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 ...