27 September 2007 Plasmonic 3D nanostructures

High aspect ratio
gold needles

ICFO research takes one step further the existing nano– structuring techniques. Metallic nanostructures are recently attracting increasing interest for their plasmonic properties, offering a great potential for sensing, spectroscopic, or nano-optical applications. In order to tap into the full potential of plasmonic nanostructures, however, techniques that allow for accurate control of their (3D) shape and position need to be developed.

Researchers from the groups of Prof. Romain Quidant and Prof. Gonçal Badenes at ICFO in collaboration with Prof Ramon Alcubilla at UPC, Center for Research in Nanoengineering (www.upc.edu/crne), have recently shown that electron-beam induced deposition (EBID) can be successfully used to create plasmonic nanoscale gold structures with accurate shape and position control. Although EBID has been known for some years as a maskless lithography tool with potential for the creation of nanoscale structures, so far it was impossible to achieve sufficient material purity and thus plasmonic effects and applications were out of reach.

In the work recently published by Graells et al. (Appl. Phys. Lett. 91, 121112 (2007)), the ICFO team achieves high aspect-ratio gold structures that exhibit plasmonic properties. The technique they propose opens new perspectives in the fabrication of substantial height-base aspect ratio plasmonic nanostructures impossible to fabricate otherwise with conventional e-beam lithography. It may become particularly relevant for non-flat substrates and overcomes the main limitations of other nano structuring techniques like lift-off.