Search results for " Coating."
showing 10 items of 2558 documents
Conductive and Capacitive Properties of the Bipolar Membrane Junction Studied by AC Impedance Spectroscopy
2001
The complete ac impedance spectrum of four bipolar membranes is analyzed both theoretically and experimentally taking into account both ionic transport and water dissociation together with the structural aspects of the bipolar junction. A theoretical model based on the Nernst-Planck and Poisson equations for the conductive and capacitive properties of the junction provides a qualitative description of the bipolar membranes for a broad range of electric currents and temperatures. Special attention is paid to the characteristics of the bipolar junction structure and the contact region between the two ion-exchange layers. It is observed that the effective area of this region increases with the…
ZnO/CdTe/CuSCN, a promising heterostructure to act as inorganic eta-solar cell
2005
Abstract The ZnO/CdTe/CuSCN heterostructure was analyzed as a candidate to act as an inorganic eta -solar cell. A ZnO film consisting of single crystal nanocolumns was electrodeposited on a transparent conducting substrate which acts as n-type material. As absorber material we used CdTe, which was deposited on the ZnO columnar film by Metal Organic Chemical Vapor Deposition. In order to complete the eta -solar cell we deposited a CuSCN layer by chemical solution deposition. A conformal and uniform CdTe coverage of the ZnO columns was achieved, producing a very efficient light trapping effect. The effective absorption (∼87%) and effective reflectance (∼10%) of the complete heterostructure in…
Co-adsorption processes, kinetics and quantum mechanical modelling of nanofilm semiconductor gas sensors
2010
A quantum mechanical model of co-adsorption on semiconductor surfaces is developed and successfully adopted towards exposure to several gases. It is related to nanofilms and thus allows the application of electric fields altering the electronic surface properties of adsorption centres (electro-adsorptive effect, EAE). The model is matched against experimental data with O 2 , NO 2 and CO measurements under the hypothesis of no direct interaction among the species. However the sequence of adsorption plays an important role where the adsorption of one gas species is opening up other sites that are filled by another sort of impinging molecules. Quantum mechanical modelling of co-adsorption: (a)…
Interligand Electron Transfer Determines Triplet Excited State Electron Injection in RuN3−Sensitized TiO2 Films
2004
Electron injection from the transition metal complex Ru(dcbpy)(2)(NCS)(2) (dcbpy = 2,2'-bipyridine-4,4'-dicarboxylate) into a titanium dioxide nanoparticle film occurs along two pathways. The dominating part of the electron injection proceeds from the initially excited singlet state of the sensitizer into the conduction band of the semiconductor on the sub-hundred-femtosecond time scale. The slower part of the injection occurs from the thermalized triplet excited state on the picosecond time scale in a nonexponential fashion, as was shown in a previous study (Benko, G.; et al. J. Am. Chem. Soc. 2002, 124, 489). Here we show that the slower channel of injection is the result of the excited s…
Novel voltage-controlled conditioning circuit applied to the ISFETs temporary drift and thermal dependency
2003
This paper describes a novel conditioning circuit applied to ion-sensitive field-effect transistors/membrane-ion-sensitive field-effect transistors (ISFETs/MEMFETs) sensors. The novel conditioning circuit allows the sensor polarization with the needed either voltage or current required in each application, thanks to two completely independent voltage-controlled blocks (current and voltage blocks). The control of the voltage block is the most critical point in our design because the voltage block maintains the sensor feedback stable, avoiding the thermal and temporary drifts of the sensor feedback.
The laser-plotter: A versatile lithographic tool for integrated optics and microelectronics
1992
Abstract The apparatus described here represents a low cost approach to artwork generation for integrated optics and microelectronics, in the resolution range around 2 μm. Its main characteristics are given below, together with some examples of the kind of patterns it can generate.
Novel constant current driver for ISFET/MEMFETs characterization
2001
Abstract In the present work a new constant current driver for ISFETs and MEMFETs sensors has been developed. The proposed circuit maintains the ISFET/MEMFET operation point at constant drain–source current and voltage. The combination of some programmable current sources and an appropriate selection of a simple precision resistor allow a good ISFET/MEMFET polarization. The use of operational amplifiers with low offset and drift are required to provide the buffering function needed by the sensor.
Theory of mercury intrusion in a distribution of unconnected wedge-shaped slits
2004
Effective mercury intrusion in a wedge-shaped slit is gradual, the intruded depth increasing with applied pressure. The Washburn equation must be modified accordingly. It relates the distance, e, separating the three-phase contact lines on the wedge faces to the hydrostatic pressure, P, wedge half-opening angle alpha, mercury surface tension gamma, and contact angle theta: e=(-2gamma/P)cos(theta-alpha) if theta-alpha>pi2. The equations relating the volume of mercury in a single slit to hydrostatic pressure are established. The total volume of mercury V(Hg)(tot)(E(0),e) intruded in a set of unconnected isomorphous slits (same alpha value) with opening width, E, distributed over interval [E(0…
Pattern image enhancement by extended depth of field
2014
Abstract Most optical defect localization techniques such as dynamic laser stimulation or photon emission microscopy require a pattern image of the device to be taken. The main purpose is for device navigation, but it also enables the analyst to identify the location of the monitored activity by superimposing it onto the pattern image. The defect localization workflow usually starts at low or medium magnification. At these scales, several factors can lead to a lack of orthogonality of the sample with the optical axis of the system. Therefore, images can be locally out of focus and poorly resolved. In this paper, a method based on Depth of Field Extension is suggested to correct the pattern …
Density Functional Theory Investigation on the Nucleation and Growth of Small Palladium Clusters on a Hyper-Cross-Linked Polystyrene Matrix
2014
Density functional theory calculations were employed to investigate the nucleation and growth of small palladium clusters, up to Pd9, into a microcavity of the porous hyper-cross-linked polystyrene (HPS). The geometries and the electronic structures of the palladium clusters inside the HPS cavity, following the one-by-one atom addition, are affected by a counterbalance between the Pd–phenyl (Pd−Φ) and Pd–Pd interactions. The analysis performed on energetics, cavity distortions, and cluster geometries indeed suggest that the cluster growth is dominated by the Pd−Φ interactions up to the formation of Pd4 aggregates, whereas the metal–metal interactions actually rule the growth of the larger c…