993 resultados para Ciència dels materials


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In this paper we will describe new bimesogenic nematic liquid crystals that have high flexoelectro-optic coefficients (e/K),of the order of 1.5 CN 1 m-1, high switching angles, up to 100° and fast response times, of the order of 100μs or less. We will describe devices constructed, using the ULH texture that may be switched to the optimum angle of 45° for a birefringence based device with the fields of 4Vμm-1 over a wide temperature range. Such devices use an "in plane" optical switching mode, have gray scale capability and a wide viewing angle. We will describe devices using the USH or Grandjean texture that have an optically isotropic "field off" black state, uses "in plane" switching E fields, to give an induced birefringence phase device, with switching times of the order of 20μs. We will briefly describe new highly reflective Blue Phase devices stable over a 50V temperature range in which an electric field is used to switch the reflection from red to green, for example. Full RGB reflections may be obtained with switching times of a few milliseconds. Finally we will briefly mention potential applications including high efficiency RGB liquid crystal laser sources. © 2006 SID.

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This paper reviews the advances that flash lamp annealing brings to the processing of the most frequently used semiconductor materials, namely silicon and silicon carbide, thus enabling the fabrication of novel microelectronic structures and materials. The paper describes how such developments can translate into important practical applications leading to a wide range of technological benefits. Opportunities in ultra-shallow junction formation, heteroepitaxial growth of thin films of cubic silicon carbide on silicon, and crystallization of amorphous silicon films, along with the technical reasons for using flash lamp annealing are discussed in the context of state-of-the-art materials processing. © 2005 IEEE.