Defect engineering has come of age. That theme is well documented by both the academic and industrial research communities in this book from MRS. Going beyond defect control, the book explores the engineering of desired properties in semiconductor materials and devices through the deliberate introduction and manipulation of defects and impurities. Papers are grouped around ten distinct topics covering materials, processing and devices. Topics include: grown-in defects in bulk crystals; grown-in defects in thin films; gettering and related phenomena; hydrogen interaction with semiconductors; defect issues in widegap semiconductors; defect characterization; ion implantation and process-induced defects; defects in devices; interfaces, quantum wells and superlattices; and defect properties, reaction, activation and passivation.