Plasmonic–Photonic Interference Coupling in Submicrometer Amorphous TiO2–Ag Nanoarchitectures

In this study, we report the crystallinity effects of submicrometer titanium dioxide (TiO2) nanotube (TNT) incorporated with silver (Ag) nanoparticles (NPs) on surface-enhanced Raman scattering (SERS) sensitivity. Furthermore, we demonstrate the SERS behaviors dependent to the plasmonic-photonic interference coupling (P-PIC) in the TNT-AgNP nanoarchitectures. Amorphous TNTs (A-TNTs) are synthesized through a two-step anodization on titanium (Ti) substrate and crystalline TNTs (C-TNTs) are then prepared by using thermal annealing process at 500 °C in air. After thermally evaporating 20-nm thick Ag on TNTs, we investigate SERS signals according to the crystallinity and P-PIC on our TNT-AgNP nanostructures. (A-TNTs)-AgNP substrates show dramatically enhanced SERS performance compared with (C-TNTs)-AgNP substrates. We attribute the high enhancement on (A-TNTs)-AgNP substrates with electron confinement at the interface between A-TNTs and AgNPs due to the high interfacial barrier resistance caused by band edge ...