The Preparation Of Silicon-based Gold Nanoparticles Active Substrate And Its Surface Enhanced Raman Scattering Properties

Monocrystalline silicon has very good conductivity and a wide range of applications in the fields of solar cells,integrated circuits,nanomaterials and etc.By using photolithography,template pressing or chemical etching,different microstructures could be prepared on the silicon surface.Surface-enhanced Raman scattering substrates can be prepared by depositing metal nanostructures through physical or chemical methods on silicon-based surface microstructures.By adjusting the surface morphology and size of the silicon-based surface microstructure and the metal nanostructure,different Raman enhancement effects can be achieved.In this thesis,silicon-based pyramidal microstructures were prepared by chemical etching of monocrystalline silicon.Then,a certain thickness of gold nanostructures was deposited on the surface of silicon-based pyramidal substrates by magnetron sputtering.Gold nanoparticles are formed on the silylated silicon-based surface and finally applied to the surface-enhanced Raman test.The specific research work is as follows:?1?A silicon pyramid structure with large coverage,good regularity and uniform particle size was prepared by chemical etching.The influences of the microstructure of silicon pyramid with different potassium silicate concentration,reaction temperature,reaction time and potassium carbonate solubility were discussed respectively.At the same time,the reflectance of silicon pyramid substrate was characterized by UV-visible?UV-2600?spectrophotometer.Combined with the morphological analysis of SEM.The optimal reaction conditions were as follows:the concentration of potassium silicate was 2wt%,the reaction temperature was 85?,the reaction time was 10min,the concentration of potassium carbonate was 10wt%.?2?Using physical method,a certain thickness of gold nanostructures was deposited on silicon-based pyramidal substrate by magnetron sputtering,and different deposition times of gold nanostructures were controlled by different sputtering times.The specific sputtering time was 60s,90s,280s,330s,395s and480s,respectively.The morphologies of gold nanostructures were characterized by SEM.The enhancing effect of Raman on the substrate was analyzed by using crystal violet as the probe.The best sputtering conditions were found at 330s.?3?Using chemical method,the silicon-based pyramid substrate was first silanized and its surface was self-assembled and adsorbed with small-size gold seeds,followed by the addition of a suitable amount of reducing agent to prepare a gold nanoparticle-modified silicon-based pyramid substrate.The size of the gold nanoparticles was analyzed by transmission electron microscopy?TEM?and the morphology of the gold/silicon composite was characterized by scanning electron microscopy?SEM?.Finally,Raman enhancement effect of the substrate was investigated using crystal violet as a probe molecule.The results show that Raman characteristic peaks of 10^-6M crystal violet solution can be detected by gold/silicon composite structure prepared by magnetron sputtering and self-assembly method.The substrate has the characteristics of good stability,good repeatability and low price,which provides the precondition and the basis for industrial application.