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Photonics

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  • People involved :
    • Permanent Researchers : Julien Cardin, Christian Dufour, Fabrice Gourbilleau, Christophe Labbé, Philippe Marie, Xavier Portier.
    • Invited Researchers : Larysa Khomenkova.
    • Young Researchers : Georges Beany (PhD), Patrick Benzo (Post-Doc), Olivier Debieu (Post-Doc), Sébastien Cueff (PhD), Christian Davesne (PhD), Céline Lecerf (PhD), Chuan-hui Liang (PhD), Pratibha R. Nalini (post-Doc), Manuel Roussel (PhD), Jennifer Weimmerskirch (Post-doc), Ahmed Zhiani (Post-doc).
  • Projects :
    • ANR PNANO DAPHNES (2009-2012),
    • DSM/ENERGIE DELOTRAC (2011-2012),
    • PHC Polonium (2012-2013),
    • Labex EMC3 – ASAP (2012-2015),
    • Labex EMC3 – LUZ (2013-2014),
    • Labex EMC3 – HELIOS (2013-2015),
    • Interreg IVA – MEET (2012-2015),

The first thematic of the team concerns the photonic field with the fabrication and studies of Light Emitting Diode (LED), optical amplifier and/or lasers doped with rare earth (RE) ions.
These researches are divided in two topics : Si-based and Transparent Oxide Semiconductor (TCO) materials.
The former topic is based on the discovery of the effective sensitizer role of Si nanoparticles (Si-Nps) towards RE ions such as Er3+ or Nd3+.
This aspect opens the way to the fabrication of compact, efficient, optical devices with less energy consumption, and full compatible with the Si CMOS technology.

It was one of the main objectives of the ANR DAPHNES Project coordinated by the NIMPH team : demonstrate the feasibility of a net gain in Nd-doped Si-based structures.
The Nd3+ ions unlike the Er3+ ones, is a four-level system (three for Er).
Such a level configuration favors the population inversion and limits the reabsorption of the emitted wave because of a low populated ground level.
The propagation loss measurements obtained on Wgs grown by sputtering technique have demonstrated the advantage of working with a four-level system (Nd3+ ion) since lower values than 0.8 dB.cm-1 have been measured whereas in the case of Er-doped Wgs prepared using the same procedure, the propagation losses were in the order of 3 dB.cm-1. Pump-probe measurements have been performed on the Si-SiO2-Nd Wgs.
A net gain of 20% (3 dB.cm_1) never reported on such silicon-based guides was measured. The simulations performed by ADE-FDTD show that a measurable net gain of up to 30 dB.cm-1 is possible in a Nd3+-doped system while only losses will exceed the low value of gain in the case of the Er3+ ion.
The investigation of RE:ZnO thin films have been carried out on Europium (Eu), Terbium (Tb) doped ZnO films prepared by RF magnetron sputtering. The objective of such RE-doped materials being LEDs related application, the optical and the electrical properties have been optimized by means of different heat treatments (substrate temperature and post-anneal treatments). The results clearly show that a maximum of the luminescence is observed when the electrical conductivity is minimum and vice versa. An Eu/Tb co-doping of ZnO allowed observing both red and green emissions from the deexcitation of these RE ions. Thus, upon optical excitation, RE:ZnO films provide an original way to produce a white emission from the RE3+ ions and the transfer mechanism from the matrix to the RE ions diminishes significantly the UV emission from the UV excitonic contribution of the matrix.
A PN junction composed of silicon for the P type material and RE-doped ZnO for the N type one has been fabricated. By contrast with the commercial LEDs, the phosphors (Eu and Tb) are embedded in the ZnO matrix and the RE concentrations are very low (a few at.%) compared to the quantity used in the commercial LEDs.
An intense electroluminescent signals for Eu:ZnO, Tb:ZnO and Tb,Eu:ZnO films of about 100 nm thick with doping rates of about 2 at.% have just been demonstrated and they are very promising.