Plasmonic coupled nanotorch structures leading to uniform surface enhanced Raman scattering detection

Nanocrescent-like structures have become important surface enhanced Raman scattering structures because instead of relying on a few nanometer gap inter-particle plasmonic coupling to achieve local field enhancement, intra-particle plasmonic coupling between the cavity modes and the tip edges are utilized to achieve high local field enhancement at the tips. Our fabrication approach creates 'nanotorch' structures with controllable cavity rim opening and deterministic orientation to yield uniform Raman measurements, consisting of three-dimensional upright-oriented nanocrescent structures resting on nanopillars. Each structure serves as a single SERS substrate. We demonstrate that a nanotorch with a smaller rim opening results in a higher enhancement factor compare to one with a larger opening. More importantly, the uniformity of all the analysed Raman modes of adsorbed benzenethiol is better than 80% due to the consistent, upright orientation of each single nanotorch SERS substrate, paving the way for practical implementation of SERS detection.