Semiconductors

1. Conductivity in among those of metals and insulators.
2. Conductivity can be changed over orders of magnitude through changes in temperature, optical excitation, and impurity content (doping).
3. Usually found in column IV and neighboring columns of the periodic table.
4. Elemental semiconductors: Si, Ge.
5. Compound semiconductors:

Binary:

GaAs, AlAs, GaP, etc. (III-V).

ZnS, ZnTe, CdSe (II- VI).

SiC, SiGe (IV compounds).

1) Ternary: GaAsP

Quaternary: InGaAsP

2) Si extensively used for rectifiers, transistors, and ICs.

3) III-V compounds extensively used in optoelectronic and high-speed applications.