Is the assumption of perfect channel-state information in fading channels a good assumption?

Fading channels, which are used as a model for wireless communication, are often analyzed by assuming that the receiver is aware of the realization of the channel. This is commonly justified by saying that the channel varies typically slowly with time, and the receiver is thus able to estimate it. However, this assumption is optimistic, since it is prima facie not clear whether the channel can be estimated perfectly. This paper investigates the quality of this assumption by means of the channel capacity. In particular, results on the channel capacity of fading channels are presented, both when the receiver is aware of the realization of the channel and when it is aware only of its statistics. A comparison of these results demonstrates that information- theoretic analyses of fading channels that are based on the assumption that the receiver is aware of the channel's realization can yield helpful insights, but have to be taken with a pinch of salt. ©2009 IEEE.

Silicon pyramids for plasmonic enhanced schottky photodetectors

We demonstrate the design, fabrication and characterization of plasmonic enhanced free space Schottky detector for telecom wavelength. Unique fabrication technique, simulation and measurement results will be presented and discussed. © OSA 2013.

Synthesis of GaN nanowires and nano-pyramids in a two-hot-boat chemical vapor deposition system via an in-doping technique

A two-hot-boat chemical vapor deposition system was modified from a thermal evaporation equipment. This system has the advantage of high vacuum, rapid heating rate and temperature separately controlled boats for the source and samples. These are in favor of synthesizing compound semiconducting nano-materials. By the system, we have synthesized high-quality wurtzite single crystal GaN nanowires and nanotip triangle pyramids via an in-situ doping indium surfactant technique on Si and 3C-SiC epilayer/Si substrates. The products were analyzed by x-ray diffraction, field emission scanning electron microscopy, highresolution transmission electron microscopy, energy- dispersive x-ray spectroscopy, and photoluminescence measurements. The GaN nanotip triangle pyramids, synthesized with this novel method, have potential application in electronic/ photonic devices for field-emission and laser.

Cathodoluminescence on GaN hexagonal pyramids on submicron dot-patterns via selective MOVPE

Three-dimensional GaN pyramids have been successfully obtained on submicron dot-patterned (0001) sapphire substrates by using the selective metalorganic vapor phase epitaxy (MOVPE) technique. The dot-pattern is a hexagon arranged with a 0.5-mu m width and 1.0-mu m spacing. The GaN structure comprises a hexagonal pyramid covered with six {1 (1) over bar 01} pyramidal facets on the side of a hexagonal pyramid having a (0001) facet on the top. Cathodoluminescence (CL) measurement was carried our. on the hexagonal pyramid at low temperature. Two distinct spectra were observed to occur at about 359 and 329 nm. The higher energy is thought to be related to GaN dot, and the lower one is due to GaN dot band edge emission. The intensities of the two spectra were investigated as a function of temperature in the range of 135-150 K. (C) 2000 Published by Elsevier Science B.V.

Micro-fabricated Al0.3Ga0.7As pyramids for potential SPM applications

A novel technique of manufacturing Al0.3Ga0.7As pyramids by liquid phase epitaxy (LPE) for scanning probe microscopy (SPM) sensors is reported Four meticulously designed conditions-partial oxidation, deficient solute, air quenching and germanium doping result in defect-free homogeneous nucleation and subsequent pyramid formation. Micrometer-sized frustums and pyramids are detected by scanning electron microscopy (SEM). The sharp end of the microtip has a radius of curvature smaller than 50 nm. It is believed that such accomplishments would contribute not only to crystal growth theory, but also to miniature fabrication technology.

Structuring by multi-beam interference using symmetric pyramids

A method for producing optical structures using rotationally symmetric pyramids is proposed. Two-dimensional structures can be achieved using acute prisms. They form by multi-beam interference of plane waves that impinge from directions distributed symmetrically around the axis of rotational symmetry. Flat-topped pyramids provide an additional beam along the axis thus generating three-dimensional structures. Experimental results are consistent with the results of numerical simulations. The advantages of the method are simplicity of operation, low cost, ease of integration, good stability, and high transmittance. Possible applications are the fabrication of photonic micro-structures such as photonic crystals or array waveguides as well as multi-beam optical tweezers. (c) 2006 Optical Society of America.

A NEW TYPE OF SILICON-ON-INSULATOR WITH A PERFECT SURFACE SILICON LAYER

A novel silicon structure consisting of a silicon-on-defect layer (SODL), with enhanced surface Hall mobility in the surface layer on a buried defect layer (DL), has been discovered [J. Li, Nucl. Instr. and Meth. B59/60 (1991) 1053]. SODL material was formed by using proton implantation and subsequent two-step annealing. The implantation was carried out with a Varian 350D ion implanter. Based on the discovery, a standard measurement method (current-voltage curve method) was adopted to measure the true resistivity value of the DL in order to replace the spreading resistivity measurement by which the true resistivity in seriously defective silicon cannot be obtained. By adopting the current-voltage current method, the true resistivity value of the DL is measured to be 4.2 x 10(9) OMEGA cm. The SODL material was proved to be a silicon-on-insulator substrate.

A ?Perfect Circle'? Alchemy in the Poetry of Hester Pulter

Archer, Jayne, 'A ?Perfect Circle'? Alchemy in the Poetry of Hester Pulter', Literature Compass (2005) 2(1) pp.1-14 RAE2008