high-sensitivity silicon-based surface-enhanced Raman scattering substrate according to any one of claims 1 to 3, characterized by, The recyclable sensitive silicon-based surface-enhanced Raman scattering substrate is placed in a plasma cleaning machine, the molecules to be measured on the surface of the substrate are made to desorb by plasma impact, and a clean and reusable high-sensitivity silicon-based surface-enhanced Raman scattering substrate is obtained.

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