Large-Area Hybrid Plasmonic Optical Cavity (HPOC) Substrates for Surface-Enhanced Raman Spectroscopy

Surface-enhanced Raman spectroscopy (SERS) is receiving increasing interests owing to its high sensitivity and molecular fingerprint information. The practical application of SERS relies on the highly enhancing, uniform, reproducible, and affordable substrates. A novel gap-free 3D SERS substrate with unique hybrid plasmonic and optical cavity (HPOC) structures to improve the uniformity and reduce the fabrication cost while maintaining the high SERS enhancement is introduced here. The gold HPOC structures are fabricated by the tunable holographic lithography followed by gold deposition and can be conveniently optimized for a specific excitation wavelength by tuning the cavity length. The substrate shows average enhancement factor larger than 10(6) and excellent uniformity with a standard deviation smaller than 6.7%. Together with the capability to be fabricated on a flexible polyethylene substrate, the HPOC SERS substrate is promising for practical applications.