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

We demonstrate surface enhanced infrared absorption spectroscopy using 1-dimensional highly doped semiconductors based on Si-doped InAsSb plasmonic nano-antennas. 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.