CN-117388231-B - SERS substrate of hemispherical hole metal nano composite structure array and preparation method thereof

Abstract

The invention discloses a SERS substrate of a hemispherical metal composite structure array and a preparation method thereof, wherein the SERS substrate comprises a hemispherical array supporting substrate; the organic dielectric layer is provided with a conical hole, is arranged on one side of the metal film layer away from the substrate, and is provided with metal nano-sphere particles in the conical hole. The surface of the metal film layer can excite the surface plasma resonance effect of propagation, the metal nanosphere particles can excite the local surface plasma resonance effect, the local surface plasma resonance effect and the surface plasma resonance effect of propagation can be mutually coupled to promote the electric field enhancement effect, and meanwhile, the special structures of the hemispherical hole array and the conical holes can further cooperatively enhance the local electric field. Thus, the electric field enhancement performance of the SERS substrate is significantly improved.

Inventors

• JIN JING
• CHENG XUDONG
• ZHOU YUN
• DONG ZHICHENG

Assignees

• 中国计量大学

Dates

Publication Date

20260512

Application Date

20230915

Claims (9)

1. 1. A SERS substrate of a hemispherical hole metal nano composite structure array is characterized in that, The substrate comprises: a hemispherical array support substrate; the metal film layer is arranged on one side of the substrate; an organic dielectric layer having a tapered hole and disposed on a side of the metal thin film layer away from the substrate, and Metal nanosphere particles disposed in the tapered bore; The surface of the metal film layer excites a surface plasmon resonance effect, the metal nanosphere particles excite a local surface plasmon resonance effect, the local surface plasmon resonance effect and the surface plasmon resonance effect are mutually coupled to promote an electric field enhancement effect, and meanwhile, structures of the hemispherical hole array and the conical holes further cooperatively enhance a local electric field.
2. 2. The SERS substrate of claim 1 wherein the hemispherical array support substrate is a silicon based material comprising one or more of monocrystalline silicon, polycrystalline silicon, silicon dioxide or a silicon based composite.
3. 3. The SERS substrate of claim 1 wherein the hemispherical array support substrate has a hemispherical array curvature in the range of (5 x 10 6 ～5×10 7 ）m -1 ).
4. 4. The SERS substrate of claim 1 wherein the metal thin film layer is one or more of Ag or Au.
5. 5. The SERS substrate of claim 1, wherein the organic dielectric layer has a thickness of 40-55nm, comprises an organic substrate and a dielectric reinforcing material dispersed in the organic substrate, the material of the organic substrate comprises one or more of polymethyl methacrylate, polyvinyl alcohol, polystyrene, polypropylene, polyimide, and silicone, and the dielectric reinforcing material is one or more of alumina, boron nitride, and silicon nitride ceramic material.
6. 6. The SERS substrate of claim 1 wherein the tapered holes in the organic dielectric layer have a height of 40-55nm.
7. 7. The SERS substrate of claim 1 wherein the metallic element of the metallic nanosphere particles is one or more of Ag or Au and the diameter of the metallic nanosphere particles is 5-10nm.
8. 8. The SERS substrate of any of claims 1-7, wherein the method of preparing comprises the steps of: Preparing a hemispherical hole array on a substrate by an electron beam lithography technology, and providing a hemispherical hole array supporting substrate; Preparing a metal film layer on one side of the hemispherical hole array support substrate; after mixing a dielectric reinforcing material and an organic substrate, spraying the mixture on one side of the metal film layer far away from the hemispherical array support substrate to form an organic dielectric layer; forming a tapered hole in the organic dielectric layer by photolithography; And mixing a metal nano-sphere particle precursor with a composite substrate consisting of a hemispherical hole array supporting substrate, a metal film layer and an organic dielectric layer, performing aftertreatment, and forming metal nano-sphere particles in a conical hole on one side of the organic dielectric layer far away from the metal film layer to form the SERS substrate.
9. 9. The SERS substrate of the hemispherical metal nano composite structure array according to claim 8, wherein the forming of the metal film layer further comprises the steps of vapor plating a metal film on a hemispherical array supporting substrate by a magnetron sputtering method, wherein the film growth rate is 0.05-0.2nm/s, the thickness of the formed metal film layer is 100-200nm, and plasma cleaning is conducted on the metal film layer after the film plating.

Description

SERS substrate of hemispherical hole metal nano composite structure array and preparation method thereof Technical Field The invention relates to the field of surface-enhanced Raman scattering (Surface Enhancement of RAMAN SCATTERING, SERS) technology and analysis detection, and discloses a SERS substrate of a hemispherical metal nano composite structure array and a preparation method thereof. Background The surface enhanced Raman scattering is a spectrum technology with single molecule detection capability, has simple operation, strong specificity and wide application range, and is widely applied to the fields of food safety, environment detection, disease diagnosis and the like, thus becoming a powerful rapid detection means. Surface Enhanced Raman Scattering (SERS) refers to the significant enhancement of raman scattering signals when molecules adsorb on roughened metal (Au, ag, cu, etc.) surfaces. For research on enhancement mechanisms of SERS, two types of enhancement mechanisms are currently mainly adopted, namely electromagnetic enhancement mainly related to resonance excitation of the metal nanoparticle surface and chemical enhancement related to photoinduced charge transfer between the fermi level and the molecular level of the substrate. Electromagnetic enhancement is generally considered to be a major contribution, since the excitation wavelength of surface plasmons resonates with the plasmon absorption curve of a specific nanoparticle, a strong electromagnetic field with evanescent properties is generated on the metal surface, and the raman mode of molecules close to the metal surface is significantly enhanced. Furthermore, when the relevant raman modes also match plasmon resonance, the raman scattered light will also undergo a second enhancement, electromagnetic SERS enhancement being dependent on the fourth power of the incident field amplitude. Because electromagnetic enhancement is related to the material, size and shape of the nanostructures, SERS substrates are critical for SERS analysis, being able to amplify weak raman scattering signals by several or even tens of orders of magnitude. Compared with other types of substrates, the noble metal SERS substrate has higher SERS enhancement factors, can realize ultrasensitive and even single-molecule level detection, has a dominant role in various SERS substrate types, and is widely applied in the fields of food safety and environmental pollution. Rare noble metals in the traditional SERS substrate have very remarkable SERS capability, and have the advantages of high sensitivity, good stability and the like. However, the SERS enhancement mechanism of the single-structure noble metal substrate is simple, the effect is not obvious, and the interface and interaction between different materials of the composite-structure SERS substrate can cause the stability problem of the composite structure. In addition to noble metal substrates, current research also finds that semiconductors and graphene also possess SERS activity, but the electromagnetic enhancement capability of these two classes of SERS substrates is much less than noble metal nanoparticle substrates, generally requiring use in combination with noble metal nanoparticles. With the rapid development of nanolithography, such as electron beam lithography, focused ion beam lithography, electrochemical strategies, and wet chemical methods, various metallic nanostructures have been precisely designed as SERS substrates. Research shows that the SERS substrate with the three-dimensional structure can provide larger specific surface area and more defects, and provides more effective signal propagation, so that SERS capability is improved from two mechanisms of electromagnetic field and charge transfer, if the three-dimensional space can be designed, the internal space can be more reasonably designed by promoting the effective signal propagation path and the like, better influence can be generated on the material performance, and the subsequent modification regulation potential of the material can be improved. Disclosure of Invention Noble metal substrates are the earliest discovered SERS substrates, which are morphologically diverse, with good SERS activity, but the enhancement effect of a single SERS structure is generally relatively low. The interface and interaction between different materials of the SERS substrate of the composite structure may cause the problem of instability of the composite structure, may cause instability of SERS signals, and the reproducibility of the SERS substrate is poor due to more complex preparation process of the composite structure. Based on the above problems, in one aspect of the present invention, the present invention provides a SERS substrate of a hemispherical metal nanocomposite array. The SERS substrate comprises a hemispherical hole array supporting substrate, a metal film layer, an organic dielectric layer film with conical holes, metal nano-sphere particles