There are some other differences, which
will become clear as we go along in this chapter Our interest in this chapter is in the study of semiconductors which
could be:
(i)
Elemental semiconductors: Si and Ge
(ii) Compound semiconductors: Examples are:
· Inorganic: CdS, GaAs, CdSe, InP, etc · Organic: anthracene, doped pthalocyanines, etc · Organic polymers:  polypyrrole, polyaniline, polythiophene, etc