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ABSTRACT: Internet web service delivery expectations grow every year but the underlying technology does not scale naturally to deal with greater demand for services. A simple service, once becoming popular, requires the service provider to invest in powerful hardware in order to deal with sudden spike in client interest. A standard solution involves employing a content distribution network resulting in spiralling costs with increasing load. In this paper we argue it is possible to scale web service delivery more naturally assuming clients take part in content replication. We propose a design and a prototype implementation of a P2P overlay network that shows optimistic preliminary results. An extensive simulation is provided in order to establish performance possibilities of such a network with no extra related costs or demands on hardware.
Systems, Signals and Image Processing (IWSSIP), 2011 18th International Conference on; 07/2011
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ABSTRACT: We report our simulations on the influence of contacts on charge collection in semi-insulating (CdZn)Te with Au contacts under radiation flux, employing simultaneous solutions of the drift-diffusion and Poisson equations. The type of the space charge and the distribution of the electric field in the Au/(CdZn)Te/Au structure at high fluxes reflect the combined influence of charge generated by band bending at the electrodes, and from photogenerated carriers trapped at deep levels. We show that the space charge originating from the latter approaches dominance at high fluxes while the influence of the contacts becomes negligible. The ratio of trapping and collection times at low fluxes strongly depends on band bending, due mainly to a change in the occupation of deep levels by injection or depletion from the contacts. Such dependence is weak at high fluxes; in this case, the space charge due to trapped carriers prevails over that formed due to band bending. These phenomena can cause the formation an electric-field minimum within the device (the pinch point), the position of which is influenced by the nature of the contacts. The field minimum can completely disappear or develop into a dead layer as band bending changes.
IEEE Transactions on Nuclear Science 09/2010; · 1.45 Impact Factor
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ABSTRACT: Electromigration of mobile charged defects in external electric field is investigated at various temperatures and biases in conductive undoped and semiinsulating In-doped CdTe, respectively. A set of electric contacts as potential probes arranged linearly along the sample was used for the detection of the drift of the local resistance modulation. The observed modulation drifting along the sample always from the positive toward negative contact after step-like bias polarity reversion points to the migration of positively charged point defects. Mobility and diffusion coefficient of mobile defects at 100degC and 600degC, respectively are determined. Electromigration of point defects is also tested by low temperature photoluminescence and a model explaining migration of charged defects is suggested.
IEEE Transactions on Nuclear Science 09/2009; · 1.45 Impact Factor
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ABSTRACT: The concentrations of near-midgap levels in high-resistivity CdTe were estimated based on a combined evaluation of room temperature lux-ampere characteristics and thermoelectric effect spectroscopy measurements (77-400 K). A simulation of experimental data was performed by a numerical solution of drift-diffusion and Poisson equations using a model with two deep levels. A comparison of crystals doped with shallow and deep dopants is given.
IEEE Transactions on Nuclear Science 09/2009; · 1.45 Impact Factor
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ABSTRACT: Chemical polishing is a process of crucial importance in the manufacture of epiready substrates for molecular beam epitaxy
(MBE) of high-quality HgCdTe layers. With the aim of fabrication of (211) CdZnTe substrates, we focused on the fundamental
research of polishing processes with respect to reducing subsurface damage. Wafers of the orientation (211) were prepared
from the as-grown crystals by a process flow including oriented slicing, several steps of mechanical polishing, and finally
chemical polishing. In the prechemical polishing process, several free and bound abrasives were applied to reach the surface
roughness close to 1 nm. The surface polishing treatment included testing of the surface quality after each polishing step.
We used an interferometer profiler, which yields detailed surface maps. Within chemical polishing processing, we have looked
for an optimum composition of etchant based on the bromine-methanol/ethylene glycol solution and adequate polishing pad. We
studied the substrate surface quality dependence on the rotation speed of the plate, sample loading weights, and duration
of polishing. Correlation between the final surface roughness and layer thickness removed was established. The chemical polishing
with a very low concentration of Br-methanol/ethylene glycol solution was found to yield very good CdZnTe surfaces with a
perfect flatness.
Journal of Electronic Materials 05/2006; 35(6):1206-1213. · 1.47 Impact Factor
