Highly doped semiconductor plasmonic nanoantenna arrays for polarization selective broadband surface-enhanced infrared absorption spectroscopy of vanillin

Abstract

Tailored plasmonic nanoantennas are needed for diverse applications, among those sensing. Surfaceenhanced infrared absorption (SEIRA) spectroscopy using adapted nanoantenna substrates is an efficient technique for the selective detection of molecules by their vibrational spectra, even in small quantity. Highly doped semiconductors have been proposed as innovative materials for plasmonics, especially for more flexibility concerning the targeted spectral range. Here, we report on rectangularshaped, highly Si-doped InAsSb nanoantennas sustaining polarization switchable longitudinal and transverse plasmonic resonances in the mid-infrared. For small array periodicities, the highest reflectance intensity is obtained. Large periodicities can be used to combine localized surface plasmon resonances (SPR) with array resonances, as shown in electromagnetic calculations. The nanoantenna arrays can be efficiently used for broadband SEIRA spectroscopy, exploiting the spectral overlap between the large longitudinal or transverse plasmonic resonances and narrow infrared active absorption features of an analyte molecule. We demonstrate an increase of the vibrational line intensity up to a factor of 5.7 of infrared-active absorption features of vanillin in the fingerprint spectral region, yielding enhancement factors of three to four orders of magnitude. Moreover, an optimized readout for SPR sensing is proposed based on slightly overlapping longitudinal and transverse localized SPR.

Phosphonate monolayers on InAsSb and GaSb surfaces for mid-IR plasmonics

“…The coupling of molecular absorption peaks as broad as the plasmonic resonance width which was investigated in this study has to be compared with spectrally sharp molecular absorption peaks coupled to spectrally broad plasmonic resonances. Such experiments were obtained with the same material system [28,40,41] where a clear separation of SPR and SEIRA was demonstrated. These previous works were focusing on physical deposition of molecules, e.g.…”

Microfluidic surface-enhanced infrared spectroscopy with semiconductor plasmonics for the fingerprint region

“…First, a 50 nm thick higher doped layer described by 12. (20,41,52). The grating fabricated for this work was characterized by a Nanoscope IV atomic force microscope (AFM) with a cantilever (PPP-NCH-10, Nanosensors).…”

“…Finally, it is a question of choosing the right degenerate semiconductor material for the envisaged spectral range. InAs and InAsSb are particularly suited to provide plasmonic resonances in the molecular fingerprint region from 5 µm to 20 µm (20,21). Despite these advantages of InAs and InAsSb for SEIRA, gold and its chemical inertness can be used in a wider range of different chemical environments.…”

Heavily Doped Semiconductor Metamaterials for Mid‐Infrared Multispectral Perfect Absorption and Thermal Emission

“…HDSCs are high crystalline quality materials, their dielectric function can be tailored by the dopant concentration to adjust the spectral range of operation, and they are compatible with standard complementary metal oxide semiconductor (CMOS) technology, which gives them the perspective of on‐chip device integration. The ternary HDSC InAs 0.91 Sb 0.09 :Si, lattice matched to readily available GaSb substrates, allows to obtain a doping level nearly as high as in InAs:Si, both reaching up to several 10 19 cm −3 . The theoretically predicted Si incorporation in InAs reaches even 10 20 cm −3 due to a high Fermi level stabilization point .…”