This monographdeals with metastable states in amorphoussemiconductors- ma- rials which lack long-range periodicity in the atoms' positions, which are in th- modynamic nonequilibrium and which, in addition, have several metastable states. Thesestates giverise tovariouspropertiesandeffects- namelya widerangeofp- toinduced changes and high photosensitivity and X-ray sensitivity - that are unique among solid-state semiconductors.Historically, amorphousselenium and seleni- based materials have played an important role in physics and technology, and they continue to do so. In these materials there exist inherent intermediate (metastable) states, structural and electronic in origin, which lead to interesting properties and effects different from those of their crystalline counterparts. In this volume, the metastable states and related effects are investigated in depth against the background of a detailed consideration of local atomic and electronic structure, and taking into account a wide range of light-induced effects. Although the rst publications on amorphous semiconductors date back to the early 1970s, studies of metastable states in these materials had not been analyzed systematically up to now, which led to erroneous ideas, even among specialists. In the present book, experimental investigations of metastable states are reported in detail for elemental selenium and selenium-based materials.

This monographdeals with metastable states in amorphoussemiconductors- ma- rials which lack long-range periodicity in the atoms' positions, which are in th- modynamic nonequilibrium and which, in addition, have several metastable states. Thesestates giverise tovariouspropertiesandeffects- namelya widerangeofp- toinduced changes and high photosensitivity and X-ray sensitivity - that are unique among solid-state semiconductors.Historically, amorphousselenium and seleni- based materials have played an important role in physics and technology, and they continue to do so. In these materials there exist inherent intermediate (metastable) states, structural and electronic in origin, which lead to interesting properties and effects different from those of their crystalline counterparts. In this volume, the metastable states and related effects are investigated in depth against the background of a detailed consideration of local atomic and electronic structure, and taking into account a wide range of light-induced effects. Although the rst publications on amorphous semiconductors date back to the early 1970s, studies of metastable states in these materials had not been analyzed systematically up to now, which led to erroneous ideas, even among specialists. In the present book, experimental investigations of metastable states are reported in detail for elemental selenium and selenium-based materials.

Amorphous chalcogenide semiconductors have commercial value and have many uses such as image formation, including x-rays, and high-definition TV pick up tubes. They have widespread application in the microelectronics industry and amorphous metallic alloys also have useful magnetic properties. This book focuses on their imaging applications and related properties. It examines the two groups of amorphous semiconductors that are of most commercial interest: the chalcogenide glasses the tetrahedrally bonded amorphous solids such as amorphous silicon, germanium and related alloys Both of these groups may be conveniently prepared in the form of thin/thick films which is of considerable importance in applications where large-area coverage of flat or curved surfaces of rigid or flexible materials is desirable such as in photovoltaic arrays, X-Ray sensors, display screens and photocopier drums.

Although amorphous semiconductors have been studied for over four decades, many of their properties are not fully understood. This book discusses not only the most common spectroscopic techniques but also describes their advantages and disadvantages.