High aspect plasmonic nanotrench structures as sensors in the near- and Mid-IR frequency range

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Titanium nitride (TiN) and aluminum-doped zinc oxide (AZO) high-aspect trench structures are fabricated using a combination of deep reactive ion etching and atomic layer deposition. These structures may be used as sensors in the near-infrared (IR, 820 - 900 nm wavelength range) and mid-IR (8 μm wavelength), respectively. We show that the refractive index sensitivity reached values up to 430 nm/RIU for TiN trenches in the near-IR region and enhanced sensitivity of molecules in AZO trenches for mid-IR wavelengths.Due to the high achievable confinement of the electric field at a metal-dielectric interface, plasmons are one of the avenues exploited for high-sensitivity sensing [1]. This confinement at the surface allows tracking of very small amounts of analytes, for example in label-free biosensing. One of the possible designs of the sensors involves grating structures [2], [3]. Depending on the analyte to be measured, either near- or mid-IR ranges can be used. In particular, the mid-IR absorption spectroscopy operating in the wavelength range of 2 - 20 μm (5000 - 500 cm−1) can be used to detect molecules by measuring the vibrational modes in their chemical bonds. They generally have specific absorption bands in this wavelength range [4]-[6], enabling label-free detection of specific molecules in solid, liquid, and gas phases. The research into these fields may enable various applications from medical diagnosis to gas sensing for environmental monitoring.
Original languageEnglish
Title of host publicationProceedings of 2018 20th International Conference on Transparent Optical Networks
Number of pages1
Publication date2018
Pages3 pp.
ISBN (Print)9781538666050
Publication statusPublished - 2018

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