This textbook is based on lectures which the author has been reading to the students of the Semiconductor Materials and Devi¬ces Faculty of the Moscow Institute of Steel and Alloys. The course in Physics of Semiconductors is read after the students become fami-liar with such courses as •’Crystallography”, “Quantum Mechanics”, etc. This is why this textbook does not treat any questions pertai¬ning to crystal lattice structure, types of atomic bonds in the lat¬tice, etc. Students’ familiarity with the principal concepts of quantum mechanics enables its methods to be used to obtain a more rigorous solution of problems arising in the course of formulating various aspects of semiconductor physics. This applies, practically, to every section of the course, and first of all to the fundamentals of the energy band structure and to the charge carrier transition pro¬cesses involving the interaction with lattice defects, phonons and photons.