APCVD of dual layer transparent conductive oxides for photovoltaic applications

We report the atmospheric pressure chemical vapour deposition (APCVD) of a dual layer transparent conductive oxide (TCO). This combines a fluorine doped tin oxide (FTO) base layer with a fluorine doped zinc oxide (FZO) top layer, where we seek to utilise the respective advantages of each material and the differences in their associated industrial deposition process technologies. Deposition of a 250 nm thick FZO layer on FTO was enough to develop features seen with FZO only layers. The crystallographic orientation determined by the FZO dopant concentration. Changes to the deposition parameters of the underlying FTO layer effected stack roughness and carrier concentration, and hence optical scattering and absorption. Photovoltaic cells have been fabricated using this TCO structure showing promising performance, with efficiencies as high as 10.21% compared to reference FTO only values of 9.02%. The bulk of the coating was FTO, providing the majority of conductivity and the large surface features associated with this material, whilst keeping the overall cost low by utilising the very fast growth rates achievable. The FTO was capped with a thinner FZO layer to provide a top surface suitable for wet chemical or plasma etching, allowing the surface morphology to be tuned for specific applications

Controlled nucleation of thin microcrystalline layers for the recombination junction in a-Si stacked cells

In high-efficiency a-Si : H based stacked cells, at least one of the two layers that form the internal n/p junction has preferentially to be microcrystalline so as to obtain sufficient recombination at the junction [1–6]. The crucial point is the nucleation of a very thin μc-Si : H layer on an amorphous (i-layer) substrate [2, 4]. In this study, fast nucleation is induced through the treatment of the amorphous substrate by a CO2 plasma. The resulting n-layers with a high crystalline fraction were, however, found to reduce the Voc when incorporated in tandem cells. The reduction of the Voc could be restored only by a precise control of the crystalline fraction of the n-layer. As a technologically more feasible alternative, we propose a new, combined n-layer, consisting of a first amorphous layer for a high Voc, and a second microcrystalline layer, induced by CO2 treatment, for a sufficient recombination at the n/p junction. Resulting tandem cells show no Voc losses compared to two standard single cells, and an efficient recombination of the carriers at the internal junction as proved by the low series resistance (15 Ωcm2) and the high FF ( 75%) of the stacked cells

Determination of Total and Free Phenytoin in Serum by Non-Isotopic Immunoassays and Gas Chromatography

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PRODUCTION OF SMALL OHMIC CONTACTS BY LASER PROCESSING FOR Si AND GaAs DEVICES

Le recuit local de contacts de petite dimension sur une couche de Si et GaAs a été réalisé à l'aide d'un laser continu focalisé (Ø = 3 µm, 0,5W) sans affecter les contacts Schottky situés quelques µm à coté des parties irradiées. Des contacts à base de Ti/Pt sur du silicium du type N ont montré une résistance inférieure à 10-6Ωcm2, des résistances de contact du Ti/AuGe/Pt sur une couche de GaAs du type N sont de l'ordre de 1.5.10-5 Ωcm2. Les résultats sont comparables à ceux obtenus pour des contacts recuit par une méthode conventionelle.Small contact patterns on Si and GaAs have been alloyed locally with a focused cw laser beam (Ø = 3µm, 0,5W), without affecting Schottky contacts few µm apart the irradiated areas. Contact resistances of less than 10-6 Ωcm2 for Ti/Pt contacts on n-Si and 1.5.10-5 Ωcm2 for Ti/AuGe/Pt on contacts on n-GaAs have been obtained. Conventional alloyed contacts show similar values

Effects of 2-(3-Methyl-cinnamyl-hydrazono)-propionate on Fatty Acid and Glucose Oxidation in the Isolated Rat Diaphragm Using 14C-Labelled Substrates. Hydrazonopropionic Acids, a New Class of Hypoglycaemic Substances, VIII

Peer Reviewe