TECHNIQUES FOR PRODUCING DEFECT-FREE SOI BY DUAL ELECTRON BEAM HEATING OF DEPOSITED POLYSILICON.

Advances in the dual electron-beam recrystallization technique arising from the fast scanning of a line beam parallel to the edges of narrow seeding windows are described. The resultant recrystallized layers are essentially defect-free, have good surface flatness, and cover large areas.

Performance of CMOS Devices in Silicon-on-Sapphire Films After Solid-Phase Epitaxial Growth With Rapid Electron-Beam Heating

The crystal quality of 0.3-μm-thick as-grown epitaxial silicon-on-sapphire (SOS) was improved using solid-phase epitaxy (SPE) by implantation with silicon to 1015 ions/cm2 at 175 keV and rapid annealing using electron-beam heating, n-channel and p-channel transistormobilities increased by 31 and 19 percent, respectively, and a reduction in ring-oscillator stage delay confirmed that crystal defects near the upper silicon surface had been removed. Leakage in n-channel transistors was not significantly affected by the regrowth process but for p-channel transistors back-channel leakage was considerably greater than for the control devices. This is attributed to aluminum released by damage to the sapphire during silicon implantation. © 1985 IEEE

Formation of silicon-on-insulator layers by electron beam recrystallization

This paper outlines the development of the electron beam recrystallization approach to the formation of silicon-on-insulator layers. The technique of recrystallizing seeded layers by a line electron beam has been widely adopted. Present practice in electron beam recrystallization is reviewed, both from materials and process points of view. Applications of silicon-on-insulator substrates formed in this way are described, particularly in three-dimensional integration. © 1988.

Tutorial on loop shaping using H-infinity robust stabilization

A new method for multivariable control was proposed in McFarlane and Glover (1988 CDC). This method involved shaping the open-loop singular values with pre and/or post compensators and then designing a controller to robustly stabilize a normalized coprime factorization of this weighted plant. The method has many attractive features including guaranteed loop shape and robust stability and performance. This talk will outline the rationale of this method and illustrate its use on a number of applications.

Beam propagation modelling of tapered waveguide lasers

A dynamic beam propagation model allows design optimization of high power low divergence tapered waveguide lasers. The model is extended to include spatially-resolved temperature profiles and a temperature dependent gain. Using this model, design parameters such as the optimum facet reflectivity, taper angle, and waveguide dimension can be calculated for low far-field divergence and high continuous wave power.

Mechanism of polarization pinning in vertical cavity surface emitting lasers using focused ion beam etching

Photoluminescence experiments have identified strain as the origin for polarization pinning in vertical cavity surface emitting lasers post-processed by focused ion beam etching. Theoretical models were applied to deduce the strain in devices. Post-annealing was used to optimize polarization pinning.

Nanostructured carbon films from supersonic cluster beam deposition: Structure and morphology

Nanostructured carbon thin films have been grown by deposition of cluster beams produced by a supersonic expansion. Due to separation effects typical of supersonic beams, films with different nanostructures can be grown by the simple intercepting of different regions of the cluster beam with a substrate. Films show a low-density porous structure, which has been characterized by Raman and Brillouin spectroscopy. Film morphology suggests that growth processes are similar to those occurring in a ballistic deposition regime.

High power laser with integrated lens using focused ion beam etching

In this study, a collimating lens is introduced at the output facet of a tapered waveguide laser to compensate for the divergence of the optical mode. The collimating lens is shown to enhance the laser efficiency while simultaneously reducing the far field divergence.

Blind frequency synchronisation for OFDM systems with pulse shaping

In multi-carrier systems, small carrier frequency offsets result in significant degradation of performance and this offset should be compensated before demodulation can be performed. In this paper, we consider a generic multi-carrier system with pulse shaping and estimate the frequency offset by exploiting the cyclostationarity of the received signal. By transforming the time domain signal to the cyclic correlation domain we are able to estimate the frequency offset without the aid of pilot symbols or the cyclic prefix. The Bayesian framework is used to obtain the estimate and we show how we can simplify the estimation process. © 1999 IEEE.

Bistable composite slit tubes. I. A beam model

Composite slit tubes with a circular cross-section show an interesting variety in their large-deformation behaviour, that depends on the layup of the surface that is used: tubes made from many antisymmetric laminae are bistable, and have a compact coiled configuration, tubes made from similar, but symmetric, laminae do not have a compact coiled state, and indeed may not be bistable, while tubes made from an isotropic sheet are not bistable. A simple model is presented here that is able to distinguish between these behaviours; it assumes that the cross-section remains circular, but allows twist, which is shown to be the key to making the distinction between the behaviours described. © 2004 Elsevier Ltd. All rights reserved.

Focused ion beam etching of GaN

We have investigated the use of focused ion beam (FIB) etching for the fabrication of GaN-based devices. Although work has shown that conventional reactive ion etching (RIE) is in most cases appropriate for the GaN device fabrication, the direct write facility of FIB etching - a well-established technique for optical mask repair and for IC failure analysis and repair - without the requirement for depositing an etch mask is invaluable. A gallium ion beam of about 20nm diameter was used to sputter GaN material. The etching rate depends linearly on the ion dose per area with a slope of 3.5×10 -4μm3/pC. At a current of 3nA, for example, this corresponds to an etch rate of 1.05μm3/s. Good etching qualities have been achieved with a side wall roughness significantly below 0.1μm. Changes in the roughness of the etched surface plane stay below 8nm.

Free space adaptive optical interconnect, using a ferroelectric liquid crystal SLM for beam steering

A free-space, board-to-board, adaptive optical interconnect demonstrator has been developed. Binary phase gratings displayed on a Ferroelectric Liquid Crystal Spatial Light Modulator are used to maintain data transfer at 1.25Gbps, given varying optical misalignment © 2005 Optical Society of America.

Model-based thermoacoustic oscillation control via ℋ ∞ loop-shaping and integral quadratic constraints

Lean premixed prevaporized (LPP) technology has been widely used in the new generation of gas turbines in which reduced emissions are a priority. However, such combustion systems are susceptible to the damage of self-excited oscillations. Feedback control provide a way of preventing such dynamic stabilities. A flame dynamics assumption is proposed for a recently developed unsteady heat release model, the robust design technique, ℋ ∞ loop-shaping, is applied for the controller design and the performance of the controller is confirmed by simulations of the closed-loop system. The Integral Quadratic Constraints(IQC) method is employed to prove the stability of the closed-loop system. ©2010 IEEE.