Fabrication Of Micro-nano Structures And Research On Its Application Of Surface-enhanced Raman Spectroscopy

Surface-enhanced Raman spectrum (SERS) technology with high sensitivity and low detection limit, compared with normal Raman method, has been widely used in biological, chemical and food detection. Fabrication of SERS substrate is a key factor for achieving high sensitivity detection. Preparing the SERS substrates with high enhancement factor, high stability and ease of fabrication is a tough challenge. With its natural benefit of high sensitivity, manufacture compatibility with the standard complementary metal-oxide-semiconductor (CMOS) process, silicon nanowires (SiNWs) are able to be fabricated with low cost and mature industrial foundries. By sputtering method, the surface of SiNWs is covered by gold film to form the gold SiNWs (AuSiNWs) SERS substrate.In this paper, we investigate the basic principle of Raman scattering and the mechanism of SERS. The physical mechanism and chemical mechanism of enhancing effects are analyzedby the numerical simulation.A major obstacle of SERS technology for the practical application is absence of large-area uniform stable SERS substrate. A high-throughput and rapidly approach to fabricate SiNWs arrays on 4-inch silicon wafer using polystyrene sphere (PS) as templates is proposed in this paper.. With PS mask instead of the traditional photolithography technology, the fabrication process is simplified and hundreds of nanometer scale patterns etching is achieved. After preparing the SiNWs arrays, a gold film is coated by the magnetron sputtering. The electric field distribution and reflectivity of the AuSiNWs are analyzed by the finite difference time domain (FDTD) method in this thesis. We designed a SERS substrate by using gold nanoshphere (AuNP). The simulation results of the electric field distribution and the reflectivity curve, show that our SERS substrate has a better local electromagnetic field enhancement, which means larger Raman signal can be obtained.Based on stimulation results, we successfully fabricated the AuSiNWs and AuNP/SiNWs SERS substrates. The measurement resultsof Raman signal spectrums for these two type SERS sbustratesproves the hybrid substrate (AuNP/AuSiNW) has the better Raman enhancement effect than the AuSiNW substrate.