ABSTRACT
The IV-VI semiconductor group includes compounds with cubic NaCl-type structure, as well as with rhombohedral and orthorhombic structures. The IV-VI cubic semiconductors comprise a class of materials that can be considered model substances. The electron spectrum likewise can easily be constructed by starting with a parent phase having an sc lattice into which the rock salt lattice is transformed if the neighboring atoms are regarded as equivalent. The energy spectrum of a crystal as a rule consists of a group of bands that can be characterized by a definite symmetry. The group-IV-VI semiconductors allow the rare possibility of an analytic treatment of the deep levels.
