Fabrication And Sensing Properties Study Of SERS Substrates Based On Noble Metal/Graphene Nanocomposite Sturcture

Surface-enhanced Raman scattering (SERS), as one of spectrum detection technology, with the virtures of high sensitivity, high selectivity,non-destructive and rapid detection, has been widely applied in chemistry,medicine, environment, food security and other fields. Preparing SERS substrates with high sensitivity, stability and uniformity is the key process for SERS detection. Au, Ag and other noble metal materials with strong electromagnetic enhancement effect have alreadly become the primary choice for preparing SERS substrates. In recent years, researchers find that graphene and its ramification graphene oxide (GO) also show the potential for SERS application due to chemical enhancement. Combining the noble metals with graphene to prepare the noble metals/graphene nanocomposite structure as substrates for SERS detection has gradually become another research focus of SERS.In this thesis, we propose to deposit Au films on the specific substrates followed by rapid thermal annealing to form Au NPs. On this basis, we prepare the SERS substrates based on Au NPs and use R6G as probe molecule for SERS detection. And we further explore the influence of annealing conditions on the SERS properties. Besides, we attempt to fabricate Au NPs/GO nanocomposite structures as SERS substrates and compare their SERS properties with those of the pure SERS substrate based on Au NPs. The research work and results are as follows:1. Au films of 4 nm thicknesses were deposited on silicon oxide substrates by magnetron sputtering, and SERS sbustrates based on Au NPs were formed followed by rapid thermal annealing which could detect R6G with the concentrations of 10-5M, and experiment results showed that when the annealing temperature was 500 degrees and the annealing time was 30 seconds the Rman characteristic peaks intensity(at 613?1365? 1509 and 1652 cm-1 band) of R6G was strongest. Besides, SERS substrates based on Au NPs were prepared at above optimal annealing conditions with the detectable concentrations of R6G as low as 10'8 M and the underestimated EF value of 105 at the 1365 cm-1 band.2. SERS substrates based on Au NPs were prepared on GaAs substrates and R6G probe molecule with the concentrations of 10'5 M detection was realized successfully, which lay the foundation for preparing rolled-up SERS substrates.3. We fabricated the Au NPs/GO nanocompostie structure as SERS substrates by spin coating GO on Au NPs with detection limit of 10-8M for R6G (the underestimated EF value was 105at the 1365 cm-1 band). In addition, compared with those of the SERS substrates based on pure Au NPs, the R6G Raman characteristic peaks intensity at 775 and 1574 cm-1 band of SERS substrates based on nanocomposite structure had more than two times enhancement.