Fabrication of Bow-Tie Nano-Gap Structures by Electron Beam Lithography

Metallic nano-particle pairs in close proximity to one another display surface-enhanced Raman scattering (SERS). Single-molecule detection has been predicted to be possible thanks to SERS. The SERS enhancement can be maximized by simultaneously increasing the curvature of the particles and bringing them into close proximity to one another. The field intensity has been predicted to increase exponentially as the gap size decreases, and hence the study of small gaps (1-20 nm) is crucial to achieving singlemolecule detection. Identification of hazardous substances such as cyanide and anthrax is then possible on an extremely small concentration level, bordering on singlemolecule detection. This work presents the fabrication of bow-tie nano-gap structures using an optimized electronbeam lithography process. Uniform sub-20 nm gaps are demonstrated.