Technological advances in semiconductor growth has opened a broad horizon for semiconductor physics and applications during the past 20 years. High quality two-. dimensional systems are achieved with nearly atomic precision by direct epitaxial growth. Such structures led to novel applications like low noise high frequency modulation doped field effect transistors and quantum well lasers. Semiconductor heterostructures of lower dimensionality like quantum wires and quantum dots are not yet as mature, partly due to the lack in precision oflateral structuring technology. In recent years, however, there was an enormous progress in novel epitaxial growth methods. This opens a wide new area of basic and applied semiconductor physics with the hope of novel applications in near future making use of the advantageous properties of one- and zero-dimensional systems. Ideas for future device applications mainly stem from the altered density of states being discrete or atomic-like for quantum dots. Optical spectroscopy has played and is playing a crucial role in the advancement of this fascinating field of semiconductor physics. The NATO school organized at Bilkent University in Ankara and in Antalya brought together experts in this field and newcomers, especially young Ph. D. students and postdocs, to learn about recent developments and to discuss open questions in the area of optical spectroscopy of low dimensional semiconductors. The school turned out to be extremely fruitful and there was a great enthusiasm among the lecturers and students during the whole two weeks.

For several years, the two parallel worlds of Molecular Conductors in one hand and Molecular Magnetism in the other have grown side by side, the former essentially based on radical organic molecules, the latter essentially based on the high spin properties of metal complexes. Over the last few years however, organometallic derivatives have started to play an increasingly important role in both worlds, and have in many ways contributed to open several passages between these two worlds. This volume recognizes this important emerging evolution of both research areas. It is not intended to give a comprehensive view of all possible organometallic materials, and polymers for example were not considered here. Rather we present a selection of the most recent research topics where organometallic derivatives were shown to play a crucial role in the setting of conducting and/or magnetic properties in crystalline materials. First, the role of organometallic anions in tet- thiafulvalenium-based molecular conductors is highlighted by Schlueter, while Kubo and Kato describe very recent ortho-metalated chelating ligands appended to the TTF core and their conducting salts. The combination of conducting and magnetic properties and the search for p-d interactions are analyzed in two comp- mentary contributions by Myazaki and Ouahab, while Valade focuses on the only class of metal bis(dithiolene) complexes to give rise to superconductive molecular materials, in association with organic as well as organometallic cations.

Proceedings of the NATO Advanced Study Institute on New Trends and Applications of Photoelectrochemistry and Photocatalysis for Environment Problems, Cafelu, Palermo, Italy, September 6-18, 1987

In 1987 a major breakthrough occurred in materials science. A new family of materials was discovered that became superconducting above the temperature at which nitrogen gas liquifies, namely, 77 K or -196 DegreesC. Within months of the discovery, a wide variety of experimental techniques were brought to bear in order to measure the properties of these materials and to gain an understanding of why they superconduct at such high temperatures. Among the techniques used were electromagnetic absorption in both the normal and the superconducting states. The measurements enabled the determination of a wide variety of properties, and in some instances led to the observation of new effects not seen by other measu- ments, such as the existence of weak-link microwave absorption at low dc magnetic fields. The number of different properties and the degree of detail that can be obtained from magnetic field- and temperature-dependent studies of electromagnetic abso- tion are not widely appreciated. For example, these measurements can provide information on the band gap, critical fields, the H-T irreversibility line, the amount of trapped flux, and even information about the symmetry of the wave function of the Cooper pairs. It is possible to use low dc magnetic field-induced absorption of microwaves with derivative detection to verify the presence of superconductivity in a matter of minutes, and the measurements are often more straightforward than others. For example, they do not require the physical contact with the sample that is necessary when using four-probe resistivity to detect superconductivity.

Corrosion behaviour is one of the most poorly understood characteristics of ceramics. A balanced mixture of scientists from material science, metallurgy, physics, chemistry and mineralogy sum up the state of the art of measurement and modelling and reveal future research directions. The book reviews the theory of corrosion of ceramics, including the diffusion of gases and the predictions of thermodynamics; it discusses critically the kinetic models and representation tools for layer growths and material destruction. Corrosion of nitrides, carbides and oxides by simple and complex gases (O2, H2O, SO2, halides) and melts (ionic and metallic) reveal current measurement and modelling methods, advanced experimental techniques, such as laser diagnostics, TV holography, Raman spectroscopy and NDE surface methods. Frontier areas (e.g. the modelling of porous materials corrosion and protection) are revealed. For scientists and engineers in materials science, dealing with ceramics and their application. A valuable source for research students, solid state physicists and physical chemists.

"Phase Change Materials: Science and Applications" provides a unique introduction of this rapidly developing field. Clearly written and well-structured, this volume describes the material science of these fascinating materials from a theoretical and experimental perspective. Readers will find an in-depth description of their existing and potential applications in optical and solid state storage devices as well as reconfigurable logic applications.

Researchers, graduate students and scientists with an interest in this field will find "Phase Change Materials" to be a valuable reference.

This book presents theory, fundamentals and applications of ferroelectricy. 24 chapters gather reviews and research reports covering the spectrum of ferroelectricity. It describes the current levels of understanding of various aspects of ferroelectricity as presented by authorities in the field. Topics include relaxors, piezoelectrics, microscale and nanoscale studies, polymers and composites, unusual properties, and techniques and devices. The book is intended for physicists, engineers and materials scientists working with ferroelectric materials.

Silicon-Based Millimeter-Wave Devices describes field-theoretical methods for the design and analysis of planar waveguide structures and antennas. The principles and limitations of transit-time devices with different injection mechanisms are discussed, as are aspects of fabrication and characterization. The physical properties of silicon Schottky contacts and diodes are treated in a separate chapter. Two chapters cover the silicon/germanium devices: physics and RF properties of the heterobipolar transistor and quantum effect devices such as the resonant tunneling element are described. The integration of devices in monolithic circuits is explained and advanced technologies are presented along with the self-mixing oscillator operation. Finally sensor and system applications are considered.

Advances in nanotechnology have generated semiconductor structures that are only a few molecular layers thick, and this has important consequences for the physics of electrons and phonons in such structures. This book describes in detail how confinement of electrons and phonons in quantum wells and wires affects the physical properties of the semiconductor. This second edition contains four new chapters on spin relaxation, based on recent theoretical research; the hexagonal wurtzite lattice; nitride structures, whose novel properties stem from their spontaneous electric polarization; and terahertz sources, which includes an account of the controversies that surrounded the concepts of Bloch oscillations and Wannier-Stark states. The book is unique in describing the microscopic theory of optical phonons, the radical change in their nature due to confinement, and how they interact with electrons. It will interest graduate students and researchers working in semiconductor physics.

After the invention of semiconductor-based recti?ers and diodes in the ?rst half of the last century, the advent of the transistor paved the way for semiconductors in electronic data handling starting around the mid of the last century. The transistors widely replaced the vacuum tubes, which had even been used in the ?rst generation of computers, the Z3 developed by Konrad Zuse in the 1940s of the last century. The ?rst transistors were individually housed semiconductor devices, which had to be soldered into the electric circuits. Later on, integrated circuits were developed with increasing numbers of individual elements per square inch. The materials changed from, e. g. , PbS and Se in rf-detectors and recti?ers used frequentlyin the ?rst halfof the last centuryoverthe groupIV element semicond- tor Ge with a band gap of 0. 7eV at room temperature to Si with a value of 1. 1eV. The increase of the gap reduced the leakage current and its temperature dependence signi?cantly. Therefore, the logical step was to try GaAs with a band gap of 1. 4eV next. However, the technology of this semiconductor from the group of III-V c- poundsprovedto be muchmoredif?cult,thoughbeautifuldeviceconceptshadbeen developed. Therefore,GaAsanditsalloysandnanostructureswithotherIII-Vc- poundslike AlGaAs or InP remained restricted in electronicsto special applications like transistors for extremely high frequencies, the so-called high electron mobility transistors (HEMT). The IT industry is still mainly based on Si and will remain so in the foreseeable nearer future.

Semiconductor materials have been studied intensively since the birth of silicon technology more than 50 years ago. The ability to physically and chemically t- lor their properties with precision is the key factor responsible for the electronic revolution in our society over the past few decades. Semiconductor material s- tems (like silicon and GaAs-related materials) have now matured and found well established applications in electronics, optoelectronics, and several other ?elds. Other materials such as III-Nitrides were developed later, in response to needs that the above mentioned semiconductors were unable to ful?ll. The properties of I- nitrides (AlN, GaN InN, and related alloy systems) make them an excellent choice for ef?cient light emitters in the visible as well as the UV region, UV detectors, and for a variety of electronic device such as high frequency unipolar power devices. There was a major upsurgein the research of the GaN material system around1970.

les Houches This Winter School on "The Physics and Fabrication of Microstructures" originated with a European industrial decision to investigate in some detail the potential of custom-designed microstructures for new devices. Beginning in 1985, GEC and THOMSON started a collaboration on these subjects, supported by an ESPRIT grant from the Commission of the European Com munity. To the outside observer of the whole field, it appears clear that the world effort is very largely based in the United States and Japan. It also appears that cooperation and dissemination of results are very well organised outside Europe and act as a major influence on the development of new concepts and devices. In Japan, a main research programme of the Research and Development for Basic Technology for Future Industries is focused on "Future Electron Devices." In Japan and in the United States, many workshops are organised annually in order to bring together the major specialists in industry and academia, allowing fast dissemination of advances and contacts for setting up cooperative efforts."

Optical data storage represents a major chapter in the history of information storage and the invention of rewritable media has indisputably been an essential addition to the optical storage family. With the multiple overwrite feature, rewritable optical discs have found application in consumer DVD+RW video recorders, professional archiving systems and computer drives for data storage, replacing the floppy disc in the latter case.

Optical Data Storage provides an overview of the recording principles, materials aspects, and application areas of phase-change optical storage. Some theoretical background is given to familiarize the reader with the basics of the phase-change processes. Elements of data recording, including mark formation, eraseability, direct overwrite strategies, data quality and data stability, etc are explained and extensively discussed. A mark formation model is described and used throughout the whole book to back-up measurement results and support the discussed applications. Two major aspects high-speed and dual-layer recording are considered in depth and solutions to achieve higher performance are analyzed.

Optical Data Storage is aimed at a broad range of readers from university teams studying the subject to industrial media manufacturers requiring insights into performance of rewritable optical media."

Semiconductor device modelling has developed in recent years from being solely the domain of device physicists to span broader technological disciplines involved in device and electronic circuit design and develop ment. The rapid emergence of very high speed, high density integrated circuit technology and the drive towards high speed communications has meant that extremely small-scale device structures are used in contempor ary designs. The characterisation and analysis of these devices can no longer be satisfied by electrical measurements alone. Traditional equivalent circuit models and closed-form analytical models cannot always provide consis tently accurate results for all modes of operation of these very small devices. Furthermore, the highly competitive nature of the semiconductor industry has led to the need to minimise development costs and lead-time associated with introducing new designs. This has meant that there has been a greater demand for models capable of increasing our understanding of how these devices operate and capable of predicting accurate quantitative results. The desire to move towards computer aided design and expert systems has reinforced the need for models capable of representing device operation under DC, small-signal, large-signal and high frequency operation. It is also desirable to relate the physical structure of the device to the electrical performance. This demand for better models has led to the introduction of improved equivalent circuit models and a upsurge in interest in using physical models.

Although it has long been possible to make organic materials emit light, it has only recently become possible to do so at the level and with the efficiency and control necessary to make the materials a useful basis for illumination in any but the most specialized uses. This book surveys the current status of the field.

The 1990 International Topical Meeting on Photonic Switching was held April 12-14, 1990, in Kobe, Japan, in conjunction with the 1990 International Meet ing on Optical Computing. It was sponsored by the Institute of Electronics, Information and Communication Engineers in cooperation with the IEEE Lasers and Electro-Optics Society, the Optical Society of America, and the Japan So ciety of Applied Physics. The attendance was in excess of 340 persons, with 18 countries represented - a testimony to the current international interest in photonic switching. This book contains expanded and more detailed versions of most of the papers presented at the topical meeting. With the success of optical fibers there is an increased demand for a switch ing system that can operate directly on the light present in the fibers. The goal is to reduce the total number of optical-to-electrical and electrical-to-optical transformations as far as possible, in addition to exploiting the large spec tral and temporal bandwidth offered by such an optically transparent system."

Twenty-four years ago, Hellmut Fritzsche came to our laboratory to evaluate our work in amorphous materials. He came many times, sometimes bringing his violin to play with our youngest son, to talk, to help, to discover, and to teach. The times with him were always exciting and rewarding. There was a camaraderie in the early years that has continued and a friendship that has deepened among Iris and me and Hellmut, Sybille and their children. The vision that Hellmut Fritzsche shared with me, the many important contributions he made, the science that he helped so firmly to establish, the courage he showed in the time of our adversity, and the potential that he recognized put all of us in the amorphous field, not only his close friends and collaborators, in his debt. He helped make a science out of intuition, and played an important role not only in the experimental field but also in the basic theoretical aspects. It has been an honor to work with Hellmut through the years.

Advances in Solar Energy is back on schedule. Volume III contains a number of interesting reviews of the different fields in solar energy conversion. We appreciate the many encouraging comments received after the second volume appeared and have incorporated some of the suggested changes. Even though most of the reviews are invited through our editors, we are always open to suggestion about subjects of importance that are ready for a com prehensive and critical review and have not been recently covered, or about potential authors. I would like to take this opportunity to thank Professor John A. Duffie for his invaluable help in starting the Advances in Solar Energy series. Although he has recently taken full responsibility as editor-in-chief for the Solar Energy Journal, his continued assistance as a member of the Board of Editors is greatly appreciated. The diligent work of the many active editors is gratefully acknowledged and constitutes the basis for a valuable review periodical with outstanding contributions. The typesetting was done by Sandra Pruitt in the Delaware office, using the TEX-program with laser print-out. Her organization and patience in coordinating with the authors, and her technical skill and diligence in preparing the submitted copy permitted the timely and high-quality assembly of this production. We wish to commend her for efforts well beyond the call of duty. The accommodating help from Plenum Press and its production staff deserves our grateful acknowledgement."

Recent years have seen silicon integrated circuits enter into an increasing number of technical and consumer applications, until they now affect everyday life, as well as technical areas. Polycrystalline silicon has been an important component of silicon technology for nearly two decades, being used first in MOS integrated circuits and now becoming pervasive in bipolar circuits, as well. During this time a great deal of informa tion has been published about polysilicon. A wide range of deposition conditions has been used to form films exhibiting markedly different properties. Seemingly contradictory results can often be explained by considering the details of the structure formed. This monograph is an attempt to synthesize much of the available knowledge about polysilicon. It represents an effort to interrelate the deposition, properties, and applications of polysilicon so that it can be used most effectively to enhance device and integrated-circuit perfor mance. As device performance improves, however, some of the proper ties of polysilicon are beginning to restrict the overall performance of integrated circuits, and the basic limitations of the properties of polysili con also need to be better understood to minimize potential degradation of circuit behavior."

In the last few years it was seen the emergence of various new quantum phenomena specifically related with electronic or optical confinement on a sub-wavelength-size. Fast developments simultaneously occurred in the field of Atomic Physics, notably through various regimes of Cavity Quantum Electrodynamics, and in Solid State Physics, with advances in Quantum Well technology and Nanooptoelectronics. Simultaneously, breakthroughs in Near-Field Optics provided new tools which should be widely applicable to these domains. However, the key concepts used to describe these new and partly related effects are often very different and specific of the Community involved in a given development. It has been the ambition of the Meeting held at "Centre de Physique des Houches" to give an opportunity to specialists of different Communities to deepen their understanding of advances more or less intimately related to their own field, while presenting the basic concepts of these different fields through pedagogical Introductions. The audience comprised advanced students, postdocs and senior scientists, with a balanced participation of Atomic Physicists and Solid State Physicists, and had a truly international character. The considerable efforts of the lecturers, in order to present exciting new results in a language accessible to the whole audience, were the essential ingredients to achieve successfully what was the main goal of this School.

This book has been written as part of a new series of scientific text-books being published by Plenum Publishing Company Limited. The scope of the series is to review a chosen topic in each volume, and in addition, to present abstracts of the most important references cited in the text. Thus allowing the reader to supplement the information contained within this book without have to refer to many additional publications. This volume is devoted to the subject of Radiation Detectors, known as Photodetectors, and particular emphasis has been placed on devices operating in the infrared region of the electromagnetic spectrum. Although some detectors which are sensitive at ultraviolet and visible wavelengths, are also described. The existence of the infrared region of the spectrum has been known for almost two hundred years but the development of detectors specifically for these wavelengths was limited for a long time due to technology limitations and difficulties in understanding and explaining the phenomena involved. Significant advances were made during World War II, when the potential military applications of being able "to see in the dar ' were demonstrated, and this progress has been maintained during the last forty years when many major advances have been achieved, such that the use of photodetectors for both civil and military applications is now relatively common and can be inexpensive.

In the decades the of the formation of structures past subject spontaneous in far from has into a branch of - systems equilibrium major physics grown search with ties to It has become evident that strong neighboring disciplines. a diverse of can be understood within a common mat- phenomena range matical framework which has been called nonlinear of continuous dynamics This name the close to the field of nonlinear systems. emphasizes relationship of with few of freedom which has evolved into a dynamics systems degrees mature in the recent features mathematically subject past. Many dynamical of continuous be described reduction few can a to a systems actually through of freedom and of the latter of continue to degrees properties type systems of continuous the inspire study systems. The of this book is to demonstrate the numerous goal through examples that exist for the of nonlinear the opportunities study phenomena through tools of mathematical and use of common analyses dynamical interpretations. Instead of overview of the a providing comprehensive rapidly evolving field, the contributors to this book are to communicate to a wide scientific trying audience the of what have learnt about the formation of essence they spon- neous structures in continuous and about the dissipative systems competition between order and chaos that characterizes these It is that systems. hoped the book will be even to those scientists whose not helpful are disciplines the authors.

Nanoscale Science, whose birth and further growth and development has been driven by the needs of the microelectronics industry on one hand, and by the sheer human curiosity on the other hand, has given researchers an unprecedented capability to design and construct devices whose function ality is based on quantum and mesoscopic effects. A necessary step in this process has been the development of reliable fabrication techniques in the nanometer scale: two-dimensional systems, quantum wires and dots, and Coulomb blockade structures with almost ideal properties can nowadays be fabricated, and subjected to experimental studies. How does one fabricate micro/nanostructures of low dimensionality? How does one perform a nanoscale characterization of these structures? What are the fundamental properties typical to the structures? Which new physical processes in nanostructures need to be understood? What new physical processes may allow us to create new nanostructures? An improved understanding of these topics is necessary for creation of new concepts for future electronic and optoelectronic devices and for characterizing device structures based on those concepts.

In the first comprehensive treatment of these technologically important materials, the authors provide theories linking the properties of semiconductor alloys to their constituent compounds. Topics include crystal structures, bonding, elastic properties, phase diagrams, band structures, transport, ab-initio theories, and semi-empirical theories. Each chapter includes extensive tables and figures as well as problem sets.

Fine Particles Science and Technology deals with the preparation, characterization and technological applications of monodisperse particles in the micro to nano size range. A broad view of this frontier field is given, covering understanding the mechanisms by which uniform fine particles are formed and the search for new processes; the mechanism of the precipitation technique, requiring knowledge of the relationship between the complex solution chemistry and the products formed; the sequence of events leading to the formation of monodisperse colloids. The following topics are presented: microparticles, nanoparticles, applications in the preparation of materials, synthesis and properties, environmental applications, and many others.