The continous development of computer technology supported by the VLSI revolution stimulated the research in the field ·of multiprocessors systems. The main motivation for the migration of design efforts from conventional architectures towards multiprocessor ones is the possibi I ity to obtain a significant processing power together with the improvement of price/performance, reliability and flexibility figures. Currently, such systems are moving from research laboratories to real field appl ications. Future technological advances and new generations of components are I ikely to further enhance this trend. This book is intended to provide basic concepts and design methodologies for engineers and researchers involved in the development of mul tiprocessor systems and/or of appl ications based on multiprocessor architectures. In addition the book can be a source of material for computer architecture courses at graduate level. A preliminary knowledge of computer architecture and logical design has been assumed in wri ting this book. Not all the problems related with the development of multiprocessor systems are addressed in th i s book. The covered range spans from the electrical and logical design problems, to architectural issues, to design methodologis for system software. Subj ects such as software development in a multiprocessor environment or loosely coupled multiprocessor systems are out of the scope of the book. Since the basic elements, processors and memories, are now available as standard integrated circuits, the key design problem is how to put them together in an efficient and reliable way.

During the past two decades there has been a considerable growth in interest in problems of pattern recognition and image processing (PRIP). This inter­ est has created an increasing need for methods and techniques for the design of PRIP systems. PRIP involves analysis, classification and interpretation of data. Practical applications of PRIP include character recognition, re­ mote sensing, analysis of medical signals and images, fingerprint and face identification, target recognition and speech understanding. One difficulty in making PRIP systems practically feasible, and hence, more popularly used, is the requirement of computer time and storage. This situation is particularly serious when the patterns to be analyzed are quite complex. Thus it is of the utmost importance to investigate special comput­ er architectures and their implementations for PRIP. Since the advent of VLSI technology, it is possible to put thousands of components on one chip. This reduces the cost of processors and increases the processing speed. VLSI algorithms and their implementations have been recently developed for PRIP. This book is intended to document the recent major progress in VLSI system design for PRIP applications.

The Handbook of Electronics Packaging Design and Engineering has been writ­ ten as a reference source for use in the packaging design of electronics equip­ ment. It is designed to provide a single convenient source for the solution of re­ curring design problems. The primary consideration of any design is that the end product meet or exceed the applicable product specifications. The judicious use of uniform design practices will realize the following economies and equipment improvements: • Economics of design. Uniform design practices will result in less engineering and design times and lower costs. They will also reduce the number of changes that may be required due to poor reliability, maintainability, or producibility. • Improved design. Better designs with increased reliability, maintainability, and producibility will result from the use of uniform design practices. • Production economies. Uniform designs employing standard available tools, materials, and parts will result in the cost control of manufacturing. The Handbook is intended primarily for the serious student of electronics packaging and for those engineers and designers actively engaged in this vital and interesting profession. It attempts to present electronics packaging as it is today. It can be used as a training text for instructional purposes and as a reference source for the practicing designer and engineer.

1.1 The Role of Silicon as a Semiconductor Silicon is unchallenged as a semiconductor base material in our present electronics indu­ stry. The reasons why it qualifies so strongly for this particular purpose are manyfold. The attractive combination of physical (electrical) properties of silicon and the unique properties of its native oxide layer have been the original factors for its breathtaking evolution in device technology. The majority of reasons, however, for its present status are correlated with industrial prosessing in terms of charge units ( economy), reliability (reproducibility), and flexibility, but also its availability.

Discovery of new transport phenomena and invention of electron devices through exploitation of these phenomena have caused a great deal of interest in the properties of compound semiconductors in recent years. Extensive re­ search has been devoted to the accumulation of experimental results, par­ ticularly about the artificially synthesised compounds. Significant ad­ vances have also been made in the improvement of the related theory so that the values of the various transport coefficients may be calculated with suf­ ficient accuracy by taking into account all the complexities of energy band structure and electron scattering mechanisms. Knowledge about these deve­ lopments may, however, be gathered only from original research contributions, scattered in scientific journals and conference proceedings. Review articles have been published from time to time, but they deal with one particular material or a particular phenomenon and are written at an advanced level. Available text books on semiconductor physics, do not cover the subject in any detail since many of them were written decades ago. There is, there­ fore, a definite need for a book, giving a comprehensive account of electron transport in compound semiconductors and covering the introductory material as well as the current work. The present book is an attempt to fill this gap in the literature. The first chapter briefly reviews the history of the developement of compound semiconductors and their applications. It is also an introduction to the contents of the book.

The Handbook of Electronics Formulas, Symbols and Defini­ tions has been compiled for engineers, technicians, armed forces personnel, commercial operators, students, hobbyists, and all others who have some knowledge of electronic terms, symbols, and theory. The author's intention has been to provide: A small, light reference book that may be easily carried in an attache case or kept in a desk drawer for easy access. A source for the majority of all electronic formulas, sym­ bols, and definitions needed or desired for today's passive and active analog circuit technology. A format in which a desired formula may be located almost instantly without the use of an index, in the desired trans­ position, and in sufficiently parenthesized linear form for direct use with any scientific calculator. Sufficient information, alternate methods, approximations, schematic diagrams, and/or footnotes in such a manner so that technicians and hobbyists may understand and use the majority of the formulas, and that is acceptable and equally useful to engineers and others very knowledgeable in the field. iii ACKNOWLEDGMENTS Much of the material is this Handbook is based upon a small loose-leaf notebook containing formulas and other reference material compiled over many years. With the passage of time, the sources of this material have become unknown. It is impos­ sible therefore to list and give the proper credit.

Some years ago it was not uncommon for materials scientists, even within the electronics industry, to work relatively independently of device engi­ neers. Neither group had a means to determine whether or not the materials had been optimized for application in specific device structures. This mode of operation is no longer desirable or possible. The introduction of a new material, or a new form of a well known material, now requires a close collaborative effort between individuals who represent the disciplines of materials preparation, materials characterization, device design and pro­ cessing, and the analysis of the device operation to establish relationships between device performance and the materials properties. The develop­ ment of devices in heteroepitaxial thin films has advanced to the present state specifically through the unusually close and active interchange among individuals with the appropriate backgrounds. We find no book available which brings together a description of these diverse disciplines needed for the development of such a materials-device technology. Therefore, the authors of this book, who have worked in close collaboration for a number of years, were motivated to collect their experiences in this volume. Over the years there has been a logical flow of activity beginning with heteroepi­ taxial silicon and progressing through the III-V and II-VI compounds. For each material the early emphasis on material preparation and characteriza­ tion later shifted to an emphasis on the analysis of the device characteristics specific to the materials involved.