SPIE

NRC publication: Ye

SPIE

NRC publication: Ye

Electroluminescent Characteristics of DBPPV–ZnO Nanocomposite Polymer Light Emitting Devices

We have demonstrated that fabrication and characterization of nanocomposite polymer light emitting devices with metal Zinc Oxide (ZnO) nanoparticles and 2,3-dibutoxy-1,4-poly(phenylenevinylene) (DBPPV). The current and luminance characteristics of devices with ZnO nanoparticles are much better than those of device with pure DBPPV. Optimized maximum luminance efficiencies of DBPPV–ZnO (3:1 wt%) before annealing (1.78 cd/A) and after annealing (2.45 cd/A) having a brightness 643 and 776 cd/m2at a current density of 36.16 and 31.67 mA/cm2are observed, respectively. Current density–voltage and brightness–voltage characteristics indicate that addition of ZnO nanoparticles can facilitate electrical injection and charge transport. The thermal annealing is thought to result in the formation of an interfacial layer between emissive polymer film and cathode

Microscale friction investigation of polysilicon surface using scanning force microscopy

Microscale phenomena between the surface of chemically vapour deposited silicon films and a silicon nitride tip was investigated using Scanning Force Microscopy. An analysis of friction forces for different scan directions is presented. For different applied forces, the friction forces were measured and consequently the friction coefficient was calculated. We found that the average friction force linearly increases with the applied force and is reversible when unloading. Connection between the surface roughness and the friction coefficient was experimentally demonstrated

On Schockley-Read-Hall Model with Finite Relaxation Time of Traps for Surface Recombination Velocity in Case of Illumination

In this paper we discuss the Schockley-Read-Hall model for the surface recombinaison velocity in the case of illumination with the photon flux density. The traps have a finite time of relaxation. We estimate for a n-type silicon the surface recombinaison velocity in all injection charge cases. Finally, we evaluate the importance of different parameters in the value of surface recombinaison velocity.Dans ce travail, nous examinons le modèle de Schockley-Read-Hall relatif à la vitesse de recombinaison de surface dans le cas d'une illumination par un flux de photons. Le temps de relaxation des pièges reste fini. Nous comparons les vitesses de recombinaison de surface du silicium de type n dans tous les configurations d'injection de charge. Nous déterminons aussi l'influence des divers paramètres sur cette vitesse de recombinaison

The usage of the historical cartographic datasets and the remote sensing data for the better understanding and mapping of the 2006 Danube floods in Romania

The advantages brought by high resolution satellite data in activities related to flood mapping and flood monitoring are well know in the scientific community. The paper aims to prove that slighter older geospatial documents, such as historical maps, are also a valuable resource for cartographers and decision makers to achieve a better understanding of flood patterns and evolution. Some preparatory actions are needed in order to integrate the old maps into GIS environments for advanced analysis. This includes scanning, color enhancements, georeferencing, reprojection and metadata creation. To illustrate the process, the paper includes a real case scenario: the April 2006 Danube River flood. For one of the most affected sectors along the Danube, close to Rast village, three generations of historical maps (the Austrian 1:200 000 ‘degree maps’, the Romanian 1:20 000 ‘Lambert-Cholesky’ maps and the Soviet Union 1:100 000 ‘Gauss-Krüger’ maps) were processed and included in a large repository. At any time, the maps can be identified and accessed through open standard protocols like CSW and WMS. In this way, we were able to integrate and analyze the flood water masks, extracted from satellite data, along with the historical data sets. The results were very promising. It was possible to understand some flood patterns and to clearly demonstrate that, after the dike failure, the water filled up an area which in the past, before river regulation, was the natural Danube floodplain

Accuracy issues in polarization mode dispersion measurements: Stokes parameter evaluation technique, state of polarization method and fixed analyzer technique

NRC publication: Ye

Spectroellipsometric Investigation of LPCVD Polysilicon: As Deposited and After Hydrogenation

Polycrystalline silicon deposited at 570 $^{\circ}$C and 620 $^{\circ}$C temperature, as-deposited and after hydrogenation, was investigated by spectroellipsometry. The behaviour of refractive and absorption index versus wavelength is presented. The paper also includes evaluation of the surface roughness and the crystallinity fraction of polysilicon via Bruggeman-Effective Medium Approximation. An attempt to evaluate the first two direct interband transitions from spectroellipsometric spectrum and comparison with other measurements is reported.On a étudié, par spectroellipsométrie, du silicium polycristallin après dépôt à 570 $^{\circ}$C et 620 $^{\circ}$C, puis après hydrogénation. Les comportements des indices de réfraction et d'absorption en fonction de la longueur d'onde sont présentés. Cet article contient l'évaluation de la rugosité de la surface et de la fraction cristalline du silicium polycristallin en utilisant l'approximation du milieu effectif de Bruggeman. Un essai d'évaluation pour les deux premières transitions interbande permet de calculer des spectres spectroellipsométriques ; la comparaison avec d'autres mesures est aussi présentée