Guides d'onde optiques plans à base de silicium poreux dopés aux ions Er3+

National audienceDes études par microanalyse X et par Photoluminescence (PL) dans l’IR ont été effectuées sur des guides d’onde plans à base de silicium poreux dopés Erbium en fonction des conditions de dopage (cathodisation électrochimique et traitements thermiques). En faisant varier la densité de courant et la durée de cathodisation, nous avons montré que le dopage est homogène dans toute la profondeur de la couche de guidage pour une densité de courant égale à 0.1 mA/cm2 pendant 10 minutes. Ensuite, l’intensité intégrée de PL autour de 1.55 µm a été étudiée en fonction de la durée d’oxydation à 900 °C d’une part et en fonction de la température de diffusion et d’activation pendant 60 minutes d’autre part

Optical properties of erbium doped porous silicon waveguides

symposium D " Silicon-Based Photonics ", poster session 2 [D-P2.19]International audiencePlanar and buried channel porous silicon waveguides (WG) were prepared from p+-type silicon substrate by a two-step anodization process. Erbium ions were incorporated into pores of the porous silicon layers by an electrochemical method using ErCl3-saturated solution. Erbium concentration of around 1020 at/cm3 was determined by energy-dispersive X-ray analysis performed on SEM cross-section. The luminescence properties of erbium ions in the IR range were determined and a luminescence time decay of 420 μs was measured. Optical losses were studied on these WG. The increased losses after doping were discussed

Highly improved optical properties of silicon nanowires by deposition of Poly[2-methoxy-5-(2 '-ethylhexyloxy)-1,4-phenylene vinylene] polymer

International audienceThis paper reports on the effect of the Poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) deposition on the chemical composition and the optical properties of silicon nanowires (SiNWs). The SiNWs were obtained by a single-step Ag-assisted chemical etching method, and then coated by MEH-PPV polymer using the electroless dipping method. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Fourier Trans-formed Infra-Red (FTIR) spectroscopy were used to probe the deposition of the polymer on the SiNWs surface and its chemical interaction with them. The optical properties of the elaborated samples were investigated by pho-toluminescence (PL) spectroscopy. The PL spectra show that the PL emission range of the nanowires is practically the same as that of the MEH-PPV. We also get an enhancement of five orders of the integrated PL intensity of MEH-PPV/SiNWs sample compared to that of untreated SiNWs sample. The PL intensity enhancement is attributed to the luminescent centers of MEH-PPV molecules as well as the passivation of silicon nanowires surface. Interchain and intrachain transitions in the polymeric layer as well as the carriers transfer between SiNWs and MEH-PPV are the main sources of the multiband PL spectra

Improvement of the quality of graphene-capped InAs/GaAs quantum dots

LGEP 2014 ID = 1648International audienceIn this paper, we study the transfer of graphene onto InAs/GaAs quantum dots (QDs). The graphene is first grown on Cu foils by chemical vapor deposition and then polymer Polymethyl Methacrylate (PMMA) is deposited on the top of graphene/Cu. High quality graphene sheet has been obtained by lowering the dissolving rate of PMMA using vapor processing. Uncapped as well as capped graphene InAs/GaAs QDs have been studied using optical microscopy, scanning electron microscopy, and Raman spectroscopy. We gather from this that the average shifts Δω of QDs Raman peaks are reduced compared to those previously observed in graphene and GaAs capped QDs. The encapsulation by graphene makes the indium atomic concentration intact in the QDs by the reduction of the strain effect of graphene on QDs and the migration of In atoms towards the surface. This gives us a new hetero-structure graphene–InAs/GaAs QDs wherein the graphene plays a key role as a cap layer