Polarization Properties of Photoluminescence of Anisotropic Polymer Films Containing Aligned Au Nanorods and Semiconductor Nanoparticles of Various Shape

Semiconductors - Anisotropic polymer films containing aligned Au nanorods and semiconductor nanoparticles of various shape were fabricated. The photoluminescence of semiconductor nanoparticles in...     

Performance of (1 1 0) p-channel SOI-MOSFETs fabricated by deep-amorphization and solid-phase epitaxial regrowth processes

The impact of local deep-amorphization (DA) and subsequent solid-phase epitaxial regrowth (SPER) are studied for the co-integration of devices with hybrid surface orientation. Thin-body p-channel transistors with 20 nm thick film and HfO₂ gate insulator/metal gate along several directions on a (1 1 0) substrate were fabricated and characterized. No deterioration of transconductance or threshold voltage was induced by DA/SPER process. Device co-integration using DA/SPER process is therefore a realistic option. 〈1 1 0〉 channel on (1 1 0) SOI film yields a 200% gain on the current for the (1 0 0) surface orientation. However, the benefit of it decreases with the channel length.     

Morphology,elemental composition,and mechanical properties of polycrystalline CdTe layers

The results of investigations of the morphology (grain size, twinning, growth features), elemental composition, and some mechanical properties of polycrystalline CdTe layers deposited on nonoriented substrates in a quasi-closed volume are presented. Dependences of microhardness on the crystallite size and layer thickness are presented. The evaluation calculations of the stresses on the substrate-layer interface caused by a difference in the linear thermal expansion coefficients are presented.     

Methods of measuring and characterising the surface geometry of road stones

Methods of measuring and characterising random rough surfaces have always been of interest in the field of engineering. Measurement and analysis of finer scales of texture of a surface are now mainly effected by the use of a stylus instrument.Because of the finite radius of the tip of the stylus, this instrument cannot sense all the scales of texture on a surface. Evaluation of scales of texture finer than that sensed by the stylus instrument is of interest in many fields of engineering and in the prediction of hysteretic friction and of abrasion of rubber in particular. Two new methods which meet this demand to a great extent are described and their application is illustrated by actual measurements on stone surfaces. A scanning electron microscope is used in one method and an optical microscope in the other. Numerical methods of solution using electronic computers are adopted for the evaluation of texture parameters in both methods.     

Thermal Oxidation of GaAs and InP in the Presence of Al2(SO4)3

The thermal oxidation of GaAs and InP is investigated when Al₂(SO₄)₃ is introduced into the oxidizing atmosphere. It is found that the stimulator accelerates the reaction in both cases. The process and films are examined by laser ellipsometry, IR spectroscopy, and XRF. On this basis the role is identified of the stimulator anionic component, which causes the oxidation to branch and increases its rate.     

Operation of a quantum-dot cellular automata (QCA) shift register and analysis of errors

Quantum-dot cellular automata (QCA) is a digital logic architecture that uses single electrons in arrays of quantum dots to perform binary operations. A QCA latch is an elementary building block which can be used to build shift registers and logic devices for clocked QCA architectures. We discuss the operation of a QCA latch and a shift register and present an analysis of the types and properties of errors encountered in their operation.     

Optical layer survivability: a post-bubble perspective

We revisit the topic of optical layer protection from a motivation and deployment perspective. We first discuss the changes that have occurred in optical networking in general and the implications for protection. We then discuss scenarios where optical protection makes sense, recognizing that other fast protection schemes at the client layer provide viable alternatives in certain cases. Our conclusion is that optical protection makes sense for metro networks, as long as they are based on simple dedicated schemes. When it gets to more complex shared ring and mesh protection, we believe that OEO-based schemes are more viable, whether crossconnect-based or packet-switch-based.     

Characterizing the statistical properties of mutual information in MIMO channels

We consider Gaussian multiple-input multiple-output (MIMO) frequency-selective spatially correlated fading channels, assuming that the channel is unknown at the transmitter and perfectly known at the receiver. For Gaussian codebooks, using results from multivariate statistics, we derive an analytical expression for a tight lower bound on the ergodic capacity of such channels at any signal-to-noise ratio (SNR). We show that our bound is tighter than previously reported analytical lower bounds, and we proceed to analytically quantify the impact of spatial fading correlation on ergodic capacity. Based on a closed-form approximation of the variance of mutual information in correlated flat-fading MIMO channels, we provide insights into the multiplexing-diversity tradeoff for Gaussian code books. Furthermore, for a given total number of antennas, we consider the problem of finding the optimal (ergodic capacity maximizing) number of transmit and receive antennas, and we reveal the SNR-dependent nature of the maximization strategy. Finally, we present numerical results and comparisons between our capacity bounds and previously reported bounds.     

Semiconductor mirror for optical noise suppression and dynamic dispersion compensation

We report on a monolithic Gires-Tournois semiconductor interferometer used for both suppression of low-intensity spontaneous noise in a high-power fiber amplifier and to generate a tunable delay. The potential of the noise suppression technique was demonstrated using a two-stage amplifier system. Gain improvement by a factor of five illustrates the capability of semiconductor gates to greatly enhance energy extraction from optical amplifiers. We demonstrate also that controllable saturable absorption in an optically pumped multiple-quantum-well semiconductor reflector provides promising means for rapidly changing the group delay of the reflector and represents a new form of dynamic dispersion compensator.     

Z-transform-based FDTD algorithm for anisotropic perfectly matched layer

An efficient method based on the Z-transform theory and the D-H anisotropic perfectly matched layer formulations is presented for truncating general FDTD grids. The formulations are simple and independent of the material properties of the FDTD domain. Numerical examples for radiation and guided-wave problems are included to validate the proposed formulations.