Surface-enhanced infrared absorption with Si-doped InAsSb/GaSb nano-antennas

Abstract

© 2017 Optical Society of America. We demonstrate surface enhanced infrared absorption spectroscopy using 1-dimensional highly doped semiconductors based on Si-doped InAsSb plasmonic nanoantennas. Engineering the plasmonic array to support the localized surface plasmon resonance aligned with the molecular vibrational absorption mode of interest involves finely setting the doping level and nano-antenna width. Heavily doped nano-antennas require a wider size compared to lightly doped resonators. Increasing the doping level, and consequently the width of the nano-antenna, enhances the vibrational absorption of a ~15 nm thick organic layer up to 2 orders of magnitude compared to the unstructured sample and therefore improves sensing. These results pave the way towards molecule fingerprint sensor manufacturing by tailoring the plasmonic resonators to get a maximum surface enhanced infrared absorption at the target vibrational mode.