Quantum plasmonics and hyperbolic material for biosensing
Résumé
In this work, we demonstrate that it is possible to use III-V semiconductors for plasmonics from the THz up to the midinfrared spectral range. We have fabricated hyperbolic nano-antenna based on heavily doped semiconductors demonstrating localized plasmon modes. This hyperbolic nano-antenna is 10 times: 10 nm doped InAs / 10 nm undoped GaSb. The free carriers are confined in the 10 nm layer of InAs. The confinement shifts the effective plasma frequency of the metamaterial towards the high frequencies, extending the possibility to probe molecules until 2000 cm-1 , thus covering the complete fingerprint frequency range for molecular and biosensing applications. The nano-structuration of the hyperbolic material allows to access two main plasmonic resonances at 800 cm-1 and 2000 cm-1. This bimodal property is appealing to detect and identify biomolecules over a large spectral range. With these hyperbolic nanoantennas, we can either enhance the absorption of rovibrational modes of molecules with surface-enhanced infrared absorption (SEIRA) spectroscopy 1 or enhance the thermal emission of molecules with surface-enhanced thermal emission spectroscopy (SETES) 2 .
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