The aim of this NATO ASI has been to present an up-to-date overview of current areas of interest in amorphous materials. In order to limit the material to a manageable amount, the meeting was concerned exclusively with insulating and semiconducting materials. The lectures and seminars fill the gap between graduate courses and research seminars. The lecturers and seminar speakers were chosen as experts in their respective areas and the lectures and seminars that were given are presented in this volume. During the first week of the meeting. an emphasis was placed on introductory lectures, mainly associated with questions relating to the glass-formation and the structure of glasses. The second week focused more on research seminars. Each day of the meeting. about four posters were presented during the coffee breaks, and these formed an important focus for discussions. The posters are not reproduced in this volume as the editors wanted to have only larger contributions to make this volume more coherent. This volume is organized into four sections, starting with general considerations of the glass forming ability and techniques for the preparation of different kinds of glasses.

Solid state physics after solving so successfully many fundamental problems in perfect or slightly imperfect crystals, tried in recent years to attack problems associated with large disorder with the aim to understand the consequences of the lack of the long-range order. Semiconductors are much more changed by disorder than metals or insulators, and appear to be the most suitable materials for fundamental work. Considerable exploratory work on amorphous and liquid semiconductors was done by the Leningrad School since the early fifties. In recent years, much research in several countries was directed to deepen the understanding of the structural, electronic, optical, vibrational, magnetic and other proper ties of these materials and to possibly approach the present level of under standing of crystalline semiconductors. This effort was stimulated not only by purely scientific interest but also by the possibility of new applications from which memory devices in the general sense are perhaps the most challenging. The research met with serious difficulties which are absent in crystals.

This book is devoted to experimental and theoretical investigations on intimate interrelations between morphology, intra-gap and near-band-gap electron spectrum N(E), and macroscopic properties of polycrystalline and spatially non-homogeneous amorphous semiconductors and insulators.

Amorphous materials differ significantly from their crystalline counterparts in several ways that create unique issues in their use. This book explores these issues and their implications, and provides a full treatment of both experimental and theoretical studies in the field. Advances in Amorphous Semiconductors covers a wide range of studies on hydrogenated amorphous silicon, amorphous chalcogenides, and some oxide glasses. It reviews structural properties, properties associated with the charge carrier-phonon interaction, defects, electronic transport, photoconductivity, and some applications of amorphous semiconductors. The book explains a number of recent advances in semiconductor research, including some of the editors' own findings. It addresses some of the problems associated with the validity of the effective mass approximation, whether K is a good quantum number, and the concepts of phonons and excitons. It also discusses recent progress made in understanding light-induced degradations in amorphous semiconductors, which is seen as the most limiting problem in device applications. The book presents a comprehensive review of both experimental and theoretical studies on amorphous semiconductors, which will be useful to students, researchers, and instructors in the field of amorphous solids.

The aim of this NATO ASI has been to present an up-to-date overview of current areas of interest in amorphous materials, with particular emphasis on electronic properties and device applications. In order to limit the material to a manageable amount, the meeting was concerned almost exclusively with semiconducting materials. This volume should be regarded as a follow-on to the NATO ASI held in Sozopol, Bulgaria in 1996 and published as "Amorphous Insulators and Semiconductors" edited by M.F. Thorpe and M.1. Mitkova (Kluwer Academic Publishers, NATO ASI series, 3 High Technology - Vol. 23). The lectures and seminars fill the gap between graduate courses and research seminars. The lecturers and seminar speakers were chosen as experts in their respective areas, and the lectures and seminars that were given are presented in this volume. During the first week of the meeting, an emphasis was placed on introductory lectures while the second week focused more on research seminars. There were two very good poster sessions that generated a lot of discussion, but these are not reproduced in this volume as the editors wanted to have only larger contributions to make the proceedings more coherent.

This comprehensive, detailed treatise on the physics and applications of the new emerging technology of amorphous semiconductors focuses on specific device research problems such as the optimization of device performance. The first part of the book presents hydrogenated amorphous silicon type alloys, whose applications include inexpensive solar cells, thin film transistors, image scanners, electrophotography, optical recording and gas sensors. The second part of the book discusses amorphous chalcogenides, whose applications include electrophotography, switching, and memory elements. This book will serve as an excellent reference source for solid state scientists and engineers, and as a useful self-contained introduction to the field for graduate students.