Fabrication of gold nanocrescents by angle deposition with nanosphere lithography for localized surface plasmon resonance applications.

The gold nanostructures fabricated on a substrate yield localized surface plasmon resonance. We describe the fabrication and characterization of nanocrescents on a silicon substrate, which are fabricated by depositing a gold film at an oblique angle through nanosphere lithography. Following the etching of the gold perpendicular to the substrate and the removal of the nanospheres by dissolution, nanocrescents with fine nanostructures are generated. By varying the deposition angle of the gold film from 0 degrees to 72 degrees , nanorings, 2D and 3D nanocrescents can be obtained. During the nanocrescent fabrication, we also compared the deposition angle difference between the e-beam and thermal evaporators for oblique depositions of the gold. The 3D nanocrescents fabricated in our experiments are expected to have improved sensitivity in localized surface plasmon resonance measurements when compared to the previously reported 2D nanocrescents, which enable broader biosensor applications. Simulations of the profiles of these 3D nanocrescents using solid geometry show good consistency with the fabricated ones.