The book summarizes and systematizes the results of numerous studies of the properties of various semiconductors by electrical, optical and magnetic measurements. The rapid development of modern technology puts forward new increased requirements for semiconductor materials and devices based on them. To satisfy them, it became necessary to significantly increase the parameters of currently used semiconductor materials. At the same time, in order to solve a number of problems, semiconductor physics and electronics are faced with important tasks: the search for new and the study of little-known semiconductor compounds, the development of methods for their synthesis, purification, doping and the production of perfect crystals of high purity.