The book provides an introductory review of the concepts in physics of semiconductor heterostructures (quantum wells) and basic problems in spin transport and spin relaxation. Materials discussed in the book are iron and iron-cobalt as conventional ferromagnets, and III-V semiconductors (GaAs, InGaAs, AlGaAs). A detailed guidance is provided on performing and analyzing spin photodiode experiments, in which spin polarized electrons are created via excitation with circularly polarized light, and transferred across the interface (the spin ejection process). The book also addresses the spin...