Vol. 9, No. 8 | 1 Aug 2018 | OPTICAL MATERIALS EXPRESS 2072 Optical properties of refractory metal based thin films 1,2,* 1 1 ARCHAN BANERJEE, ROBERT M. HEATH, DMITRY MOROZOV, DILINI 1 1 1 HEMAKUMARA, UMBERTO NASTI, IAIN THAYNE, AND ROBERT H. 1 HADFIELD 1School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK 2Presently at: Centre for Quantum Photonics, University of Bristol, Bristol BS8 1TH, UK *[email protected] Abstract There is growing interest in refractory metal thin films for a range of emerging nanophotonic applications, including high temperature plasmonic structures and infrared superconducting single photon detectors. We present a detailed comparison of optical properties for key representative materials in this class (NbN, NbTiN, TiN and MoSi) with texture varying from crystalline to amorphous. NbN, NbTiN and MoSi have been grown in an ultra-high vacuum sputter deposition system on silicon substrates at room temperature. Two different techniques (sputtering and atomic layer deposition) have been employed to deposit TiN. We have carried out variable angle ellipsometric measurements of optical properties from ultraviolet to mid-infrared wavelengths. We compare with high resolution transmission electron microscopy analysis of microstructure. Sputter-deposited TiN and MoSi have shown the highest optical absorption in the infrared wavelengths relative to NbN, NbTiN and ALD- deposited TiN. We have also modelled the performance of a semi-infinite metal air interface as a plasmonic structure with the above mentioned refractory metal based thin films as the plasmonic components. This study has implications for the design of next-generation superconducting nanowire single photon detectors and plasmonic nanostructure-based devices. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. 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