Simulations of solar cell absorption enhancement using resonant modes of a nanosphere array

We propose an approach for enhancing the absorption of thin-film amorphous silicon solar cells using periodic arrangements of resonant dielectric nanospheres deposited as a continuous film on top of a thin planar cell. We numerically demonstrate this enhancement using 3D full field finite difference time domain simulations and 3D finite element device physics simulations of a nanosphere array above a thin-film amorphous silicon solar cell structure featuring back reflector and anti-reflection coating. In addition, we use the full field finite difference time domain results as input to finite element device physics simulations to demonstrate that the enhanced absorption contributes to the current extracted from the device. We study the influence of a multi-sized array of spheres, compare spheres and domes and propose an analytical model based on the temporal coupled mode theory

Efficient Coupling between Dielectric-Loaded Plasmonic and Silicon Photonic Waveguides

The realization of practical on-chip plasmonic devices will require efficient coupling of light into and out of surface plasmon waveguides over short length scales. In this letter, we report on low insertion loss for polymer-on-gold dielectric-loaded plasmonic waveguides end-coupled to silicon-on-insulator waveguides with a coupling efficiency of 79 ± 2% per transition at telecommunication wavelengths. Propagation loss is determined independently of insertion loss by measuring the transmission through plasmonic waveguides of varying length, and we find a characteristic surface-plasmon propagation length of 51 ± 4 μm at a free-space wavelength of λ = 1550 nm. We also demonstrate efficient coupling to whispering-gallery modes in plasmonic ring resonators with an average bending-loss-limited quality factor of 180 ± 8

Adsorption behavior of conjugated {C}3-oligomers on Si(100) and HOPG surfaces

A pi-conjugated {C}3h-oligomer involving three dithienylethylene branches bridged at the meta positions of a central benzenic core has been synthesized and deposited either on the Si(100) surface or on the HOPG surface. On the silicon surface, scanning tunneling microscopy allows the observation of isolated molecules. Conversely, by substituting the thiophene rings of the oligomers with alkyl chains, a spontaneous ordered film is observed on the HOPG surface. As the interaction of the oligomers is different with both surfaces, the utility of the Si(100) surface to characterize individual oligomers prior to their use into a 2D layer is discussed

Persistent enhancement of the carrier density in electron irradiated InAs nanowires

We report a significant and persistent enhancement of the conductivity in free-standing non intentionnaly doped InAs nanowires upon irradiation in ultra high vacuum. Combining four-point probe transport measurements performed on nanowires with different surface chemistries, field-effect based measurements and numerical simulations of the electron density, the change of the conductivity is found to be caused by the increase of the surface free carrier concentration. Although an electron beam of a few keV, typically used for the inspection and the processing of materials, propagates through the entire nanowire cross-section, we demonstrate that the nanowire electrical properties are predominantly affected by radiation-induced defects occuring at the nanowire surface and not in the bulk.Comment: 18 pages, 5 figure

Application of the proper generalized decomposition method to a viscoelastic mechanical problem with a large number of internal variables and a large spectrum of relaxation times

We here extend the use of the PGD to the case of a viscoelastic mechanical problem with a large number of internal variables and with a large spectrum of relaxation times. Such a number of internal variables leads to solving a system of non linear differential equations which correspond to the return to the equilibrium state. The feasibility and the robustness of the method are discussed in a simple case; a future application is the simulation of a polymer reaction under cyclic loading

Modélisation prédictive de la cinétique de cuisson des époxys avec prise en compte de la diffusion et de la dépendance en température : application à la résine LY 556

International audienceCe travail traite des possibilités de prédiction du degré d'avancement de la réaction chimique de thermodurcissement lors de la cuisson des époxys. Pour cela le modèle phénoménologique de Kamal et Sourour modifié par Fournier et al. avec la prise en compte d'un facteur correctif relatif à la diffusion des espèces est étudié au niveau de ses capacités prédictives pour le domaine de température autre que celui utilisé pour l'identification des paramètres. Si les paramètres du modèle de Kamal et Sourour sont clairement évolutifs en fonction de la température selon une loi d'Arrhenius, il n'existe pas de proposition concernant les paramètres du facteur de diffusion. Plutôt qu'une simple formulation linéaire pour la dépendance à la température de ceux-ci, des lois d'évolution non linéaires sont proposées et en particulier une expression Arrhenius pour le paramètre de diffusion. Ces analyses ont été effectuées à propos de la cinétique chimique de l'époxy DGEBA LY556 avec un durcisseur anhydride au moyen d'essais de type DSC en cuisson isotherme et dynamique. Les prédictions de cinétique chimique en dehors du domaine d'identification sont très satisfaisantes pour les cuissons isothermes et assez bonnes pour les cuissons dynamiques, lesquelles démontrent toutefois quelque peu les limitations de la modélisation