Dual length-scale nanotip arrays with controllable morphological features for highly sensitive SERS applications

Hexagonally ordered, dual length-scale nanotip arrays were fabricated using a combination of prism holographic lithography, reactive ion etching, and electron-beam evaporation. Double layered, face-centered cubic structures were prepared using prism holographic lithography and were used as templates for the nanotip arrays. The morphological features of the nanotip arrays were easily controlled in the subsequent etching process by varying the etching time and etchant gases. The surfaces of the nanotips were covered with, and roughened by, small protrusions. The nanotip arrays showed tunable surface-enhanced Raman scattering activities that depended on the sharpness, shape, and surface roughness. The simple tunability and high sensitivity of these nanotip arrays make them very promising as a high-fidelity sensing platform.