PREM researchers at North Carolina A&T State University (NCAT) and the University of California at San Diego recently created thin films of titanium oxynitride (TiNO)—a material with excellent optical and light-manipulating (plasmonic) properties—using a method where a laser pulses to deposit the material in a vacuum.

As part of their research, recently published in the Journal of Physical Chemistry, the team tested different temperatures and gas environments (some with nitrogen, some with oxygen). The best results came from films made at 700°C in a high vacuum, which reflected about 95 percent of light, had strong negative electrical response (good for plasmonics), and the highest performance score. They also found that lower temperatures or adding gas like oxygen reduced the material’s performance.

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 “The significance of titanium (oxy) nitride-based plasmonic research lies in their potential to replace noble metal-based components in plasmonic devices,” says Dhananjay Kumar, Professor of Mechanical Engineering at NCAT and Director of NSF’s PREM Center for Collaborative Research and Education in Advanced Materials. “A controllably oxidized titanium nitride thin films can have free electron density, as in noble metals, and they can also possess excellent refractory metal properties.”

What’s more, the benefit of using titanium oxynitride over titanium nitride (TiN) is that it keeps the useful electrical properties of TiN but adds new features like the ability to act as a semiconductor, depending on how much oxygen is included.

 “The NCAT research may offer a solution to the photon absorption limit by improving light absorption, which will have a broad impact on applications such as thin-film solar cells and photocatalysts,” says Kumar.