For the first time in the book, the issues of flaw formation in single crystals of semiconductors are considered from a single position on the basis of modern theoretical ideas. Particular attention is paid to the laws of the formation of the dislocation structure and the generation of intrinsic point defects in single crystals directly during their cultivation, the role of the interaction of defects in the formation of the real structure of the crystal, the influence of various defects on the properties of semiconductors. The main consideration is carried out for crystals with a lattice of diamond and sphalerite, primarily silicon, germanium and AIIIBV compounds, although the established patterns in most cases are general. The book is intended for a wide range of scientific and engineering workers specializing in the field of physics, technology and materials science of semiconductors, as well as devices and integrated circuits based on them.