The last decade has seen radical changes in our understand- ing of the physical properties of semiconductors. It has been es- tablished that the energy spectrum of electrons is much more complex than had originally been predicted: in many cases, there are several energy bands with different parameters. It has been found that the effective carrier mass, which had been assumed to be constant for a given material, depends on the carrier energy, temperature, pressure, and even the nature and number of de- fects. Our understanding of the mechanism of the motion and scat- tering of carriers,...

In recent years, considerable progress has been made in the study of organic semiconductors. The main directions of investigation, have been determined and substantial results have been achieved in the theoretical treatment of many questions. However, the range of investigations is so broad that it is impossible to discuss all branches fully in a short monograph. In fact, the chemist synthe- sizing systems with conjugated bonds and studying their reactivity, the physical chemist studying the catalytic and absorption proper- ties of substances with conjugated bonds, the physicist studying the...

Recently, there has been a considerable upsurge of interest in heavily doped semiconductors. This interest is due primarily to the expanding range of applications of such. materials. Moreover, the heavy doping of semiconductors produces new effects (the forma tion of impurity aggregates, the appearance of allowed states in the forbidden band, etc J, which are of great interest in solid-state physics. The rapid growth in the number of papers on heavily doped semiconductors makes it difficult to review the results obtained so far. Therefore, many investigations carried out in 1966-7, par...