Electromagnetic Field Enhancement of Nanostructured TiN Electrodes Probed with Surface-Enhanced Raman Spectroscopy

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Nanostructured titanium nitride (TiN) exhibits unique optical properties.
• Understanding electromagnetic field enhancement is crucial for applications in plasmonics and sensing.
• Titanium dioxide (TiO2) nanotube arrays can be converted to nanostructured TiN.

Purpose of the Study:

• To develop a facile approach for determining the electromagnetic field enhancement of nanostructured TiN electrodes.
• To investigate the origin of optical activity in TiN nanostructures.
• To correlate electromagnetic field enhancement with electronic absorption.

Main Methods:

• Fabrication of nanostructured TiN from nitridation of TiO2 nanotube arrays.
• Surface-enhanced Raman scattering (SERS) spectroscopy using azidobenzene as a non-surface binding reporter.
• Rigorous coupled wave analysis (RCWA) for simulating near-field enhancement and far-field absorption.

Main Results:

• Electromagnetic field enhancement factors (EFs) were determined across the optical region.
• EFs correlated with the electronic absorption profile, reaching 3.9 at 786 nm excitation.
• Simulations showed good agreement with experimental observations, attributing optical activity to collective localized plasmonic modes.

Conclusions:

• The study presents an effective method for quantifying electromagnetic field enhancement in nanostructured TiN.
• The observed optical activity in TiN nanostructures primarily arises from collective localized plasmonic modes around 700 nm.
• The findings provide insights into the plasmonic behavior of TiN for potential optoelectronic applications.