"This book presents the current level of understanding of the structural, electronic and optical properties of amorphous semiconductors. A number of recent advancements, including some of the authors' own research efforts, are discussed. As amorphous materials depart significantly from their crystalline counterparts, some of the basic problems associated with the validity of the effective mass approximation, where k is not a good quantum number, and concepts of excitons and phonons are addressed in detail. A significant part of the book is devoted to recent progress made in the understanding of light-induced degradations in amorphous semiconductors, regarded as the most limiting problem in device applications. The monograph presents a comprehensive review of both experimental and theoretical studies on amorphous semiconductors."--BOOK JACKET.