Investigation On The Optical Properties Of Gold/Silicon Nanoporous Pillar Array Nano-composites

In this thesis, a quasi-periodic structure of Au/Si-NPA was fabricated by immersionplating gold on Si-NPA, and its’ optical absorption properties were tested. Au/Si-NPAsamples were optimized to the Au/Si-NPA active substrate by controlling preparationconditions, surface oxidation state. The optimized Au/Si-NPA active substrate was used tocarried out effective detection of probe molecule, such as Rhodamine6G(R6G), and relevantmechanism was also analyzed. The results showed that Si-NPA was an ideal template tofabricate silicon-based SERS active substrate, and Au/Si-NPA active substrate had a lot ofadvantages, such as, significantly enhancement, process easy, and so on. The specific workwas listed as followings:1. A regular array structure of Si-NPA was fabricated by hydrothermal etching, and itssurface activity was used to prepare Au/Si-NPA nanocomposites by immersion platinggold nanoparticles from the dipping solution. Field emission scanning electronmicroscopy (FE-SEM), X-ray diffraction (XRD) were used to characterize thisnanocomposites, and its optical absorption properties were measured and studied with UVspectrophotometer. The association between its surface morphology, structure and itsoptical absorption was found while investigating the Au/Si-NPA system. The opticalabsorption curves of the samples indicated that, surface plasmon resonance (SPR) peak ofAu nanoparticles in the samples appeared a large blue-shift, compared to pure Aunanoparticles. Due to the limitations of the absorption of Au nanoparticles and thechanges of Au/Si-NPA internal structure, samples’ optical absorption properties werereduced. Moreover, because of Au nanoparticles’ dipping regioselectivity on Si-NPAsurface, optical absorption obtained from Au/Si-NPA samples using aging substrates werebetter than those using fresh substrates, except15minutes sample.2. A quasi-periodic structure of the Au/Si-NPA active substrate was prepared by usingimmersion technique. The Au/Si-NPA samples were optimized by controlling immersionconditions and Si-NPA substrate’ s surface oxidation state to obtain the preparationcondition of the optimum Au/Si-NPA active substrate, that was using one week agedSi-NPA and immersing it in0.0004mol/L AuCl3solution about6min. The optimumAu/Si-NPA active substrate was characterized by FE-SEM and XRD, its SERSenhancement was tested with probe molecule R6G, and the relevant enhance mechanismwas analyzed. Based on SERS spectral, it could be inferred that R6G molecules were flat absorbed on the surface of Au nanoparticles. The signal enhancing might mainly comefrom the Au nanoparticles composed to Ring-network and the gaps between Aunanoparticles.