Modification of alumina matrices through chemical etching and electroless deposition of nano-Au array for amperometric sensing

Simple nanoporous alumina matrix modification procedure, in which the electrically highly insulating alumina barrier layer at the bottom of the pores is replaced with the conductive layer of the gold beds, was described. This modification makes possible the direct electron exchange between the underlying aluminum support and the redox species encapsulated in the alumina pores, thus, providing the generic platform for the nanoporous alumina sensors (biosensors) with the direct amperometric signal readout fabrication

Light amplification due to free and localized exciton states in ZnCdSe GRINSCH structures

International audienceIn this paper we present measurements of light amplification in optically pumped ZnCdSe GRINSCH (graded refraction index separate confinement heterostructures), In several differently designed samples we observe the presence of two gain mechanisms, which involve localized excitons and exciton-exciton inelastic scattering processes, respectively. The influence of the GRINSCH sample structure on gain is discussed in terms of their improved light-guiding properties

Determination of light amplification processes in MOCVD grown ZnCdSe GRINSCH structures

International audienceIn this paper we present measurements of light amplification in optically pumped ZnCdSe graded refraction index separate confinement heterostructures (GRINSCH). In several differently designed samples we observe the presence of two gain mechanisms, which involve localized excitons and exciton-exciton inelastic scattering processes, respectively, The influence of the GRINSCH structure on gain is discussed with respect to light guiding variations due to sample design. A numerical simulation is used to investigate the phenomenon of gain quenching with decreasing barrier width

Aluminium oxide film for 2D photonic structure: room temperature formation

We report about aluminium anodic oxide films (AOFs) as self-organising microstructures for photonic band gap (PBG) crystal application. Structural analysis show that aluminium anodic oxide has formed a structure of randomly oriented clusters each of them consisting of neatly ordered submicrometer cells. Measurements show that at room temperature pores of up to 460 nm wide can be formed, thus, opening a PEG in the visible. Doping of aluminium AOFs by Ag and CdS, is demonstrated

Three-dimensional nanopillar-array photovoltaics on low-cost and flexible substrates

Solar energy represents one of the most abundant and yet least harvested sources of renewable energy. In recent years, tremendous progress has been made in developing photovoltaics that can be potentially mass deployed1, 2, 3. Of particular interest to cost-effective solar cells is to use novel device structures and materials processing for enabling acceptable efficiencies4, 5, 6. In this regard, here, we report the direct growth of highly regular, single-crystalline nanopillar arrays of optically active semiconductors on aluminium substrates that are then configured as solar-cell modules. As an example, we demonstrate a photovoltaic structure that incorporates three-dimensional, single-crystalline n-CdS nanopillars, embedded in polycrystalline thin films of p-CdTe, to enable high absorption of light and efficient collection of the carriers. Through experiments and modelling, we demonstrate the potency of this approach for enabling highly versatile solar modules on both rigid and flexible substrates with enhanced carrier collection efficiency arising from the geometric configuration of the nanopillars