Fabrication Of Metallic Nanostructures And Their Applications In Sensing

Nanoscale metallic materials have attracted extensive attention and been widely studied due to their unique photoelectrical properties compared with bulk metallic material. Recently, more and more metallic nanostructures were applied in the sensing fields, such as gas sensing, heavy metal ion detection and biosensing. It’s worth noting that their photoelectrical properties can be controlled by changing their mopholigies or sizes.We demonstrate new methods to fabricate metallic nanostructures based on nanoimprint and nanosphere lithography. The metal nanowires, metal nanograting and silver nanoparticles deposited on the Si nanopillar array(Ag NPs@nanopillar) wer e fabricated and their sensing performances were investigated. This thesis includes the following three parts:Firstly, we demonstrated a new method to fabricate silver nanowires arrays based on the combination of nanoimprint lithography(NIL) and electroless metal deposition(EMD). The polymer patterns were fabricated with NIL for the direct deposition of silver particles. With the optimized parameters, silver nanowires arrays of 95 nm in width and 195 nm in period were created. The silver nanowires arrays were used for ammonia sensing.Secondly, we proposed a simple method to improve the plasmonic sensing performance of gold gratings. The gratings consist of periodic polymer gratings covered with a gold layer, created by nanoimprint lithography and metal deposition. We investigated the effect of gold thickness and the incident angles on the plasmonic sensing performance. With the optimized gold layer, the full-width at half maximum of this grating was reduced by 60 % using the oblique incident light instead of the normal incident light. A maximum value of the figure of merit at oblique incidence is 12, which is double of the one at normal incidence.Thirdly, we improved the surface-enhanced Raman scattering(SERS) performance of silver nanoparticles(Ag NPs) by depositing them on the Si nanopillar array. We fabricated the Ag NPs@nanopillar arrays by the combination of nanosphere lithography and EMD. The enhancement factor of the optimal Ag NPs@nanopillar is 9.6×105 and the limit of detection for 4-MPy can be down to nanomolar concentration. Moreover, the deviation of SERS signal is 5.43%, which showed good uniformity. Compared with Ag NPs deposited on blank Si, the optimal Ag NPs@nanopillar showed better SERS performance due to the templated deposition of Si nanopillar.