The 5.5-Nanometre Layer That Turns a Good SERS Chip Into a Femtomolar One
Inserting a 5.5 nm fluorine-doped tin oxide interlayer between ZnO:Cu nanoneedles and silver nanoparticles lifts a SERS substrate to a 5.95×10⁸ enhancement factor and a 1 femtomolar rhodamine-6G detection limit — every result measured on the MRID (532 nm).