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A New Heterostructured SERS Substrate: Free-standing Silicon Nanowires Decorated with Graphene-encapsulated Gold Nanoparticles

Authors: Yuan Li; John Dykes; Todd Gillium; Nitin Chopra

Publication Date: -0001-11-30  Article ASAP

Heterostructures of one-dimensional nanowires supported graphene/plasmonic nanoparticles are promising for future SERS-based chemical sensors. In this paper, we report a novel heterostructured SERS substrate composed of free-standing Si nanowires and surface-decorating Au/graphene nanoparticles. We successfully developed a unique CVD approach for the cost-effective and large-scale growth of free-standing Si nanowires. Au nanoparticles were decorated on the Si nanowires using a galvanic deposition – annealing approach. This was followed by the selective growth of multilayer graphene shell on the Au nanoparticles via a xylene-based CVD approach. Discrete Dipole Approximation simulation was used to understand the plasmonic properties of These Si nanowire-based heterostructures. The results indicate the incorporation of Au nanoparticles and graphene on Si nanowires has a significant influence on their light absorption and scattering properties. Meanwhile, strong surface plasmon coupling was observed at the interface regions of different materials (e.g., Si/Au, Au/graphene), introducing multiple co-enhanced “hot spots” on the heterostructures. We found our new heterostructures have a combined effect of electromagnetic mechanism and chemical mechanism for SERS and demonstrate an enhancement factor of 106~107.  Read more