Tuning the plasmonic resonance in TiN refractory metal

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Plasmonic coatings are crucial for enhancing solar panel efficiency and developing energy-saving smart windows.
• Thin, low-temperature coatings on diverse substrates are needed for practical applications.
• Titanium nitride (TiN) is a promising material for plasmonic applications due to its tunable properties.

Purpose of the Study:

• To investigate and tune the plasmonic resonance of titanium nitride thin films in the 20-60 nm thickness range.
• To explore the growth of high-quality, ultrathin TiN films at low temperatures.
• To understand the relationship between film thickness, stoichiometry, and plasmonic absorption.

Main Methods:

• Cathodic vacuum arc deposition was used to grow TiN thin films on glass substrates at ~200°C.
• Film thickness was varied from 20 to 60 nm with a bias voltage of -60 V.
• Optical properties were characterized, and finite-difference-time-domain (FDTD) simulations were performed.

Main Results:

• High-quality crystalline TiN films with roughness <0.5 nm were successfully grown.
• A local surface-enhanced plasmon resonance was observed between 400-500 nm.
• Thicker films exhibited a blueshift in plasmonic frequency, attributed to increased carrier mobility.

Conclusions:

• Ultrathin titanium nitride films possess tunable plasmonic properties suitable for solar energy applications.
• Low-temperature deposition of high-quality TiN films is achievable, enabling use on various substrates.
• Understanding the interplay of thickness and stoichiometry is key to optimizing electromagnetic absorption for energy applications.