Physics and applications of wide bandgap semiconductors

Wide bandgap semiconductors are electronic materials in which the energy of the band-to-band electronic transitions exceeds approximately 2 eV. These materials have different kinds of chemical bonds and of crystal lattice structures, but the electronic and optical processes taking place in them have a great deal in common. Diamond, silicon carbide SiC, gallium phosphide GaP, cadmium sulfide CdS, and some other related compounds of the A^IIB^VI type occupy a special place among the widegap semiconductors. Recent developments in optoelectronics and other fields of practical applications (in particular, high-temperature devices and methods of detecting photons and charged particles) have stimulated a wide interest in wide bandgap semiconductors. The data available for some of the most widely studied members of the very large family of wide bandgap semiconductors have been used to analyse the most characteristic properties of the processes taking place in these materials, and especially those induced by the strong excitation of their electronic subsystem and by the phenomena associated with the unavoidably present carrier localisation centres.