Silicon nanowire-gold nanoparticle heterostructures for Surface-enhanced Raman Spectroscopy

In this paper, we report a facile approach for the fabrication of silicon (Si) nanowire-gold (Au) nanoparticle heterostructures and their application in molecular sensing using Surface-enhanced Raman Spectroscopy (SERS). Si nanowires were grown via an atmospheric pressure chemical vapor deposition (APCVD) method. The growth conditions such as silicon source feed rate, growth duration, temperature, and catalyst amount were studied to control the morphology and structure evolution of Si nanowires. Further surface decoration of Si nanowires with Au nanoparticles was achieved using a galvanic deposition approach combined with a subsequent annealing process. This process enabled the formation of uniformly- and tightly-packed Au nanoparticles on Si nanowires with controlled size and inter-particle spacing. Such novel Si nanowire-Au nanoparticle heterostructures were subjected to SERS-based chemical detection of water-containing organic dyes. The results indicate that these heterostructured substrates have significantly improved Raman sensitivity and uniformity, and will be potential for future SERS-based bio/chemical sensors.