Semiconducting materials have non-overlapping valence and conduction band with a band gap less than 4 eV. Semiconductors can be simple, compound and oxide type.
Intrinsic semiconductor
A simple semiconductor such as Silicon or Germanium without doping
Extrinsic semiconductor
A simple semiconductor such as Si or Ge with n type (pentavalent) or p type (trivalent) doping.
Compound semiconductor
Semiconductor of two or more elements such as III-V (GaAs) or II-VI (CdS) group elements
Oxide semiconductor
Wide bandgap oxide compounds such as ZnO
