This collection aims to address the fundamental aspects, as well as the technological problems, which are associated with defects in electronic materials and devices. The volume comprises 93 contributions; among them, 14 invited papers, from more than 20 different countries. The invited papers, submitted by internationally recognized experts in the field, review the state-of-the-art and likely future trends in their respective research field. Upon comparing this volume with previous volumes, it is clearly seen that defect engineering in photovoltaics is becoming a topic of ever-increasing interest. The collection is divided into the chapters: - Multi-crystalline silicon for solar cells, - Advanced semiconductor materials: Strained Si, SOI, SiGe, SiC, - Impurities (oxygen, carbon, nitrogen, metals) and point defects in Si and SiGe, - Modeling and simulation of growth, gettering and characterization, - Defect aspects and defect engineering, - Gettering and hydrogen passivation, - Defect and impurity characterization, - Nanostructures and new devices, - Silicon-based opto-electronics and defect luminescence.