This book is concerned primarily with the fundamental theory underlying the physical and chemical properties of crystalIine semiconductors. After basic introductory material on chemical bonding, electronic band structure, phonons, and electronic transport, some emphasis is placed on surface and interfacial properties, as weil as effects of doping with a variety of impurities. Against this background, the use of such materials in device physics is examined and aspects of materials preparation are discussed briefty. The level of presentation is suitable for postgraduate students and research workers in solid-state physics and chemistry, materials science, and electrical and electronic engineering. Finally, it may be of interest to note that this book originated in a College organized at the International Centre for Theoretical Physics, Trieste, in Spring 1984. P. N. Butcher N. H. March M. P. Tosi vii Contents 1. Bonds and Bands in Semiconductors 1 E. Mooser 1. 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. 2. The Semiconducting Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. 3. Bond Approach Versus Band Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1. 4. Construction of the Localized X by Linear Combination of n Atomic Orbitals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1. 5. The General Octet Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 1. 6. The Aufbau-Principle of the Crystal Structure of Semiconductors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 1. 7. A Building Principle for Polyanionic Structures . . . . . . . . . . . . . . . . . . . . . . 29 I. H. Structural Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 1. 9. Chemical Bonds and Semiconductivity in Transition-Element Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 1. 10. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 2. Electronic Band Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 G. Grosso 2. 1. Two Different Strategies for Band-Structure Calculations . . . . . . . 55 2. 2. The Tight-Binding Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The aim of the workshop was to bring together specialists in various fields where non-exponential relaxation is observed in order to compare models and experimental results and to examine the general physical principles governing this type of behaviour. Non-exponential relaxation is found in extremely diverse physical systems all of which can be classified as complex. The form of the relaxation is generally parametrized using logarithmic, algebraic or stretched exponential decay forms. The conceptually simplest mechanism for the non-exponential decay is a spectrum of relaxation rates due to non-interacting units each of which relaxes with a different intrinsic time constant. Clear experimental examples can be given where for instance the relaxation of a collection of isolated polymer molecules leads to an overall stretched exponential decay. Non-exponential relaxation is observed in all strongly interacting complex systems (structural glasses, spin glasses, etc ... ) where each elementary unit is in interaction with many other units.

Proceedings of the Eleventh Latin American Conference on the Applications of the Moessbauer Effect, La Plata, Argentina, 9-14 November 2008. The broad scope of the Applications of the Moessbauer Effect to interdisciplinary subjects makes this volume an outstanding source of information to researchers and graduate students, who will find the unique results of Moessbauer spectroscopy a valuable aid and complement to their research in conjunction with other techniques. In this volume, applications to mineralogy, catalysis, soil science, amorphous materials, nanoparticles, magnetic materials, nanotechnology, metallurgy, corrosion, and magnetism, have been put together in original works produced by invited speakers and different research teams across the continent.

This book explains concepts of transmission electron microscopy (TEM) and x-ray diffractometry (XRD) that are important for the characterization of materials. The fourth edition adds important new techniques of TEM such as electron tomography, nanobeam diffraction, and geometric phase analysis. A new chapter on neutron scattering completes the trio of x-ray, electron and neutron diffraction. All chapters were updated and revised for clarity. The book explains the fundamentals of how waves and wavefunctions interact with atoms in solids, and the similarities and differences of using x-rays, electrons, or neutrons for diffraction measurements. Diffraction effects of crystalline order, defects, and disorder in materials are explained in detail. Both practical and theoretical issues are covered. The book can be used in an introductory-level or advanced-level course, since sections are identified by difficulty. Each chapter includes a set of problems to illustrate principles, and the extensive Appendix includes laboratory exercises.

Presenting the latest advances in artificial structures, this volume discusses in-depth the structure and electron transport mechanisms of quantum wells, superlattices, quantum wires, and quantum dots. It will serve as an invaluable reference and review for researchers and graduate students in solid-state physics, materials science, and electrical and electronic engineering.

"Physics of Nanostructured Solid State Devices"introduces readers to theories and concepts such as semi-classical and quantum mechanical descriptions of electron transport, methods for calculations of band structures in solids with applications in calculation of optical constants, and other advanced concepts. The information presented here will equip readers with the necessary tools to carry out cutting edge research in modern solid state nanodevices."

of progress has been made in the development of In the last twenty years a great amount new magnetic materials. Permanent magnets have progressed from the AlNiCo's (with (BH)m-8 MGOe) to the strong rare-earth magnets of SmCo BH)m-20 MGOe), Sm2(Co, Fe, Cu, Zrh7 s BH)m-30 MGOe) and the recently discovered Nd-Fe-B super-magnets with (BH)m-50 MGOe. For years the magnetic storage industry has employed Fe0 and CrO for storage media and 2 3 z permalloys and ferrites for recording heads. The recent development of thin film heads, the demand of higher density of information storage and the emergence of completely new technologies, like magneto-optics, call for entirely new types of magnetic materials. Another area in which new techniques of materials preparation have made a dramatic impact is the epitaxial growth of magnetic films. Recent work has shown that this process can be controlled on the scale of atomic monolayers permitting the growth of totally artificial structures, such as artificial superlattices with a resolution on this scale. Epitaxial growth has also permitted the stabilization of metastable phases in thin film form. These new phases often possess striking properties, such as strong perpendicular anisotropies, which may prove useful for technological applications such as recording. Research on magnetic multilayers and superlattices is increasing at an accelerating pace. Complex couplings between different magnetic layers lead to new properties not seen in bulk materials.

The aim of this book is a discussion, at the introductory level, of some applications of solid state physics. The book evolved from notes written for a course offered three times in the Department of Physics of the University of California at Berkeley. The objects of the course were (a) to broaden the knowledge of graduate students in physics, especially those in solid state physics; (b) to provide a useful course covering the physics of a variety of solid state devices for students in several areas of physics; (c) to indicate some areas of research in applied solid state physics. To achieve these ends, this book is designed to be a survey of the physics of a number of solid state devices. As the italics indicate, the key words in this description are physics and survey. Physics is a key word because the book stresses the basic qualitative physics of the applications, in enough depth to explain the essentials of how a device works but not deeply enough to allow the reader to design one. The question emphasized is how the solid state physics of the application results in the basic useful property of the device. An example is how the physics of the tunnel diode results in a negative dynamic resistance. Specific circuit applications of devices are mentioned, but not emphasized, since expositions are available in the elec trical engineering textbooks given as references.

In response to the demands of contemporary solid material analysis-greater powers of detection, speed, depth, and precision-glow devices are receiving increased attention by specialists. This volume covers fundamental plasma processes, laser-based methods, thin film analysis, and many other processes to provide the researcher with an extensive technical reference of these devices.

The Institute for Amorphous Studies was founded in 1982 as the international center for the investigation of amorphous mate rials. It has since played an important role in promoting the und er standing of disordered matter in general. An Institute lecture series on "Fundamentals of Amorphous Materials and Devices" was held during 1982-83 with distinguished speakers from universities and industry. These events were free and open to the public, and were attended by many representatives of the scientific community. The lectures themselves were highly successful inasmuch as they provided not only formal instruction but also an opportunity for vigorous and stimulating debate. That last element could not be captured within the pages of a book I but the lectures concentrated on the latest advances in the field I which is why their essential contents are he re reproduced in collective form. Together they constitute an interdisciplinary status report of the field. The speakers brought many different viewpoints and a variety of back ground experiences io bear on the problems involved I but though language and conventions vary I the essential unity of the concerns is very clear I as indeed are the ultimate benefits of the many-sided approach."

This volume represents the written account of the NATO Advanced Study Institute "Lower-Dimensional Systems and Molecular Electronics" held at Hotel Spetses, Spetses Island, Greece from 12 June to 23 June 1989. The goal of the Institute was to demonstrate the breadth of chemical and physical knowledge that has been acquired in the last 20 years in inorganic and organic crystals, polymers, and thin films, which exhibit phenomena of reduced dimensionality. The interest in these systems started in the late 1960's with lower-dimensional inorganic conductors, in the early 1970's with quasi-one-dimensional crystalline organic conductors. which by 1979 led to the first organic superconductors, and, in 1977, to the fITSt conducting polymers. The study of monolayer films (Langmuir-Blodgett films) had progressed since the 1930's, but reached a great upsurge in . the early 1980's. The pursuit of non-linear optical phenomena became increasingly popular in the early 1980's, as the attention turned from inorganic crystals to organic films and polymers. And in the last few years the term "moleculw' electronics" has gained ever-increasing acceptance, although it is used in several contexts. We now have organic superconductors with critical temperatures in excess of 10 K, conducting polymers that are soluble and processable, and used commercially; we have films of a few monolayers that have high in-plane electrical conductivity, and polymers that show great promise in photonics; we even have a few devices that function almost at the molecular level.

There is a certain fascination associated with words. The manipulation of strings of symbols according to mutually accepted rules allows a language to express history as well as to formulate challenges for the future. But language changes as old words are used in a new context and new words are created to describe changing situations. How many words has the computer revolution alone added to languages? "Inorganometallic" is a word you probably have never encountered before. It is one created from old words to express a new presence. A strange sounding word, it is also a term fraught with internal contradiction caused by the accepted meanings of its constituent parts. "In organic" is the name of a discipline of chemistry while "metallic" refers to a set of elements constituting a subsection of that discipline. Why then this Carrollian approach to entitling a set of serious academic papers? Organic, the acknowledged doyenne of chemistry, is distinguished from her brother, inorganic, by the prefix "in," i. e. , he gets everything not organic. Organometallic refers to compounds with carbon-metal bonds. It is simple! Inorganometallic is everything else, i. e. , compounds with noncarbon-metal element bonds. But why a new term? Is not inorganic sufficient? By virtue of training, limited time, resources, co-workers, and so on, chemists tend to work on a specific element class, on a particular compound type, or in a particular phase. Thus, one finds element-oriented chemists (e. g.

The role of high pressure experiments in the discovery of supercon ducting materials with a T. above liquid nitrogen temperature has demon strated the importance of such experiments. The same role holds true in the tailoring of materials for optoelectronic devices. In addition, much progress has been made recently in the search for metallic hydro gen, and the application of high pressure in polymer research has brought forth interesting results. These facts together with the suc cess of previous small size meetings (such as the "First International Conference on the Physics of Solids at High Pressure", held in 1965 in Tucson, Arizona, U. S. A. ; "High Pressure and Low Temperature Physics", held in 1977 in Cleveland, Ohio, U. S. A. ; and "Physics of Solids Under High Pressure", held in 1981 in bad Honnef, Germany), motivated us to organize a workshop with emphasis on the newest results and trends in these fields of high pressure research. Furthermore, it was intended to mix experienced and young scien tists to realize an idea best expressed in a letter by Prof. Weinstein: "I think it is an excellent idea. I have often felt that the number of excellent young researchers in the high pressure field need an opportu nity to put forward their work with due recognition. " Thanks to the support of the key speakers, we were able to achieve this goal and had more than 50\ young participants.

This book represents Volume 2 in a series on the use of Mossbauer spectroscopy in the study of magnetism and materials. However, the perceptive reader will notice some differences from Volume 1. Specifically, in order to market the book at a more affordable price for most universities and research laboratories, the book has been prepared in camera ready format The editors and the authors agreed to do this because there is a demand for such a book in the Mossbauer community. This format has placed an extra burden on the editors and the authors and we hope we have overcome all the difficulties generated by the transfer of files between different computers. In order to make the book more attractive to materials scientists who are not experts in Mossbauer spectroscopy, this volume is particularly oriented towards the study of materials by Mossbauer spectroscopy and related complementary techniques, such as neutron scattering and a variety of surface scattering techniques. The authors of this volume can be proud of the high quality professional effort they have devoted to clearly presenting their specific topics. As a result we very much enjoyed working with the authors on this volume. We hope that their effort will help to educate the next generation of Mossbauer effect spectroscopists, a generation which will face the challenge of maintaining equally high scientific and professional standards in their research work.

The author integrates discussions of fractal geometry, surface modeling techniques, and applications to real world problems to provide a comprehensive, accessible overview of the field. His work will equip researchers with the basic tools for measurement and interpretation of data, stimulating more work on these problems and, perhaps, leading to an understanding of the reasons that Nature has adopted this geometry to shape much of our world.

This volume contains a sequence of reviews presented at the NATO Advanced Study Institute on 'Low Dimensional Structures in Semiconductors ... from Basic Physics to Applications.' This was part of the International School of Materials Science and 1990 at the Ettore Majorana Centre in Sicily. Technology held in July Only a few years ago, Low Dimensional Structures was an esoteric concept, but now it is apparent they are likely to playa major role in the next generation of electronic devices. The theme of the School acknowledged this rapidly developing maturity.' The contributions to the volume consider not only the essential physics, but take a wider view of the topic, starting from material growth and processing, then prog ressing right through to applications with some discussion of the likely use of low dimensional devices in systems. The papers are arranged into four sections, the first of which deals with basic con cepts of semiconductor and low dimensional systems. The second section is on growth and fabrication, reviewing MBE and MOVPE methods and discussing the achievements and limitations of techniques to reduce structures into the realms of one and zero dimensions. The third section covers the crucial issue of interfaces while the final section deals with devices and device physics."

This volume contains the invited papers and selected contributed papers presented at the biennial International Symposium on ELECTRON COLLISIONS WITH MOLECULES, CLUSTERS AND SURF ACES held at Royal Holloway, University of London from 29th to 30th July, 1993. This Symposium was a Satellite Meeting of the XVIII International Conference on the Physics of Electronic and Atomic Collisions (ICPEAC) and follows a 16 year tradition of Satellite Conferences in related areas of collisions held in association with previous ICPEAC's. In the past each of these electron -molecule symposia covered the broad field of electron-molecule scattering at rather low energies, but also included hot topics. This time as well as covering the whole field, well defined electron collisions with clusters and with particles in the complex potential of a surface were emphasized. Not many details are known about such collisions, although they become more and more important in surface characterisation, plasma-wall interactions, electron induced desorption and reorganisation of adsorbed particles. Recently, much work, theoretical and experimental, has been devoted to electron collisions with rather large carbon, silicon and halogen containing molecules. These problems are of relevance in plasma assisted thin film formation and etching of surfaces and can now be approached with advanced theoretical methods and experimental equipment.

This proceedings volume, "Plastic Deformation of Ceramics," constitutes the papers of an international symposium held at Snowbird, Utah from August 7-12, 1994. It was attended by nearly 100 scientists and engineers from more than a dozen countries representing academia, national laboratories, and industry. Two previous conferences on this topic were held at The Pennsylvania State University in 1974 and 1983. Therefore, the last major international conference focusing on the deformation of ceramic materials was held more than a decade ago. Since the early 1980s, ceramic materials have progressed through an evolutionary period of development and advancement. They are now under consideration for applications in engineering structures. The contents of the previous conferences indicate that considerable effort was directed towards a basic understanding of deformation processes in covalently bonded or simple oxide ceramics. However, now, more than a decade later, the focus has completely shifted. In particular, the drive for more efficient heat engines has resulted in the development of silicon-based ceramics and composite ceramics. The discovery of high-temperature cupric oxide-based superconductors has created a plethora of interesting perovskite-Iike structured ceramics. Additionally, nanophase ceramics, ceramic thin films, and various forms of toughened ceramics have potential applications and, hence, their deformation has been investigated. Finally, new and exciting areas of research have attracted interest since 1983, including fatigue, nanoindentation techniques, and superplasticity.

This volume contains the papers presented at the NATO Advanced Research Workshop on "Magnetism and Structure in Systems of Reduced Dimension," held at l'Institut d'Etudes Scientifiques de Cargese - U.M.S. - C.N.R.S. - Universite de Corte Universite de Nice Sophia - Antipolis during June 15-19, 1992. The ordering of papers in the volume reflects the sequence of papers presented at the workshop. The aim was not to segregate the papers into rigidly defmed areas but to group the papers into small clusters, each cluster having a common theme. In this way the parallel, rather than serial, development of areas such as preparation of films, magnetic and structural characterization was highlighted. Indeed the success of the field depends on such parallel development and is assisted by workshops of this nature and the international collaborations which they foster. The organizers and participants of the NATO workshop express their thanks to Mme. Marie-France Hanseier and the staff at l'Institut d'Etudes Scientifiques de Cargese U.M.S. - C.N.R.S. - Universite de Corte - Universite de Nice Sophia - Antipolis for making the workshop and local arrangements a memorable success. Warm thanks are also expressed to Varadachari Sadagopan and Pascal Stefanou for their encouragement and help in making the workshop a reality. We are also grateful to Kristl Hathaway, Larry Cooper and Gary Prinz for advice in developing the workshop program."

The aim of this NATO Advanced Study Institute was to bring together scientists and students working in the field of laser matter interactions in order to review and stimulate developmentoffundamental science with ultra-short pulse lasers. New techniques of pulse compression and colliding-pulse mode-locking have made possible the construction of lasers with pulse lengths in the femtosecond range. Such lasers are now in operation at several research laboratories in Europe and the United States. These laser facilities present a new and exciting research direction with both pure and applied science components. In this ASI the emphasis is on fundamental processes occurring in the interaction of short laser pulses with atoms, molecules, solids, and plasmas. In the case of laser-atom (molecule) interactions, high power lasers provide the first access to extreme high-intensity conditions above 10'8 Watts/em', a new frontier for nonlinear interaction of photons with atoms and molecules. New phenomena observed include multiphoton ionization processes, atomic collisions in the presence of a strong laser field, Coulomb explosion following rapid ionization of a molecule and the production of high harmonics of the laser source. Another important topic reviewed in this ASI is the lasercooling ofatoms.

The Nato Advanced Study Institute "Phase Transitions in Liquid Crystals" was held May 2-12, 1991, in Erice, Sicily. This was the 16th conference organized by the International School of Quantum Electronics, under the auspices of the "Ettore Majorana" Centre for Scientific Culture. The subject of "Liquid Crystals" has made amazing progress since the last ISQE Course on this subject in 1985. The present Proceedings give a tutorial introduction to today's most important areas, as well as a review of current results by leading researchers. We have brought together some of the world's acknowledged experts in the field to summarize both the present state of their research and its background. Most of the lecturers attended all the lectures and devoted their spare hours to stimulating discussions. We would like to thank them all for their admirable contributions. The Institute also took advantage of a very active audience; most of the students were active researchers in the field and contributed with discussions and seminars. Some of these student seminars are also included in these Proceedings. We did not modify the original manuscripts in editing this book, but we did group them according to the following topics: 1) "Theoretical Foundations"; 2) "Thermotropic Liquid Crystals"; 3) "Ferroelectric Liquid Crystals"; 4) "Polymeric Liquid Crystals"; and 5) "Lyotropic Liquid Crystals".

Molecular similarity has always been an important conceptual tool of chemists, yet systematic approaches to molecular similarity problems have only recently been recognized as a major contributor to our understanding of molecular properties. Advanced approaches to molecular similarity analysis have their foundation in quantum similarity measures, and are important direct or indirect contributors to some of the predictive theoretical, computational, and also experimental methods of modern chemistry. This volume provides a survey of the foundations and the contemporary mathematical and computational methodologies of molecular similarity approaches, where special emphasis is given to applications of similarity studies to a range of practical and industrially significant fields, such as pharmaceutical drug design. The authors of individual chapters are leading experts in various sub-fields of molecular similarity analysis and the related fundamental theoretical chemistry topics, as well as the relevant computational and experimental methodologies. Whereas in each chapter the emphasis is placed on a different area, nevertheless, the overall coverage and the wide scope of the book provides the reader with a general yet sufficiently detailed description that may serve as a good starting point for new studies and applications of molecular similarity approaches. The editors of this volume are grateful to the authors for their contributions, and hope that the readers will find this book a useful and motivating source of information in the rapidly growing field of molecular similarity analysis.

This Advanced Study Institute on the topic of SOLID STATE MICROBATTERIES is the third and final institute on the general theme of a field of study now termed "SOLID STATE IONICS". The institute was held in Erice, Sicily, Italy, 3 - 15 July 1988. The objective was to assemble in one location individuals from industry and academia expert in the fields of microelectronics and solid state ionics to determine the feasibility of merging a solid state microbattery with microelectronic memory. Solid electrolytes are in principle amenable to vapor deposition, RF or DC sputtering, and other techniques used to fabricate microelectronic components. A solid state microbattery 1 1 mated on the same chip carrier as the chip can provide on board memory backup power. A solid state microbattery assembled from properly selected anode/solid electrolyte/cathode materials could have environmental endurance properties equal or superior to semiconductor memory chips. Lectures covering microelectronics, present state-of-art solid state batteries, new solid electrolyte cathode materials, theoretical and practical techniques for fabrication of new solid electrolytes, and analytical techniques for study of solid electrolytes were covered. Several areas where effort is required for further understanding of materials in pure form and their interactions with other materials at interfacial contact points were identified. Cathode materials for solid state batteries is one particular research area which requires attention. Another is a microscopic model of conduction in vitreous solid electrolytes to enhance the thermodynamic macroscopic Weak ~lectrolyte Iheory (WET).