This book is concerned with compound semiconductor bulk materials and has been written for students, researchers and engineers in material science and device fabrication. It offers them the elementary and intermediate knowledge of compound semiconductor bulk materials necessary for entering this field. In the first part, the book describes the physical properties, crystal growth technologies, principles of crystal growth, various defects in crystals, characterization techniques and applications. In the second and the third parts, the book reviews various compound semiconductor materials, including important industrial materials and the results of recent research.