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Nano-silicon antennas to capture infrared

Ordered arrays of doped silicon nanodisks extend plasmonics to infrared

par Guy Molénat - publié le

The appearance of localized surface plasmon resonances in ordered arrays of doped silicon nanodisks allows plasmonics to be extended to the infrared range. The resonance frequency is simply adjusted with the free charge concentration given by dopants. Up to now restricted to noble metals, plasmonic antennas are now made of silicon, a non-toxic and abundant material. These results are essential for the detection of molecules or thermal imaging.

Plasmonics, using the collective oscillations of free electrons located in metallic nanostructures (plasmon resonances) allows light to be manipulated at a much smaller scale than its wavelength, down to nanometric dimensions. This opens the field towards nano-optics, making it possible to bridge the dimensional gap between electronic and optical devices.

In a study that has just been published, researchers from CEMES associated with colleagues from LAAS and in collaboration with CEA-LETI, have produced for the first time a plasmonic antenna array made up of nano objects in doped silicon, a material nontoxic and abundant of the semiconductor family, at the base of microelectronics (header image : three of these nano objects whose height of the red foot is 23 nanometers. Colorized image obtained by transmission electron microscopy which shows in blue silica regions and in red those in silicon).

With their extensive knowledge in materials science, nanotechnology and infrared optics, they have used a top-down approach consisting first in optimizing the doping of thin silicon on insulator (here silica) layers beyond the usual doses by means of pulsed laser thermal annealing. Then, dense hexagonal arrays of identical disks of nanometric sizes are formed by electron lithography etching. These doped nanostructures exhibit intense localized surface plasmon resonances, measured from the medium to the near infrared by Fourier Transform Infrared Spectroscopy. This wide spectral window can be covered by simply tuning the free carrier concentration, hence the active phosphorus dopant concentration.


Numerical simulations have made it possible to study the optical properties of a single nanodisk as well as the metasurface, thus identifying the collective effects and near-field coupling in the metasurface.


These results open up very promising prospects for the development of all-silicon integrated plasmonic devices targeting applications requiring broadband and high-resolution infrared detection, such as micro-integrated bolometers or miniaturized infrared cameras.


This work is funded by ANR DONNA (Doping at the Nanoscale) (ANR-18-CE09-0034).


Publication : Hyper-Doped Silicon Nanoantennas and Metasurfaces for Tunable Infrared Plasmonics

Jean-Marie Poumirol, Clément Majorel, Nicolas Chery, Christian Girard, Peter R. Wiecha, Nicolas Mallet, Richard Monflier, Guilhem Larrieu, Filadelfo Cristiano, Anne-Sophie Royet,Pablo Acosta Alba, Sébastien Kerdiles, Vincent Paillard and Caroline Bonafos, ACS Photonics 8, 5, 1393-1399 (2021) 


Contacts :

Jean-Marie Poumirol, jean-marie.poumirol [at] cemes.fr

Guilhem Larrieu, guilhem.larrieu [at] laas.fr

Sébastien Kerdilès, sebastien.kerdiles [at] CEA.fr