Research advances in III-nitride semiconductor materials and device have led to an exponential increase in activity directed towards electronic and optoelectronic applications. There is also great scientific interest in this class of materials because they appear to form the first semiconductor system in which extended defects do not severely affect the optical properties of devices. The volume consists of chapters written by a number of leading researchers in nitride materials and device technology with the emphasis on the dopants incorporations, impurities identifications, defects engineering, defects characterization, ion implantation, irradiation-induced defects, residual stress, structural defects and phonon confinement. This unique volume provides a comprehensive review and introduction of defects and structural properties of GaN and related compounds for newcomers to the field and stimulus to further advances for experienced researchers. Given the current level of interest and research activity directed towards nitride materials and devices, the publication of the volume is particularly timely. Early pioneering work by Pankove and co-workers in the 1970s yielded a metal-insulator-semiconductor GaN light-emitting diode (LED), but the difficulty of producing p-type GaN precluded much further effort. The current level of activity in nitride semiconductors was inspired largely by the results of Akasaki and co-workers and of Nakamura and co-workers in the late 1980s and early 1990s in the development of p-type doping in GaN and the demonstration of nitride-based LEDs at visible wavelengths. These advances were followed by the successful fabrication and commercialization of nitride blue laser diodes by Nakamura et al at Nichia. The chapters contained in this volume constitutes a mere sampling of the broad range of research on nitride semiconductor materials and defect issues currently being pursued in academic, government, and industrial laboratories worldwide.

This book provides a coherent and comprehensive overview of the generation and application of mono-energetic positron beams. It has been written by acknowledged experts, at a level accessible to graduate students working, or planning to work, with positron beams, and to scientists in other areas who want to know something about the field.The book begins with a brief historical introduction and an overview of how positron beams are generated and transported. A description of the fate of slow positrons in gaseous and condensed matter, with reference to many of the fundamental measurements made possible by the advent of positron beams, is followed by a discussion on applications in the study of solid surfaces, defect profiling in subsurface regions, interfaces and thin films, and the probing of bulk properties in novel ways. The book ends with a look at the future, considering the prospects for intense positron beams and their potential for further research.

The only critical discussion available on the chemistry of the two "strange" light particles, the positron and positronium, with much space devoted to the excess electron. Positron annihilation allows the investigation of many unusual phenomena in the reaction kinetics of the positron, positronium, and excess electron, and in radiation chemistry and physics, while also providing important information on defects in solids.