10.1021/nn1017507.s001 Seungwoo Lee Seungwoo Lee Jonghwa Shin Jonghwa Shin Yong-Hee Lee Yong-Hee Lee Jung-Ki Park Jung-Ki Park Fabrication of the Funnel-Shaped Three-Dimensional Plasmonic Tip Arrays by Directional Photofluidization Lithography American Chemical Society 2010 Directional Photofluidization LithographyPlasmonics plasmonic light enhancement nanofabrication technique photofluidization lithography plasmonic tip tip features nanofunnel tips nanophotonic applications fabrication method EM field enhancement 2010-12-28 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Fabrication_of_the_Funnel_Shaped_Three_Dimensional_Plasmonic_Tip_Arrays_by_Directional_Photofluidization_Lithography/2702149 Plasmonics allow localization of an electromagnetic (EM) field into nanoscale “hotspots”, a feature that is of technological significance due to potential applications related to spectroscopic sensing and nanofocusing. In relation to this, many researchers have sought to fabricate metallic nanostructures with sharp edges, as they provide much higher EM field enhancement compared with rounded structures. However, a fabrication method satisfying stringent requirements for the efficient EM field enhancement including three-dimensionality, vertical orientation, large-area fabrication, and tunability of structural features, which are of practical importance for efficient plasmonic light enhancement at hotspots, has yet to be achieved. Herein, we fabricate large-area, vertically aligned three-dimensional plasmonic tip (<i>i.e.</i>, nanofunnel) arrays with unprecedented flexibility in the control of the structural features by directional photofluidization lithography. Using this approach, the structural features of nanofunnel tips including the sharpness, shape, and orientation were precisely controlled in a scalable and deterministic manner. The effects of the structural features of the nanofunnel on the EM field enhancement were systematically investigated and analyzed, and the optimum tip features for maximum EM field enhancement were thereupon identified. The suggested nanofabrication technique and resulting structures will be of practical importance in spectroscopic and nanophotonic applications.