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The applications of conducting organic polymers in combination with semiconductor oxides are promising candidates as active materials for air-stable hybrid electronic applications such as transistors, light emitting diodes or organic photovoltaics. In this work, we report our last results on the application of SnO2 thin films in all solid-state hybrid solar cells. We also compare the results with other five solar cells developed in our laboratories applying MEH-PPV and semiconductor oxides like TiO2, Nb2O5, ZnO, CeO2 or CeO2–TiO2. In this work, SnO2 thin films, obtained from sol–gel solutions, have been applied in HSC in a configuration ITO/SnO2 thin film/MEH-PPV/Ag. The effects of factors, such as UV light, polymer thickness, stabilization in the dark and performance under irradiation conditions, have been investigated. Open circuit voltage and short circuit current values were about −0.45 V and 0.17 mA/cm2, with fill factors around 30%. Photoaction spectra show the activity of the semiconductor oxide below 340 nm and about 490 nm for the polymer. Lifetime behavior of the HSC showed an initial increase in current density reaching a maximum after about 1 h of irradiation. Blocking the UV-wavelength range by the application of a filter showed no significant difference in HSC properties with respect to the sample without UV filter. Comparison with other 5 semiconductor oxides revealed a direct relation between semiconductor oxide applied and V oc from the solar cell.

International audience; We have studied different aspects of the magnetic behavior of Fe(5 nm)/MnAs(100 nm) bilayers epitaxially grown on GaAs( 1 0 0 ). Ferromagnetic resonance (FMR) measurements were performed in order to characterize the magnetic anisotropies of the films and the interlayer coupling between them. The chemical composition of the interface was investigated by X-ray photoemission spectroscopy (XPS). The iron layer FMR spectrum is highly temperature dependent between 280K and 320K as its parameters are strongly altered in the alpha/beta phase coexistense regime of the MnAs layer, revealing a strong interlayer coupling in this T-region. Additionally, the XPS experiments demonstrate the existence of an Fe-MnAs intermixed interface. This result would explain appearance of an additional uniaxial anisotropy in the plane of the Fe films, together with a strong reduction in its magnetocrystalline anisotropy and a negligible direct exchange coupling in the MnAs ferromagnetic state. (C) 2012 Published by Elsevier B.V.

A single layer of the Cationic polyelectrolyte poly(allyamine) hydrochloride (PAH) deposited, using the layer-by-layer technique, on a silicon substrate containing 5 nm oxide layer is investigated by XPS while applying an external potential bias to the sample to control and manipulate the charge built-up on the oxide layer. Under application of a -10 V bias, the oxide layer is positively charged due to Photoemission process, evidenced by the measured Si2p binding energy of 104.4 eV. Application of a +10 V bias attracts the low energy neutralizing electrons, stemming from a hot filament, and leads to a negatively charged oxide layer, also evidenced by the measured Si2p binding energy of 102.9 eV. The single polyelectrolyte overlayer also responds to this polarity change of the oxide layer underneath by displaying a somewhat larger shifts both in the C1s and Nls peaks. In addition to the shifts in the positions, the N1s peaks undergo a significant intensity depletion, mostly on the positively charged -N+ component. We interpret this intensity depletion to be the result of reorientation of some of the dangling positively charged groups by moving toward the negatively charged oxide underlayer. To our knowledge this is the first time that a chemically specific response to an electrical stimuli is reported using XPS. A bilayer LbL film consisting of PAH and PSS, exhibits even a larger charging shift, but this time no intensity alteration is observed, most probably due to locking of the -N+ groups by the -SO3 + counterions of the second layer. © 2009 American Chemical Society.

The use of two truly two-dimensional gapless semiconductors, monolayer and bilayer graphene, as current-carrying components in field-effect transistors (FET) gives access to new types of nanoelectronic devices. Here, we report on the development of graphene-based FETs containing two decoupled graphene monolayers manufactured from a single one folded during the exfoliation process. The transport characteristics of these newly-developed devices differ markedly from those manufactured from a single-crystal bilayer. By analyzing Shubnikov-de Haas oscillations, we demonstrate the possibility to independently control the carrier densities in both layers using top and bottom gates, despite there being only a nano-meter scale separation between them., Comment: 4 Pages, 4 Fugures

The fabrication and characterisation of a double-arm cantilever-type metallic DC-contact MEMS actuator with low pull-down voltage are reported. Bi-layer TiW cantilevers with an internal stress gradient were fabricated using a microwave-compatible fabrication process. Owing to its small size, cantilever length (L=5-50m) and width (W=2-40m), i.e. ∼10-100 times smaller in lateral dimensions than a standard MEMS actuator, this actuator showed actuation voltages lower than 10 V. RF measurements of the 10m-wide actuators yielded an average insertion loss less than 1dB and isolation higher than 40dB up to 25GHz. The developed actuator is well suited for integration in reconfigurable microwave circuits and systems such as reconfigurable antennas and arrays. © 2009 The Institution of Engineering and Technology.