Morphology tuned plasmonic TiN nanostructures formed by angle-dependent sputtering process for SERS measurements

Abstract

Nowadays, most SERS platforms are based on plasmonic metals like silver and gold. The current scientific achievement is to construct SERS non-metallic platform with SERS activity not worse than in case of standard metallic platforms. The prominent combination of opto-electronic properties of TiN (titanium nitride) makes it a promising alternative plasmonic material for noble metals. So far, the TiN nanostructures are widely tested in catalysis, especially in photocatalysis. Despite the TiN potential in SERS sensing applications, there are still several fundamental issues preventing its wide practical application. In this work, the surface morphology of TiN layers was tuned from planar 2D to a high aspect ratio 1D nanorod-like structures by industrially scalable normal and glancing angle deposition (GLAD) pulsed DC reactive sputtering. The morphology of formed samples was studied by SEM microscopy, while the crystallographic properties were examined by Raman and XRD method. The opto-electrical parameters measured by spectroscopic ellipsometry, and DRS spectroscopy revealed substantial changes in optical properties of the TiN films with the variation of glancing angle. This in turn opened the way for tailoring the surface plasmon resonance and hence for SERS activity.