Enhanced plasmonic effects in AG decorated amorphous TiO2 nanotube arrays

In the present investigation SERS sensitivity and plasmonic-photonic interference coupling (P-PIC) in amorphous TiO₂ nanotube (A[TNT]) and crystalline silver (Ag) nanoparticles was studied. TNT were synthesized by two step anodization on titanium (Ti) substrate. Using thermal evaporation, 20 nm Ag film overcoating on TNT structures was synthesized, which coalescence to form Ag nanoparticles, acting as a three dimensional (3D) surface enhanced raman spectroscopy (SERS) substrate for rhodamine 6G (R6G) molecule detection. The nanoarchitecture phase formation is confirmed by X-ray diffraction (XRD) analysis, Raman spectroscopy analysis. Surface morphology and the salient features are studied by scanning electron microscopy (SEM). Current decay time is also studied and compared for the samples respectively which show large current decay time for A[TNT]-Ag as compared to C[TNTAg]. UV-visible absorption studies shows larger red shift in the absorption band gap edge of A[TNT]-Ag samples as compared to C[TNT-Ag] samples. Moreover the TNT length variation in A[TNT]-Ag samples results into constructive or destructive interference, which in turn affect the P-PIC and R6G molecule detection as well as SERS intensity which was approximately three time higher than C[TNT-Ag].