Oblique angle deposited silver islands on Ge20Se70Te10 film substrate for surface-enhanced infrared spectroscopy

Abstract

Surface-enhanced infrared absorption (SEIRA) spectroscopy is a powerful tool for characterizing and identifying chemical/biological species. Though SEIRA technique has enabled detection up to few molecule levels with sophisticated device structures, there is still room for improvement (can extend to detect down to a single molecule). Superior sensor platforms can be developed by incorporating advanced substrate material, so as to be actively employed in trace analysis, forensic sciences etc. In this work, chalcogenide glass of composition Ge20Se70Te10 is characterized to probe its usability as a SEIRA substrate. Silver island structures were developed on Ge20Se70Te10 film via oblique angle deposition and its SEIRA response was recorded using FTIR spectrometer with Hexa Decane Thiol (HDT) as the analyte. Investigations reveal an optimum silver thickness at which maximum absorption enhancement is obtained. The response of the system to variations in the analyte concentration is also explored. Studies prove them to be a promising candidate as an IR substrate which can be used to develop integrated optical waveguide for highly sensitive SEIRA spectroscopy.