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Dielectric Structure (dielectric + structure)

Distribution by Scientific Domains
Physics and Astronomy40%

Selected Abstracts

Conducting Polymers: An Optically Active Polythiophene Exhibiting Electrochemically Driven Light-Interference Modulation (Adv. Funct.

ADVANCED FUNCTIONAL MATERIALS, Issue 9 2009
Mater.
This frontispiece shows a polarizing optical microscopy image of optically active polythiophene (PT) prepared in cholesteric liquid-crystal electrolyte solution containing a cholesterol derivative. The PT film exhibits a variable diffraction function, electrochemically driven refractive index modulation, and electrochromism originating from the periodic dielectric structure, representing a form of structural electrochromism, as described on page 1335. [source]

An Optically Active Polythiophene Exhibiting Electrochemically Driven Light-Interference Modulation

ADVANCED FUNCTIONAL MATERIALS, Issue 9 2009
Hiromasa Goto
Abstract Optically active polythiophene (PT*) is successfully prepared by electrochemical polymerization using a cholesteric liquid crystal (CLC) electrolyte solution. Polarizing optical microscopy observations of the polymer reveal a well-resolved fingerprint texture similar to the optical texture of the CLC. Circular dichroism measurements indicate a Cotton effect. The PT* film produced by the asymmetric polymerization in CLC exhibits a variable diffraction function, electrochemically driven refractive index modulation, and electrochromism originating from the periodic dielectric structure, representing a form of structural electrochromism. [source]

Dielectric wedge antenna with stepped phase correction in a nonradiative mode

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2007
J. A. G. Malherbe
Abstract The performance of a dielectric wedge antenna with stepped phase correction in a nonradiative dielectric structure is described. The stepped wave numbers are achieved by perforating the dielectric with a series of holes designed to modify the dielectric constant in a predetermined fashion. The aperture of the wedge is then divided into a number of zones, each with its own dielectric constant. The step correction of the aperture phase error results in a substantial improvement in radiation pattern. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2030,2032, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22607 [source]

Optical properties of delta poly-type quasiregular dielectric structures made of porous silicon

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2007
V. Agarwal
Abstract To investigate the reflection of light in quasi-regular dielectrics, we study here the optical properties of porous-silicon-based Fibonacci, Thue-Morse and Period Doubling heterostructures. The multilayered systems are fabricated in such a way that each element in the two-block substitutional sequence has a poly-type structure. Both delta-like and traditional configurations are considered. The results for the optical transmittance are analyzed and compared with the classical periodic structure. Numerical simulation for the transmittance along the lines of the transfer matrix approach is also presented. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Tunneling current in gate dielectric stack in sub-45 nanometer CMOS devices

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2009
Hitender Kumar Tyagi
Abstract Direct tunneling current through dual layer SiO2/high-K dielectric structures are investigated for substrate injection. Correlation of dielectric constants and band offsets with respect to silicon has been taken into consideration in order to identify possible materials to construct these devices. The direct tunneling current in oxide/high-K dielectric structures with equivalent oxide thickness (EOT) of 2.0 nm can be significantly lower than that through single layer oxides of the same thickness. Various structures and materials of high-K stacks of interest have been examined and compared to access the reduction of gate current in these structures. It is estimated that HfO2/SiO2 dual stack structure can reduce gate leakage current by four orders of magnitude as compared with pure SiO2 layer of same EOT. The importance of interfacial layer in dual stack structure is high-lighted for the reduction of gate leakage current. The present approach is capable of modeling high-K stack structures consisting of multiple layers of different dielectrics (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]