Optical properties of refractory metal based thin films

Archan Banerjee*, Robert M. Heath, Dmitry Morozov, Dilini Hemakumara, Umberto Nasti, Iain Thayne, Robert H. Hadfield

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

28 Citations (Scopus)
465 Downloads (Pure)


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 ALDdeposited 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.

Original languageEnglish
Pages (from-to)2072-2088
Number of pages17
JournalOptical Materials Express
Issue number8
Early online date5 Jul 2018
Publication statusPublished - 1 Aug 2018


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