Electronic Materials: Science & Technology – serie

The concept of micromachining of silicon to form micron-scale structures such as cantilevers, free-standing bridges, membranes, and channels and its combination with microelectronics fabrication methodology and technology has resulted in the em- gence of a new category of functional systems called MEMS (microelectomechanical systems). MEMS are miniature systems containing devices or arrays of devices that combine electronics with other components such as sensors, transducers and actuators, and are fabricated by IC (Integrated Circuits) batch processing techniques. The ?eld of electroceramics (inorganic, non-metallic materials, often polycr- talline, with useful electrical and other functional properties) provides a vast number of active materials for sensors, actuators, and electrical and electronic components. Electroceramic thin ?lms can add therefore many useful functionalities to MEMS.At the same time, because the fabrication of ceramics is commonly a high temperature process that often necessitates an oxygen containing atmosphere, because most cer- ics are inert and corrosion resistant, and because the properties of electroceramics are verysensitivetotheprocessingconditions,theintegrationofelectroceramiclayersonto silicon or other substrates and their patterning into functional elements need complex technologies that are still under development. This situation is re?ected in the current positionofelectroceramic-basedMEMSinthemarket:Whilethepotentialisexcellent, ?rst devices are being commercialized only these present days.

Nanocomposites have been receiving more and more attention given the improvement of synthesis techniques and the availability of powerful characterization techniques. The aim of the book is to introduce nanocomposite materials using a broad range of inorganic and organic solids. Furthermore, it is intended to present recent and not very common developments in especially spectroscopic characterization techniques, including Mössbauer, EXAFS, NMR. This should make the book attractive for a broad range of readers, including chemists and physicists.

Flexible-electronics is rapidly finding many main-stream applications where low-cost, ruggedness, light weight, unconventional form factors and ease of manufacturability are just some of the important advantages over their conventional rigid-substrate counterparts. Flexible Electronics: Materials and Applications surveys the materials systems and processes that are used to fabricate devices that can be employed in a wide variety of applications, including flexible flat-panel displays, medical image sensors, photovoltaics, and electronic paper. Materials discussed range from polymeric semiconductors to nanotube transparent conductors, highlighting the important characteristics of each system and their target applications. An overview of the performance benchmarks for the different materials is given in order to allow a direct comparison of these different technologies. Furthermore, the devices and processes most suitable for given applications in flexible electronics are identified. Topics covered include:An overview and history of flexible electronicsNovel materials for solution-processable thin-film electronic devices and their propertiesLow-temperature processing of conventional materials and devices on plastic foils Novel techniques, such as printing and roll-to-roll processing, for large-area flexible electronics manufacturingMaterials and device physics relevant to flexible electronicsDevice integration on flexible substratesMechanical and electronic characteristics for thin-film transistors and nano-scale transparent conductors on flexible platformsApplications towards flexible displays, sensors, actuators, solar energy, radio-frequency identification, and micro-electro-mechanical systemsWritten by leading researchers in the field, Flexible Electronics: Materials and Applications serves as a reference for researchers, engineers, and students interested in the characteristics, capabilities, and limitations of these exciting materials and emerging applications.

Nanostructured materials have at least one dimension in the nanometer range. They became a very active research area in solid state physics and chemistry in recent years with anticipated applications in various domains, including solar cells, electronics, batteries and sensors. Nanocrystalline metals and oxides are dense polycrystalline solids with a mean grain size below 100 nm. This book is intended to give an overview on selected properties and applications of nanocrystalline metals and oxides by leading experts in the field. The first three chapters provide a very complete theoretical treatment of thermodynamics and atom/ion transport for nanocrystalline materials. The following chapters are experts' views on the development of experimental characterization techniques for nanocrystalline solids with emphasis on electroceramic materials. Nanocrystalline Metals and Oxides is intended for a broad range of readers, foremost chemists, physicists and materials scientists. Theoretical physicists and chemists will certainly also profit from this book. The electroceramics and solid state ionics community are particularly addressed, given the main interests of the editors.

219 8. 2 Sensors 221 8. 3 Physical Sensors 222 8. 3. 1 Electrical Sensing Means 223 8. 3. 2 Magnetic Field Methods 231 8. 3. 3 Optical Methods 232 8. 4 Chemical Sensors 241 8. 4. 1 Electrical Gas and Chemical Sensors 243 8. 4. 2 Guided-Optics Intrinsic Chemical Sensors 246 8. 4. 3 Extrinsic Chemical Sensors 250 8. 4. 4 Polymer Waveguide Chemical Sensors 251 8. 4. 5 Surface Plasmon Chemical Sensors 252 8. 4. 6 Indicator-Mediated Extrinsic Sensing 253 8. 4. 7 Optical Biosensors 256 8. 4. 8 Ultrasonic Gas and Chemical Sensors 257 8. 4. 9 Intelligent Sensors 258 8. 5 Connections/Links and Wiring 258 8. 5. 1 Optical Links 260 8. 5. 2 Requirement on the Processing Unit/Intelligence 262 8. 6 Actuators 263 8. 7 Signal Processing/Computing 264 8. 7. 1 Implicit Computation 266 8. 7. 2 Explicit Computation 267 8. 8 References 274 Subject Index 279 Micro-Actuators (Electrical, Magnetic, Thermal, Optical, Mechanical, and Chemical) It has become quite apparent that sensors and actuators are the main bottleneck of the modem information processing and control systems. Microprocessors and computers used to be the main limiting element in most information processing systems. But thanks to the enonnous progress in the microelectronics industry, most information analysis tasks can be processed in real time. The data has to be acquired by the processor in some form and processed and used to produce some useful function in the real world.

Amorphous silicon solar cell technology has evolved considerably since the first amorphous silicon solar cells were made at RCA Laboratories in 1974. Scien­ tists working in a number of laboratories worldwide have developed improved alloys based on hydrogenated amorphous silicon and microcrystalline silicon. Other scientists have developed new methods for growing these thin films while yet others have developed new photovoltaic (PV) device structures with im­ proved conversion efficiencies. In the last two years, several companies have constructed multi-megawatt manufacturing plants that can produce large-area, multijunction amorphous silicon PV modules. A growing number of people be­ lieve that thin-film photovoltaics will be integrated into buildings on a large scale in the next few decades and will be able to make a major contribution to the world's energy needs. In this book, Ruud E. I. Schropp and Miro Zeman provide an authoritative overview of the current status of thin film solar cells based on amorphous and microcrystalline silicon. They review the significant developments that have occurred during the evolution of the technology and also discuss the most im­ portant recent innovations in the deposition of the materials, the understanding of the physics, and the fabrication and modeling of the devices.

The discovery by J. G. Bednorz and K. A. Mtllier in 1986 that the superconducting state can exist in oxides at temperatures above 30 K stimulated research in the field of superconductivity and opened up a new field of research. Within a few years a large number of cuprate superconductors with transition temperatures well above the boiling point of liquid nitrogen have been found. The possibility of using liquid nitrogen as coolant re-stimulated interest in power applications of supercon­ ductivity. In this book an overview of the known high-Te superconductors and their physical properties is presented. Aspects related to conductor fabrication and high-current applications are emphasised. The material should be suitable for use in graduate­ level courses on superconductivity. Researchers in the field may profit from the large number of tables and references describing its status at the end of 1997. An introduction to high-To superconductivity must be based on the fundamental physical principles of normal-state electrical conductivity and the well-known characteristics of conventional superconductors. In Chapter 2 this background is provided. Crystal structures, anisotropic properties and general trends of the critical temperatures of the cuprate superconductors are described in Chapters 3 and 4. The processing of superconductor powders addressed in Chapter 5 affects considerably the current-carrying capacity of high-T. wires. In Chapter 6 several fabrication techniques for superconducting wires are described. In addition, the factors limiting the transport critical currents ofhigh-Te wires are discussed.

A Practitioner's Handbook for Real-Time Analysis: Guide to Rate Monotonic Analysis for Real-Time Systems contains an invaluable collection of quantitative methods that enable real-time system developers to understand, analyze, and predict the timing behavior of many real-time systems. The methods are practical and theoretically sound, and can be used to assess design tradeoffs and to troubleshoot system timing behavior. This collection of methods is called rate monotonic analysis (RMA).The Handbook includes a framework for describing and categorizing the timing aspects of real-time systems, step-by-step techniques for performing timing analysis, numerous examples of real-time situations to which the techniques can be applied, and two case studies.A Practitioner's Handbook for Real-Time Analysis: Guide to Rate Monotonic Analysis for Real-Time Systems has been created to serve as a definitive source of information and a guide for developers as they analyze and design real-time systems using RMA. The Handbook is an excellent reference, and may be used as the text for advanced courses on the subject.

The use of diamond for electronic applications is not a new idea. As early as the 1920's diamonds were considered for their use as photoconductive detectors. However limitations in size and control of properties naturally limited the use of diamond to a few specialty applications. With the development of diamond synthesis from the vapor phase has come a more serious interest in developing diamond-based electronic devices. A unique combination of extreme properties makes diamond partiCularly well suited for high speed, high power, and high temperature applications. Vapor phase deposition of diamond allows large area films to be deposited, whose properties can potentially be controlled. Since the process of diamond synthesis was first realized, great progress have been made in understanding the issues important for growing diamond and fabricating electronic devices. The quality of both intrinsic and doped diamond has improved greatly to the point that viable applications are being developed. Our understanding of the properties and limitations has also improved greatly. While a number of excellent references review the general properties of diamond, this volume summarizes the great deal of literature related only to electronic properties and applications of diamond. We concentrate only on diamond; related materials such as diamond-like carbon (DLC) and other wide bandgap semiconductors are not treated here. In the first chapter Profs. C. Y. Fong and B. M. Klein discuss the band structure of single-crystal diamond and its relation to electronic properties.

The photorefractive effect is now firmly established as one of the highest-sensitivity nonlinear optical effects, making it an attractive choice for use in many optical holographic processing applications. As with all technologies based on advanced materials, the rate of progress in the development of photorefractive applications has been principally limited by the rate at which breakthroughs in materials science have supplied better photorefractive materials. The last ten years have seen an upsurge of interest in photorefractive applications because of several advances in the synthesis and growth of new and sensitive materials. This book is a collection of many of the most important recent developments in photorefractive effects and materials. The introductory chapter, which provides the necessary tools for understanding a wide variety of photorefractive phenomena, is followed by seven contributed chapters that offer views of the state-of-the-art in several different material systems. The second chapter represents the most detailed study to date on the growth and photorefractive performance of BaTi03, one of the most important photorefractive ferroelectrlcs. The third chapter describes the process of permanently fixing holographic gratings in ferroelectrics, important for volumetric data storage with ultra-high data densities. The fourth chapter describes the discovery and theory of photorefractive spatial solitons. Photorefractive polymers are an exciting new class of photo refractive materials, described in the fifth chapter. Polymers have many advantages, primarily related to fabrication, that could promise a breakthrough to the marketplace because of ease and low-cost of manufacturing.

This volume begins by describing the material needs defined by various optoelectronic functions. Basic aspects of the materials' specific properties are presented, including the relevant properties of semiconductors in terms of electron-photon interactions. Since the semiconductors for optoelectronics are generally based on alloys, the thermodynamic properties of interest are developed as well. Next, semiconductors for detection, emission and modulation are detailed. The fabrication of these materials is presented through a comparison and review of the epitaxial techniques. The III-V semiconductors for IR and visible light devices are presented. The II-VI family is also considered, with an emphasis on recent developments for visible light emission. A description of the status of silicon for optoelectronics is given as well. Finally, non-semiconductors for optoelectronics, namely optical fibers for telecommunications, electrooptic materials, and organic materials, are also presented.

Remarkable developments have taken place in the field of mechatronics in recent years. As symbolized by the "Janglish (Japanese English)" word, mechatronics, the technology and the social adaptation for introducing electronics into mechanics has been readily accepted in Japan. Currently robots are producing many products under computer control in Japanese factories, and supermarkets are utilizing automation systems for sample displays and sales. Further, the fast paced change in semiconductor chip technology has given rise to the need for micro-displacement positioning techniques. Actuators utilizing piezoelectridelectrostrictive effects are expected to meet these needs in mechanical components in the next micro­ mechatronic age. This book, in English, builds on my earlier publications concerned with ceramic actuators. The first edition titled "Essentials for Development and Applications of Piezoelectric Actuators" was published in 1984 through the Japan Industrial Technology Center. The second edition "PiezoelectriclElectrostrictive Actuators" published in Japanese through Morikita Pub. Co. (Tokyo) became one of the best sellers in that company in 1986, and was then translated into Korean. The problem solving edition "Piezoelectric Actuators -Problem Solving" was also published through Morikita, which was sold in conjunction with a 60 minute video tape to provide easy understanding.

Electro-optic devices based on doped wide-band materials are present in industrial uses, in military applications and in everyday life. Whether one engages in laser surgery with a neodymium-Y AG laser or one communicates overseas using optical fibers, the development of these materials is both scientifically and commercially of great interest. Much of the most innovative work has been done in the last 15 years in this area. A minor revolution in optical fiber communications has occurred with the development of erbium-doped fiber amplifiers. Solid-state laser development shifted into high-gear with the theoretical and experimental study of doubly-doped garnet lasers. Recent developments on semiconductor laser arrays are making diode­ pumped solid-state lasers commercially feasible. The purpose of this book is to detail these developments and to point out that many of the same underlying physical processes control advances in several diverse applications. For example, the basic science of energy transfer will be discussed by Zharikov et al. and Rotman for energy transfer and dopant-defect interactions, respectively; it will also be crucial in understanding cerium-doped scintilla tors, neodymium-chromium lasers, and up-conversion fiber lasers. As another example, phonon-induced non-radiative relaxation will appear in every chapter in this book.

The past five years have witnessed some dramatic developments in the general area of ferroelectric thin films materials and devices. Ferroelectrics are not new materials by any stretch ofimagination. Indeed, they have been known since the early partofthis century and popular ferroelectric materials such as Barium Titanate have been in use since the second world war. In the late sixties and seventies, a considerable amountofresearch and development effort was made to create a solid state nonvolatile memory using ferroelectrics in a vary simple matrix-addressed scheme. These attempts failed primarily due to problems associated with either the materials ordue to device architectures. The early eighties saw the advent of new materials processing approaches, such as sol-gel processing, that enabled researchers to fabricate sub-micron thin films of ferroelectric materials on a silicon substrate. These pioneering developments signaled the onsetofa revival in the areaofferroelectric thin films, especially ferroelectric nonvolatile memories. Research and development effort in ferroelectric materials and devices has now hit a feverish pitch, Many university laboratories, national laboratories and advanced R&D laboratories oflarge IC manufacturers are deeply involved in the pursuit of ferroelectric device technologies. Many companies worldwide are investing considerable manpower and resources into ferroelectric technologies. Some have already announced products ranging from embedded memories in micro­ controllers, low density stand-alone memories, microwave circuit elements, andrf identification tags. There is now considerable optimism that ferroelectric devices andproducts will occupy a significant market-share in the new millennium.

Nanostructured Materials: Selected Synthesis Methods, Properties and Applications presents several important recent advances in synthesis methods for nanostructured materials and processing of nano-objects into macroscopic samples, such as nanocrystalline ceramics. This book will not cover the whole spectrum of possible synthesis techniques, which would be limitless, but it presents especially interesting highlights in the domains of research of the editors. Subjects that are covered include the following: *"chimie douce" approaches for preparation of a large variety of nanostructured materials, including metals, alloys, semiconductors and oxides; *hydrothermal synthesis with water as solvent and reaction medium can be specifically adapted to nanostructured materials;*"electrospraying" as a powerful new route for the preparation of nanoparticles, especially of oxides for electroceramics; *nanoparticles processed into nanostructured ceramics, by using dynamic compaction techniques; *applications of nanostructured materials. This book complements the previous volume in this series (P. Knauth, J. Schoonman, eds.,Nanocrystalline Metals and Oxides: Selected Properties and Applications, Kluwer, Boston, 2002).

The concept of micromachining of silicon to form micron-scale structures such as cantilevers, free-standing bridges, membranes, and channels and its combination with microelectronics fabrication methodology and technology has resulted in the em- gence of a new category of functional systems called MEMS (microelectomechanical systems). MEMS are miniature systems containing devices or arrays of devices that combine electronics with other components such as sensors, transducers and actuators, and are fabricated by IC (Integrated Circuits) batch processing techniques. The ?eld of electroceramics (inorganic, non-metallic materials, often polycr- talline, with useful electrical and other functional properties) provides a vast number of active materials for sensors, actuators, and electrical and electronic components. Electroceramic thin ?lms can add therefore many useful functionalities to MEMS.At the same time, because the fabrication of ceramics is commonly a high temperature process that often necessitates an oxygen containing atmosphere, because most cer- ics are inert and corrosion resistant, and because the properties of electroceramics are verysensitivetotheprocessingconditions,theintegrationofelectroceramiclayersonto silicon or other substrates and their patterning into functional elements need complex technologies that are still under development. This situation is re?ected in the current positionofelectroceramic-basedMEMSinthemarket:Whilethepotentialisexcellent, ?rst devices are being commercialized only these present days.

Nanocomposites have been receiving more and more attention given the improvement of synthesis techniques and the availability of powerful characterization techniques. The aim of the book is to introduce nanocomposite materials using a broad range of inorganic and organic solids. Furthermore, it is intended to present recent and not very common developments in especially spectroscopic characterization techniques, including Mössbauer, EXAFS, NMR. This should make the book attractive for a broad range of readers, including chemists and physicists.

Flexible-electronics is rapidly finding many main-stream applications where low-cost, ruggedness, light weight, unconventional form factors and ease of manufacturability are just some of the important advantages over their conventional rigid-substrate counterparts. Flexible Electronics: Materials and Applications surveys the materials systems and processes that are used to fabricate devices that can be employed in a wide variety of applications, including flexible flat-panel displays, medical image sensors, photovoltaics, and electronic paper. Materials discussed range from polymeric semiconductors to nanotube transparent conductors, highlighting the important characteristics of each system and their target applications. An overview of the performance benchmarks for the different materials is given in order to allow a direct comparison of these different technologies. Furthermore, the devices and processes most suitable for given applications in flexible electronics are identified. Topics covered include:An overview and history of flexible electronicsNovel materials for solution-processable thin-film electronic devices and their propertiesLow-temperature processing of conventional materials and devices on plastic foils Novel techniques, such as printing and roll-to-roll processing, for large-area flexible electronics manufacturingMaterials and device physics relevant to flexible electronicsDevice integration on flexible substratesMechanical and electronic characteristics for thin-film transistors and nano-scale transparent conductors on flexible platformsApplications towards flexible displays, sensors, actuators, solar energy, radio-frequency identification, and micro-electro-mechanical systemsWritten by leading researchers in the field, Flexible Electronics: Materials and Applications serves as a reference for researchers, engineers, and students interested in the characteristics, capabilities, and limitations of these exciting materials and emerging applications.

Nanostructured materials have at least one dimension in the nanometer range. They became a very active research area in solid state physics and chemistry in recent years with anticipated applications in various domains, including solar cells, electronics, batteries and sensors. Nanocrystalline metals and oxides are dense polycrystalline solids with a mean grain size below 100 nm. This book is intended to give an overview on selected properties and applications of nanocrystalline metals and oxides by leading experts in the field. The first three chapters provide a very complete theoretical treatment of thermodynamics and atom/ion transport for nanocrystalline materials. The following chapters are experts' views on the development of experimental characterization techniques for nanocrystalline solids with emphasis on electroceramic materials. Nanocrystalline Metals and Oxides is intended for a broad range of readers, foremost chemists, physicists and materials scientists. Theoretical physicists and chemists will certainly also profit from this book. The electroceramics and solid state ionics community are particularly addressed, given the main interests of the editors.

Optoelectronics ranks one of the highest increasing rates among the different industrial branches. This activity is closely related to devices which are themselves extremely dependent on materials. Indeed, the history of optoelectronic devices has been following closely that of the materials. KLUWER Academic Publishers has thus rightly identified "Materials for Optoelectronics" as a good opportunity for a book in the series entitled "Electronic Materials; Science and Technology". Although a sound background in solid state physics is recommended, the authors have confined their contribution to a graduate student level, and tried to define any concept they use, to render the book as a whole as self-consistent as possible. In the first section the basic aspects are developed. Here, three chapters consider semiconductor materials for optoelectronics under various aspects. Prof. G. E. Stillman begins with an introduction to the field from the point of view of the optoelectronic market. Then he describes how III-V materials, especially the Multi­ Quantum Structures meet the requirements of optoelectronic functions, including the support of microelectronics for optoelectronic integrated circuits. In chapter 2, Prof.

Remarkable developments have taken place in the field of mechatronics in recent years. As symbolized by the "Janglish (Japanese English)" word, mechatronics, the technology and the social adaptation for introducing electronics into mechanics has been readily accepted in Japan. Currently robots are producing many products under computer control in Japanese factories, and supermarkets are utilizing automation systems for sample displays and sales. Further, the fast paced change in semiconductor chip technology has given rise to the need for micro-displacement positioning techniques. Actuators utilizing piezoelectridelectrostrictive effects are expected to meet these needs in mechanical components in the next micro­ mechatronic age. This book, in English, builds on my earlier publications concerned with ceramic actuators. The first edition titled "Essentials for Development and Applications of Piezoelectric Actuators" was published in 1984 through the Japan Industrial Technology Center. The second edition "PiezoelectriclElectrostrictive Actuators" published in Japanese through Morikita Pub. Co. (Tokyo) became one of the best sellers in that company in 1986, and was then translated into Korean. The problem solving edition "Piezoelectric Actuators -Problem Solving" was also published through Morikita, which was sold in conjunction with a 60 minute video tape to provide easy understanding.

The photorefractive effect is now firmly established as one of the highest-sensitivity nonlinear optical effects, making it an attractive choice for use in many optical holographic processing applications. As with all technologies based on advanced materials, the rate of progress in the development of photorefractive applications has been principally limited by the rate at which breakthroughs in materials science have supplied better photorefractive materials. The last ten years have seen an upsurge of interest in photorefractive applications because of several advances in the synthesis and growth of new and sensitive materials. This book is a collection of many of the most important recent developments in photorefractive effects and materials. The introductory chapter, which provides the necessary tools for understanding a wide variety of photorefractive phenomena, is followed by seven contributed chapters that offer views of the state-of-the-art in several different material systems. The second chapter represents the most detailed study to date on the growth and photorefractive performance of BaTi03, one of the most important photorefractive ferroelectrlcs. The third chapter describes the process of permanently fixing holographic gratings in ferroelectrics, important for volumetric data storage with ultra-high data densities. The fourth chapter describes the discovery and theory of photorefractive spatial solitons. Photorefractive polymers are an exciting new class of photo refractive materials, described in the fifth chapter. Polymers have many advantages, primarily related to fabrication, that could promise a breakthrough to the marketplace because of ease and low-cost of manufacturing.

The use of diamond for electronic applications is not a new idea. As early as the 1920's diamonds were considered for their use as photoconductive detectors. However limitations in size and control of properties naturally limited the use of diamond to a few specialty applications. With the development of diamond synthesis from the vapor phase has come a more serious interest in developing diamond-based electronic devices. A unique combination of extreme properties makes diamond partiCularly well suited for high speed, high power, and high temperature applications. Vapor phase deposition of diamond allows large area films to be deposited, whose properties can potentially be controlled. Since the process of diamond synthesis was first realized, great progress have been made in understanding the issues important for growing diamond and fabricating electronic devices. The quality of both intrinsic and doped diamond has improved greatly to the point that viable applications are being developed. Our understanding of the properties and limitations has also improved greatly. While a number of excellent references review the general properties of diamond, this volume summarizes the great deal of literature related only to electronic properties and applications of diamond. We concentrate only on diamond; related materials such as diamond-like carbon (DLC) and other wide bandgap semiconductors are not treated here. In the first chapter Profs. C. Y. Fong and B. M. Klein discuss the band structure of single-crystal diamond and its relation to electronic properties.

A Practitioner's Handbook for Real-Time Analysis: Guide to Rate Monotonic Analysis for Real-Time Systems contains an invaluable collection of quantitative methods that enable real-time system developers to understand, analyze, and predict the timing behavior of many real-time systems. The methods are practical and theoretically sound, and can be used to assess design tradeoffs and to troubleshoot system timing behavior. This collection of methods is called rate monotonic analysis (RMA).The Handbook includes a framework for describing and categorizing the timing aspects of real-time systems, step-by-step techniques for performing timing analysis, numerous examples of real-time situations to which the techniques can be applied, and two case studies.A Practitioner's Handbook for Real-Time Analysis: Guide to Rate Monotonic Analysis for Real-Time Systems has been created to serve as a definitive source of information and a guide for developers as they analyze and design real-time systems using RMA. The Handbook is an excellent reference, and may be used as the text for advanced courses on the subject.

Electro-optic devices based on doped wide-band materials are present in industrial uses, in military applications and in everyday life. Whether one engages in laser surgery with a neodymium-Y AG laser or one communicates overseas using optical fibers, the development of these materials is both scientifically and commercially of great interest. Much of the most innovative work has been done in the last 15 years in this area. A minor revolution in optical fiber communications has occurred with the development of erbium-doped fiber amplifiers. Solid-state laser development shifted into high-gear with the theoretical and experimental study of doubly-doped garnet lasers. Recent developments on semiconductor laser arrays are making diode­ pumped solid-state lasers commercially feasible. The purpose of this book is to detail these developments and to point out that many of the same underlying physical processes control advances in several diverse applications. For example, the basic science of energy transfer will be discussed by Zharikov et al. and Rotman for energy transfer and dopant-defect interactions, respectively; it will also be crucial in understanding cerium-doped scintilla tors, neodymium-chromium lasers, and up-conversion fiber lasers. As another example, phonon-induced non-radiative relaxation will appear in every chapter in this book.

The discovery by J. G. Bednorz and K. A. Mtllier in 1986 that the superconducting state can exist in oxides at temperatures above 30 K stimulated research in the field of superconductivity and opened up a new field of research. Within a few years a large number of cuprate superconductors with transition temperatures well above the boiling point of liquid nitrogen have been found. The possibility of using liquid nitrogen as coolant re-stimulated interest in power applications of supercon­ ductivity. In this book an overview of the known high-Te superconductors and their physical properties is presented. Aspects related to conductor fabrication and high-current applications are emphasised. The material should be suitable for use in graduate­ level courses on superconductivity. Researchers in the field may profit from the large number of tables and references describing its status at the end of 1997. An introduction to high-To superconductivity must be based on the fundamental physical principles of normal-state electrical conductivity and the well-known characteristics of conventional superconductors. In Chapter 2 this background is provided. Crystal structures, anisotropic properties and general trends of the critical temperatures of the cuprate superconductors are described in Chapters 3 and 4. The processing of superconductor powders addressed in Chapter 5 affects considerably the current-carrying capacity of high-T. wires. In Chapter 6 several fabrication techniques for superconducting wires are described. In addition, the factors limiting the transport critical currents ofhigh-Te wires are discussed.

219 8. 2 Sensors 221 8. 3 Physical Sensors 222 8. 3. 1 Electrical Sensing Means 223 8. 3. 2 Magnetic Field Methods 231 8. 3. 3 Optical Methods 232 8. 4 Chemical Sensors 241 8. 4. 1 Electrical Gas and Chemical Sensors 243 8. 4. 2 Guided-Optics Intrinsic Chemical Sensors 246 8. 4. 3 Extrinsic Chemical Sensors 250 8. 4. 4 Polymer Waveguide Chemical Sensors 251 8. 4. 5 Surface Plasmon Chemical Sensors 252 8. 4. 6 Indicator-Mediated Extrinsic Sensing 253 8. 4. 7 Optical Biosensors 256 8. 4. 8 Ultrasonic Gas and Chemical Sensors 257 8. 4. 9 Intelligent Sensors 258 8. 5 Connections/Links and Wiring 258 8. 5. 1 Optical Links 260 8. 5. 2 Requirement on the Processing Unit/Intelligence 262 8. 6 Actuators 263 8. 7 Signal Processing/Computing 264 8. 7. 1 Implicit Computation 266 8. 7. 2 Explicit Computation 267 8. 8 References 274 Subject Index 279 Micro-Actuators (Electrical, Magnetic, Thermal, Optical, Mechanical, and Chemical) It has become quite apparent that sensors and actuators are the main bottleneck of the modem information processing and control systems. Microprocessors and computers used to be the main limiting element in most information processing systems. But thanks to the enonnous progress in the microelectronics industry, most information analysis tasks can be processed in real time. The data has to be acquired by the processor in some form and processed and used to produce some useful function in the real world.

Amorphous silicon solar cell technology has evolved considerably since the first amorphous silicon solar cells were made at RCA Laboratories in 1974. Scien­ tists working in a number of laboratories worldwide have developed improved alloys based on hydrogenated amorphous silicon and microcrystalline silicon. Other scientists have developed new methods for growing these thin films while yet others have developed new photovoltaic (PV) device structures with im­ proved conversion efficiencies. In the last two years, several companies have constructed multi-megawatt manufacturing plants that can produce large-area, multijunction amorphous silicon PV modules. A growing number of people be­ lieve that thin-film photovoltaics will be integrated into buildings on a large scale in the next few decades and will be able to make a major contribution to the world's energy needs. In this book, Ruud E. I. Schropp and Miro Zeman provide an authoritative overview of the current status of thin film solar cells based on amorphous and microcrystalline silicon. They review the significant developments that have occurred during the evolution of the technology and also discuss the most im­ portant recent innovations in the deposition of the materials, the understanding of the physics, and the fabrication and modeling of the devices.

The past five years have witnessed some dramatic developments in the general area of ferroelectric thin films materials and devices. Ferroelectrics are not new materials by any stretch ofimagination. Indeed, they have been known since the early partofthis century and popular ferroelectric materials such as Barium Titanate have been in use since the second world war. In the late sixties and seventies, a considerable amountofresearch and development effort was made to create a solid state nonvolatile memory using ferroelectrics in a vary simple matrix-addressed scheme. These attempts failed primarily due to problems associated with either the materials ordue to device architectures. The early eighties saw the advent of new materials processing approaches, such as sol-gel processing, that enabled researchers to fabricate sub-micron thin films of ferroelectric materials on a silicon substrate. These pioneering developments signaled the onsetofa revival in the areaofferroelectric thin films, especially ferroelectric nonvolatile memories. Research and development effort in ferroelectric materials and devices has now hit a feverish pitch, Many university laboratories, national laboratories and advanced R&D laboratories oflarge IC manufacturers are deeply involved in the pursuit of ferroelectric device technologies. Many companies worldwide are investing considerable manpower and resources into ferroelectric technologies. Some have already announced products ranging from embedded memories in micro­ controllers, low density stand-alone memories, microwave circuit elements, andrf identification tags. There is now considerable optimism that ferroelectric devices andproducts will occupy a significant market-share in the new millennium.