The dramatic impact of low dimensional semiconductor structures on c- rent and future device applications cannot be overstated. Research over the last decade has highlighted the use of quantum engineering to achieve p- viously unknown limits for device performance in research laboratories. The modi?ed electronic structure of semiconductor quantum structures results in transport and optical properties, which di?er from those of constituent bulk materials. The possibility to tailor properties, such as bandgap, strain, band o?set etc. , of two-dimensional (2D) semiconductors, e. g. quantum wells, for speci?c purposes has had an extensive impact on the electronics, which has resulted in a dramatic renewal process. For instance, 2D structures are today used in a large number of high speed electronics and optoelectronic appli- tions (e. g. detectors, light emitting diodes, modulators, switches and lasers) and in daily life, in e. g. LED-based tra?c lights, CD-players, cash registers. The introduction of impurities, also in very small concentrations, in a semiconductor can change its optical and electrical properties entirely. This attribute of the semiconductor is utilized in the manifoldness of their app- cations. This fact constitutes the principal driving force for investigation of the properties of the impurities in semiconductors. While the impurities in bulk materials have been investigated for a long time, and their properties are fairly well established by now, the corresponding studies of impurities in quantum wells is a more recent research area.

High density digital magnetic and magneto-optical storage devices are widely used in audio, video, and data processing information technology, as well as in CAD/CAM computer systems. These widespread uses generate a continually increasing demand for both increased information storage densities and capacities, and for reduced access times. Hence, the materials engineering of high density storage media, with a high signal to noise ratio, and the associated design of sophisticated read and write heads, form the basis of major technological research. This research is especially complex because, ideally, the recorded information should be both erasable and, at the same time, secure and accessible over periods of many decades. As a result, research on these complex problems requires a multidisciplinary approach which utilizes the expertise in such widely differing fields as organic, inorganic, and solid state chemistry, metallurgy, solid state physics, electrical and mechanical engineering, and systems analysis. Often, further research specialization is necessary in each of these different disciplines. For instance, solid state physics and chemistry address the problems of crystallographic structure and phase diagram determination, magnetism, and optics, but more advanced research methods, such as high resolution electron microscopy and electronic band structure calculations, are necessary to understand the microstructure of particulate recording media or the electronic spectra of magneto-optical recording media.

This volume (>Ie) NEMATICS Mathematical and Physical aspects constitutes the proceedings of a workshop which was held at l'Universite de Paris Sud (Orsay) in May 1990. This meeting was an Advanced Research Workshop sponsored by NATO. We gratefully acknowledge the help and support of the NATO Science Committee. Additional support has been provided by the Ministere des affaires etrangeres (Paris) and by the Direction des Recherches et Etudes Techniques (Paris). Also logistic support has been provided by the Association des Numericiens d'Orsay. (*) These proceedings are published in the framework of the "Contrat DRET W 90/316/ AOOO." v Contents (*) FOREWORD v INTRODUCTION 1. M. CORON, 1. M. GHIDAGLIA, F. HELEIN xi AN ENERGY-DECREASING ALGORITHM FOR HARMONIC MAPS F. ALOUGES 1 A COHOMOLOGICAL CRITERION FOR DENSITY OF SMOOTH MAPS IN SOBOLEV SPACES BETWEEN TWO MANIFOLDS F. BETHUEL, 1. M. CORON, F. DEMENGEL, F. HELEIN 15 ON THE MATHEMATICAL MODELING OF TEXTURES IN POLYMERIC LIQUID CRYSTALS M. C. CAmERER 25 A RESULT ON THE GLOBAL EXISTENCE FOR HEAT FLOWS OF HARMONIC MAPS FROM D2 INTO S2 K. C. CHANG, W. Y. DING 37 BLOW-UP ANALYSIS FOR HEAT FLOW OF HARMONIC MAPS Y. CHEN 49 T AYLOR-COUETTE INSTABILITY IN NEMATIC LIQUID CRYSTALS P. E. ClADIS 65 ON A CLASS OF SOLUTIONS IN THE THEORY OF NEMATIC PHASES B. D. COLEMAN, 1. T. JENKINS 93 RHEOLOGY OF THERMOTROPIC NEMATIC LIQUID CRYSTALLINE POLYMERS M. M. DENN, 1. A.

The purposes of this book are many. First, we must point out that it is not a device book, as a proper treatment of the range of important devices would require a much larger volume even without treating the important physics for submicron devices. Rather, the book is written principally to pull together and present in a single place, and in a (hopefully) uniform treatment, much of the understanding on relevant physics for submicron devices. Indeed, the understand ing that we are trying to convey through this work has existed in the literature for quite some time, but has not been brought to the full attention of those whose business is the making of submicron devices. It should be remarked that much of the important physics that is discussed here may not be found readily in devices at the 1.0-JLm level, but will be found to be dominant at the O.I-JLm level. The range between these two is rapidly being covered as technology moves from the 256K RAM to the 16M RAM chips."

Multi-chip modules (MCMs) with high wiring density, controlled impedance interconnects, and thermal management capability have recently been developed to address the problems posed by advances in electronic systems that make demands for higher speeds and complexity. MCM-C/Mixed Technologies and Thick Film Sensors highlights recent advances in MCM-C technology. Developments in materials and processes which have led to increased interconnection density are reviewed: finer resolution thick film inks, high performance-low temperature dielectric tapes, precision via generation by both laser and mechanical methods, and enhanced screen printing technologies have given us feature resolution to the 50 mum line/space level. Thermal management has greatly benefitted from such new materials as cofire AIN and diamond. MCM-C technology is compatible with thick film sensors, and work is reviewed on environmental gas sensors, pressure and temperature sensors, and the development of novel materials in this area.

Nonlinear Optics in Signal Processing covers the applications of nonlinear optics to optical processing in a range of areas including switching, computing, and telecommunications.

Magnetostatic Waves and their Applications is the first book devoted to magnetostatic waves. The book gives a thorough review of the field suitable for scientists, engineers and advanced students involved in magnetism and microwave electronics new to this area. It covers the field from essential physics to applications in microwave electronics, with details of the materials and materials processing methods included.

In the rapidly developing information society there is an ever-growing demand for information-supplying elements or sensors. The technology to fabricate such sensors has grown in the past few decades from a skilful activity to a mature area of scientific research and technological development. In this process, the use of silicon-based techniques has appeared to be of crucial importance, as it introduced standardized (mass) fabrication techniques, created the possibility of integrated electronics, allowed for new transduction principles, and enabled the realization of micromechanical structures for sensing or actuation. Such micromechanical structures are particularly well-suited to realize complex microsystems that improve the performance of individual sensors. Currently, a variety of sensor areas ranging from optical to magnetic and from micromechanical to (bio)chemical sensors has reached a high level of sophistication. In this MESA Monograph the proceedings of the Dutch Sensor Conference, an initiative of the Technology Foundation (STW), held at the University of Twente on March 2-3, 1998, are compiled. It comprises all the oral and poster contributions of the conference, and gives an excellent overview of the state of the art of Dutch sensor research and development. Apart from Dutch work, the contributions of two external invited experts from Switzerland are included.

MICROELECTRONIC INTERCONNECTIONS AND MICROASSEMBL Y WORKSHOP 18-21 May 1996, Prague, Czech Republic Conference Organizers: George Harman, NIST (USA) and Pavel Mach (Czech Republic) Summary of the Technical Program Thirty two presentations were given in eight technical sessions at the Workshop. A list of these sessions and their chairpersons is attached below. The Workshop was devoted to the technical aspects of advanced interconnections and microassembly, but also included papers on the education issues required to prepare students to work in these areas. In addition to new technical developments, several papers presented overviews predicting the future directions of these technologies. The basic issue is that electronic systems will continue to be miniaturized and at the same time performance must continue to improve. Various industry roadmaps were discussed as well as new smaller packaging and interconnection concepts. The newest chip packages are often based on the selection of an appropriate interconnection method. An example is the chip-scale package, which has horizontal (x-y) dimensions,;; 20% larger than the actual silicon chip itself. The chip is often flip-chip connected to a micro ball-grid-array, but direct chip attach was described also. Several papers described advances in the manufacture of such packages.

It is not good to have zeal without knowledge * . . . Book of Proverbs This volume constitutes the proceedings of the Third International Workshop on Materials Processing at High Gravity. It offers the latest results in a new field with immense potential for commercialization, making this book a vital resource for research and development professionals in industry, academia and government. We have titled the proceedings Centrifugal Materials Processing to emphasize that centrifugation causes more than an increase in acceleration. It also introduces the Coriolis force and a gradient of acceleration, both of which have been discovered to play important roles in materials processing. The workshop was held June 2-8, 1996 on the campus of Clarkson University in Potsdam, New York, under the sponsorship of Corning Corporation and the International Center for Gravity Materials Science and Applications. The meeting was very productive and exciting, with energetic discussions of the latest discoveries in centrifugal materials processing, continuing the atmosphere of the first workshop held in 1991 at Dubna (Russia) and the second workshop held in 1993 in Potsdam, New York. Results and research plans were presented for a wide variety of centrifugal materials processing, including directional solidification of semiconductors, crystallization of high Tc superconductors, growth of diamond thin films, welding, alloy casting, solution behavior and growth, protein crystal growth, polymerization, and flow behavior. Also described were several centrifuge facilities that have been constructed for research, with costs beginning at below $1000.

The Tenth International Symposium on Gaseous Dielectrics was held at the Astir Palace Vouliagmeni Hotel, Athens, Greece, March 29-April 2, 2004. The symposium. continued the interdisciplinary character and comprehensive approach of the preceding nine symposia. Gaseous Dielectrics X is a detailed record of the symposium proceedings. It covers recent advances and developments in a wide range of basic, applied, and industrial areas of gaseous dielectrics. It is hoped that Gaseous Dielectrics X will aid future research and development in, and encourage wider industrial use of, gaseous dielectrics. The Organizing Committee of the Tenth International Symposium on Gaseous Dielectrics consisted of L. G. Christophorou (Chainnan, Greece), J. K. Olthoff (co-Chainnan, USA), A. Bulinski (Canada), A. H. Cookson (USA), C. T. Dervos (Greece), J. de Urquijo (Mexico), J. Blackman (USA), O. Farish (UK), M. E. Frechette (Canada), I. Gillimberti (Italy), A. Garscadden (USA), A. Gleizes (France), H. Hama (Japan), T. Kawamura (Japan), E. Marode (France), I. W. McAllister (Denmark), H. Morrison (Canada), A. H. Mufti (Saudi Arabia), L. Niemeyer (Switzerland), W. Pfeiffer (Germany), Y. Qiu (China), I. Sauers (USA), M. Schmidt (Germany), H.-H. Schramm (Germany), L. van der Zel (USA), S. Yanabu (Japan), Y. Wang (USA), and J. W. Wetzer (The Netherlands). The Local Arrangements Committee consisted of J. N. Avaritsiotis, P. Vassiliou, C. T. Dervos of The National Technical University of Athens, C. A. Stassinopoulos of the Aristotelian University of Thessaloniki, and D.

The MESA Research Institute of the University of Twente was created in 1990 through the joining of the research unit Sensors and Actuators with the department of Microelectronics. The multidisciplinary institute, with participation from the faculties of Electrical Engineering, Applied Physics and Chemical Technology, was recently recognized as a Centre of Excellence by the Dutch Science Foundation. It is fully 2 equipped with modem Clean Room facilities (1000 m ) and a number of research laboratories. The objective of MESA is to perform research and development of systems in modem information technology, and on the units on which they are based: the microstructures that process and transduce signals. The institute gradually expanded during the past few years till some 125 persons in 1994. Given the wide variety of research subjects within MESA, it has been decided to start a MESA Monographs series, appearing on a more or less regular, yearly basis. In this way, after some time a good overview of research topics under investigation at MESA will be obtained. The first volume of this series coincides with the Proceedings of pTAS '94, the first Workshop on Micro Total Analysis Systems, held on November 21-22 at the University of Twente in Enschede, The Netherlands. IlTAS has recently been defined as the first strategic research orientation of MESA, aiming at synergetic collaboration between the different disciplines present in MESA.

The Workshop on Physics and Application of Non-crystalline Semiconductors in Optoelectronics was held from 15 to 17 October 1996 in Chisinau. republic of Moldova and was devoted to the problems of non-crystalline semiconducting materials. The reports covered two mjlin topics: theoretical basis of physics of non -crystalline materials and experimental results. In the framework of these major topics there were treated many subjects. concerning the physics of non-crystalline semiconductors and their specific application: -optical properties of non-crystalline semiconductors; -doping of glassy semiconductors and photoinduced effects in chalcogenide glasses and their application for practical purposes; -methods for investigation of the structure in non-crystalline semiconductors -new glassy materials for IR trasmittance and optoelectronics. Reports and communications were presented on various aspects of the theory. new physical principles. studies of the atomic structure. search and development of optoelectronics devices. Special attention was paid to the actual subject of photoinduced transformations and its applications. Experimental investigations covered a rather wide spectrum of materials and physical phenomena. As a novel item it is worth to mention the study of nonlinear optical effects in amorphous semiconducting films. The third order optical non linearities. fast photoinduced optical absorption and refraction. acusto-optic effects recently discovered in non-crystalline semiconductors could potentially be utilised for optical signal processing. The important problems of photoinduced structural transformations and related phenomena. which are very attractive and actual both from the scientific and practical points of view. received much attention in discussions at the conference."

The phenomenonofspontaneous ordering in semiconductoralloys, which can be categorized as a self-organized process, is observed to occur sponta neously during epitaxial growth of certain ternary alloy semiconductors and results in a modification of their structural, electronic, and optical properties. There has been a great dealofinterest in learning how to control this phenome non so that it may be used for tailoring desirable electronic and optical properties. There has been even greater interest in exploiting the phenomenon for its unique ability in providing an experimental environment of controlled alloy statistical fluctuations. As such, itimpacts areasofsemiconductorscience and technology related to the materials science ofepitaxial growth, statistical mechanics, and electronic structure of alloys and electronic and photonic devices. During the past two decades, significant progress has been made toward understanding the mechanisms that drive this phenomenon and the changes in physical properties that result from it. A variety of experimental techniques have been used to probe the phenomenon and several attempts made atproviding theoretical models both for the ordering mechanisms as well as electronic structure changes. The various chapters of this book provide a detailed account of these efforts during the past decade. The first chapter provides an elaborate account of the phenomenon, with an excellent perspective of the structural and elec tronic modifications itinduces.

Magnetic Components for Power Electronics concerns the important considerations necessary in the choice of the optimum magnetic component for power electronic applications. These include the topology of the converter circuit, the core material, shape, size and others such as cost and potential component suppliers. These are all important for the design engineer due to the emergence of new materials, changes in supplier management and the examples of several component choices. Suppliers using this volume will also understand the needs of designers.Highlights include: * Emphasis on recently introduced new ferrite materials, such as those operating at megahertz frequencies and under higher DC drive conditions; * Discussion of amorphous and nanocrystalline metal materials; * New technologies such as resonance converters, power factors correction (PFC) and soft switching; * Catalog information from over 40 magnetic component suppliers; * Examples of methods of component choice for ferrites, amorphous nanocrystalline materials; * Information on suppliers management changes such as those occurring at Siemens, Philips, Thomson and Allied-Signal; * Attention to the increasingly important concerns about EMI. This book should be especially helpful for power electronic circuit designers, technical executives, and material science engineers involved with power electronic components.

Advances in the semiconductor technology have enabled steady, exponential im- provement in the performance of integrated circuits. Miniaturization allows the integration of a larger number of transistors with enhanced switching speed. Novel transistor structures and passivation materials diminish circuit delay by minimizing parasitic electrical capacitance. These advances, however, pose several challenges for the thermal engineering of integrated circuits. The low thermal conductivities of passivation layers result in large temperature rises and temperature gradient magni- tudes, which degrade electrical characteristics of transistors and reduce lifetimes of interconnects. As dimensions of transistors and interconnects decrease, the result- ing changes in current density and thermal capacitance make these elements more susceptible to failure during brief electrical overstress. This work develops a set of high-resolution measurement techniques which de- termine temperature fields in transistors and interconnects, as well as the thermal properties of their constituent films. At the heart of these techniques is the thermore- flectance thermometry method, which is based on the temperature dependence of the reflectance of metals. Spatial resolution near 300 nm and temporal resolution near IOns are demonstrated by capturing transient temperature distributions in intercon- nects and silicon-on-insulator (SOl) high-voltage transistors. Analyses of transient temperature data obtained from interconnect structures yield thermal conductivities and volumetric heat capacities of thin films.

The study of deep levels in semiconductors has seen considerable growth in recent years. Many new techniques have become available for investigating both the electronic properties of deep levels and the chemical nature of the defects from which they arise. This increasing interest has been stimulated by the importance of the subject to device technology, in particular those microwave and opto-electronic devices made from GaAs, InP and their alloys. While previous conferences have covered specialist areas of deep level technology, the meeting described here was arranged to draw together workers from these separate fields of study. The following papers reflect the breadth of interests represented at the conference. For the sake of uniformity we have chosen the English alternative where an American expression has been used. We have also sought to improve grammar, sometimes without the approval of the author in the interests of rapid publication. The Editor wishes to thank the referees for their ready advice at all stages, Paul Jay who helped with many of the editorial duties and Muriel Howes and Lorraine Jones for rapid and accurate typing.

When I was contacted by Kluwer Academic Publishers in the Fall of 200 I, inviting me to edit a volume of papers on the issue of electron transport in quantum dots, I was excited by what I saw as an ideal opportunity to provide an overview of a field of research that has made significant contributions in recent years, both to our understanding of fundamental physics, and to the development of novel nanoelectronic technologies. The need for such a volume seemed to be made more pressing by the fact that few comprehensive reviews of this topic have appeared in the literature, in spite of the vast activity in this area over the course of the last decade or so. With this motivation, I set out to try to compile a volume that would fairly reflect the wide range of opinions that has emerged in the study of electron transport in quantum dots. Indeed, there has been no effort on my part to ensure any consistency between the different chapters, since I would prefer that this volume instead serve as a useful forum for the debate of critical issues in this still developing field. In this matter, I have been assisted greatly by the excellent series of articles provided by the different authors, who are widely recognized as some of the leaders in this vital area of research.

The international market is very competitive for high-tech manufacturers to day. Achieving competitive quality and reliability for products requires leader ship from the top, good management practices, effective and efficient operation and maintenance systems, and use of appropriate up-to-date engineering de sign tools and methods. Furthermore, manufacturing yield and reliability are interrelated. Manufacturing yield depends on the number of defects found dur ing both the manufacturing process and the warranty period, which in turn determines the reliability. the production of microelectronics has evolved into Since the early 1970's, one of the world's largest manufacturing industries. As a result, an important agenda is the study of reliability issues in fabricating microelectronic products and consequently the systems that employ these products, particularly, the new generation of microelectronics. Such an agenda should include: * the economic impact of employing the microelectronics fabricated by in dustry, * a study of the relationship between reliability and yield, * the progression toward miniaturization and higher reliability, and * the correctness and complexity of new system designs, which include a very significant portion of software.

Silicon, as an electronic substrate, has sparked a technological revolution that has allowed the realization of very large scale integration (VLSI) of circuits on a chip. These 6 fingernail-sized chips currently carry more than 10 components, consume low power, cost a few dollars, and are capable of performing data processing, numerical computations, and signal conditioning tasks at gigabit-per-second rates. Silicon, as a mechanical substrate, promises to spark another technological revolution that will allow computer chips to come with the eyes, ears, and even hands needed for closed-loop control systems. The silicon VLSI process technology which has been perfected over three decades can now be extended towards the production of novel structures such as epitaxially grown optoelectronic GaAs devices, buried layers for three dimensional integration, micromechanical mechanisms, integrated photonic circuits, and artificial neural networks. This book begins by addressing the processing of electronic and optoelectronic devices produced by using lattice mismatched epitaxial GaAs films on Si. Two viable technologies are considered. In one, silicon is used as a passive substrate in order to take advantage of its favorable properties over bulk GaAs; in the other, GaAs and Si are combined on the same chip in order to develop IC configurations with improved performance and increased levels of integration. The relationships between device operation and substrate quality are discussed in light of potential electronic and optoelectronic applications.

This volume contains the papers presented at the First Mexico-U.S.A. Symposium on Materials Sciences and Engineering held in Ixtapa, Guerrero, Mexico, during Septem ber 24-27, 1991. The conference was conceived with the primary objective of increas ing the close ties between scientists and engineers in both Mexico and the U.S. with an interest in materials. The conference itself would have not taken place without the drive, determination and technical knowledge of John K. Tien of the University of Texas at Austin and of Francisco Mejia Lira of the Universidad de San Luis Potosi. This book is dedicated to their memory. The event brought together materials scientists and engineers with interests in a broad range of subjects in the processing, characterization and properties of advanced materials. Several papers were dedicated to structural materials ranging from ferrous alloys to intemetallics, ceramics and composites. The presentation covered properties, processing, and factors that control their use, such as fatigue and corrosion. Other materials and properties were also explored by U.S. and Mexican participants. Sev eral papers dealt with the characterization and properties of magnetics, optical and superconductor materials, nanostructured materials, as well as with computational and theoretical aspects likely to impact future materials research and development."

Summary of the recent progress in ceramics research. Several novel concepts for materials selection and microstructural design are presented, as are experimental results that substantiate the ideas.

Broadband Integrated Services Digital Network (B-ISDN) is conceived as an all-purpose digital network supporting interactive and distributive services, bursty and continuous traffic, connection-oriented and connectionless services, all in the same network. The concepts of ISDN in general and B-ISDN in particular have been evolving since CCIIT adopted the rrrst set ofISDN recommendations in 1984. Thirteen recommendations outlining the fundamental principles and initial specifications for B-ISDN were approved in 1990, with Asynchronous Transfer Mode (ATM) being the transfer mode of choice for B-ISDN. It seems fair to say that B-ISDN concepts have changed the face of networking. The expertise we have developed for a century on telephone systems and over a number of decades on packet networks is proving to be insufficient to deploy and operate the envisioned B-ISDNs. Much more needs to be understood and satisfactorily addressed before ATM networks can become a reality. Tricomm'93 is dedicated to A TM networks. The technical program consists of invited papers addressing a large subset of issues of practical importance in the deployment of ATM networks. This is the sixth in a series of Research Triangle Conferences on Computer Communications, which emerged through the efforts of the local chapter of IEEE Communications Society.

For the eighth Advanced Study Institute (ASI) on Techniques and Concepts of High-Energy Physics we returned once again to the Hotel on the Cay on that speck of land in the harbor of Christiansted, St. Croix, U. S. Virgin Islands. This time, the ASI brought together a total of 73 participants, from 21 countries. The primary support for the meeting was provided, as usual, by the Scientific Affairs Division of the North Atlantic Treaty Organization (NATO). The ASI was cosponsored by the U. S. Department of Energy, by the Fermi National Accelerator Laboratory (Fermilab), by the U. S. National Science Foundation, and by the University of Rochester. A special contribution from the Oliver S. and Jennie R. Donaldson Charitable Trust provided an important degree of flexibility, as well as support for worthy students from developing countries. In addition, the International Science Foundation contributed very generously to the support of a participant from Russia. As in the case of the previous ASls, the scientific program was designed for advanced graduate students and recent PhD recipients in experimental particle physics. The present volume of lectures, although, unfortunately, short of three contributions, should complement the material published in the first seven ASIs, and prove to be of value to a wider audience of physicists. It is a pleasure to acknowledge the encouragement and support that I have continued to receive from colleagues and friends in organizing this meeting.

The quality of physical models is decisive for the understanding of the physical processes in semiconductor devices and for a reliable prediction of the behavior of a new generation of devices. The first part of the book contains a critical review on models for silicon device simulators, which rely on moments of the Boltzmann equation. With reference to fundamental experimental and theoretical work, an extensive collection of widely used models is discussed in terms of physical accuracy and application results. The second part outlines the derivation of physics-based models for bulk mobility, band-to-band tunneling, defect-assisted tunneling, thermal recombination, non-ideal metal-semiconductor contact, and direct and multiphonon-assisted tunneling through insulating layers, all from a microscopic level. The models are compared with experimental data and applied to a number of simulation examples. This part also describes some new approaches of "taylored quantum mechanics for deriving device models from "first principles and the fundamental problems therein."