Search results for "surface"
showing 10 items of 9345 documents
Nano-lithography by electron exposure using an Atomic Force Microscope
1999
Abstract We have used a conductive Atomic Force Microscope (AFM) tip to expose a very thin resist film. An exposing current of low energy electrons was induced from the tip to the substrate by applying a small bias voltage. Uniform resist films as thin as 10 nm were fabricated using the Langmuir–Blodgett technique. To orient the defined pattern and to make electrical connections a special larger scale alignment structure was first defined by conventional electron beam lithography, either directly in the Langmuir–Blodgett resist film or in a separate first lift-off process with a thicker resist. The results from the one resist process gave conducting 50 nm lines with a 60 A thick vacuum depo…
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…
Cluster formation and rheology of photoreactive nanoparticle dispersions.
2008
We show how photocrosslinking of small nanoparticles within a very dilute colloidal dispersion leads to the formation of large fractal particle clusters, which have a strong influence on the viscosity of the dispersion although the overall solid content is well below 5 wt %. Furthermore, the solvent plays an important role because of its function as an optical filter, for example, in toluene only photocrosslinking but no photocleavage takes place. Therefore, a diffusion-controlled cluster growth mechanism, leading to clusters with low fractal dimension, is expected; on the other hand, in tetrahydrofuran the photoreaction is partially reversible. Therefore, the cluster growth in this case is…
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.
Trusted Computing and DRM
2015
Trusted Computing is a special branch of computer security. One branch of computer security involves protection of systems against external attacks. In that branch we include all methods that are used by system owners against external attackers, for example Firewalls, IDS, IPS etc. In all those cases the system owner installs software that uses its own means to determine if a remote user is malicious and terminates the attack. (Such means can be very simple such as detecting signatures of attacks or very complex such as machine learning and detecting anomalies in the usage pattern of the remote user). Another branch of attacks requires protection by the system owner against internal users. …
Remote photoplethysmography device with adaptive illumination for skin microcirculation assessment
2020
Measuring blood perfusion is important in medical care. However, currently available devices to measure blood perfusion are bulky, expensive and not easy-to-use. In this work a compact and portable low-cost prototype device for remote monitoring of palm skin microcirculation has been developed. Presented device consists of precisely controlled near-infrared illuminators (760nm peak wavelength) and video camera. The device with the custom designed software provides stable uniform illumination of curved skin surfaces, using feedback algorithm. Verification tests of this device showed improvements in the quality of skin blood perfusion maps in the case when the feedback system was used.
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.